Abstract:
An antenna array includes a dielectric substrate comprising an integral center hub including a pivotal center section therein, and a pivotal wings extending radially from the integral center hub. An active antenna element is on the pivotal center section of the integral center hub, and passive antenna elements are on the pivotal wings. The active antenna element and the passive antenna elements are pivotal between a stored position and an operational position. The active antenna element and the passive antenna elements are substantially planar when in the stored position, and are substantially perpendicular to the integral center hub when in the operational position.

Description:
RELATED APPLICATION 
   This application is a continuation of U.S. application Ser. No. 10/288,256 filed Nov. 4, 2002 now U.S. Pat. No. 6,774,852 which is a continuation-in-part of a U.S. application Ser. No. 09/852,598 filed May 10, 2001 now U.S. Pat. No. 6,476,773. The entire teachings of the above applications are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   This invention relates to mobile or portable cellular communication systems, and more particularly to a compact configurable 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 wireless Bluetooth standard. All such wireless communications techniques require the use of an antenna at both the receiving and transmitting site. It is well-known by experts in the field that increasing the antenna gain in any wireless communication system has beneficial affects. 
   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 antenna 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 antenna to the base station. Forward link signals received by the subscriber unit antenna 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 employed by mobile subscriber units is described in U.S. Pat. No. 5,617,102. The directional antenna comprises two elements which are 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 available to 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 signal input to each antenna element. However, phased array antennas suffer decreased efficiency and gain as the element spacing becomes electrically small 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 device housing or enclosure. For example, cellular telephone handsets 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 case. A separate 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, they are generally in the form of protrusions from the communications device, except for a patch antenna. 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 change it&#39;s 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 transmitted from and received by the communications device satisfy pre-determined operational limits, 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 achieve 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. If the antenna is a half-wave dipole, the length 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 relatively 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 from 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, the receiver receives two versions of the same radio frequency (RF) signal: 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 or completely 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 can 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 received antenna and is then reflected back to the intended receiver from the opposite direction as the signal received directly from the source, then a 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 adjoin 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&#39;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 edge of a cell typically transmit at higher power levels so that their transmitted signal 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 on 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&#39;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 base station, it may not be able to properly differentiate a signal transmitted from within its cell from a signal transmitted from the adjacent cell. A mechanism is required to reduce the subscriber unit antenna&#39;s apparent field of view, which can have a marked effect on the operation of the forward link (base to subscriber) by reducing the apparent number of interfering transmissions received at a base station. A similar mechanism is needed for the forward link, to improve the received signal quality at the subscriber unit. 
   In summary, in wireless communications technology, it is of utmost importance to maximize antenna performance while minimizing size and manufacturing complexity. The present invention addresses these needs. 
   BRIEF DESCRIPTION OF THE PRESENT INVENTION 
   An integral low profile directional antenna comprises a plurality of elongated antenna arms extending radially from an integral center hub wherein the antenna arms are deformably foldable upwardly into a substantially perpendicular orientation from the center hub to form a directional antenna array. The antenna further comprises a center arm extending from the integral center hub. For storage and transportation, the low profile directional antenna is compactly retractable by deforming the elongated arms into the plane of the integral center hub. The antenna arms and the integral center hub are formed from a homogeneous deformable material, by die cutting, for example, thereby avoiding the need for a separate hinged or pivotal joint for attaching the antenna arms to the integral center hub. The homogeneous deformable material simplifies manufacturing of the antenna and installation into the antenna enclosure. 
   In one embodiment, the low profile directional antenna includes five elongated arms and a center arm, all of which are cut from a single sheet of deformable material. Each of these six elements is deformable from an orientation where all elements are in a single plane, into an active or deployed configuration where each element is bent upwardly to form an approximately 90 degree angle with the center hub. Fabricating the antenna from a single sheet avoids all gluing, soldering, etc. operations that are otherwise required to connect the various elements to form the antenna. Also, there are no joints to be created since a deformable material is used. Conductive traces, ground planes, radiating structures, vias, etc. are disposed on the deformable material or on parallel layers bonded above or below the deformable material. These conductive components are produced on the deformable material by an etching or printing process. The fabrication parts count is low (there is only one piece part) and thus labor costs are minimized through fabrication of all the antenna elements from the single part. 
