Information
-
Patent Grant
-
6480157
-
Patent Number
6,480,157
-
Date Filed
Friday, May 18, 200123 years ago
-
Date Issued
Tuesday, November 12, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- DeAngelis, Jr.; John L.
- Beusse Brownlee Bowdoin & Wolter, P.A.
-
CPC
-
US Classifications
Field of Search
US
- 343 700 MS
- 343 795
- 343 797
- 343 915
- 343 833
- 343 834
-
International Classifications
-
Abstract
A foldable antenna includes a plurality of passive elements radially spaced apart from a center active element. The radial passive elements are joined to the active element to create a deformable union. In this way, the surrounding passive elements can be folded toward the midplane of the antenna array to create a relatively compact stored configuration.
Description
FIELD OF THE INVENTION
This invention relates to mobile or portable cellular communication systems, and more particularly to a compact foldable antenna apparatus for use with mobile or portable subscriber units.
BACKGROUND OF THE INVENTION
Code division multiple access (CDMA) communication systems provide wireless communications between a base station and one or more mobile or portable subscriber units. The base station is typically a computer-controlled set of transceivers that are interconnected to a land-based public switched telephone network (PSTN). The base station further includes an antenna apparatus for sending forward link radio frequency signals to the mobile subscriber units and for receiving reverse link radio frequency signals transmitted from each mobile unit. Each mobile subscriber unit also contains an antenna apparatus for the reception of the forward link signals and for the transmission of the reverse link signals. A typical mobile subscriber unit is a digital cellular telephone handset or a personal computer coupled to a cellular modem. In such systems, multiple mobile subscriber units may transmit and receive signals on the same center frequency, but unique modulation codes distinguish the signals sent to or received from individual subscriber units.
In addition to CDMA, other wireless access techniques employed for communications between a base station and one or more portable or mobile units include those described by the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard and the industry-developed Bluetooth standard. All such wireless communications techniques require the use of an antenna at both the receiving and transmitting end. It is well-known by experts in the field that increasing the antenna gain in any wireless communication system has beneficial affects on wireless systems performance.
A common antenna for transmitting and receiving signals at a mobile subscriber unit is a monopole antenna (or any other antenna with an omnidirectional radiation pattern) A monopole consists of a single wire or antenna element that is coupled to a transceiver within the subscriber unit. Analog or digital information for transmission from the subscriber unit is input to the transceiver where it is modulated onto a carrier signal at a frequency using a modulation code (i.e., in a CDMA system) assigned to that subscriber unit. The modulated carrier signal is transmitted from the subscriber unit to the base station. Forward link signals received by the subscriber unit are demodulated by the transceiver and supplied to processing circuitry within the subscriber unit.
The signal transmitted from a monopole antenna is omnidirectional in nature. That is, the signal is sent with approximately the same signal strength in all directions in a generally horizontal plane. Reception of a signal with a monopole antenna element is likewise omnidirectional. A monopole antenna does not differentiate in its ability to detect a signal in one azimuth direction versus detection of the same or a different signal coming from another azimuth direction. Also, a monopole antenna does not produce significant radiation in the elevation direction. The antenna pattern is commonly referred to as a donut shape with the antenna element located at the center of the donut hole.
A second type of antenna that may be used by mobile subscriber units is described in U.S. Pat. No. 5,617,102. The directional antenna comprises two antenna elements mounted on the outer case of a laptop computer, for example. A phase shifter attached to each element imparts a phase angle delay to the input signal, thereby modifying the antenna pattern (which applies to both the receive and transmit modes) to provide a concentrated signal or beam in the selected direction. Concentrating the beam increases the antenna gain and directivity. The dual element antenna of the cited patent thereby directs the transmitted signal into predetermined sectors or directions to accommodate for changes in orientation of the subscriber unit relative to the base station, thereby minimizing signal loss due to the orientation change. In accordance with the antenna reciprocity theorem, the antenna receive characteristics are similarly effected by the use of the phase shifters.
CDMA cellular systems are interference limited systems. That is, as more mobile or portable subscriber units become active in a cell and in adjacent cells, frequency interference increases and thus bit error rates also increase. To maintain signal and system integrity in the face of increasing error rates, the system operator decreases the maximum data rate allowable for one or more users, or decreases the number of active subscriber units, which thereby clears the airwaves of potential interference. For instance, to increase the maximum available data rate by a factor of two, the number of active mobile subscriber units is halved. However, this technique cannot generally be employed to increase data rates due to the lack of service priority assignments to the subscribers. Finally, it is also possible to avert excessive interference by using directive antennas at both (or either) the base station and the portable units.
Typically, a directive antenna beam pattern is achieved through the use of a phased array antenna. The phased array is electronically scanned or steered to the desired direction by controlling the phase angle of the input signal to each antenna element. However, phased array antennas suffer decreased efficiency and gain as the element spacing becomes electrically small when compared to the wavelength of the received or transmitted signal. When such an antenna is used in conjunction with a portable or mobile subscriber unit, generally the antenna array spacing is relatively small and thus antenna performance is correspondingly compromised.
