Patent Application
20130088404
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
The present invention relates generally to antenna apparatus for use within electronic devices such as wireless radio devices, and more particularly in one exemplary aspect to a multi-band long term evolution (LTE) or LTE-Advanced antenna, and methods of tuning and utilizing the same.
Internal antennas are an element found in most modern radio devices, such as mobile computers, mobile phones, Blackberry® devices, smartphones, personal digital assistants (PDAs), or other personal communication devices (PCDs). Typically, these antennas comprise a planar radiating plane and a ground plane parallel thereto, which are connected to each other by a short-circuit conductor in order to achieve the matching of the antenna. The structure is configured so that it functions as a resonator at the desired operating frequency. It is also a common requirement that the antenna operate in more than one frequency band (such as dual-band, tri-band, or quad-band mobile phones), in which case two or more resonators are used.
Increased proliferation of long term evolution (LTE) mobile data services creates an increased demand for compact multi-band antennas typically used in mobile radio devices, such as cellular phones. Typically, it is desired for an LTE-compliant radio device to support operation in multiple frequency bands (such as, for example, 698 MHz to 960 MHz, 1710 MHz to 1990 MHz, 2110 MHz to 2170 MHz, and 2500 MHz to 2700 MHz). Furthermore, radio devices will need to continue to support legacy 2G, 3G, and 3G+ air interface standards, in addition to supporting LTE (and ultimately LTE-A). Additionally, implementation of the various air interface standards vary from network operator and/or region based on the various spectrums implemented, such as for example in the case of inter-band carrier aggregation, which comprises receiving data simultaneously on two or more carriers located in different frequency bands. The two frequency bands allocated vary based on geographic region, as well as the spectrum owned by the particular network operator, thereby creating a multitude of possible band pair implementations.
Typical mobile radio devices implement a single-feed portioned RF front-end. The single-feed RF front-end normally includes one single-pole multi-throw antenna switch with a high number of throws connected to the different filters or diplexers to support the various modes of operation. Therefore, by increasing the number of modes of operation supported by the device, additional circuitry is required, which is problematic given both the increasing size constraints of mobile radio devices, and the desire for reduced cost and greater simplicity (for, e.g., reliability). In order for a single-feed RF-front end to support inter-band carrier aggregation, diplexers for the two frequency bands need to be simultaneously connected to the antenna feed. This is achieved by modifying the antenna control logic to have two simultaneously active switch throws. Hardwired duplexer matching is required between the antenna switch throws and the band duplexers. Different matching would be required for different combinations of inter-band carrier aggregation pairs, therefore making single-feed RF front-end impractical to support the various specific band pair implementations.
Accordingly, there is a salient need for a small form-factor radio frequency antenna solution which enables various operator-specific frequency band operational configurations using the same hardware.
The present invention satisfies the foregoing needs by providing, inter alia, a space-efficient multi-feed antenna apparatus and methods of tuning and use thereof.
In a first aspect of the invention, a multi-feed antenna apparatus is disclosed. In one embodiment, the antenna apparatus includes a first antenna element operable in a first frequency region, first antenna element comprising a first radiator and a first feed portion, the first feed portion configured to be coupled to a first feed port, a second antenna element operable in at least a second frequency region and a third frequency region. The second antenna element includes a second radiator, a second feed portion configured to be coupled to a second feed port, and a third feed portion configured to be coupled to a third feed port. In one variant, the second frequency region includes a first carrier frequency and the third frequency region includes a second carrier frequency, and the second and the third feed portions cooperate to: (i) enable inter-carrier aggregation of the first carrier and the second carrier into a single band, and (ii) to obviate diplexer matching specific to the single band.
In another embodiment, a triple-feed antenna apparatus is disclosed which includes a first antenna element operable in a lower frequency band and comprising a first feed portion configured to be coupled to a first feed port, a second antenna element operable in a second frequency band and comprising a second feed portion configured to be coupled to a second feed port, and a third antenna element operable in an upper frequency band and comprising a third feed portion configured to be coupled to a third feed port. The first and third antenna elements are each configured to form a radiation pattern disposed primarily in a first orientation, and the second antenna element is configured to form a radiation pattern disposed primarily in a second orientation that is substantially orthogonal to the first.
In one variant, the antenna apparatus includes a matching network.