   Further, the deformable material can include conductive traces disposed thereon for interconnecting microelectronic elements mounted onto homogeneous material surface. An external interface connects the microelectronic elements to a power source and to the communications device. By forming the electronic antenna elements on the deformable, homogeneous surface, a large electrical aperture is formed when the antenna is deployed, yet the antenna presents a low profile, compact package in the closed or stowed configuration. 

   
     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 typical communications cell. 
       FIGS. 2 ,  3  and  4  illustrate views of an antenna embodiment constructed according to the teachings of the present invention. 
       FIGS. 5 ,  6  and  7  illustrate cross sectional views of the embodiments of the antennas of  FIGS. 2 ,  3  and  4 . 
       FIGS. 8 ,  9  and  10  depict antenna enclosures constructed according to the teachings of the present invention where the antenna elements are illustrated in both deployed and stored configurations. 
       FIG. 11  illustrates the mechanism for integrating the radial wings of  FIG. 2  into the enclosure  FIG. 8 . 
       FIG. 12A  is an exploded view of the enclosures of  FIGS. 8 ,  9  and  10 . 
       FIG. 12B  illustrates an alternate arrangement of the ground plane. 
       FIG. 13  illustrates an antenna constructed according to the teachings of the present invention in a deployed configuration and without the surrounding enclosure of  FIG. 8 . 
   

   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 base station  65 . Each subscriber unit  60  is equipped with an antenna  70 , which may be constructed according to the present invention. The subscriber units  60  are provided with wireless data and/or voice services by the system operator, through which devices such as, for example, laptop computers, portable computers, personal digital assistants (PDAs) or the like can be connected to the 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 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  may be 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) transmitted 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 from the base station  65 , the antenna apparatus  70  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 outwardly 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 unit  60  to the base station  65 . 
     FIG. 2  illustrates an antenna array  120  formed on and fabricated from a single dielectric substrate of flexible or deformable material  122 . The components of the antenna array  120 , to be discussed further hereinbelow, are formed by cutting or stamping a blank sheet of the dielectric substrate material in the pattern of  FIG. 2 . Cutting the dielectric material forms a plurality of radial wings  126  (five radial wings as shown in  FIG. 2  are merely exemplary) and a center element  130 . In another embodiment wherein the antenna array  120  operates as a phased array, the center element  130  is not present. Each of the radial wings  126  and the center element  130  extend from a center hub  128 . As shown, the radial wings  126  extend from the circumference of the center hub  128  and the center element  130  extends from approximately the center of the center hub  128 . When the radial wings  126  and the center element  130  are fabricated from the dielectric sheet, a gap in the dielectric substrate  122  is formed between adjacent radial wings, and a gap is formed on each side of the center element  130 . In  FIG. 2 , a ground plane  132  is located below the dielectric substrate  122 . Since in the exemplary embodiment of  FIG. 2  the ground plane  132  has a diameter slightly larger than the diameter of the center hub  128 , the ground plane  132  is visible through the gaps. 
   In  FIG. 2 , the radial wings  126 , the center element  130  and the center hub  128  are illustrated in a stored or flat configuration. That is, the radial wings  126 , the center element  130  and the center hub  128  are in the same plane. In the operational mode, each of the radial wings  126  is deformed upwardly with respect to the center hub  128  along a fold line  134  in the deformable material of the dielectric substrate  122 . The center element  130  is similarly deformed upwardly along a fold line  135 . In one embodiment the fold lines  134  and  135  merely represent the line along which the respective element is folded due to the deformable property of the dielectric substrate  122 . In another embodiment, the fold line represents a perforation line or zipper holes included to enhance the foldability or flexural properties (i.e., allowing deformation of the joint without exceeding the stress limits of the joint) of the antenna elements. 
