Patent Grant
8531337
The present invention relates to an antenna diversity system in particular to an antenna diversity system of a wireless device.
In known wireless systems, different mechanisms contribute to the propagation of a radio frequency signal. As the radiated electromagnetic waves travel from the emitter to the receiver, they encounter obstacles (like for example walls and furniture in indoor environments, or buildings, trees and vehicles in outdoor environments) and as a result some of the energy carried by the waves is absorbed, reflected, scattered and/or diffracted. Thus, not only the signal component that comes from the emitter following a direct path arrives at the receiver, but also other components of the same signal that follow either reflected, diffracted or scattered paths. However, since these other components follow longer paths, they arrive at a later time (i.e., with different phase) than the direct path. The propagation can be furthermore complicated by the fact that in some cases no direct path (or line-of-sight, LOS) will be possible between emitter and receiver.
In typical wireless systems the transmitted signal will encounter several obstacles, giving rise to a multiplicity of propagation paths, and signal components arriving at the receiver with different delays. Furthermore, since the transmitter, the receiver and the obstacles can change their position over time, the characteristics of the multipath propagation channel will be time-variant.
The multipath propagation results in the combination of several signal components with different phases at the receiving antenna. This out-of-phase addition can result in a temporary cancellation of the received signal (phenomenon known as fading), with the subsequent loss of information. This problem becomes more critical for wireless systems involving data transmission, because fading is responsible for the interruption of the communication, the loss of data (and subsequent increase in bit error rate, BER), and the decrease of the data bit rate. All these aspects degrade the quality of service (QoS) of the system.
An important technique used to overcome these impairments of the quality of communication available in the wireless channel is antenna diversity. The basic concept of diversity is to provide the receiver with more than one versions (also referred to as branches) of the transmitted signal, where each version is received through a different channel. If the channels are substantially independent (or uncorrelated), then the probability of having simultaneously a fading in all of them will be very small, which means that the signal formed from combining all the branches at the receiver will have many fewer deep fades than either one of the individual signals.
Antenna diversity is also useful in Multiple-input Multiple-Output (MIMO) systems. In such systems, a transmitter uses a first set of antennas to transmit different data streams over the same wireless propagation channel. At the receiver, a second set of antennas (wherein said second set does not need to comprise the same number of antennas as the ones in said first set) provides a MIMO detector with a plurality of received signals. Each one of these signals comprises multipath components of different transmitted data streams. A MIMO detector is able to extract from the received signals at least some of the data streams sent by the transmitter. Therefore, the use of antenna diversity in MIMO systems makes it possible to attain higher data bit rates and/or higher capacity.
There are several ways of implementing diversity using more than one antenna like space diversity, polarization diversity and radiation pattern diversity. Although these techniques can improve substantially the QoS of the system, it is difficult to implement an effective antenna diversity system in a wireless portable device (such as for instance a mobile phone, a smartphone, a PDA, a MP3 player, a headset, a USB dongle, a laptop, a PCMCIA or Cardbus 32 card) due to the reduced dimensions and form factors of current wireless devices, which will become even more critical in future devices as the trend is towards reducing even further their dimensions.
Space diversity is achieved by having at least two antennas separated in space as to obtain sufficiently low correlation between the signals received by any pair of antennas. It is known by a skilled-in-the-art person that low correlation will occur when the antennas are separated a distance of at least a half of the free-space operation wavelength of the antennas.
However, the typical dimensions of the printed circuit boards (PCB) of wireless devices makes space diversity difficult to implement in such devices and lead to a poor diversity gain (i.e., improvement in the QoS). Furthermore, the real estate requirements of several printed antennas or chip antennas (both in terms of antenna footprint and antenna clearance from ground plane) on the same PCB might be prohibitive for a typical wireless device. The problem will only aggravate as the trend is to put more functionality and services in smaller PCBs.
Polarization diversity takes advantage of the fact that the propagation phenomena in the wireless channel tend to be independent for orthogonal polarizations. This diversity technique can be implemented using two collocated antennas with orthogonal polarizations, or instead one cross-polarized antenna. Although this approach would ease the requirements of PCB area for the antenna, the shapes and form factors of real PCBs make it difficult to obtain nearly orthogonal polarizations.
Radiation pattern diversity uses directional antennas oriented to cover different angular regions of the space to obtain little correlation between the detected signals. However, as it happens with polarization diversity, the shapes and form factors of real PCBs lead to antennas with fairly omnidirectional pattern, hence resulting in poor diversity gain.
Further the invention relates to an antenna in a package or an antenna component.
The current trend in the market of wireless handheld devices, and more generally wireless portable devices, is the addition of more and more functionality and added-value services (such as for instance but not limited to internet and/or email browsing, personal organizers, geo-positioning and emergency location services, short-range connectivity with peripherals, television and/or radio receivers using DVB-H, DMB or DAB standards, MP3 player, digital cameras, or digital video recorders and/or players) into the devices, while at the same time reducing their overall dimensions.
Typically, a wireless handheld device contains a multilayer PCB which carries the electronic components, modules and other circuitry of said device. One or more layers of the multilayer PCB contain tracks that interconnect the different electronic components or modules mounted on the PCB. Other layers of said PCB are used to power the electronic components or modules and to ground them. These layers are commonly referred to as the power plane and the ground plane respectively.
A technique commonly used to mount electronic components on the PCB is the surface mount technology (SMT). An SMT component can be mounted (for example by means of soldering) directly onto a surface of the PCB without requiring fitting components with wire leads into holes in the PCB. Moreover, an SMT component is usually smaller than its leaded counterpart because it has either no leads, or smaller leads. An SMT component can have short pins, flat contacts, a matrix of balls (Ball Grid Array or BGA), terminations on the body of the component (passives), or short leads in a gull-wing formation (Quad Flat Package or QFP).
As the dimensions of a wireless handheld device or a wireless portable device are reduced, so does its PCB, requiring a high density of components on the PCB. Since SMT allows electronic components to be smaller in size and be mounted on both sides of the PCB of a handheld device, this technology has widely replaced through-hole technology in the electronics industry.
As far as the integration of the antenna into a wireless handheld device or a wireless portable device is concerned, small-sized antenna solutions requiring a small region of ground plane clearance are clearly preferred. Moreover, standard low-cost antenna solutions that can be used throughout a wide range of wireless devices with different shapes and form factors are highly desired.
In some cases, a wireless handheld device or a wireless portable device comprises an antenna printed on a layer of the multilayer PCB. However, printed antennas typically are not small in size, since their dimensions are approximately a quarter of an operating wavelength of the antenna. In addition to it, they have the disadvantage of not being modular, making it necessary to design the antenna to fit in a specific device. Therefore, for the sake of modularity, it is advantageous to embed an antenna into a standard SMT-type component featuring small dimensions and low profile, and that can be mounted on the PCB of a handheld device or a portable device.
Known SMT-type antenna components use monopole antennas or inverted-F antennas (IFAs), which despite achieving some degree of miniaturization (for instance by loading the antenna with a material with high dielectric constant) still require a ground plane clearance region around the extension of the SMT antenna component to enhance the radiation process of the antenna.
WO2004042868 discloses an integrated circuit (IC) package comprising an antenna. Although the antenna comprised in the IC package can take the form of a slot antenna, the document does not provide indication on how a conducting sheet internal to the IC package and containing the slot of a slot antenna should be connected to an external ground plane (such as for example that of a PCB) in order to ensure good grounding of said conducting sheet.
Moreover, in the case of an IC package comprising an antenna as described in WO2004042868, the antenna is fed with a radio-frequency (RF) feeding signal originating in a die also contained in the IC package (i.e., no coupling of the RF feeding signal from the outside of the IC package to the inside of said IC package is required).
The present invention discloses a new antenna diversity system for wireless devices (such as for instance a mobile phone, a smartphone, a PDA, a MP3 player, a headset, a USB dongle, a laptop, a PCMCIA or Cardbus 32 card) that exhibits good diversity gain, while requiring little PCB area overhead.
One aspect of the invention relates to the technique to implement polarization diversity in a wireless device combining a first antenna and a second antenna, with the second antenna being a slot antenna and requiring very small area of the PCB.
According to the present invention, good polarization diversity can be obtained by appropriately choosing the orientation on the PCB, and by selecting the antenna type (i.e., whether a given antenna substantially behaves as an electric current source, or as a magnetic current source) for each one of the antennas comprised in the diversity system.
A diversity system for a wireless device 10 subject of an investigative study, like the one presented in
In some cases each antenna, the first antenna and the second antenna, can be for instance and without limitation a monopole antenna, an inverted-F antenna (IFA), a patch antenna, or a planar inverted-F antenna (PIFA).
The typical electrical results for a wireless device with the antenna diversity system of
The present invention relates to a slot-antenna component that can be mounted in a wireless handheld device, and generally in any wireless portable device, to enable the transmission and reception of electromagnetic wave signals.
It is an object of the present invention to provide a handheld or portable device (such as for instance a mobile phone, a smartphone, a PDA, an MP3 player, a headset, a USB dongle, a laptop computer, a gaming device, a digital camera, a PCMCIA or Cardbus 32 card), which comprises an antenna for mobile communications and/or wireless connectivity services, said antenna being a slot antenna, being at least partially embedded in a surface mount technology (SMT) component, and requiring very small area on a printed circuit board (PCB) of said handheld or portable device.