In another variant, the first, second and third antenna elements are disposed on a common carrier, at least a portion of the carrier being configured substantially parallel to a ground plane, the radiation pattern of the first and third antenna elements each comprise an axis of maximum radiation that is substantially perpendicular to the ground plane, and the radiation pattern of the second antenna element includes an axis of maximum radiation substantially parallel to the ground plane.
In another variant, the first antenna element and the third antenna element each comprise a quarter-wavelength planar inverted-L antenna (FILA), and the second antenna element includes a half-wavelength loop antenna.
In yet another variant, the antenna apparatus includes a common carrier, the common carrier having a dielectric element having a plurality of surfaces, the first antenna element and the third antenna element are disposed at least partly on a first surface of the plurality of surfaces, and the second antenna element is disposed at least partly on a second surface of the plurality of surfaces, the second surface being disposed substantially parallel to a ground plane of the antenna apparatus, and the first surface being disposed substantially perpendicular to the ground plane.
In a second aspect of the invention, a radio frequency communications device is disclosed. In one embodiment, the radio frequency device includes an electronics assembly comprising a ground plane and one or more feed ports, and a multiband antenna apparatus. The antenna apparatus includes a first antenna structure comprising a first radiating element and a first feed portion coupled to a first feed port, a second antenna structure comprising a second radiating element and a second feed portion coupled to a second feed port, and a third antenna structure comprising an third radiating element and a third feed portion coupled to a third feed port.
In one variant, the second antenna structure and second feed port are disposed substantially between the first and third antenna structures, and the antenna apparatus is disposed proximate a bottom end of the ground plane.
In another variant, the first and third radiating elements have radiation patterns which are substantially orthogonal to a radiation pattern of the second radiating element, and the substantially orthogonal radiation patterns provide sufficient antenna isolation between each radiating element to enable operation of the device in at least three distinct radio frequency bands.
In a third aspect of the invention, matching network for use with a multi-feed antenna apparatus is disclosed. In one embodiment, the matching network includes first, second, and third matching circuits configured to couple a radio frequency front-end to first, second, and third feeds, respectively, and the first, second, and third matching circuits each enable tuning of respective ones of antenna radiators to desired frequency bands.
In another embodiment, the matching network includes first, second and third matching circuits configured to couple a radio frequency transceiver to first, second, and third feeds, respectively, and the first, second, and third matching circuits each provide impedance matching to a feed structure of the transceiver by at least increasing input resistance of the first, second, and third feeds.
In another embodiment, the matching network includes first, second and third matching circuits configured to couple a radio frequency front-end to first, second, and third feeds, respectively, and wherein the first, second, and third matching circuits each provide band-pass filtration, such filtration ensuring low coupling between respective ones of first, second, and third radiators.
In a fourth aspect of the invention, a method of tuning a multi-feed antenna is disclosed. In one embodiment, the multi-feed antenna includes first, second and third radiating elements and associated first, second, and third feed ports and matching circuits, and the method includes tuning a reactance of at least one of the matching circuits so as to create a dual resonance response in the radiating element associated therewith.
In one variant, the tuning is accomplished via at least selection of one or more capacitance values within the at least one matching circuit.
In another variant, the first and the third radiating elements each comprise a planar inverted-L antenna (PILA)-type element, and the tuning a reactance of at least one matching circuit includes tuning the reactance associated with the first and the third circuits so as to produce multiple frequency bands within the emissions of the first and the third elements.
In a fifth aspect of the invention, a method of radiator isolation for use in a multi-feed antenna apparatus of a radio frequency device is disclosed. In one embodiment, the multi-feed antenna apparatus includes first, second, and third antenna radiating elements, and at least first, second, and third feed portions, and the method includes electrically coupling the first feed point to the first radiating element, the coupling configured to effect a first radiation pattern having maximum sensitivity along a first axis, and electrically coupling the second feed point to the second radiating element, the electric coupling configured to effect a second radiation pattern having maximum sensitivity along a second axis. The third feed portion is also electrically coupled to the third radiating element. The foregoing coupling configured to effect a third radiation pattern having maximum sensitivity along the first axis.
In one variant the second axis is configured orthogonal to the first axis, and the axis configurations cooperate to effect isolation of the first radiating element from the third radiating element.
In a sixth aspect of the invention, a method of using a multiband antenna apparatus is disclosed.
Further features of the present invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description.
The features, objectives, and advantages of the invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, wherein:
All Figures disclosed herein are © Copyright 2011 Pulse Finland Oy. All rights reserved.