   Conductive elements  136  are formed on each of the radial wings  126 . A conductive element  137  is formed on the center element  130 . In one embodiment the interacting elements are formed on both the front and back surfaces of the radial wings  126  and the center element  130 . As will be discussed herein below, in one embodiment the conductive element  137  is an active element for sending or receiving a signal, and the conductive elements  136  are configured as either reflective elements or directive elements with respect to the received or transmitted signal. The shape of the conductive elements  136  and  137  as shown in  FIG. 2  is merely exemplary. In another embodiment, the conductive elements  136  are monopole antennas, which are selectably coupled to or decoupled from the ground plane  132  to effectuate the directive and reflective properties. A switch not shown in  FIG. 2  controls this connectivity between the conductive elements  136  and the ground plane  132 . The switch can be implemented with a junction diode, a MOSFET, a bipolar junction transistor or a MEMS (microelectronics machine structure) switch. 
   The antenna of  FIG. 2  is enclosed within a housing for use in conjunction with a communications device. Thus, the shape and dimensions of an operative antenna and its constituent elements depend on the desired antenna performance characteristics (e.g., operational frequency, input impedance, gain, bandwidth) and the dimensions and shape of the preferred housing. Additionally, if the housing dimensions dictate a certain maximum conductive element dimension, an element width, for example, then it may be necessary to increase another conductive element dimension to compensate for the restraint on the other dimension. Not only are the dimensions of the conductive elements affected by these parameters, but the actual shape employed must also take these factors into consideration. 
   Note in the  FIG. 2  embodiment, that a segment  138  of the conductive elements  136  may extend onto the center hub  128  and thus is intersected by the center hub circumference and the fold line  138 . Similarly, a segment  139  of the conductive element  137  extend beyond the fold line  135  onto the center hub  128 . The segments  138  and  139  are flexible or deformable to avoid breaking or splintering of the conductive material when the conductive elements  136  and  137  are folded or deformed. The segments  138  and  139  are connected to vias (not shown in  FIG. 2 ) within the center hub  128 . These vias contact conductive traces (not shown in  FIG. 2 ) running along the lower or upper surface or in a buried layer of the center hub  128 . Certain traces requiring connection to an external device terminate in an interface  141 . The conductive traces and vias carry power, control and RF signals for the elements of the antenna array  120  and also interconnect electronics components (not shown in  FIG. 2 ) mounted on the top or bottom surface of the center hub  128 , on one or more of the radial wings  126  or on the center element  130 . The interface  141  connects to external components (via a connector not shown) for supplying electrical power, control signals, the transmitted signal in the transmit mode and the received signal in the receive mode. Further, the switches for providing the connectivity to the ground plane  132  as discussed above, constitute such electronics components. 
   The conductive elements  136  and  137  are formed of a conductive material and disposed on the dielectric substrate  122  by printing or etching. In one embodiment the dielectric substrate  122  comprises mylar or Kapton with a copper surface disposed thereon. The conductive elements  136  and  137  comprise copper patterns formed by etching the copper from the mylar or Kapton substrate. Alternatively, conductive ink or epoxy can be used to print the conductive elements  136  and  137  on a dielectric substrate. 
     FIG. 3  is a side view of the antenna array  120 , showing in particular two radial wings  126  and the center hub  128 . The ground plane  132  is also visible. Note that in this embodiment the ground plane  132  extends beyond the circumference of the center hub  128 . Such is not a requirement of the present invention. 