Another aspect of the invention relates to the corresponding technique to feed and to ground a slot-antenna component. Further aspects of the present invention relate to the control over the electrical parameters of the slot-antenna component, by appropriately selecting the placement and orientation of the slot-antenna component on the PCB of a handheld or portable device, and by carefully defining a portion of the slot on said PCB.
Another aspect of the invention relates to the technique to control the electrical parameters of the slot-antenna component (such as for instance its polarization) by appropriately selecting the placement and orientation of said slot-antenna component on the PCB of a handheld or portable device.
The above mentioned drawbacks are overcome with an antenna diversity system as of claim 1 and 47 and a wireless device as of claim 48. Further embodiments are disclosed in the dependent claims.
The present invention discloses a new antenna diversity system for wireless devices (such as for instance a mobile phone, a smartphone, a PDA, a MP3 player, a headset, a USB dongle, a laptop, a PCMCIA or Cardbus 32 card) that exhibits good diversity gain, while requiring little PCB area overhead.
One aspect of the invention relates to the technique to implement polarization diversity in a wireless device combining a first antenna and a second antenna, with the second antenna being a slot antenna and requiring very small area of the PCB.
In an antenna diversity system at least one operating frequency or frequency band of the two or more antennas is the same or at least partially overlapping.
The first antenna may be an electric current source and the second antenna may be a magnetic current source. The magnetic current source may be e.g. a slot antenna or a slot-loop antenna.
The first antenna may be e.g. a monopole, a dipole, a patch antenna, and IFA (inverted F-antenna) a PIFA (planar inverted F-antenna). Further it may be a multiband band antenna which has multiple operating frequency bands. In general any of those antennas may be formed by being printed as a conductive layer on a circuit board or by being etched from a conductive layer of a circuit board. Circuit boards in general are also referred to by the term printed circuit board or in short PCB. A conductive layer of a circuit board preferably is adapted such that it may at the same time act as a ground plane.
In some examples, it will be advantageous to have the slot antenna inscribed in a rectangular area of width smaller than 1/50 of the free-space operating wavelength, and length smaller than ¼ of the free-space operating wavelength. Being more general, in some embodiments the said width divided by the free-space operating wavelength of the slot antenna will be smaller than, or equal to, at least one of the following fractions: 1/10, 1/30, 1/50, 1/60, 1/70, or 1/80. In the same way, for some embodiments the said length divided by the free-space operating wavelength of the slot antenna will be smaller than, or equal to, at least one of the following fractions: ½, ⅓, or ¼, or even smaller than, or equal to, at least one of the following fractions: ⅕, ⅙, ⅛. In some other instances, it will be advantageous that the sum of the length and the width of the rectangular area in which the slot is inscribed be smaller than ½ of the free-space operating wavelength, or even smaller than ¼ of the free-space operating wavelength.
Furthermore, it will be advantageous in some cases that the separation between the two edges of the slot to be within a range from approximately the 0.08% of the free-space operating wavelength to approximately the 8% of the free-space operating wavelength, including any subinterval of said range. Some possible lower bounds and/or upper bounds within said range include: 0.08%, 0.16%, 0.32%, 0.5%, 1%, 2%, 4%, 6% and 8%.
The shape of the slot can comprise straight and curved segments, not necessarily all segments being of the same length. They may, however, also all, or all but one, two or three, be of the same length. In the same way, the separation between the conductive edges of each segment of the slot does not have to be the same for all segments, nor constant for any given segment (i.e., any segment of the slot can be tapered). The separation may, however, be the same for all segments, or all but one, two or three segments. Further the separation may be constant in one, two three or more or all segments.
In some cases, it is advantageous to design the slot such that it is substantially parallel to the longer side of the PCB, because the currents excited on said PCB by the resonating mode of the first antenna tend to be substantially parallel to said longer side of the PCB. The same effect can be achieved if the longest straight segment of the slot is arranged substantially parallel to the longest extension or to the longest symmetry axis (symmetry axis which extends the longest way inside the PCB).
At least one end of the slot is preferably open. In this way short slot antennas can be realized. Further like this it is conveniently possible to connect such an open end to another slot of another conducting layer or surface or of a ground plane such that a combined slot is formed.
The slot antenna in some examples will be implemented as a slot printed or etched on the ground plane of the PCB, while in other cases the slot will be contained in a SMT type component mounted on the PCB of the wireless device. When the slot is contained in a SMT type component, said component will comprise a sheet of metal on which the slot is created. The SMT type component will provide at least one contact terminal accessible from the exterior of said SMT component to electrically connect said sheet of metal with the ground plane of the PCB. In some embodiments, this contact terminal can take the form of a pad, or a pin, or a solder ball.
It will be advantageous in some cases to define on the PCB a region of clearance of the ground plane on the orthogonal projection of the component on the PCB on which it is mounted. In other cases, there will be ground plane on a portion of the orthogonal projection of the SMT component on the PCB, but not under the orthogonal projection of the slot on said PCB.
Details of such a component are given in any of claims 52 to 76 and explained in more detail below and details of a wireless device with such a component are given in any of claims 77 to 109 and explained in more detail below.
Further it is advantageous, that at least two, three, four or more portions of the slot are parallel to each other. This may apply to straight and to non-straight segment. With this parallel arrangement very compact antennas can be achieved.
In order to maintain as much space as possible for other devices within the wireless device it will be advantageous to have the slot of the slot antenna occupying as little area as possible. Preferred values of the fraction which is occupied by the slot are indicated in claim 24.
In yet other cases, wherein the first antenna substantially behaves as an electric current source and the second antenna substantially behaves as a magnetic current source, good polarization diversity is achieved when the electric currents excited on at least a portion of the PCB by the radiating mode of the said first antenna are substantially parallel to the magnetic currents excited on at least a portion of the extension of the said second antenna.
In the context of this application, two directions are considered to be substantially parallel if they form an angle of less than, or equal to, approximately 30, approximately 20 or approximately 10 degrees.
It is also possible two have two antennas which are magnetic current sources such as e.g. slot or slot-loop antennas.
In some cases, the first antenna and the second antenna will be slot antennas aligned respectively along a first direction and a second direction, being said first direction substantially orthogonal to said second direction. In the context of this application, two directions are considered to be substantially orthogonal if they form an angle in the range from approximately 60 degrees to approximately 120 degrees, approximately 70 degrees to approximately 110 degrees or approximately 80 degrees to approximately 100 degrees. Also in the context of this application, the direction of slot can e.g. be defined by the direction of the longest side of the rectangular area in which said slot is inscribed.
In other cases, wherein the first and second antenna behave as magnetic current sources (for instance, but not limited to, slot antennas), good polarization diversity is achieved when the magnetic currents excited on at least a portion of the extension of the first antenna are substantially orthogonal to the magnetic currents excited on at least a portion of the extension of the second antenna.
Each of the first and second antenna or only one of those first and second antennas may have any of the characteristics of any of claims 6 to 10, 12 to 25. The ground plane of a circuit board on which the first and second antennas are provided may have the characteristic of claim 11.
Any slot antenna mentioned herein may be a multiband slot antenna.
It will also be possible to have two electric current sources as antennas.
In those cases, wherein the first and second antenna substantially behave as electric current sources (for instance, but not limited to, monopole antennas), good polarization diversity is achieved when the electric currents excited on the PCB by the radiating mode of the first antenna are substantially orthogonal to the electric currents excited on the said PCB by the radiating mode of the second antenna, in at least a portion of the PCB.
The antennas of the antenna diversity system have at least one operating frequency or frequency band in common. It will be, however, preferable to have at least two, three, four or more operating frequencies or frequency bands in common. Thereby an antenna diversity system can be achieved at multiple operating frequencies or frequency bands. Further at least one, two, three or more of the antennas of the antenna diversity system have operating frequencies or frequency bands which are not in common with the other antennas of the diversity system. This allows the use of such an antenna for other applications where an antenna diversity system is not desired or required without the need of a separate antenna.
The antennas are preferably located on or close to corners of the ground plane. Thereby they are provided close to an area without a ground plane such that radiation can be effectively transmitted to the outside. The same applies to the location of an antenna on or close to an edge of the ground plane.
For symmetry reasons it is advantageous to place at least one antenna on or close to an edge of a ground plane and there on or close to the middle of the edge. Thereby currents in the ground plane which are induced in a direction perpendicular to the longest side or extension of the ground plane are not redirected in this longer direction of the ground plane and therefore a good polarization diversity can be achieved.
In some embodiments, it will be preferable to keep the separation between the first antenna and the second antenna small in order to facilitate the connection of the two antennas to a common radio frequency RF hardware part of the wireless device. However, in other embodiments it will be preferable to have the first antenna and the second antenna further apart to maximize the isolation between the first antenna and the second antenna.