In a communication system in which portable or mobile units communicate with a base station, such as a CDMA communication system, the portable or mobile unit is typically a hand-held device or a relatively small device, such as, for instance, the size of a laptop computer. In some embodiments, the antenna is inside or protrudes from the devices housing or enclosure. For example, cellular telephone hand sets utilize either an internal patch antenna or a protruding monopole or dipole antenna. A larger portable device, such as a laptop computer, may have the antenna or antenna array mounted in a separate enclosure or integrated into the laptop housing. A separately-enclosed antenna may be cumbersome for the user to manage as the communications device is carried from one location to another. While integrated antennas overcome this disadvantage, such antennas, except for a patch antenna, generally are in the form of protrusions from the communications device. These protrusions can be broken or damaged, as the device is moved from one location to another. Even minor damage to a protruding antenna can drastically alter its operating characteristics.
SUMMARY OF THE INVENTION
Problems of the prior art
Several considerations must be taken into account in integrating a wireless-network antenna into an enclosure, whether the enclosure comprises a unit separate from the communications device or the housing of the communications device itself. In designing the antenna and its associated enclosure, careful consideration must be given to the antenna electrical characteristics so that signals propagating over the wireless link satisfy pre-determined system standards, such as, the bit error rate, signal-to-noise ratio or signal-to-noise-plus-interference ratio. The electrical properties of the antenna, as influenced by the antenna physical parameters, are discussed further herein below.
The antenna must also exhibit certain mechanical characteristics to satisfy user needs and meet the required electrical performance. The antenna length, or the length of each element of an antenna array, depends on the received and transmitted signal frequencies. If the antenna is configured as a monopole, the length is typically a quarter wavelength of the signal frequency. For operation at 800 MHz (one of the wireless frequency bands), a quarter-wavelength monopole is 3.7 inches long. The length of a half-wavelength dipole is 7.4 inches.
The antenna must further present an aesthetically pleasing appearance to the user. If the antenna is deployable from the communications device, sufficient volume within the communications device must be allocated to the stored antenna and its peripheral components. But since the communications device is used in mobile or portable service, the device must remain relative small and light with a shape that allows it to be easily carried. The antenna deployment mechanism must be mechanically simple and reliable. For those antennas housed in an enclosure separate form the communications device, the connection mechanism between the antenna and the communications device must be reliable and simple.
Not only are the electrical, mechanical and aesthetic properties of the antenna important, but it must also overcome unique performance problems in the wireless environment. One such problem is called multipath fading. In multipath fading, a radio frequency signal transmitted from a sender (either a base station or mobile subscriber unit) may encounter interference in route to the intended receiver. The signal may, for example, be reflected from objects, such as buildings, thereby directing a reflected version of the original signal to the receiver. In such instances, two versions of the same radio frequency signal are received; the original version and a reflected version. Each received signal is at the same frequency, but the reflected signal may be out of phase with the original due to the reflection and consequent differential transmission path length to the receiver. As a result, the original and reflected signals may partially cancel each other out (destructive interference), resulting in fading or dropouts in the received signal.
Single element antennas are highly susceptible to multipath fading. A single element antenna cannot determine the direction from which a transmitted signal is sent and therefore cannot be tuned to more accurately detect and receive a transmitted signal. Its directional pattern is fixed by the physical structure of the antenna components. Only the antenna position and orientation can be changed in an effort to obviate the multipath fading effects.
The dual element antenna described in the aforementioned patent reference is also susceptible to multipath fading due to the symmetrical and opposing nature of the hemispherical lobes of the antenna pattern. Since the antenna pattern lobes are more or less symmetrical and opposite from one another, a signal reflected to the back side of the antenna may have the same received power as a signal received at the front. That is, if the transmitted signal reflects from an object beyond or behind the intended receiver and then reflects into the back side of the antenna, it will interfere with the signal received directly from the source, where the phase difference in the two signals creates destructive interference due to multipath fading.
Another problem present in cellular communication systems is inter-cell signal interference. Most cellular systems are divided into individual cells, with each cell having a base station located at its center. The placement of each base station is arranged such that neighboring base stations are located at approximately sixty degree intervals from each other. Each cell may be viewed as a six sided polygon with a base station at the center. The edges of each cell abut the neighboring cells and a group of cells form a honeycomb-like pattern. The distance from the edge of a cell to its base station is typically driven by the minimum power required to transmit an acceptable signal from a mobile subscriber unit located near the edge of the cell to that cell's base station (i.e., the power required to transmit an acceptable signal a distance equal to the radius of one cell).
Intercell interference occurs when a mobile subscriber unit near the edge of one cell transmits a signal that crosses over the edge into a neighboring cell and interferes with communications taking place within the neighboring cell. Typically, signals in neighboring cells on the same or closely spaced frequencies cause intercell interference. The problem of intercell interference is compounded by the fact that subscriber units near the edges of a cell typically transmit at higher power levels so that the transmitted signals can be effectively received by the intended base station located at the cell center. Also, the signal from another mobile subscriber unit located beyond or behind the intended receiver may arrive at the base station at the same power level, representing additional interference.