Reference is now made to the drawings wherein like numerals refer to like parts throughout.
As used herein, the terms “antenna,” “antenna system,” “antenna assembly”, and “multi-band antenna” refer without limitation to any apparatus or system that incorporates a single element, multiple elements, or one or more arrays of elements that receive/transmit and/or propagate one or more frequency bands of electromagnetic radiation. The radiation may be of numerous types, e.g., microwave, millimeter wave, radio frequency, digital modulated, analog, analog/digital encoded, digitally encoded millimeter wave energy, or the like.
As used herein, the terms “board”' and “substrate” refer generally and without limitation to any substantially planar or curved surface or component upon which other components can be disposed. For example, a substrate may comprise a single or multi-layered printed circuit board (e.g., FR4), a semi-conductive die or wafer, or even a surface of a housing or other device component, and may be substantially rigid or alternatively at least somewhat flexible.
The terms “frequency range”, “frequency band”, and “frequency domain” refer without limitation to any frequency range for communicating signals. Such signals may be communicated pursuant to one or more standards or wireless air interfaces.
As used herein, the terms “portable device”, “mobile computing device”, “client device”, “portable computing device”, and “end user device” include, but are not limited to, personal computers (PCs) and minicomputers, whether desktop, laptop, or otherwise, set-top boxes, personal digital assistants (PDAs), handheld computers, personal communicators, tablet computers, portable navigation aids, J2ME equipped devices, cellular telephones, smartphones, personal integrated communication or entertainment devices, or literally any other device capable of interchanging data with a network or another device.
Furthermore, as used herein, the terms “radiator,” “radiating plane,” and “radiating element” refer without limitation to an element that can function as part of a system that receives and/or transmits radio-frequency electromagnetic radiation; e.g., an antenna or portion thereof.
The terms “RF feed,” “feed,” “feed conductor,” and “feed network” refer without limitation to any energy conductor and coupling element(s) that can transfer energy, transform impedance, enhance performance characteristics, and conform impedance properties between an incoming/outgoing RF energy signals to that of one or more connective elements, such as for example a radiator.
As used herein, the terms “loop” and “ring” refer generally and without limitation to a closed (or virtually closed) path, irrespective of any shape or dimensions or symmetry.
As used herein, the terms “top”, “bottom”, “side”, “up”, “down”, “left”, “right”, and the like merely connote a relative position or geometry of one component to another, and in no way connote an absolute frame of reference or any required orientation. For example, a “top” portion of a component may actually reside below a “bottom” portion when the component is mounted to another device (e.g., to the underside of a PCB).
As used herein, the term “wireless” means any wireless signal, data, communication, or other interface including without limitation Wi-Fi, Bluetooth, 3G (e.g., 3GPP, 3GPP2, and UMTS), HSDPA/HSUPA, TDMA, CDMA (e.g., IS-95A, WCDMA, etc.), FHSS, DSSS, GSM, PAN/802.15, WiMAX (802.16), 802.20, narrowband/FDMA, OFDM, PCS/DCS, Long Term Evolution (LTE) or LTE-Advanced (LTE-A), analog cellular, CDPD, satellite systems such as GPS, millimeter wave or microwave systems, optical, acoustic, and infrared (i.e., IrDA).
The present invention provides, in one salient aspect, a multi-feed (e.g., triple-feed) antenna apparatus for use with a radio device the antenna advantageously providing reduced size and cost, as well as improved antenna performance suitable for serving multiple operational needs using the same hardware configuration
In one embodiment, the antenna assembly includes three (3) separate radiator structures disposed on a common antenna carrier or substrate. Each of the three antenna radiators is connected to separate feed ports of a radio device radio frequency front end. In this embodiment, the first and the third radiators (that are connected to the first and third feed ports, respectively) comprise quarter-wavelength planar inverted-L antennas (PILA). The second radiator (connected to the second feed port) includes a half-wavelength grounded loop-type antenna, and is disposed in between the first and the third radiators. In one implementation, the second radiator further includes a slot structure, configured to effect resonance in the desired frequency band.
The first radiator is in the exemplary embodiment configured to operate in a lower frequency band (LFB), while the second radiator structure is configured to operate in multiple frequency bands. The third radiator is configured to operate in an upper frequency band (UFB).
