Patent Publication Number: US-2002011953-A1

Title: Wide beamwidth antenna

Description:
FIELD OF THE INVENTION  
       [0001] The present invention pertains to antenna systems, and more particularly, to patch antenna systems.  
       BACKGROUND OF THE INVENTION  
       [0002] Wireless communication systems most often utilize a series of transceivers installed on a building wall, utility pole or other structure. In order to transmit and receive signals, these transceivers require an antenna. Commonly, the antennas are directly connected to the transceiver housing through a bulkhead connector. Antennas directly connected to a transceiver housing are typically small, omni-directional antennas. Alternately, stand alone antennas can be mounted at a remote location and are connected to a transceiver through an extended cable. The physical size of stand alone antennas generally reduces their applicability to small transceivers, particularly when the transceivers are intended to be mounted to the sides of buildings or on top of a utility pole. The aesthetic impact of such obtrusive antennas further detracts from their applicability in a residential or congested area where zoning regulations may prevent the use of larger structures.  
       [0003] Patch antennas, a type of microstrip structure, are another type of antenna used in transceivers. Patch antennas are partially formed from a thin sheet of low-loss insulating material, called a dielectric substrate. In addition to its electrical characteristics, the substrate often forms the structural base of the patch antenna. To complete the antenna structure, the dielectric substrate is covered with metal on one side, (the ground plane), and is partially metalized on the other side, where the patch antenna pattern is printed or otherwise formed. The substrate typically serves two purposes. First, it may act as a mechanical backbone by providing a stable support for the other antenna elements. Second, the substrate fulfills an electrical function by concentrating electromagnetic fields and preventing unwanted radiation in the associated circuits. The permittivity and thickness of the dielectric substrate affects the electrical characteristics of the antenna.  
       [0004] The coverage that an antenna achieves is determined in large part by the geometry of the radiating element or elements. A microstrip patch antenna in particular, may have a gain within the 5-6 dB range and exhibit a 3-dB beamwidth between 70° and 90° (See FIGS. 8 and 9 for these and other plane definitions). Applications which require wide beam patterns, such as mobile and personnel communication systems, usually benefit from a patch antenna arrangement utilizing a single radiating element. When a narrower beamwidth is required or a more directive antenna is needed, a number of identically radiating elements may be grouped together to form a periodic array providing a higher degree of directivity. The selection of a particular shape for the radiating element usually depends on the parameters one wishes to optimize. Rectangular patches are commonly used to realize microstrip patch antennas in wireless communication systems due to the wide beamwidth and large coverage area of the radiation pattern.  
       [0005] In general, antennas interact with objects that are placed close to them and must usually be mounted at a sufficient distance from walls or at the top of a tall mast or pole. But since microstrip patch antennas become somewhat shielded by the presence of the ground plane, whatever is placed behind them typically does not significantly affect their operation or the effective radiation pattern. Microstrip patch antennas can normally be mounted directly on the walls of buildings and, due to their relatively low profile and small size, become less conspicuous than other antennas. In the realm of personal wireless communication systems, this feature of microstrip patch antennas is an advantage when transceivers are placed in congested urban areas or in otherwise conspicuous locations.  
       [0006] The bandwidth of a microstrip patch antenna can also be increased by the use of parasitic elements (dipoles) next to or otherwise in close proximity to the main radiating element. Parasitic elements are excited through a capacitive coupling to the main radiating element.  
       [0007] Particularly in wireless communication systems, the integration of a patch antenna system into a transceiver enclosure is of particular importance. U.S. patent application Ser. No. 09/316,459 entitled “Radiating Enclosure”, and Ser. No. 09/316,457 entitled “Capacitive Signal Coupling Device”, both filed on May 21, 1999, describe preferred embodiments of such an integrated antenna system. The entirety of these disclosures are hereby incorporated into the present application by reference.  
       [0008] In the personal communications industry, the PCS (1850 MHz-1990 MHz) and the DCS (1710 MHz-1880 MHz) ranges, require an antenna system which is optimized for performance in these ranges. Thus, what is needed is an antenna system integrated into the transceiver housing while simultaneously meeting the performance requirements for coverage and impedance match, low gain and wide beamwidth hemispherical coverage in the PCS and DCS frequency ranges.  
       SUMMARY OF THE INVENTION  
       [0009] The present invention allows for integration of an antenna in a transceiver housing while providing wide beamwidth and hemispherical coverage. An antenna constructed in accordance with the present invention comprises a substrate and a folded radiating element that defines a resonant cavity.  
       [0010] In a preferred embodiment, the folded radiating element includes a first component oriented at an angle to the substrate and a second component oriented substantially parallel to the plane of the substrate. The second component is spaced a distance from the substrate and the resonant cavity is defined by the substrate and the folded radiating element.  