The intercell interference problem is exacerbated in CDMA systems since the subscriber units in adjacent cells typically transmit on the same carrier or center frequency. For example, two subscriber units in adjacent cells operating at the same carrier frequency but transmitting to different base stations interfere with each other if both signals are received at one of the base stations. One signal appears as noise relative to the other. The degree of interference and the receiver's ability to detect and demodulate the intended signal is also influenced by the power level at which the subscriber units are operating. If one of the subscriber units is situated at the edge of a cell, it transmits at a higher power level, relative to other units within its cell and the adjacent cell, to reach the intended base station. But, its signal is also received by the unintended base station, i.e., the base station in the adjacent cell. Depending on the relative power level of two same-carrier frequency signals received at the unintended base station, it may not be able to properly differentiate a signal transmitted from within its cell from the signal transmitted from the adjacent cell. A mechanism is required to reduce the subscriber unit antenna's apparent field of view, which can have a marked effect on the operation of the reverse link (subscriber to base) by reducing the number of interfering transmissions received at a base station. A similar improvement in the antenna pattern for the forward link, allows a reduction in the transmitted signal power to achieve a desired receive signal quality.
In summary, it is clear that in the wireless communications technology, it is of utmost importance to maximize antenna performance, while minimizing size and manufacturing complexity.
Brief Description of the Present Invention
A directional antenna having a center element and a plurality of radial elements spaced apart from the center element, further including a deformable or pivotable joint between the center element and each radial element providing for pivotable displacement of the radial elements relative to the center element, such that the entire antenna including the center element and the radial elements are foldable into a flattened or stacked orientation. If the radial elements are formed on deformable or flexural material, they are affixed to the center element, creating a deformable union there between, with an adhesive or mating soldered vias. Alternatively, if the radial elements are formed on a rigid dielectric material, a piece of deformable or flexural material is interposed between the rigid dielectric material of the radial elements and the center element to form the deformable union therebetween. The piece of deformable or flexural material can be affixed to both the rigid dielectric material of the radial elements and the center element by several techniques that are known in the art, including use of an adhesive material or by mated solderable vias.
Essentially, each radial element comprises a first elongated dielectric substrate section on which a conductive element is disposed, and a second elongated section perpendicular to the first elongated section, and forming an interconnecting arm between the first elongated section and the center element. Likewise, the center element comprises an elongated dielectric substrate on which a conductive element is disposed. The distal end of the interconnecting arm is joined to the elongated dielectric substrate carrying the center element by way of the deformable union as discussed above.
When deployed, the antenna array provides advantageous directional characteristics. In particular, in one embodiment each of the radial elements is controllably operated in either a reflector or director mode, with respect to signals transmitted from or received by the center element. Further, the center element and the plurality of radial elements are each disposed on a dielectric substrate, wherein one or more of the dielectric substrates is configured to carry microelectronic components for controlling operational aspects of the center element and the radial elements. Included among these microelectronic components are certain switches connected between an upper conductive portion and a lower conductive portion of the conductive element for each one of the plurality of radial elements. Signals supplied to the antenna array control the active switches for shorting or opening the connection between the upper portion and the lower linear portion of each radial element, to achieve either the directive or the reflective operational state. In yet another embodiment the center element is absent and the radial elements are controllably operated as a phased array antenna.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings in which like referenced characters refer to the same parts throughout the different figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
FIG. 1
illustrates a cell of a cellular-based wireless communications system.
FIGS. 2 through 5
illustrate various views of an antenna constructed according to the teachings of the present invention.
FIG. 6
is a more detailed view of a radial element shown in FIG.
2
.
FIG. 7
is a pictorial representation of the microelectronics module of FIG.
6
.
FIGS. 8 through 17
illustrate additional embodiments of antennas constructed according to the teaching of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1
illustrates one cell
50
of a typical CDMA cellular communication system. The cell
50
represents a geographical area in which mobile subscriber units
60
-
1
through
60
-
3
communicate with a centrally located base station
65
. Each subscriber unit
60
is equipped with an antenna
70
configured according to the present invention. The subscriber units
60
are provided with wireless data and/or voice services by the system operator and can connect devices such as, for example, laptop computers, portable computers, personal digital assistants (PDAs) or the like through base station
65
(including the antenna
68
) to a network
75
, which can be the public switched telephone network (PSTN), a packet switched computer network, such as the Internet, a public data network or a private network. The base station
65
communicates with the network
75
over any number of different available communications protocols such as primary rate ISDN, or other LAPD based protocols such as IS-634 or V5.2, or even TCP/IP if the network
75
is a packet based Ethernet network such as the Internet. The subscriber units
60
may be mobile in nature and may travel from one location to another while communicating with the base station
65
. As the subscriber units leave one cell and enter another, the communications link is handed off from the base station of the exiting cell to the base station of the entering cell.
FIG. 1
illustrates one base station
65
and three mobile subscriber units
60
in a cell
50
by way of example only and for ease of description of the invention. The invention is applicable to systems in which there are typically many more subscriber units communicating with one or more base stations in an individual cell, such as the cell
50
. The invention is further applicable to any wireless communication device or system.
It is also to be understood by those skilled in the art that
FIG. 1
represents a standard cellular type communications system employing signaling schemes such as a CDMA, TDMA, GSM or others, in which the radio frequency channels are assigned to carry data and/or voice between the base stations
65
and subscriber units
60
. In a preferred embodiment,
FIG. 1
is a CDMA-like system, using code division multiplexing principles such as those defined in the IS-95B standards for the air interface.