The exemplary PILA radiators are characterized by radiation patterns having axes of maximum radiation that are perpendicular to the antenna plane (the carrier plane). The loop radiator is characterized by radiation pattern having an axis of maximum radiation that is parallel to the antenna plane. The above configuration of radiating patterns advantageously isolates the third radiator structure from the first radiator structure. In one variant, the third radiator structure is isolated from the second radiator structure over at least one frequency band.
By placing the loop radiator structure in between the two PILA structures, and the second feed between the first and third feeds, significant isolation of the first and third radiators from one another is achieved, thereby enhancing the performance of the antenna apparatus.
The exemplary multi-feed antenna apparatus and RF front-end also advantageously enable inter-band carrier aggregation. In one implementation, each of the aggregated bands is supported by a separate antenna radiator (for example, the second and the third radiators). In another implementation, the inter-band aggregation is achieved using the same element for both bands (for example, the third antenna radiator).
Detailed descriptions of the various embodiments of the apparatus and methods of the invention are now provided. While primarily discussed in the context of radio devices useful with LTE or LTE-A wireless communications systems, the various apparatus and methodologies discussed herein are not so limited. In fact, many of the apparatus and methodologies of the invention are useful in any number of complex antennas, whether associated with mobile or fixed devices that can benefit from the multi-feed antenna methodologies and apparatus described herein.
Referring now to
One exemplary embodiment of a multiband antenna apparatus 100 for use with a radio device is presented in
A detailed configuration of the multi-feed antenna assembly 101 is shown in
In one variant, the first feed port 106 covers a frequency range of approximately 700-960 MHz, known in LTE as the “Low Band”. The second feed port 108 covers approximately 1,425-1,505 MHz (band 11) as well as 2.3-2.7 GHz (bands 7, 40, and 41). The third feed port 110 is designed to cover approximately 1,710-2,170 MHz (high band). The exemplary bands referenced above are configured according to Evolved Universal Terrestrial Radio Access (E-UTRA) air interface specification, described in the 3rd Generation Partnership Project (3GPP) Technical Specification Group Radio Access Network (E-UTRA), 3GPP TS 36 series, incorporated herein by reference in its entirety. As will be appreciated by those skilled in the art, the above frequency band references and bounds may be varied or adjusted from one implementation to another based on specific design requirements and parameters, such as for example antenna size, target country or wireless carrier of operation, etc. Furthermore, embodiments of the present invention may be used with the High Speed Packet Access (HSPA) and 3GPP Evolved HSPA wireless communications networks, described in the 3rd Generation Partnership Project (3GPP) Technical Specification Group Universal Mobile Telecommunications System (UMTS);), 3GPP TS 25 series, incorporated herein by reference in its entirety. Typically, each of the operational frequency ranges may support one or more distinct frequency bands configured in accordance with the specifications governing the relevant wireless application system (such as, for example, HSPA, HSPA+, LTE/LTE-A, or GSM).
The multi-feed antenna apparatus and RF front-end (such as shown and described with respect to
The antenna configuration of the embodiment shown in
The first 112 and the third 116 radiators shown in the embodiment of
As shown in the embodiment of
In one exemplary variant, the radiators elements 112, 114, and 116 are further configured to be bent over the edge of the device (as shown in
The radiators 112, 114, and 116 of
In the implementation shown in
Referring now to
The placement of the loop-type antenna structure 116 between the two PILA antenna structures 112 and 114 as shown in
By placing the loop antenna structure 116 between the two PILA antenna structures 112, 114, the field ports achieve high isolation between the first and the third antenna structures. In addition, due to the orthogonal polarization of the loop 116 antenna and PILA antenna 114, the coupling between the antenna structures 114, 116 is greatly reduced (especially when considering the relative proximity of their operating frequency bands), thereby providing sufficient isolation between the frequency bands corresponding to the two antennas (for example a −12 dB isolation between 2.1 GHz and 2.3-2.6 GHz bands).
Referring now to
In another aspect of the invention, the triple-feed antenna assembly (such as the antenna assembly 101 of
By a way of example, PILA antenna radiators 112, 114 typically do not offer 50-Ohm impedance (radiational resistance) at their respective resonant frequencies F1, F3, as is desired for proper matching to the feed ports 106, 110. Hence, the matching network 300 is used to match the radiators 112, 114 to the feed ports as follows. The matching component of the circuits 302, 304 is selected to have resonances at frequencies Fm1=F1+X1, Fm3=F3+X3. In one variant, the frequencies Fm1, Fm3 are configured on exactly the opposite side of a Smith chart, with respect to frequencies F1, F3. The actual values of the frequency shift X1, X3 are determined by the respective antenna operating bands: i.e. LB/HB. In combination with the antenna radiators 112, 114, the matching circuits 302, 304 form a “dual resonance” type frequency response. Such frequency response effectively forms a band pass filter, advantageously attenuating out-of-band signal components and, hence, increasing band isolation. By way of example, the circuit 302 passes the LB signals and attenuates the HB/B7 signals, while the circuit 304 passes the HB signals and attenuates the LB/B7 signals.