Generally, the present invention can be arranged inside several kinds of wireless devices to facilitate the integration of the antennas in a way that it is compatible with high density of components on the PCB of the device. For miniaturization purposes, at least a portion of the curve defining the conducting trace, conducting wire or contour of the conducting sheet of at least one antenna of the diversity system will advantageously be a space-filling curve, a box-counting, a grid-dimension curve, or a fractal based curve. The conducting trace, conducting wire or contour of the conducting sheet of said at least one antenna might take the form of a single curve, or might branch-out in two or more curves, which at the same time in some embodiments will be also of the space-filling, box-counting, grid-dimension, or fractal kinds. Additionally, in some embodiments a part of the curve will be coupled either through direct contact or electromagnetic coupling to a conducting polygonal or multilevel surface.
In some preferred embodiments the wireless device is operating at one, two, three or more of the following communication and connectivity services: In some preferred embodiments a wireless (e.g. handheld or portable) device including a slot antenna component according to the present invention is operating at one, two, three or more of the following communication and connectivity services: Bluetooth, 2.4 GHz Bluetooth, 2.4 GHz WiMAX, ZigBee, ZigBee at 860 MHz, ZigBee at 915 MHz, GPS, GPS at 1.575 GHz, GPS at 1.227 GHz, Galileo, GSM 450, GSM 850, GSM 900, GSM 1800, American GSM, DCS-1800, UMTS, CDMA, DMB, DVB-H, WLAN, WLAN at 2.4 GHz-6 GHz, PCS 1900, KPCS, WCDMA, SDARs, XDARS, DAB, WiFi, UWB, 2.4-2.483 GHz band, 2.471-2.497 GHz band, IEEE802.11ba, IEEE802.11b, IEEE802.11g and FM.
According to the present invention, good polarization diversity can be obtained by appropriately choosing the orientation on the PCB, and by selecting the antenna type (i.e., whether a given antenna substantially behaves as an electric current source, or as a magnetic current source) for each one of the antennas comprised in the diversity system.
The beforehand mentioned drawbacks of know antenna components are overcome by the SMT-type slot-antenna component of claim 52 and the wireless device of claim 77 and 109. Preferred embodiments are disclosed in the dependent claims.
The present invention discloses a slot antenna integrated in a SMT component that minimizes the ground plane clearance region needed on the PCB. Embedding a slot antenna in a discrete SMT component is difficult due to the necessity to ensure good grounding of the conducting sheet in which the slot has been created, and to the complexity to couple the feeding signal into the SMT component.
One aspect of the present invention relates to the grounding of the slot antenna integrated in an SMT component. Another aspect of the present invention refers to the feeding means to couple an RF feeding signal into the SMT slot-antenna component.
Contrary to the disclosure of WO2004042868, an aspect of a slot-antenna component according to the present invention relates to the feeding means to couple an RF feeding signal coming from the outside of the SMT component into said SMT component to feed the slot contained inside the SMT component.
The present invention discloses a slot-antenna component for mobile communications and/or wireless connectivity services that can be mounted as a standard SMT component on the PCB of a handheld or portable device (such as for instance a mobile phone, a smartphone, a PDA, an MP3 player, a headset, a USB dongle, a laptop computer, a gaming device, a digital camera, a PCMCIA or Cardbus 32 card).
An SMT-type slot-antenna component according to the present invention comprises:
With this component it is possible to provide a slot antenna as a separate component which can be connected from the outside. The antenna may further comprise:
It will in principle also be possible to couple a feeding signal into the component indirectly by a capacitive or inductive coupling. For a good feeding, however, a direct electrical connection is preferred. This can be achieved by the feeding terminal. In any case the component has no internal means for generating an RF signal with which the antenna may be fed.
Further it will be preferred that the component further comprises a
The dielectric substrate allows for the backing of thin metal layers and is a widely used technique for the preparation of components for the electronics industry.
The terms sheet of metal and conductive surface are used for the same namely a conductive layer supported by a circuit board or a rigid piece of metal such as e.g. a stamped metal piece.
The antenna may be part of an antenna diversity system. It may, however also not be part of an antenna diversity system depending on the requirements of the application.
A contact terminal can take the form of a pad, a pin, or a solder ball. In some embodiments according to the present invention, it is advantageous to use a single contact terminal as grounding terminal and as feeding terminal, while in others it is preferred to use a contact terminal as grounding terminal only or as feeding terminal only. Further multiple contacts may be provided each of which is only for grounding, only for feeding or for both.
Additional pads may be provided which are not electrically connected inside the component or to the ground plane or a feeding element of the circuit board. Those pads may be useful fore mechanically holding the antenna component by the solder connection at that pad between the component and the circuit board.
In some embodiments according to the present invention, the SMT component can also include one or several electronic elements or circuits, or the SMT component can take the form of an IC package. When the slot-antenna component takes the form of an IC package, then the slot contained in said IC package is excited with an RF feeding signal coupled from the outside of said IC package, and not directly from a semiconductor die comprised inside said IC package.
In certain of these embodiments, the electronic elements or circuits included in the SMT component or IC package will be preferably placed within the SMT component or IC package in such a way that they are not on the projection of the slot contained in the SMT component.
In some other embodiments, a slot-antenna component may comprise more than one, two or three conductive surfaces in which a slot or a portion of a slot is created. By this technique it will be possible to “fold” the slot in vertical direction away from the PCB. Therefore the footprint area on the PCB required for such an antenna will be significantly reduced in comparison to antennas where the slot is “folded” in a plane parallel to the PCB surface plane. Most conveniently two conducting surfaces can be provided on the two opposite large sides of a circuit substrate. If a multilayer circuit substrate is used, further surfaces can be provided in order to form the slot antenna in the component.
The different surfaces may be connected or may remain unconnected. The connection may be done by a via hole or by a connection around the edge of a circuit substrate.
In order to protect a conducting layer it will be advantageous to cover that layer with a protection layer. This prevents corrosion. Further such a protection layer can be used to define terminals of the conducting layer which are then available for e.g. a solder connection.
The antenna characteristics can further be chosen by using open-ended or closed-ended slot geometries. Any end of the antenna may be open or closed.
In some embodiments it is advantageous to place grounding terminals to connect the conductive surface with the ground plane of the PCB close to at least two opposite edges of the slot-antenna component, preferably those two opposite edges that are the farthest apart from each other, so that the electric currents induced by the operation of the slot antenna on the conductive surface can flow through grounding terminals into the ground plane of the PCB as if the conductive surface and the ground plane of the PCB were one single conductive surface.
In certain cases it might be interesting to place a grounding terminal substantially close to at least two corners of said at least two opposite edges of the component, but preferably the four corners of said two opposite edges of said component.
Further it is preferred to extend one or more ground terminal along a major part of the length of an edge of the component or of the conductive surface. Preferably the ground terminal may extend along at least 40%, 50%, 60%, 70%, 80%, 90% or 95% of the length of an edge. Thereby a good connection of the conducting surface to the ground plane of the PCB is achieved. This is in particular the case where two grounding terminals extend along opposite edges such as the short and/or the long edges. One ground terminal may also be bent such that it is L-, U- or O-shaped and is preferably provided along one, two, three or four neighboring edges.
Furthermore, in some examples it can be advantageous to place grounding terminals at two sides of a feeding terminal and substantially close to said feeding terminal. This arrangement can be used to effectively excite the slot.
Further in some cases it will be advantageous to provide the feeding terminals on two sides of the slot. Then it is possible to combine the slot with another slot by connecting the respective two edges of the two slots, thereby forming a larger slot.
In some embodiments the feeding means of the slot-antenna component comprise a feeding contact and a conductive strip. Said conductive strip can be advantageously printed or etched on the same conductive surface as the slot, thus making the feeding means coplanar with the slot. The conductive strip connects the feeding terminal with the edge of slot that is farther away from the contact terminal.
Preferably a clearance region is provided at least on one, two, or three sides of the feeding terminal. This is in particular useful if the terminal is only used for feeding purposes. If the feeding terminal is also used for grounding purposes such clearance might not be present.
Also for the conductive strip a clearance may be provided. This clearance may not be necessary if the conductive strip is provided on a different level as the conductive surface with the slot. If the conductive strip is provided on a different level it may be connected to the conductive surface of the slot by a via hole or capacitive or inductive coupling. In the same way the coupling between the feeding terminal and the conductive strip may be made by capacitive, inductive or direct electrical contact coupling.
It will be advantageous in some cases to define on the PCB of the wireless device a region of clearance of ground plane on the orthogonal projection of the slot-antenna component on the PCB on which it is mounted. In other cases, there will be some ground plane on a portion of the orthogonal projection of the slot-antenna component on the PCB, but not under the orthogonal projection of the slot created in the conductive surface of the slot-component on the PCB. Yet in other embodiments, there will be ground plane also in a portion of the orthogonal projection of said slot on the PCB. In some examples, the fraction of the projection of the slot occupied by ground plane will be less than, or approximately equal to, a 50%, 40%, 30%, 25%, 20%, 10% or 5% of the projection of the slot on the PCB.
In order to form accepting pads on the PCB for receiving the terminals of the antenna component without however unnecessarily reducing the ground plane clearance it is advantageous to provided protrusions of the ground plane which extend into clearance.
Further the size of the area of the clearance e.g. given in mm2 may be smaller than the size of the antenna component.