In one embodiment of the cell-based system, the mobile subscriber units
60
employ an antenna
70
that provides directional reception of forward link radio signals transmitted from the base station
65
, as well as directional transmission of reverse link signals (via a process called beam forming) from the mobile subscriber units
60
to the base station
65
. This concept is illustrated in
FIG. 1
by the example beam patterns
71
through
73
that extend outwardly from each mobile subscriber unit
60
more or less in a direction for best propagation toward the base station
65
. By directing transmission more or less toward the base station
65
, and directively receiving signals originating more or less from the location of the base station
65
, the antenna apparatus
100
reduces the effects of intercell interference and multipath fading for the mobile subscriber units
60
. Moreover, since the antenna beam patterns
71
,
72
and
73
extend outward in the direction of the base station
65
but are attenuated in most other directions, less power is required for transmission of effective communications signals from the mobile subscriber units
60
-
1
,
60
-
2
and
60
-
3
to the base station
65
.
FIG. 2
illustrates an antenna array
100
constructed according to the teachings of the present invention. The antenna array
100
includes a center element
102
surrounded by six passive elements
104
A through
104
F, each of which can be operated in a reflective or a directive mode as will be discussed further herein below. The antenna array
100
is not restricted to six passive elements. Other embodiments include fewer (e.g., four) or more (e.g., eight) passive elements. In yet another embodiment where the antenna operates as a phased array, to be discussed further below, the center element is absent.
The center element
102
comprises a conductive radiator
106
disposed on a dielectric substrate
108
. Each passive element
104
A through
104
F comprises an upper conductive segment
110
A through
110
F and a lower conductive segment
112
A through
112
F disposed on a dielectric substrate
113
A through
113
F, respectively. The lower conductive segments
112
A through F are grounded. Generally, the upper (
110
A-
110
F) and the lower (
112
A-
112
F) conductive segments are of equal length. When the upper conductive segment of one of the passive elements (for example, the upper conductive segment
110
A) is connected to the respective lower conductive segment (the lower conductive segment
112
A) the passive element
104
A operates in a reflective mode such that all received radio frequency (RF) energy is reflected back from the passive element
104
A toward the source. When the upper conductive segment
110
A, for example, is open (i.e., not connected to the lower conductive segment
112
A) the passive element
104
A operates in a directive mode in which the passive element
104
A essentially is invisible to the propagating RF energy which passes therethrough.
In one embodiment, the center element
102
and the passive elements
104
A and
104
D are fabricated from a single dielectric substrate, such as a printed circuit board, with the respective antenna elements disposed thereon. The passive elements,
104
B and
104
C are disposed on a deformable or flexural substrate and attached or mounted to one surface of the center element
102
. Thus the passive elements
104
B and
104
C are foldable into a compact arrangement when not in use, and deformable into the radial positions illustrated in
FIG. 2
for optimum operation. This is accomplished by folding (or deforming) the passive elements
104
B and
104
C about the attachment point toward the passive element
104
A and
104
D, respectively. Similarly, the passive elements
104
E and
104
F are disposed on a deformable or flexural substrate and attached or mounted to an opposing surface of the center element
102
so that the passive elements
104
E and
104
F are foldable into a compact arrangement when not in use or deployable into the configuration illustrated in
FIG. 2
during operation. In another embodiment, each of the passive elements
104
A through
104
F are formed on a separate flexible dielectric substrate and deformably joined to the center element
102
. In still another embodiment, the passive elements
104
A through
104
F are formed on individual rigid dielectric substrates and deformably joined to the center element
102
by use of a deformable material interposed therebetween.
There are many devices and techniques available for attaching the deformable substrates carrying the passive elements
104
A through
104
F to the center element
102
. An adhesive can be used to join the surface of the center element
102
to the deformable substrates or the deformable material. Solderable vias can also be disposed into each of the surfaces to be mated. The joints are mated and the vias soldered so that the joints remain deformable. If it is required for signals to pass between the center element
102
and each of the passive elements
104
A through
104
F, then in another embodiment the solderable vias are connected to the appropriate conductive traces disposed on the center element
102
and the passive elements
104
A through
104
F. In this way, the soldered mated vias establish an electrical interconnection and a mechanical union between the passive elements
104
A through
104
F and the center element
102
. Also, a mechanical fastener can also be utilized to join the various passive elements
104
A through
104
F to the center element
102
.
In yet another embodiment the center element
102
and the passive elements
104
A and
104
D are fabricated on a first deformable substrate, the passive elements
104
B and
104
C are fabricated on a second deformable substrate and the passive elements
104
E and
104
F are fabricated on a third deformable substrate. The three deformable substrates carrying the antenna elements are joined as discussed above. In yet another embodiment, the center element
102
is formed of a rigid dielectric material, for example, printed circuit board, while the passive element
104
A is disposed on a first deformable substrate, the passive elements
104
B and
104
C are formed on a second deformable substrate, the passive element
104
D is formed on a third deformable substrate and the passive element
104
E and
104
F are disposed on a fourth deformable substrate. The four deformable substrates are then joined to the center element by way of soldered vias or an adhesive as discussed above.
In still another embodiment of the present invention, each of the passive elements
104
A through
104
F is disposed on a rigid dielectric substrate material and joined to the center element
102
by way of a deformable union. In particular, one edge of deformable or flexural material is attached to each of the passive elements
104
A through
104
F and the opposing edge of the material is attached to the center element
102
. Thus in this embodiment, each antenna element is disposed on a rigid surface, yet the antenna array
100
retains the foldabilty characteristic by the use of the deformable material. Solderable vias or an adhesive are used to affix the deformable material to the center element
102
.