     FIG. 4  is a bottom view of the antenna array  120 , and in this embodiment there is included a substrate  150  patterned for accepting electronics components  151  for operation in conjunction with the conductive elements  136  and  137 . Traces  152  and vias  153 , for interconnecting the conductive elements  136  and  137 , the electronics components  151  and the interface  141 , as shown on the bottom surface of the substrate  150 , are merely examples. 
     FIG. 4  also depicts conductive elements  154  on the rear surface of each radial wing  126 . A conductive element  155  is disposed on the rear surface of the center element  130 . Neither the conductive elements  154  and  155  are required in certain embodiments. The conductive elements  154  operate in cooperation with the conductive elements  136  (either conductively or inductively coupled thereto) to serve either a reflective or directive function with respect to the received or transmitted signal. For example, in one embodiment the conductive elements  154  form a transmission line for feeding the conductive elements  136 , e.g., a sleeve dipole antenna. Similarly, the conductive element  155  operates in conjunction with the conductive element  137  (both located on the center element  130 ). Recall that the center element  130  serves as an active element of the antenna array  120 , but is unnecessary when the antenna array operates in a phased array mode, wherein the phase of the input signal to each of the conductive elements  136 / 154  is controllable to steer the antenna beam. 
     FIG. 5  is a side view of the various layers discussed in conjunction with  FIGS. 2 ,  3  and  4 . The layers are shown in exaggerated form for clarity. The ground plane  132  is positioned below the dielectric substrate  122 , and the substrate  150  is oriented below and surrounding the ground plane  132 . Note that the ground plane  132  extends slightly beyond the circumference of the center hub  128 .  FIG. 5  also illustrates exemplary traces  157  and vias  158  in the dielectric substrate  122  and the substrate  150  for providing electrical connectivity among the conductive elements  136 ,  137 ,  154  and  155 , the electronics components  151  and the interface  141 . It is also recognized that some form of insulation must be provided between the traces  157  and the ground  132  and further that additional traces not in the plane of  FIG. 5  are disposed on the dielectric substrate  122 . The traces  157  are typically constructed from the flex-circuit conductive material consistent with the deformable characteristics of the dielectric substrate. 
     FIG. 6  illustrates another embodiment excluding the substrate  150 . In this embodiment, the microelectronics component  151  are mounted on the dielectric substrate  122  preferably within the center hub  128 . The traces  157  and the vias  158  provide a conductive path from the segments  138  and  139  of the conductive elements  136  and  137 , respectively, to the various microelectronic components  151  and are also in conductive communication with the conductive elements  154  and  155 . (See  FIG. 4 ). In another embodiment, the traces  157  are disposed on the top surface of the dielectric substrate  122  or on both the top and bottom surfaces thereof. Generally, with respect to all of the embodiments described herein, the copper surfaces are encapsulated with a protective dielectric material to seal the surfaces against exposure to the elements. Techniques for accomplishing this are well known in the art. 
     FIG. 7  illustrates an additional embodiment for forming the various parallel layers of the antenna array  120 . In particular, a dielectric substrate  180  is formed with flexible conductive traces  182  (referred to as flex circuit) on both top and bottom surfaces thereof. Vias  184  connect the conductive traces  182  as required to carry signals to and from the antenna array  120  via the interface  141  and further between the microelectronic components  151  and the conductive elements  136 ,  137 ,  154  and  155 . In a region  188  the dielectric substrate  180  is thickened. This thickened region can coincide with the location of the radial wings  126  and the center element  130  to provide the deformable joint with greater durability. A dielectric substrate  190  is situated above the dielectric substrate  180  and a dielectric substrate  192  is situated below the dielectric substrate  180 . The dielectric substrates  190  and  192  are also formed of rigid or deformable material. However, if the dielectric substrates  190  and  192  are located so as to not interfere with the fold lines  135  and  138  (see  FIG. 2 ) then the dielectric substrates  190  and  192  can be formed of a rigid material. Although not shown in  FIG. 7 , a ground plane can be disposed below the dielectric substrate  192 . 