In certain embodiments the slot-antenna component is electrically coupled by means of feeding terminals with a slot created on the ground plane of the PCB of the wireless (e.g. handheld or portable) device. In other words, a slot antenna is formed by combining the slot pattern printed or etched in the ground plane of the PCB with the slot pattern included in the SMT component. Having a portion of the slot antenna printed or etched in the ground plane of the PCB can be advantageous, particularly because this:
Since this is achieved by acting only on the portion of the slot printed or etched on the ground plane of a PCB, while leaving the geometry of the slot contained in a conductive surface of an SMT component unchanged, such embodiments are effective in providing a standard component that can be used in a great variety of application environments.
In order to arrange the antenna such that as much space as possible is left over for other components it is advantageous to orient an edge and in particular a long edge of the SMT-type slot antenna component substantially parallel to the short or long edge of the circuit board.
The antenna component should not be to far away from the edge of the circuit board. This facilitates providing a clearance and assures good radiation characteristics.
In some embodiments the antenna component is preferably located on or close to the middle of an edge and in particular on or close to the middle of a long edge of the circuit board or the ground plane. A symmetric location with respect to the ground plane can provide a more predictable polarization characteristic since currents induced in the ground plane are not redirected in an asymmetric way by the shape of the ground plane. This may apply even if the antenna itself is not symmetric but the location of the antenna on the ground plane is symmetric or almost symmetric.
The slot of the component may be excited by balanced or unbalanced feeding. This can be done with the help of a coplanar or coaxial transmission line or a microstrip transmission line.
In a preferred embodiment there are two slot-antenna components. This allows for the coverage of different frequencies or frequency bands or the coverage of the same frequency or frequency bands in a diversity system, such as a polarization and/or space diversity system or in MIMO systems. For a polarization diversity system it will be advantageous to provide two slot-antenna components (or their longer sides) substantially orthogonal to each other.
In general the (e.g. two, three or more) antennas of an antenna diversity system may be preferably identical apart from their orientation. This applies in particular to the case where slot antennas in the ground plane and/or in a component are used for forming the diversity system.
The circuit board may comprise a pad which is connected to the feeding pad. Depending on the feeding scheme this pad may or may not be connected to the ground plane of the circuit board.
By combining the slot of a ground plane and the slot of a slot-antenna component it is possible to obtain combined slots which are open at none, one, or two ends.
If such a combined slot is provided this combined slot may be excited by exciting the slot portion of the antenna component or the slot portion of the ground plane. The latter may be preferred since with this technique it is possible to connect to RF-generator directly with the ground plane of the circuit board on which the RF-generator itself is provided.
If the slot of the antenna component or a combined slot (see above) has a closed end it is preferable to excite the slot at a certain distance from the closed end. The distance along the slot geometry divided by the free space operating frequency is preferably less than 0.002, 0.004, 0.008, 0.012, 0.016, 0.025, 0.033, 0.04, 0.08, 0.1 or 0.15.
In some preferred embodiments a wireless (e.g. handheld or portable) device including a slot antenna component according to the present invention is operating at one, two, three or more of the following communication and connectivity services: Bluetooth, 2.4 GHz Bluetooth, 2.4 GHz WiMAX, ZigBee, ZigBee at 860 MHz, ZigBee at 915 MHz, GPS, GPS at 1.575 GHz, GPS at 1.227 GHz, Galileo, GSM 450, GSM 850, GSM 900, GSM 1800, American GSM, DCS-1800, UMTS, CDMA, DMB, DVB-H, WLAN, WLAN at 2.4 GHz-6 GHz, PCS1900, KPCS, WCDMA, SDARs, XDARS, DAB, WiFi, UWB, 2.4-2.483 GHz band, 2.471-2.497 GHz band, IEEE802.11ba, IEEE802.11b, IEEE802.11g and FM.
Any reference in this document to a or the free-space operating wavelength may refer to any free-space operating wavelength of an antenna or in particular to the largest free-space operating wavelength of different possible operating wavelengths.
In wireless devices the possible free-space operating wavelengths are usually given by the RF-generator or RF-receiver circuit which may be included in the wireless device.
Further characteristics and advantages of the invention will become apparent in view of the detailed description which follows of a preferred embodiment of the invention given for purposes of illustration only and in no way meant as a definition of the limits of the invention, made with reference to the accompanying drawings, in which shows:
In the example of
Two segments of the slot 3′ including to the longest straight segment are oriented parallel to the edge of the PCB. They are connected by a slot 3′ section which is oriented perpendicular to the long two sections. The slot 3′ ends open ended since it ends on one edge of the ground plane. The other end of the slot 3′ is closed.
In
A rectangle 7 in which the slot 3′ is inscribed is shown in
In
The arrangement of
In
h and 5i show that the slot antenna may have non-straight segments. In
At the first antenna 63, 67 and 70 a clearance 64, 69 of the ground plane is provided. The AiP component is provided partially above the ground plane and partially above the clearance. In
In
e shows the longest extension 76 of a PCB 75.
f shows the separation 79 between two antennas 77 and 78. The separation is given by the shortest distance between any antenna part such as a part of the slot of a slot antenna or the part of conductive portion of a monopole antenna or the like.
Another aspect of the invention relates to the technique to implement space diversity and/or polarization diversity in a wireless device combining at least two antennas, wherein at least one of the at least two antennas is an antenna integrated in a semiconductor package, as depicted in
In some examples, the diversity system will comprise at least an antenna integrated in a semiconductor package, and at least another antenna that can be a monopole antenna, and IFA, a patch antenna or a PIFA.
In comparison to
In
In some embodiments, the present invention is used to obtain a diversity system for a wireless device that exhibits good diversity gain and requires little PCB area overhead.
Embodiment 1:
In this embodiment (for instance, the one shown in
Embodiment 2:
This other embodiment, represented in
Embodiment 3:
In another example in
Embodiment 4:
A further embodiment of the wireless device with diversity system shown in
Embodiment 5:
In this example, see
Embodiment 6:
Another embodiment, in
Embodiment 7:
In yet another embodiment as the one of
Embodiment 8:
This embodiment, represented in
More Detailed Description of Slot-Antenna Component
The conductive surface 111 is backed by a dielectric substrate 112. In this particular example of
In a preferred embodiment, the conductive surface 111 is covered by another dielectric layer (such as for example a layer of ink, or a layer of protective epoxy coating for environmental protection), in which some windows are left in order to create one or more contact terminals 114,115 of the component 110. In
All contact terminals 114, 115 are arranged on or close to the edge of the conductive surface 111 and at the same time on or close to the edge of antenna component 110.
In
In
The major region in
As can be seen in
In
The component 140 can also include other dielectric layers, such as for instance a cover ink layer. Again in this particular example, and without limiting purposes, the contour of the slot 143 is inspired by the Hilbert curve; however, other shapes (including periodic, irregular, or even random-like shapes) could also be used. In
The slot-antenna component 140 can be mounted in a similar way to the component 110 on a PCB 121 as the one shown in
In
The ground plane 151 has a region of clearance 152 underneath the projection of the component 140, which is indicated by rectangle 150 in dashed line. The ground plane 151 extends partially underneath the projection of the component 140 within the rectangular region 150. Inside said region 150 there is the footprint of the accepting pads 154, 155 for the contact terminals of the component 144, 145. The ground plane 151 further comprises a slot section 153 that is connected to the accepting pads 154.
b is the same detailed view of the ground plane of the PCB 151 as in
In some embodiments it will be preferred not to have electronic components or modules mounted on the PCB 121 and connected to its ground plane 151, if they are in the projection of the slot section 153.
In
The slot-antenna component 160 of
In the embodiment of
Another aspect of the invention refers to the feeding means used to excite the slot 113, 143, 163, 204 included in the SMT component 110, 140, 160, 200.
A slot-antenna component can be excited in an unbalanced mode or in a balanced mode. When a slot-antenna component is excited in an unbalanced manner, an unbalanced voltage is applied to the two opposite edges of the slot created in a conductive surface of the component, or to the two opposite edges of a slot section created in the ground plane of the PCB. A first edge is connected to a positive potential (referenced to a ground potential) and a second edge is connected to said ground potential. When a slot-antenna component is excited in a balanced manner, a balanced voltage is applied to the two opposite edges of the slot created in a conductive surface of the component, or to the two opposite edges of a slot section created in the ground plane of the PCB. A first edge is connected to a positive potential (referenced to a ground potential) and a second edge is connected to a negative potential (referenced to a ground potential) of the substantially same amplitude as said positive potential.
In some embodiments, such as for instance but not limited to the examples of
In said region 119, 169, the edge of the slot 113, 163 that is closer to the feeding terminal 114, 164 is interrupted, so that the conductive strip 118, 168 can cross the slot 113, 163 reaching the farther edge of said slot 113, 163. A clearance region 120, 170 is created at both sides of the conductive strip 118, 168 and the feeding terminal 114, 164. The width of the clearance region 120, 170 does not need to be necessarily the same on both sides of the conductive strip 118, 168 and the feeding terminal 114, 164 (d1 and d2 do not need to be the same), although in some embodiments d1 and d2 will be substantially equal. The input impedance of the slot antenna can be appropriately selected by means of the distance of the region 119, 169 to an end of slot 117, 167, the width of the conductive strip 118, 168 and the widths d1 and d2 of the clearance region 120, 170 on each side of the conductive strip 118, 168 and the feeding terminal 114, 164.