A top view of the antenna array
100
is illustrated in FIG.
3
. In particular, the formable joints
105
are shown.
FIG. 4
is a top view of the antenna array
100
in a folded configuration. The distance between adjacent passive elements (for example, between the passive elements
104
A and
104
B) is exaggerated in
FIG. 4
for clarity.
The deformable joints allow the adjacent elements to come into contact so that the antenna array
100
is storable in a very compact configuration.
FIG. 5
is a perspective view of the antenna
100
in a folded configuration. Although the performance will be degraded, it is possible for the antenna array
100
to operate in the folded configuration of
FIGS. 4 and 5
.
Returning to
FIG. 2
, there is shown a microelectronics module
116
A through
116
F interposed between the upper conductive segments
110
A through
110
F and the lower conductive segments
112
A through
112
F of each passive element
104
A through
104
F. There is further shown a microelectronics module
122
disposed on the dielectric substrate
108
, comprising, for example, transceiver circuitry. Conductive traces
124
conduct signals between the microelectronics module
122
and of the microelectronics modules
116
A through
116
F. The signals carried on the conductive traces
124
control components within the microelectronics modules
116
A through
116
F for operating the passive elements
104
A through
104
F in either the reflective or the directive state. Further connected to the microelectronics module
122
is an interface
125
for providing electrical connectivity between the antenna array
100
and the external communications device. The interface
125
can be constructed from either rigid or flexible material for interfacing (via a ribbon cable, for example) to a connector mounted on an enclosure enclosing the antenna array
100
. In use, a conductor is inserted into the connector for connecting the antenna array
100
to the external device. It will be appreciated by those skilled in the art that various placements and conductor routing paths are available for the microelectronics modules and the conductive traces, as required for a specific antenna design and configuration.
FIG. 6
is an enlarged view of one of the passive elements
104
D, for example including the microelectronics module
116
D and the conductive traces
124
. The other passive elements are similarly constructed. The dielectric substrate
113
D comprises a deformable (flexural) material or a rigid material having a first portion on which the upper conductive segment
110
D and the lower conductive segment
112
D are formed, and a second arm portion perpendicular to the first portion. In the embodiment where the passive element
104
D is constructed of rigid material, the second arm portion includes a deformable material (not shown in
FIG. 6
) affixed to the end of the second arm portion. In one embodiment, the first portion carrying the upper and lower conductive segments and the second arm portion are formed by shaping or cutting a single sheet of the dielectric substrate material. The rigid embodiment can be formed from printed circuit board material including FR4 material, and the deformable embodiment can be formed from Kapton, polyimide, mylar, or any other deformable material. The selection of a suitable material is based on the desired mechanical and electrical properties of the antenna elements, including loss, permittivity and permeability. Three exemplary conductive traces
124
traversing the arm portion of the dielectric substrate
113
D and connected to contacts (not shown) of the microelectronics module
116
D are shown. Depending upon the characteristics of the switch employed within the microelectronics module
116
D (to be discussed in conjunction with
FIG. 7
) fewer than three conductive traces
124
may be required for controlling that switch. Finally, as shown, a conductive trace
125
connects the lower conductive segment
112
D to a grounded terminal, for example on the interface
125
shown in FIG.
2
. The microelectronics module
116
D is not confined to a switching function, but can include other functions related to operation of the antenna array
100
and its constituent elements. As is known to those skilled in the art, conductive material for forming the upper conductive segment
110
D, the lower conductive segment
112
D and the conductive traces
124
can be applied to the dielectric substrate by printing conductive epoxies or conductive inks thereon. Also, the conductive elements are formable by etching away the unwanted portions from a copper clad dielectric substrate.
FIG. 7
illustrates an exemplary microelectronics module
116
D, including a mechanical SPDT switch
140
. Those skilled in the art recognize that the mechanical switch
140
is a simplistic representation of a switching device typically implemented with a junction diode, a MOSFET, a bipolar junction transistor, or a mechanical switch, including one fabricated using MEMS technology (microelectromechanical system). Under control of a signal carried on one of the conductive traces
124
, the switch
140
is switched between contact with a conductor
142
and a conductor
144
. When switched to the conductor
142
, the upper conductive segment
110
D is connected to an impedance element
146
. The impedance element
146
compensates for reactances (i.e., capacitive or inductive) within the switch
140
so that the upper conductive segment
110
D sees an open circuit when the switch
140
closes into the conductor
142
. Alternatively, when the switch
140
connects to the conductor
144
, the upper conductive segment
110
D sees a grounded lower conductive segment
112
D via an impedance element
148
. The impedance element
148
cancels any reactances (i.e., capacitive or inductive) created in the switch
140
so that the upper conductive segment
110
D sees a short to ground. In one embodiment, there are shown three conductive traces
124
, for carrying a positive and negative bias voltage for biasing the electronic component implementing the SPDT switch
140
, and further a control voltage signal for selecting the switch position. Depending upon the specific electronic or mechanical component implementing the switch
140
, only a positive or a negative bias voltage may be required or the component may be switched without a bias voltage as determined solely by a control voltage. Thus, other embodiments of the present invention may require numbers of conductive traces
124
connected to the microelectronics module
116
D.
FIG. 8
illustrates another embodiment
300
of an antenna array according to the teachings of the present invention, wherein the passive elements and the center element in the
FIG. 8
embodiment are similar to those illustrated in FIG.