   Instead of creating the radial wings  126  and the center element  130  from a single dielectric sheet, as discussed above, in another embodiment of the present invention the antenna elements are separately formed and joined. In one embodiment, the radial wings  126  and the center element  130  are formed from a flexural or deformable material and joined to the center hub  128  by an adhesive joint. Alternatively, the radial wings  126  and the center element  130  can be joined to the center hub  128  by first forming solderable vias in each of the mating elements. The two piece parts are brought into contact with each other and then the vias soldered to create a junction therebetween. Since in this embodiment the radial wings  126  and the center element  130  are formed from a deformable material, the radial wings  126  and the center element  130  can be deformed along the fold lines  135  and  138 , as indicated in  FIG. 2 . Alternatively, either or both of the radial wings  126  (and the center element  130 ) and the center hub  128  can be formed of a rigid material and joined by interposing a piece of deformable or pivotable material therebetween. The fold lines  135  and  138  are therefore formed in the joining material. For example, the radial wings  122  and the center element  130  can be formed from a rigid dielectric material, and joined to the center hub  128  with a piece of deformable material affixed to each radial wing  126  and to the center hub  128  (by gluing, for example). The center element  130  is similarly affixed to the center hub  128 . In this embodiment, the center hub  128  can be constructed from a rigid material, printed circuit board material, for example, or from a flexible or deformable material. As an alternative to using an adhesive to join the radial wings  126  and the center element  130  to the center hub  128 , solderable vias can be disposed on each of the two mating flexible surfaces. The two piece parts are mated and the vias soldered to create a deformable junction between the two pieces. 
   In one embodiment of the present invention the conductive elements  136 ,  137 ,  154  and  155  are disposed on opposite sides of the dielectric substrate  122  (by printing or etching, for example). A second layer of deformable material (typically the same material used to form the dielectric substrate  122 ) is then laminated over both the bottom and top surfaces of the dielectric substrate  122  to form a multi-layer substrate with the various conductive elements disposed between the dielectric layers, thereby protecting the conductive surfaces. 
   In one operational mode, the conductive center element  137  (in conjunction with conductive element  155 ) transmits and receives radio frequency signals, while the conductive elements  136  (operating in conjunction with the conductive elements  154 ) serve either as reflectors or directors. The effective length of each of the conductive elements  136  is controllable to achieve a reflective mode by making the effective length longer than the resonant length so that energy incident on the conductive element  136  is reflected back toward the source. In a directive mode (when the effective length is less than the resonant length) the conductive element  136  is essentially invisible to the radio frequency signal. In this way, the radiating pattern from the active element  132  can be steered or directed to a specific sector of a 360 degree azimuth circle. In another operative embodiment, the conductive elements  136  and  154  on each of the radial wings  126  operate as a phased array wherein the phase angle of the signal input to each antenna element is controllable to steer the antenna beam. The center element  130  is absent in the phased array mode 
   The antenna array  120  constructed according to the teachings of the present invention is relatively easy to manufacture using low-cost components and few assembly steps. The reduced number of processing operations during assembly results in higher repeatability and product yields, and lower cost. The use of a single sheet of a deformable dielectric substrate for the antenna elements avoids the formation of separate mechanical joints, and provides a compact stored configuration and a fully functional operable configuration by simply folding the center element  130  and the radial wings  126  into their operative vertical positions. 
   One exemplary housing  198  for packaging the antenna array  120  is illustrated in  FIG. 8  where the individual radial elements  126  and the center element  128  are encased within a plastic or dielectric frame  200  that mates with respective recesses  202  in a base  204 . As is known to those skilled in the art, there are several plastic materials suitable for forming the housing  198 , for example, Lexan, polypropylene, polycarbonate and ABS plastic. Each of the dielectric frames  200  enclosing a radial wing  126  further comprises a lip  208  for mating with respective recesses  210  formed in the edge  212  of the base  204 . The center element  127  is enclosed within a dielectric frame  216 . The dielectric frame  216  mates with a recess  220  within the base  204 . For optimum operation of the antenna array  120 , the radial wings  126  and the center element  130  must be folded or rotated upwardly to form a predetermined angle with the base  204 . In one embodiment, this angle is 90 degrees. To ensure the radial wings  126  and the center element  130  are placed into the optimum angle, a stop position is built into the housing  198 . The stop position is controlled by the mating or abutting surfaces between the dielectric frames  200  and  216  and the base  204  when in the operational mode. 