In certain examples, the widths d1 and d2 will be substantially equal. In some cases, the width of the conductive strip 118, 168 and the widths d1 and d2 can be advantageously selected as to form a coplanar transmission line. The width of the conductive strip 118, 168 and the widths d1 and d2 will be preferably smaller than a maximum width. Some possible values for said maximum width comprise 1/2400, 1/1200, 1/800, 1/600, 1/480, 1/400, 1/300, 1/240, 1/200, 1/150 and 1/120 of a free-space operating wavelength of the slot antenna.
In some cases, it will be advantageous to place a grounding terminal 115e, 115a, 165a, 165b at each side of the feeding terminal 114, 164. In other examples, the feeding terminal 114, 164 might not be coplanar with the slot 113, 163, making it necessary to couple a feeding signal from the feeding terminal 114, 164 to the conductive strip 118, 168 either by direct contact (such as for instance by means of a via hole), or by electromagnetic coupling (either capacitive or inductive). Capacitive (or inductive) coupling can be preferred in some cases to compensate for an inductive (or capacitive) component of the input impedance of the slot antenna, without having to use external circuit elements such as capacitors or inductors.
In other embodiments, such as for instance but not limited to the example of
a shows an example of unbalanced feeding of the slot antenna. An RF generator 171 provides a positive potential V (referenced to a ground potential 0). Said positive potential V is applied to the left-hand-side edge of the slot section 153 in region 158. Said reference ground potential 0 is then applied to the opposite edge (the right-hand-side edge in this example) of the slot section 153 in region 158.
b shows an example of balanced feeding of the slot antenna. An RF generator 172 provides a positive potential +V (referenced to a ground potential 0) and a negative potential −V (referenced to the same ground potential 0), with approximately the same amplitude as said positive potential +V. Said positive potential +V is applied to the left-hand-side edge of the slot section 153 in region 158, while said negative potential −V is applied to the right-hand-side edge of the slot section 153 in region 158.
In the case of
The example in
A further example is provided in
Examples of slot-antenna components comprising more than one conductive surfaces are shown in
c shows an example of a slot-antenna component 200 comprising a first conducting surface 201 containing a first slot portion 203, and a second conducting surface 202 containing a second slot portion 204, wherein there is no electrical connection between the said first and second conductive surfaces 201, 202, so that one slot portion acts as a parasitic element.
In
As mentioned above in some other embodiments, a slot-antenna component may comprise more than one conductive surface in which a slot is created. For instance,
As can be seen in
In other cases it can be advantageous not to have electrical continuity between a slot portion created in a first conducting surface and another slot portion created in a second conductive surface, having thus an electrically driven slot portion and a parasitic slot portion.
An example of a wireless (e.g. handheld or portable) device comprising two slot-antenna components arranged on the PCB of said device is shown in
In some embodiments the slot-antenna component 110, 140, 160, 190, 200 has advantageously a rectangular shape, while in others it is substantially square. In certain cases, the length L of the component 110, 140, 160, 190, 200 divided by a free-space operating wavelength of the slot antenna will be preferably smaller than, or approximately equal to, at least one of the following fractions: ⅕, ⅛, 1/10, 1/12, 1/13, 1/14, 1/15, 1/16, 1/18 or 1/20. In the same way, for some embodiments the width W of the component 110, 140, 160, 190, 200 divided by a free-space operating wavelength of the slot antenna will be smaller than, or approximately equal to, at least one of the following fractions: 1/10, 1/15, 1/18, 1/20, 1/21, 1/22, 1/23, 1/24, 1/25 or 1/30. In some other instances, it will be advantageous that the sum of the length L and the width W of the slot-antenna component 110, 140, 160, 190, 200 be smaller than ½ of the free-space operating wavelength, or even smaller than ¼ of the free-space operating wavelength. As far as height H is concerned, the slot-antenna component 110, 140, 160, 190, 200 features very low profile. In some instances the height H of the component 110, 140, 160, 190, 200 is less than a fortieth ( 1/40), a sixtieth ( 1/60) or even a one hundred twentieth ( 1/120) of a free-space operating wavelength of the slot antenna.
In some embodiments according to the present invention which comprise a slot 143 included in a component 140 and a slot section 153 printed or etched in the ground plane of a PCB 151, the unfolded length of the slot section 153 will be less than 50%, 40%, 30%, 25%, 20%, 18%, 16%, 14%, 12%, 10% or even 5% of the unfolded length of the combination of the slot 143 and the slot section 153.
Moreover, in some cases it will be advantageous that a slot-antenna component 140 together with a slot section 153 printed or etched on the ground plane of the PCB 151 fit within a rectangular area 156 (indicated in dotted line in
In the example of
In the case of
In some preferred cases, the unfolded length of the slot antenna formed by a slot 113, 163 or by the combination of a slot 143 and a slot section on the ground plane of the PCB 153, will be approximately a quarter of an operating wavelength of the slot antenna. In some other cases, the unfolded length of the slot 113, 163, or the combination of the slot 143 and the slot section on the ground plane of the PCB 153, will be approximately three times, or approximately five times, or approximately another odd integer number of times, the length of one quarter of an operating wavelength of the slot antenna.
In other embodiments, a first end 116, 166 and a second end 117, 167 of the slot 113, 163 might both intersect the perimeter of the conductive layer 111, 161 of the slot-antenna component 110, 160. Yet in some other embodiments, both the first end 116, 166 and the second end 117, 167 of the slot 113, 163 might be closed-ended. In other embodiments, a first end 146 of the slot 143 intersects the perimeter of the conductive layer 141 of the slot-antenna component 140, while at the same time the end 157 of the slot section 153 intersects the perimeter of the ground plane 151.
In some embodiments in which a first end 116, 146, 166 and a second end 117, 167, or the end of slot section 157, are either both open-ended or both closed-ended, it might be advantageous that the unfolded length of the slot antenna formed by a slot 113, 163, or by the combination of a slot 143 and a slot section on the ground plane of the PCB 153, be approximately twice, or approximately four times, or approximately another even integer number of times, the length of one quarter of an operating wavelength of the slot antenna.
In some other embodiments, an open end of the slot 116, 146, 166 included in the slot-antenna component 110, 140, 160 can be coupled to a slot section printed or etched on the ground plane of a PCB. In that case, a slot-antenna component 110, 140, 160 should include an additional contact terminal on each edge of the slot 113, 143, 163 near said open end 116, 146, 166 to allow the coupling of an electrical signal from the slot 113, 143, 163 to a slot section created in the ground plane of the PCB. For example, in the embodiments of
The shape of a slot 113, 143, 163, 193, 194, 195, 203, 204 inside a slot-antenna component 110, 140, 160, 190, 200 and/or a slot section on the PCB 153 can comprise straight and curved segments, not necessarily all segments being of the same length. In the same way, the separation between the conductive edges of each segment of the slot 113, 143, 163, 193, 194, 195, 203, 204, and/or a slot section on the PCB 153, does not have to be the same for all segments, nor constant for any given segment (i.e., any segment of the slot 113, 143, 163, 193, 194, 195, 203, 204 or the slot section on the PCB 153 can be tapered).
Furthermore, it will be advantageous in some cases that the separation between the two edges of a slot 113, 143, 163, 193, 194, 195, 203, 204 and/or a slot section on the PCB 153 be within a range from approximately the 0.08% of the free-space operating wavelength to approximately the 8% of the free-space operating wavelength, including any subinterval of said range. Some possible upper bounds for a subinterval of said range include: 4%, 2%, 1% or 0.5%. Some possible lower bounds for a subinterval of said range include: 0.12%, 0.16%, 0.20% or 0.24%.
In some examples, the slot 113, 143, 163, 193, 194, 195, 203, 204, and/or the slot section on the PCB 153 might have one, two, three, or more bends. In general, as the number of bends in the slot 113, 143, 163, 193, 194, 195, 203, 204 and/or in the slot section on the PCB 153 increases, the shape of the slot 113, 143, 163, 193, 194, 195, 203, 204 and/or the slot section on the PCB 153 becomes more and more convoluted, leading to a higher degree of miniaturization of the resulting slot antenna.
For miniaturization purposes, at least a portion of the curve defining the slot 113, 143, 163, 193, 194, 195, 203, 204 or the slot section on the PCB 153 will advantageously be a space-filling curve, a box-counting curve, a grid-dimension curve, or a fractal based curve. The curve defining said slot 113, 143, 163, 193, 194, 195, 203, 204 and/or said slot section 153 might take the form of a single curve, or might branch-out in two or more curves, which at the same time in some embodiments will be also of the space-filling, box-counting, grid-dimension, or fractal kinds. Additionally, in some embodiments a part of the curve will be coupled either through direct contact or electromagnetic coupling to a conducting polygonal or multilevel surface.
One aspect of the present invention relates to the connection of a slot-antenna component 110, 140, 160 to the ground plane 131, 151 of the PCB on which it is mounted in order to ensure a good electrical continuity between the conductive surface 111, 141, 161 contained in the component 110, 140, 160 and said ground plane 131, 151.