2
. Each of the passive elements
104
A,
104
B,
104
D and
104
E is disposed on a rigid substrate (e.g., FR
4
material) and joined to the center element
102
via a deformable material, such as mylar, as indicated by a reference character
302
. The passive elements
104
F and
104
C are disposed on the same substrate as the center element
102
.
In yet another embodiment of an antenna array
318
illustrated in
FIGS. 9A and 9B
, the passive elements
104
A and
104
B are formed on a first deformable material, the passive elements
104
D and
104
E are formed on a second deformable material, and the center element
102
and the passive elements
104
C and
104
F are formed on a third deformable material. The three deformable materials are joined together using an adhesive or mating vias soldered together to create the deformable union
320
. The antenna array
318
is illustrated in the deployed configuration in FIG.
9
B and in the stowed configuration in FIG.
9
A. In a derivative embodiment, the antenna array
318
does not include the center element
102
, such that the six antenna elements surrounding the deformable union
320
operate as an antenna phased array.
In the various embodiments discussed herein, for optimum antenna performance each of the passive elements
104
A through
104
F must be oriented at a specified angle or range of angles with respect to each other and the center element
102
(in those embodiments where a center element is present). This can be accomplished by mounting the antenna array on a base surface (not shown) and placing marks or mechanical stops on the base surface to ensure that each of the passive elements
104
A through
104
F is deployed to the correct position. Alternatively, if the antenna array is mounted within a case or enclosure, various mechanical structures or stops can be incorporated into the enclosure so that in the deployed orientation, each of the passive elements
104
A through
104
F is situated at the optimum position.
FIGS. 10A and 10B
illustrate another embodiment of the present invention, that is an antenna array
350
including four elements
352
,
354
,
356
and
358
each formed on a rigid dielectric substrate. As can be seen, the antenna elements
352
and
354
are formed on individual deformable substrates and joined by deformable material
360
. Similarly, the antenna elements
356
and
358
are formed on individual sheets and joined by material
362
. The deformable materials
360
and
362
are joined at a junction
364
. As discussed above, vias can be utilized to create the junction
364
or the materials can be joined by an adhesive process.
FIG. 10B
illustrates the antenna array
350
in a stowed configuration.
FIG. 11
illustrates the deployed state of an antenna array
370
comprising four elements
372
,
374
,
376
and
378
disposed on flexible or deformable material and joined at a junction
380
. Conventionally, since the antenna arrays
350
(Figures
10
A and
10
B) and
370
(
FIG. 11
) lack a center element, they operate as phased array antennas for scanning the antenna beam as desired.
FIGS. 12A and 12B
illustrate a five element antenna array
390
including elements
392
,
394
,
396
,
398
and
400
. In the
FIG. 12A and 12B
embodiment the elements
392
through
400
are disposed on a rigid dielectric substrate and joined at a deformable union. As can be seen, the antenna elements
392
and
400
are formed on individual dielectric substrates and joined by deformable material
402
. The elements
394
and
396
are also formed separately and joined by deformable material
400
. Finally, the element
398
includes a joining surface
406
. The deformable materials
402
and
404
and the joining surface
406
are mated and attached either adhesively or through mating vias as discussed above. The antenna array
390
is shown in the folded or stowed configuration in FIG.
12
B.
FIG. 13
illustrates an antenna array
410
having five elements
412
,
414
,
416
,
418
and
420
disposed on flexible or deformable material. In particular, the antenna elements
412
and
420
are disposed on a single sheet of deformable material and the antenna elements
414
and
416
are likewise disposed on a sheet of single material. The antenna element
418
is disposed on a single sheet of deformable material. As can be seen, the elements
412
through
420
are then joined at a mating junction
422
created by adhesively connecting or soldered vias as discussed above. In another embodiment (not shown) a center element can be disposed on the same deformable material as the antenna element
418
.
An antenna array
430
is illustrated in the deployed configuration in FIG.
14
A and the folded or stowed configuration in FIG.
14
B. The antenna array
430
includes antenna elements
432
,
434
,
436
,
438
,
440
and
442
. The antenna elements are joined in a center hub
443
using the soldered vias or adhesive techniques discribed above. The antenna array
430
includes radii
444
on each side of the element
432
and the element
438
. As shown in
FIG. 14B
, the use of the radii
444
provides a more compact stowed configuration as each of the remaining elements
434
,
436
,
440
, and
442
fit within the radii
444
.
A five element antenna array
450
, including a center element is shown in
FIGS. 15A and 15B
. Radial elements
452
,
454
,
456
and
458
are spaced apart from a center element
460
. The elements
452
,
454
,
456
and
458
in one embodiment are disposed on a flexible or deformable material
462
(not shown in FIG.
15
A), while in another embodiment, the elements
452
,
454
,
456
and
458
are disposed on a rigid dielectric substrate and attached to deformable material
462
. The various sheets of deformable material
462
are joined at the center element
460
using the same techniques discussed above in conjunction with FIG.
2
. The antenna array
450
is illustrated in the folded configuration in FIG.
15
B.
FIGS. 16A and 16B
illustrate another embodiment of the antenna array
450
, including an additional antenna element
451
. Thus the antenna array
450
as illustrated in
FIGS. 16A and 16B
is a five element array. Due to the odd number of elements, one of the elements, specifically, the element
451
is disposed singly on a rigid dielectric material, which is in turn mated with the deformable material
462
, and joined to the other two pairs of elements and to the center element
460
as shown in FIG.