     FIG. 9  shows the dielectric frames  200  in a closed or recessed position within the base  204 .  FIG. 10  is a side view of the base  204 , wherein the dielectric frames  200  are again shown in the stored position. Note the low profile offered by an antenna constructed according to the teachings of the present invention, especially suitable for portable communications equipment. The dielectric frames  200  and their associated radial wings  126  and the dielectric frame  216  and its associated center element  130  are easily deployed to provide advantageous directional characteristics and a large electrical antenna aperture for the communications device. 
     FIG. 11  illustrates a dielectric frame  200 , which includes a top outer cover  230  and a lower captivation cover  232 . The radial wing  126  extends through an opening in the lower portion of the dielectric frame  200  and extends upwardly adjacent the top outer cover  230 . Once the radial wing  126  is in place, the lower captivation cover  232  is attached to the top outer cover  230  by, for example, an adhesive, a plastic snap or an ultrasonic welding process. Although not shown in  FIG. 11 , the lower captivation cover  232  in one embodiment includes a boss for mating with a hole in the top outer cover  230 . The boss further protrudes through a hole in the radial wing  126 , holding the radial wing  126  in a fixed position with respect to the top outer cover  230  and the lower captivation cover  232 . The dielectric frame  200  rotates downwardly to fit within the recess  202 , which is also illustrated in  FIG. 8 . This rotational movement occurs about a pivot point placed within the area shown generally by reference character  238 . Those skilled in the art recognize that there are several pivot mechanisms that can be employed in the present invention. One such pivot technique utilizes a plastic rod or axle placed within the area  238  and mating with receiving holes in the base  204 . The center element  127  is fitted within the dielectric frame  216  in a similar fashion. 
     FIG. 12A  is an exploded view of the housing  198  of  FIG. 8 , including the various elements of the present invention as discussed above. The dielectric substrate  122  is separately assembled and the radial wings passed through one or more openings in the dielectric frames  200  as shown in  FIG. 11 . The dielectric frames  200  are then pivotably mounted within the base  204  (as also discussed in conjunction with  FIG. 11 ) and the base  204  is fixedly attached to a base  249  by snaps or screws  254 . The  FIG. 11  embodiment also includes a base plate. 
     FIG. 12B  is a view similar to that of  FIG. 12A  but showing an alternate type of ground plane. Here, the ground plane is not simply a disk  132  as previously described. Rather, in this embodiment, the ground plane consists of a number of fingers  132 - 1  that extend outwardly from the central hub  128 . The fingers are positioned radailly about the hub in approximately the same position as the radiating elements  126 . In a preferred embodiment, there are the same number of fingers  132 - 1  as there are radial wings  126 , and each fingers are of a same general shape as one of the radial wings  126 . 
   In this embodiment, when the conductive elements  136  are monopole antennas, they are typically each coupled to or decoupled from a respective one of the ground plane fingers  132 - 1  to effectuate the directive and reflective properties. 
     FIG. 13  is another illustration of certain elements illustrated in  FIGS. 2 and 13 . However, in the  FIG. 13  orientation the radial wings  126  and the center element  130  are folded upwardly into an upright or approximately vertical position for operation. Otherwise, the radial wings  126  and the center element  130  are deformable into a substantially planner stowed or folded configuration, as shown in  FIG. 12 . 
   While the invention has been described with references 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.