In the example of
The slot component 140 in
Furthermore, in some examples it can be advantageous to place grounding terminals at two sides of a feeding terminal and substantially close to said feeding terminal. In
In some other embodiments, in order to guarantee good grounding of the component 110, 140, 160 it will be advantageous to have one, two, three, four, five, six, or even more grounding terminals 115, 144, 145, 165 in the slot-antenna component 110, 140, 160.
In some cases, a slot antenna comprising a slot-antenna component 110, 140, 160 will be advantageously excited by applying a voltage difference between the opposite conductive edges of a slot 113, 163, or between the opposite conductive edges of a slot section 153, at a particular point 119, 158, 169 along the geometry of the slot 113, 163, or slot section 153. In some embodiments, said point 119, 158, 169 will be closer to a closed end of the slot 117, 167, or a closed end 157 of a slot section 153, than to an open end of the slot 116, 146, 166. In certain examples, the distance between said point 119, 158, 169 and a closed end 117, 167 of the slot 113, 163, or a closed end 157 of a slot section 153, will be less than, or equal to, 0.2%, 0.4%, 0.8%, 1.2% 1.6%, 2.5%, 3.3%, 4%, 8%, 10% or 15% of a free-space operating wavelength of the slot antenna.
A further aspect of the present invention relates to the control on the electrical parameters of the slot-antenna component by appropriately selecting the orientation and placement of the component on a PCB. The polarization of the radiating mode of the slot-antenna component 110, 140, 160, 190, 200 mounted as depicted in
Space Filling Curves
In some examples, at least one antenna of the antenna diversity system may be miniaturized by shaping at least a portion of the conducting trace, conducting wire or contour of a conducting sheet of the antenna (e.g., a part of the arms of a dipole, the perimeter of the patch of a patch antenna, the slot in a slot antenna, the loop perimeter in a loop antenna, or other portions of the antenna) as a space-filling curve (SFC).
In some examples, at least one slot antenna of the slot-antenna component may be miniaturized by shaping at least a portion of the slot of said at least one slot antenna as a space-filling curve (SFC). Also a portion of a slot in a ground plane or a combined slot of a slot portion in a ground plane and a slot portion in an slot-antenna component may be shaped as a space filling curve.
A SFC is a curve that is large in terms of physical length but small in terms of the area in which the curve can be included. More precisely, for the purposes of this patent document, a SFC is defined as follows: a curve having at least five segments, or identifiable sections, that are connected in such a way that each segment forms an angle with any adjacent segments, such that no pair of adjacent segments define a larger straight segment. In addition, a SFC does not intersect with itself at any point except possibly the initial and final point (that is, the whole curve can be arranged as a closed curve or loop, but none of the lesser parts of the curve form a closed curve or loop).
A space-filling curve can be fitted over a flat or curved surface, and due to the angles between segments, the physical length of the curve is larger than that of any straight line that can be fitted in the same area (surface) as the space-filling curve.
Additionally, to shape the structure of a miniature antenna, the segments of the SFCs should be shorter than at least one fifth of the free-space operating wavelength, and possibly shorter than one tenth of the free-space operating wavelength. The space-filling curve should include at least five segments in order to provide some antenna size reduction, however a larger number of segments may be used. In general, the larger the number of segments, and the narrower the angles between them, the smaller the size of the final antenna.
Box-Counting Curves
In other examples, at least one antenna of the antenna diversity system may be miniaturized by shaping at least a portion of the conducting trace, conducting wire or contour of a conducting sheet of the antenna to have a selected box-counting dimension.
In other examples, at least one slot antenna of the slot-antenna component may be miniaturized by shaping at least a portion of the slot of said at least one slot antenna to have a selected box-counting dimension. Also a portion of a slot in a ground plane or a combined slot of a slot portion in a ground plane and a slot portion in an slot-antenna component may be shaped as a box-counting curve.
For a given geometry lying on a surface, the box-counting dimension is computed as follows. First, a grid with substantially squared identical cells boxes of size L1 is placed over the geometry, such that the grid completely covers the geometry, that is, no part of the curve is out of the grid. The number of boxes N1 that include at least a point of the geometry are then counted. Second, a grid with boxes of size L2 (L2 being smaller than L1) is also placed over the geometry, such that the grid completely covers the geometry, and the number of boxes N2 that include at least a point of the geometry are counted. The box-counting dimension D is then computed as:
For the purposes of the antennas of the antenna diversity system described herein, the box-counting dimension may be computed by placing the first and second grids inside a minimum rectangular area enclosing the conducting trace, conducting wire or contour of a conducting sheet of the antenna and applying the above algorithm.
For the purposes of the slot antenna of the slot-antenna component described herein, the box-counting dimension may be computed by placing the first and second grids inside a minimum rectangular area enclosing the curve of the antenna and applying the above algorithm.
The first grid should be chosen such that the rectangular area is meshed in an array of at least 5×5 boxes or cells, and the second grid should be chosen such that L2=½ L and such that the second grid includes at least 10×10 boxes. The minimum rectangular area is an area in which there is not an entire row or column on the perimeter of the grid that does not contain any piece of the curve.
The desired box-counting dimension for the curve may be selected to achieve a desired amount of miniaturization. The box-counting dimension should be larger than 1.1 in order to achieve some antenna size reduction. If a larger degree of miniaturization is desired, then a larger box-counting dimension may be selected, such as a box-counting dimension ranging from 1.5 to 3. For the purposes of this patent document, curves in which at least a portion of the geometry of the curve has a box-counting dimension larger than 1.1 are referred to as box-counting curves.
For very small antennas, for example antennas that fit within a rectangle having maximum size equal to one-twentieth the longest free-space operating wavelength of the antenna, the box-counting dimension may be computed using a finer grid. In such a case, the first grid may include a mesh of 10×10 equal cells, and the second grid may include a mesh of 20×20 equal cells. The box-counting dimension (D) may then be calculated using the above equation.
In general, for a given resonant frequency of the antenna, the larger the box-counting dimension, the higher the degree of miniaturization that will be achieved by the antenna. One way to enhance the miniaturization capabilities of the antenna is to arrange the several segments of the curve of the antenna pattern in such a way that the curve intersects at least one point of at least 14 boxes of the first grid with 5×5 boxes or cells enclosing the curve. If a higher degree of miniaturization is desired, then the curve may be arranged to cross at least one of the boxes twice within the 5×5 grid, that is, the curve may include two non-adjacent portions inside at least one of the cells or boxes of the grid.
Grid Dimension Curves
In further examples, at least one antenna of the antenna diversity system may be miniaturized by shaping at least a portion of the conducting trace, conducting wire or contour of a conducting sheet of the antenna to include a grid dimension curve.
In further examples, at least one slot antenna of the slot-antenna component may be miniaturized by shaping at least a portion of the slot of said at least one slot antenna to include a grid dimension curve. Also a portion of a slot in a ground plane or a combined slot of a slot portion in a ground plane and a slot portion in an slot-antenna component may be shaped as a box-counting curve.
For a given geometry lying on a planar or curved surface, the grid dimension of curve may be calculated as follows. First, a grid with substantially identical cells of size L1 is placed over the geometry of the curve, such that the grid completely covers the geometry, and the number of cells N1 that include at least a point of the geometry are counted. Second, a grid with cells of size L2 (L2 being smaller than L1) is also placed over the geometry, such that the grid completely covers the geometry, and the number of cells N2 that include at least a point of the geometry are counted again. The grid dimension D is then computed as:
For the purposes of the antennas of the antenna diversity system described herein, the grid dimension may be calculated by placing the first and second grids inside the minimum rectangular area enclosing the curve of the antenna and applying the above algorithm.
For the purposes of the slot antenna of the slot-antenna component described herein, the grid dimension may be calculated by placing the first and second grids inside the minimum rectangular area enclosing the curve of the antenna and applying the above algorithm.
The minimum rectangular area is an area in which there is not an entire row or column on the perimeter of the grid that does not contain any piece of the curve.
The first grid may, for example, be chosen such that the rectangular area is meshed in an array of at least 25 substantially equal cells. The second grid may, for example, be chosen such that each cell of the first grid is divided in 4 equal cells, such that the size of the new cells is L2=½ L1, and the second grid includes at least 100 cells.
The desired grid dimension for the curve may be selected to achieve a desired amount of miniaturization. The grid dimension should be larger than 1 in order to achieve some antenna size reduction. If a larger degree of miniaturization is desired, then a larger grid dimension may be selected, such as a grid dimension ranging from 1.5-3 (e.g., in case of volumetric structures). In some examples, a curve having a grid dimension of about 2 may be desired. For the purposes of this patent document, a curve having a grid dimension larger than 1 is referred to as a grid dimension curve.
In general, for a given resonant frequency of the antenna, the larger the grid dimension the higher the degree of miniaturization that will be achieved by the antenna. One example way of enhancing the miniaturization capabilities of the antenna is to arrange the several segments of the curve of the antenna pattern in such a way that the curve intersects at least one point of at least 50% of the cells of the first grid with at least 25 cells enclosing the curve. In another example, a high degree of miniaturization may be achieved by arranging the antenna such that the curve crosses at least one of the cells twice within the 25-cell grid, that is, the curve includes two non-adjacent portions inside at least one of the cells or cells of the grid.