16
A. The techniques for attaching the elements
451
,
452
,
454
,
456
and
458
at the center element
450
are discussed above.
FIG. 16B
illustrates the antenna array
450
wherein the five elements are shown in the folded or stowed configuration.
FIGS. 17A and 17B
illustrate an antenna array having seven elements including radial elements
482
,
484
,
486
,
488
,
490
and
492
and a center element
494
. In one embodiment as shown, the radial elements
482
and
484
are disposed on a rigid dielectric material and joined by way of a sheet of deformable material
496
. The radial elements
488
and
490
are likewise constructed and joined by way of a sheet of deformable material
497
. In both cases, the radial elements can be disposed on the rigid dielectric material by printing or etching. The radial elements
486
and
492
and the center element
494
are disposed on a rigid dielectric substrate
498
. The deformable sheets
496
and
497
are attached to the center element
494
by way of vias, an adhesive or a mechanical fastener as discussed above. The antenna array
480
is shown in the folded or stowed configuration in FIG.
17
B. In another embodiment (not shown) the radial elements
482
,
484
,
486
,
488
,
490
and
492
are disposed on flexible or deformable material and joined as shown.
The teachings of the present invention have been described in conjunction with various antenna arrays having an active center element and a plurality of radial elements spaced apart therefrom, or having only a plurality of spaced apart radial elements operation as conventional phased arrays or digital beam formers. In a first such embodiment, the antenna array comprises a plurality of active or passive elements, including a single active element at the center and a plurality of radially spaced apart active or passive elements deformably joined to the center active element. In another embodiment, each of the radial elements is joined to one or more other radial elements at the central intersecting point. Control signals and radio frequency signals are input to or received from the various antenna embodiments through an interface (similar to the interface
125
of
FIG. 2
) affixed to the intersecting point of the plurality of antenna elements. Various devices and techniques are known and available for attaching the antenna elements to the center element or to a center point if the center element is absent. Included among these devices and techniques are solderable vias, adhesives, and mechanical fasteners as discussed above.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalent elements may be substituted for the elements of the invention without departing from the scope thereof. The scope of the present invention further includes any combination of the elements from the various embodiments set forth herein. In addition, modifications may be made to adapt a particular situation to the teachings of the present invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this intention, but that the invention will include all other constructions falling within the scope of the appended claims.
Claims
- 1. An antenna array comprising:an active element; a plurality of controllable passive elements, each one comprising: a dielectric substrate having a first and a second portion; a conductive surface disposed on said first portion of said dielectric substrate; wherein said second portion of said dielectric substrate comprises a connecting arm substantially perpendicular to said first portion; wherein the distal end of said connecting arm is joined to said active element so as to form a deformable union therebetween.
- 2. The antenna array of claim 1 wherein the deformable union allows the plurality of controllable passive elements to be oriented in a deployable configuration spaced apart from each other, and in a stowed configuration proximate to each other.
- 3. The antenna array of claim 1 wherein the dielectric substrate is formed from a deformable material.
- 4. The antenna array of claim 3 wherein the dielectric substrate is formed from a material selected from among: mylar, Kapton and polyimide.
- 5. The antenna array of claim 3 wherein each one of the plurality of connecting arms further comprises a first mating element, and wherein the active element further comprises a second mating element, and wherein the deformable union is formed by joining said first and said second mating elements.
- 6. The antenna array of claim 5 wherein the first and the second mating elements are first and second solderable vias and wherein the deformable union is formed by soldering the first and the second solderable vias.
- 7. The antenna array of claim 6 wherein the first solderable vias are connected to first conductive traces disposed on at least one of the plurality of connecting arms, and wherein the second solderable vias are connected to second conductive traces disposed on the active element, such that said first conductive traces and said second conductive traces are interconnected.
- 8. The antenna array of claim 1 wherein the dielectric substrate material is formed from a rigid material and wherein the dielectric substrate further comprises a deformable material affixed to the distal end of the connecting arm, and wherein said deformable material is affixed to the active element to form the deformable union.
- 9. The antenna array of claim 1 wherein each one of the plurality of connecting arms comprises a conductive trace disposed thereon for carrying signals.
- 10. The antenna array of claim 1 wherein the active element is disposed on a dielectric substrate, and wherein the distal end of each one of the connecting arms is joined to said dielectric substrate to form the deformable union therebetween.
- 11. The antenna array of claim 1 wherein each one of said plurality of conductive surfaces includes an upper conductive segment, a lower conductive segment, and a switch interposed therebetween for controlling the coupling between said upper and said lower conductive segments.
- 12. The antenna array of claim 11 wherein the switch comprises a semiconductor device.
- 13. The antenna array of claim 12 wherein the switch further comprises a first reactance element in series with the switch when in the closed position and a second reactance element to which the switch connects when in the open position.
- 14. The antenna array of claim 11 wherein the switch comprises a microelectromechanical system structure.
- 15. The antenna array of claim 11 wherein the switch controllably connects the upper conductive segment to the lower conductive segment such that each one of the controllable passive elements operates in a reflective mode, and wherein the controllable passive element otherwise operates in a directive mode.
- 16. The antenna array of claim 1 wherein the dielectric substrate is a printable dielectric and wherein the conductive surface disposed on each one of the plurality of dielectric substrates is printed thereon.