The antenna 112, 114 isolation is further enhanced by the placement of the feed port 108 in-between the feed ports 106, 110. The use of a loop antenna structure (e.g., the structure 116) coupled to the feed port 108 further increase isolation between the feed ports 106, 110. Furthermore, the loop structure coupled to the fed port 108 enables to achieve high isolation between the feed port 108 and the radiators 112, 114.
In another embodiment, a PILA radiator structure is coupled to the feed-port 108 in place of the loop structure 116. Such configuration advantageously increases the isolation between the feed ports 106, 110. However, the feed 108 to radiator 112, 114 isolation may be reduced when the frequency band spacing (gap) between the HB and the feed port 108 frequency band becomes narrow, as illustrates by the examples below.
Feed port 106: LB (PILA), feed port 108: 2.5-23 GHz (PILA), feed port 110: HB (PILA). This configuration provides sufficient feed to radiator isolation between the feed ports 108 and 110 due to a wide frequency gap (about 200 MHz) between the feed port 108 and 110 frequency bands.
Feed port 106: LB (PILA), feed port 108: 2.3-2.7 GHz (PILA), feed port 110: HB (PILA). This configuration does not provide sufficient feed to radiator isolation between the feed ports 108 and 110 due to a small frequency gap (about few MHz) between the feed port 108 and 110 frequency bands.
Feed port 106: LB (PILA), feed port 108: 2.3-2.7 GHz (Loop), feed port 110: HB (PILA). This configuration provides very good feed to radiator isolation for all feed ports in all frequency bands despite a small frequency gap between the feed ports 108 and 110 frequency bands.
In one embodiment, the matching circuits for the first and third feed ports are realized through use of tapped inductors 310, 314, respectively. The inductor 310, 314 are implemented, in one variant, as narrow conductive traces on the PCB, configured to achieve the desired inductance values. In another variant, the inductors 310, 314 are implemented using discrete components, e.g. chip inductors, wound toroids, ceramic multilayer, and wire-wound inductors, etc. Residual reactance of the circuits 302, 304 can be tuned with the shunt capacitors 312, 316, respectively, so as to create a dual resonance type of response in the first and third feed ports 106, 108. The matching circuit 308, corresponding to the feed port 108, is properly matched over the target frequency range using a shunt capacitor 318. In other implementations, additional matching components may be used expand the resonance response of the radiators 112, 114, and 116 in order to cover additional desired frequency bands.
In order to minimize space occupied by the antenna assembly 101 of
Referring now to
In one exemplary implementation, the radiator elements 112, 114, and 116 are fabricated using stamped metal sheet of approximately 70 mm (2.76 in.) in length and 30 mm (1.18 in.) in width, although these dimensions may vary depending on the application and desired performance attributes. It is appreciated by those skilled in the arts that other fabrication approaches and/or materials are compatible with the invention including without limitation use of flex circuits, metal deposition, plated plastic or ceramic carrier, or yet other technologies.
Referring now to
An efficiency of zero (0) dB corresponds to an ideal theoretical radiator, wherein all of the input power is radiated in the form of electromagnetic energy. The data in
It will be recognized that while certain aspects of the invention are described in terms of a specific sequence of steps of a method, these descriptions are only illustrative of the broader methods of the invention, and may be modified as required by the particular application. Certain steps may be rendered unnecessary or optional under certain circumstances. Additionally, certain steps or functionality may be added to the disclosed embodiments, or the order of performance of two or more steps permuted. All such variations are considered to be encompassed within the invention disclosed and claimed herein.
While the above detailed description has shown, described, and pointed out novel features of the invention as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the invention. The foregoing description is of the best mode presently contemplated of carrying out the invention. This description is in no way meant to be limiting, but rather should be taken as illustrative of the general principles of the invention. The scope of the invention should be determined with reference to the claims.