An example of a grid dimension curve 1300 is shown in
Multilevel Structures
In some examples, at least a portion of the conducting trace, conducting wire or conducting sheet of at least one antenna of the antenna diversity system may be coupled, either through direct contact or electromagnetic coupling, to a conducting surface, such as a conducting polygonal or multilevel surface.
In some examples, at least a portion of the slot of at least one slot antenna of the slot-antenna component may be coupled, either through direct contact or electromagnetic coupling, to a conducting surface, such as a conducting polygonal or multilevel surface. Also the slot or a portion of a slot may be shaped as multilevel structure or polygonal.
A multilevel structure is formed by gathering several polygons or polyhedrons of the same type (e.g., triangles, parallelepipeds, pentagons, hexagons, circles or ellipses as special limiting cases of a polygon with a large number of sides, as well as tetrahedral, hexahedra, prisms, dodecahedra, etc.) and coupling these structures to each other electromagnetically, whether by proximity or by direct contact between elements. The majority of the component elements of a multilevel have more than 50% of their perimeter (for polygons) not in contact with any of the other elements of the structure. Thus, the component elements of a multilevel structure may typically be identified and distinguished, presenting at least two levels of detail: that of the overall structure and that of the polygon or polyhedron elements that form it.
Additionally, several multilevel structures may be grouped and coupled electromagnetically to each other to form higher-level structures. In a single multilevel structure, all of the component elements are polygons with the same number of sides or are polyhedrons with the same number of faces. However, this characteristic may not be true if several multilevel structures of different natures are grouped and electromagnetically coupled to form meta-structures of a higher level.
A multilevel antenna includes at least two levels of detail in the body of the antenna: that of the overall structure and that of the majority of the elements (polygons or polyhedrons) which make it up. This may be achieved by ensuring that the area of contact or intersection (if it exists) between the majority of the elements forming the antenna is only a fraction of the perimeter or surrounding area of said polygons or polyhedrons.
One example property of multilevel antennae is that the radioelectric behavior of the antenna can be similar in more than one frequency band. Antenna input parameters (e.g., impedance and radiation pattern) remain similar for several frequency bands (i.e., the antenna has the same level of adaptation or standing wave relationship in each different band), and often the antenna presents almost identical radiation diagrams at different frequencies. The number of frequency bands is proportional to the number of scales or sizes of the polygonal elements or similar sets in which they are grouped contained in the geometry of the main radiating element.
In addition to their multiband behavior, multilevel structure antennae may have a smaller than usual size as compared to other antennae of a simpler structure (such as those consisting of a single polygon or polyhedron). Additionally, the edge-rich and discontinuity-rich structure of a multilevel antenna may enhance the radiation process, relatively increasing the radiation resistance of the antenna and reducing the quality factor Q (i.e., increasing its bandwidth).
A multilevel antenna structure may be used in many antenna configurations, such as dipoles, monopoles, patch or microstrip antennae, coplanar antennae, reflector antennae, wound antennae, antenna arrays, or other antenna configurations. In addition, multilevel antenna structures may be formed using many manufacturing techniques, such as printing on a dielectric substrate by photolithography (printed circuit technique); dieing on metal plate, repulsion on dielectric, or others.
While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05104026 | May 2005 | EP | regional |
| 06110437 | Feb 2006 | EP | regional |
This application is related to the European patent applications EP 05104026 filed on May 13, 2005 and EP06110437 filed on Feb. 27, 2006 and to the U.S. patent applications US60/680,693 filed on May 13, 2005 and US60/778,323 filed on Mar. 2, 2006. The priority of those four applications is claimed and they are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/062285 | 5/12/2006 | WO | 00 | 11/12/2007 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2006/120250 | 11/16/2006 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3680135 | Boyer | Jul 1972 | A |
| 3750017 | Bowman et al. | Jul 1973 | A |
| 4633519 | Gotoh et al. | Dec 1986 | A |
| 4843468 | Drewery | Jun 1989 | A |
| 5363114 | Shoemaker | Nov 1994 | A |
| 5420599 | Erkocevic | May 1995 | A |
| 5572226 | Tuttle | Nov 1996 | A |
| 5608413 | Macdonald | Mar 1997 | A |
| 5719586 | Tuttle | Feb 1998 | A |
| 5778308 | Sroka et al. | Jul 1998 | A |
| 5784032 | Johnston et al. | Jul 1998 | A |
| 5867126 | Kawahata | Feb 1999 | A |
| 5990838 | Burns | Nov 1999 | A |
| 6005524 | Hayes | Dec 1999 | A |
| 6011518 | Yamagishi et al. | Jan 2000 | A |
| 6040803 | Spall | Mar 2000 | A |
| 6052093 | Yao et al. | Apr 2000 | A |
| 6087990 | Thill et al. | Jul 2000 | A |
| 6326924 | Muramoto et al. | Dec 2001 | B1 |
| 6448933 | Hill | Sep 2002 | B1 |
| 6535172 | Hirabayashi | Mar 2003 | B2 |
| 6570538 | Väisänen et al. | May 2003 | B2 |
| 6657593 | Nagumo | Dec 2003 | B2 |
| 6781545 | Sung | Aug 2004 | B2 |
| 6806835 | Iwai | Oct 2004 | B2 |
| 6836254 | Kalis et al. | Dec 2004 | B2 |
| 6882320 | Park | Apr 2005 | B2 |
| 7209011 | Welland et al. | Apr 2007 | B2 |
| 7233291 | Elkobi et al. | Jun 2007 | B2 |
| 7511675 | Puente-Baliarda et al. | Mar 2009 | B2 |
| 7796956 | Khayrallah et al. | Sep 2010 | B2 |
| 20010050637 | Aoyama | Dec 2001 | A1 |
| 20020033773 | Hirabayashi | Mar 2002 | A1 |
| 20030193437 | Kangasvieri et al. | Oct 2003 | A1 |
| 20040137971 | Shoji | Jul 2004 | A1 |
| 20050179607 | Gorsuch | Aug 2005 | A1 |
| 20060076658 | Wu | Apr 2006 | A1 |
| 20070152885 | Sorvala | Jul 2007 | A1 |
| 20070171131 | Sorvala et al. | Jul 2007 | A1 |
| 20070194992 | Puente Baliarda et al. | Aug 2007 | A1 |
| 20080088511 | Sorvala et al. | Apr 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 0108816 | May 1984 | EP |
| 0969375 | Jan 2000 | EP |
| 1137100 | Sep 2001 | EP |
| 1248317 | Oct 2002 | EP |
| 1280230 | Jan 2003 | EP |
| 009090089.5 | Aug 2005 | EP |
| 2112163 | Mar 1998 | ES |
| 2849288 | Jun 2004 | FR |
| 9083240 | Mar 1997 | JP |
| 11220319 | Aug 1999 | JP |
| 2001332924 | Nov 2001 | JP |
| 2006174449 | Jun 2006 | JP |
| 9706578 | Feb 1997 | WO |
| 9927608 | Jun 1999 | WO |
| 0154225 | Jul 2001 | WO |
| 02089246 | Nov 2002 | WO |
| 03073552 | Sep 2003 | WO |
| 03096475 | Nov 2003 | WO |
| 2004042868 | May 2004 | WO |
| 2004070874 | Aug 2004 | WO |
| 2004105182 | Dec 2004 | WO |
| 2005081358 | Sep 2005 | WO |
| 2006097496 | Sep 2006 | WO |
| Entry |
|---|
| Plicanic, V., Antenna diversity studies and evaluation, University of Carolina and Ericsson Mobile Communications, MAster of Science Thesis, May 2004. |
| Rowell, C.R et al., Design of diversity antennas for mobile telephones, International Symposium on Radio Propagation, Agosto, 1997. |
| Cetiner, B.A., Diversity characterization of a wideband multi-element antennas for indoor wireless communication, ICCES 03 international Conference on Computational and Experimental Engineering and Sciences, 2003, Corfu, Greece. |
| Cetiner, B.A., Small size broadband multielement antenna for RF/Wireless systems, Antennas and Wireless Propagation Letters, 2003. |
| Ramirez, R., Small size single and multiband antenna arrays with diversity capabilities for portable devices, IEEE Radio and Wireless Conference, 2001. RAWCON 2001. |
| Karaboikis, M., Compact dual-printed inverted-F antenna diversity systems for portable wireless devices, IEEE Antennas and Propagation Letters, 2004, vol. 3. |
| Antenna designs for MIMO systems, Antennova, 2004. |