- 17. The antenna array of claim 1 wherein the dielectric substrate comprises a copper clad dielectric substrate, and wherein the conductive surface disposed on each one of the plurality of dielectric substrates is formed by etching portions of the copper cladding.
- 18. The antenna array of claim 1 wherein two of the plurality of controllable passive elements are formed on a dielectric substrate having a deformable joint therebetween, and wherein said deformable joint is affixed to the active element.
- 19. The antenna array of claim 1 wherein the plurality of controllable passive elements comprise four passive elements, and wherein each one of the four controllable passive elements is located at the corner of a rectangle in the deployed orientation of the antenna array.
- 20. The antenna array of claim 1 wherein the plurality of controllable passive elements comprise five passive elements, and wherein said five passive elements are oriented at the equidistant points of a five-sided star when the antenna array is in the deployed orientation.
- 21. The antenna array of claim 1 wherein the plurality of controllable passive elements comprises three passive elements, oriented at the vertices of an equilateral triangle when the antenna array is in the deployed orientation.
- 22. The antenna array of claim 1 wherein the plurality of controllable passive elements comprises six passive elements, and wherein said six passive elements are situated at the midpoints of the sides of a hexagon when the antenna array is oriented in the deployable condition.
- 23. An antenna array comprising:a first dielectric substrate; a conductive element disposed on said first dielectric substrate; a plurality of radial elements spaced at a distance from said conductive element and oriented approximately parallel to said conductive element, wherein each one of said plurality of radial elements comprises: a second dielectric substrate; a conductive element disposed on said second dielectric substrate; an interconnecting arm substantially perpendicular to said second dielectric substrate; wherein the free end of each of said plurality of interconnecting arms is deformably joined to said first dielectric substrate.
- 24. The antenna array of claim 23 wherein the second dielectric substrate is deformable.
- 25. The antenna array of claim 23 wherein the conductive element disposed on the first dielectric substrate transmits radio frequency signals provided thereto or receives radio signals directed there toward, and wherein the plurality of conductive elements disposed on the like plurality of second dielectric substrates cooperate with the conductive element disposed on the first dielectric substrate.
- 26. The antenna array of claim 23 wherein at least one of the plurality of radial elements operates as a directive element.
- 27. The antenna array of claim 23 wherein at least one of the plurality of radial elements operates as a reflective element.
- 28. The antenna array of claim 23 wherein the plurality of conductive elements disposed on the like plurality of second dielectric substrates include an upper conductive segment and a lower conductive segment, wherein the upper conductive segment is controllably operated in either a reflective or a directive mode as determined by the electrical connectivity between the upper conductive segment and the lower conductive segment.
- 29. The antenna array of claim 28 wherein the electrical connectivity between the upper conductive segment and the lower conductive segment is determined by the position of a switching device interposed between the upper conductive segment and the lower conductive segment.
- 30. The antenna array of claim 28 wherein the lower conductive segment is grounded.
- 31. The antenna array of claim 23 wherein each one of the plurality of second dielectric substrates and each one of the like plurality of interconnecting arms form a single unified surface.
- 32. An antenna array comprising:a center element; a plurality of controllable passive elements spaced radially about said center element and oriented approximately parallel thereto; wherein at least one of said plurality of controllable passive elements and said center element are formed on a single substrate; and wherein each one of the remaining plurality of controllable passive elements is joined to said center element via a deformable union.
- 33. The antenna array of claim 32 wherein each one of the remaining plurality of passive elements comprises a first portion having conductive material disposed thereon and a second portion extending perpendicularly from said first portion, and wherein the free end of said second portion is deformably joined to the center element.
- 34. The antenna array of claim 33 wherein the conductive material disposed on the first portion includes an upper conductive segment and a lower conductive segment, and wherein the electrical connectivity between said upper conductive segment and said lower conductive segment determines the operational characteristics of the passive element.
- 35. The antenna array of claim 32 wherein the deformable union allows the plurality of controllable passive elements to be oriented in a deployable configuration spaced apart from each other, and in a stowed configuration.
- 36. (Once amended) An antenna array comprising:a dielectric substrate center antenna element disposed on said dielectric substrate; at least one additional element disposed on said dielectric substrate and spaced apart from said center element; two spaced-apart elements joined by a deformable member there between; and wherein said deformable member is joined to said center element such that said two spaced-apart elements are deformable with respect to said center element.
- 37. (Once amended) An antenna array comprising:first and second antenna elements formed on a first H-shaped dielectric substrate; third and fourth antenna elements formed on a second H-shaped dielectric substrate; wherein the horizontal bar of said first and second H-shaped dielectric substrates are joined so as to form a deformable union therebetween; and wherein each one of the plurality of the antenna elements comprises a conductive surface for receiving and transmitting radio frequency energy.
- 38. (Once amended) The antenna array of claim 37 wherein the first and second H-shaped dielectric substrates are formed from a deformable material.
- 39. (Once amended) An antenna array comprising:a plurality of antenna elements spaced radially about and parallel to a center axis and joined to form a rotationally deformable union at said center axis ; and wherein said rotationally deformable union allows the plurality antenna elements to be oriented in a deployable configuration spaced apart from each other, and in a stowed configuration proximate to each other, by rotation about said center axis.
US Referenced Citations (7)