| Green, B., Diversity performance of dual-antenna handsets near operator tissue, IEEE Transactions on Antennas and Propagation, Jul. 2000, vol. 48, No. 7. |
| Braun, C. Antenna diversity for mobile telephones, IEEE Antennas and Propagation, Jun. 1998. |
| Kim, H.J., Dual-frequency small-chip meander antenna, Microwave and Optical Technology Letters, Nov. 2002, vol. 35, No. 4. |
| Moon, S. Folded meander line and multilayered dielectric chip antenna for surface mount, Proceedings of APMC2001, Taipei, Taiwan. |
| Choi, W., Ceramic chip antenna using meander conductor lines, Electronic Letters, Jul. 2001, vol. 37, No. 15. |
| Behdad, N., Bandwith enhancement and further size reduction of a class of miniaturized slot antennas, IEEE Transactions on Antennas and Propagation, Aug. 2004, vol. 52, No. 8. |
| Waldschmidt, C., Compact wide-band multimode antennas for MIMO and Diversity, IEEE Transactions on Antennas and Propagation, Aug. 2004, vol. 52, No. 8. |
| Pham, N. Minimized dual-band coupled line meander antenna for system-in-a-package applications, IEEE Antennas and Propagations Society International Symposium, Jun. 2004. |
| Soler, J., FracWave Antenna Technology for full wireless system in package (FWSiP), Sep. 2005. |
| Bhavsar, Samir A.: Letter: Fractus v. Samsung et al., Case No. 6:09-cv-00203-LED: Disclosure of Material Information to the USPTO; Oct. 28, 2009. |
| Wille, David G.: HTC's First Amended Answer and Counterclaim; Oct. 2, 2009. |
| Wimer, Michael C.; USPTO Office Actions for U.S. Appl. No. 10/422,578; Oct. 4, 2004, Apr. 7, 2005, Aug. 24, 2005, Jan. 26, 2006, Mar. 12, 2007, Aug. 23, 2007 and Mar. 26, 2008. |
| D.A. Russell, J.D. Hanson, E. Ott, “Dimension and Strange Attractors”, Phys. Rev. Lett. 45 (1980) 1175-1178. |
| Paul So., Ernest Barreto, and Brian R. Hunt, “Box-counting dimension without boxes: Computing D0 from average expansion rates”, Physical Review E (Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics)—Jul. 1999—vol. 60, Issue 1, pp. 378-385. |
| http://www.redbrick.dcu.ie/˜bolsh/thesis/node16.html. |
| http://www.redbrick.dcu.ie/˜bolsh/thesis/node22.html. |
| http://www.sewanee.edu/physics/PHYSICS123/BOX%20COUNTING%20DIMENSION.html. |
| Heinz-Otto Peitgen, et al, “Chaos and Fractals—New Frontiers of Science” (1992), pp. 212-216, 387-388. |
| Paul S. Addison, “Fractals and Chaos—An illustrated Course” (Institute of Physics Publishing, Bristol and Philadelphia; IOP Publishing 1997), pp. 30, 31 &33. |
| Kenneth Falconer, “Fractal Geometry—Mathematical Foundations and Applications” (2nd edition) (John Wiley & Sons. Ltd., 2003) (the first edition is from 1990). |
| Yuan Y. Tang. et al., “The application of Fractal Analysis to Feature Extraction” (1999 IEEE). pp. 875-879. |
| Vincent Ng. et al., “Diagnosis of Melanoma with Fractal Dimensions” (IEEE TENCON'93 / Beijing), pp. 514-517. |
| S. Kobayashi et al., “Estimation of 3d Fractal Dimension of Real Electrical Tree Patterns” (IEEE 1994; Proceedings of the 4th International Conference on Properties and Applications of Dielectric Materials, Jul. 3-8, 1994 Brisbane, Australia), pp. 359-362. |
| Jie Feng et al., “Fractional Box-Counting Approach to Fractal Dimension Estimation”, (IEEE 1996; Proceedings of ICPR'96), pp. 854-858. |
| S. Rouvier, et al., “Fractal Analysis of Bidimensional Profiles and Application to Electromagnetic Scattering from Soils” (1996 IEEE), pp. 2167-2169. |
| Nirupam Sarkar, et al., “An Efficient Differential Box-Counting Approach to Compute Fractal Dimension of Image” (IEEE Transactions on Systems, Man, and Cybernetics, vol. 24, No. 1, Jan. 1994), pp. 115-120. |
| Susan S. Chen, et al., “On the Calculation of Fractal Features from Images” (IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 15, No. 10, Oct. 1993), pp. 1087-1090. |
| Alan I. Penn, et al., “Fractal Dimension of Low-Resolution Medical Images” (18th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Amsterdam 1996; 4.5.3: Image Pattern Analysis I), pp. 1163-1165. |
| Fabrizio Berizzi, et al., “Fractal Analysis of the Signal Scattered from the Sea Surface” (IEEE Transactions on Antennas and Propagation, vol. 47, No. 2, Feb. 1999), pp. 324-338. |
| Hendrik F. V Boshoff, “A Fast Box Counting Algorithm for Determining the Fractal Dimension of Sampled Continuous Functions” (1992 IEEE), pp. 43-48. |
| Aug. 14, 2003 Reply to Examination Report for EP1258054 (00909089.5). |
| Oct. 28, 2004 Summons for EP1258054 (00909089.5). |
| Dec. 15, 2004 Letter Dealing with Oral Proceedings for EP1258054 (00909089.5). |
| Jan. 2005 Minutes from Oral Proceedings for EP1258054 (00909089.5). |
| International Preliminary Examination Report and International Search Report of Aug. 29, 2002 for PCT/EP00/00411 published as WO 01/54225 A1. |
| EPO Office Action for EP1258054 (00909089.5) dated Feb. 7, 2003. |
| Hansen, R. C.: “Fundamental Limitations in Antennas”; Proceedings of the IEEE, IEEE. New York, US; Feb. 1981; ISSN 0018-9219, vol. 2, NR. 69, pp. 170-182. |
| Ramesh Garg et al., “Microstrip Antenna Design Handbook” (2001, Artech House, Inc.), selected pages. |
| Richard C. Johnson (Editor), “Antenna Engineering Handbook” (McGraw Hill Inc.), Chapter “Microstrip Antennas” by Robert E. Munson, selected pages. |
| Constantine A. Balanis, “Antenna Theory” (1982, John Wiley & Sons, Inc.),selected pages. |
| Keith R. Carver et al., “Microstrip Antenna Technology” (IEEE Transactions on Antennas and Propagation, vol. AP-29, No. 1, Jan. 1981), pp. 2-23. |
| David M. Pozar et al., “Microstrip Antennas—The Analysis and Design of Microstrip Antennas and Arrays” (1995, Institute of Electrical and Electronic Engineers, Inc.), p. ix and 3. |
| John D. Kraus, “Antennas” (1988, McGraw-Hill, Inc.), preface and list of contents. |
| Waldschmidt, C. Compact wide-band multimode antenna for MIMO and diversity, IEEE Transactions on Antennas and Propagation, Aug. 2004, vol. 52, No. 8. |
| Kemp, D.C., Antenna diversity and user interaction at 1800 MHz, IEEE Antennas and Propagtion Society International Symposium, 2005, vol. 3A, pp. 479-482. |
| Dietrich C., Adaptive arrays and diversity antenna configurations for handheld wireless communication terminals, Dissertation submitted to the Faculty of the Virginia Polytechnic Institute , Feb. 15, 2005. |
| Martin, C., Multiple-input multiple-output (MIMO) radio channel measurements, IEEE Antennas and Propagation Society International Symposium, 2001. |
| Breur, J.J. et al., Bluetooth radio module with embedded antenna diversity, Proceedings of the 6th European Conference on Wireless Technologies, Oct. 2003, pp. 221-225, Munich. |
| Rosengren, K. et al. Radiation efficiency, correlation, diversity gain and capacity of a six-monopole antenna array for a MIMO system: theory, simulation and measurement in reverberation chamber, IEE Proceedings Microwave Antennas and Propagation, Feb. 2005, vol. 152. |
| Loredo, S. et al, An experimental analysis of the advantages of polarization diversity in indoor scenarios at 1.8 and 2.5 GHz, Microwave and optical technology letters, Dec. 5, 2001. |
| Zhang, Y.P., Antenna-in-package technology for modern radio systems, IWAT, Mar. 6, 2006. |
| Latif, S.I. et al, Bandwidth enhancement and size reduction of microstrip slot antennas, IEEE Transactions on Antennas and Propagation, Mar. 2005. |
| FLOWS project—Antenna feasibility study on the printed antenna elements and the multiple input multiple output ( MIMO ) antenna topologies to be used in Flow mobile terminals, FLOWS project, Nov. 18, 2002. |
| Raman, J. et al, Single- and dual-polarized millimeter-wave slot-ring antennas, IEEE Transactions on antennas and propagation, Nov. 1996. |
| Jaggard , D. L. Rebuttal expert report of Dr. Dwight L. Jaggard (redacted version). Fractus. Feb. 16, 2011. |
| Long , S. A. Rebuttal expert report of Dr. Stuart A. Long (redacted version). Fractus. Feb. 16, 2011. |
| Jaggard , D. L. Expert report of Dwight L. Jaggard (redacted)—expert witness retained by Fractus. Jan. 18, 2011. |
| Ko , S. Compact integrated diversity antenna for wireless communications, IEEE Transactions on Antennas and Propagation , vol. 49 , No. 6 , Jun. 2001. |
| Number | Date | Country | |
|---|---|---|---|
| 20080198082 A1 | Aug 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60680693 | May 2005 | US | |
| 60778323 | Mar 2006 | US |