       [0011] In a further preferred embodiment, a transceiver comprises an enclosure, transceiver circuitry and an antenna constructed in accordance with the present invention. The antenna produces a wide beamwidth and substantially hemispherical radiation pattern suitable for use in PCS and DCS wireless communication systems.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012]FIGS. 1A and 1B are perspective views of a wall or pole mounted transceiver (with the cover open) which incorporates a wide beamwidth folded patch antenna constructed in accordance with the present invention;  
     [0013]FIG. 2 is an exploded perspective view of a wide beamwidth folded patch antenna constructed in accordance with the present invention;  
     [0014]FIG. 3 is a top plan view of the antenna of FIG. 2;  
     [0015]FIG. 4 is a bottom plan view of the antenna of FIG. 2;  
     [0016]FIG. 5 is a cross sectional view of the antenna of FIG. 3, taken at section marks A-A;  
     [0017]FIG. 6 is an exploded perspective view of a folded patch antenna radiating element and its associated mounting flange;  
     [0018]FIGS. 7A and 7B are diagrammatic perspective views of the folded patch antenna element mounted to a substrate;  
     [0019]FIG. 8 is a diagram defining the H-plane and E-plane radiation patterns;  
     [0020]FIG. 9 is a diagram defining the polarized 45°+−45° planes in an antenna radiation pattern;  
     [0021]FIG. 10 shows a preferred embodiment of the substrate of a folded patch antenna constructed in accordance with the present invention;  
     [0022]FIGS. 11A &amp; 11B show a preferred embodiment of the radiating antenna element of a folded patch antenna constructed in accordance with the present invention;  
     [0023]FIGS. 12A &amp; 12B show a preferred embodiment of the parasitic disk of a folded patch antenna constructed in accordance with the present invention;  
     [0024]FIGS. 13A &amp; 13B show a preferred embodiment of the dielectric cylinder of a folded patch antenna constructed in accordance with the present invention;  
     [0025]FIG. 14 is a graph of the E-plane, H-plane, and 3 Db radiation patterns of a wide beamwidth folded patch antenna integrated into a transceiver at a frequency of 1850 MHz.  
     [0026]FIG. 15 is a graph of the E-plane, H-plane, and 3 Db radiation patterns of a wide beamwidth folded patch antenna integrated into a transceiver at a frequency of 1920 MHz.  
     [0027]FIG. 16 is a graph of the E-plane, H-plane, and 3 Db radiation patterns of a wide beamwidth folded patch antenna integrated into a transceiver at a frequency of 2000 MHz.  
     [0028]FIG. 17 is a graph of the −45° plane, +45° plane, and 3 Db radiation patterns of a wide beamwidth folded patch antenna integrated into a transceiver at a frequency of 1850 MHz.  
     [0029]FIG. 18 is a graph of the −45° plane, +45° plane, and 3 Db radiation patterns of a wide beamwidth folded patch antenna integrated into a transceiver at a frequency of 1920 MHz.  
     [0030]FIG. 19 is a graph of the −45° plane, +45° plane, and 3 Db radiation patterns of a wide beamwidth folded patch antenna integrated into a transceiver at a frequency of 2000 MHz. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0031] Structure of the Patch Antenna  
     [0032]FIG. 1A shows a transceiver  10 . The transceiver  10  includes a housing  12 . Preferably, the housing  12  is formed from a cover  14  and a container  16 . The cover  14  is preferably hinged to the container  16  for quick and simple access to the contents of the container  16 . In FIG. 1, the housing  12  is shown with the cover  14  opened in order to illustrate several of the various components mounted within the transceiver  10 . The cover  14  can also be attached by clamps  18  or a similar fastening device that would ensure that the components mounted within the transceiver  10  are not exposed to adverse environmental conditions such as moisture, dirt or oil. A gasket seal  20  may also be incorporated into the cover  14  or the container  16  in order to further ensure that the cover  14  forms a tight seal with the container  16  and that the components within the transceiver  10  are adequately protected.  
     [0033] The transceiver  10  is a self contained unit designed to provide a wireless link between a ground based communication device, such as a phone or a computer network, and a base station (not shown) such as a GSM base station. The transceiver  10  includes circuitry  21  as well as an antenna system  100 . The antenna system  100  is attached to the cover  14  and is connected to the circuitry  21  via a cable  23 . Preferably, the transceiver  10  is mounted to the side of a building or on top of a tall pole in close proximity to the area it provides service to.  
     [0034] The transceiver  10  is connected to an external power supply via a power cable  22 . Data is transferred to and from the transceiver  10  via an appropriate data cable  24 . Preferably, the data cable  24  is a coaxial cable.  
     [0035]FIG. 1B shows the transceiver  10  with the antenna system  100  incorporated into the container  16 , rather than in the cover  14 .  
     [0036] In operation, the transceiver  10  acts like a wireless phone or pager. Upon activation, the transceiver  10  establishes a link to a base station. The base station in turn routes the signal through either a land line based system or a satellite based system to a local public switched telephone network (PSTN) or another data distribution network. From the PSTN the signal is routed to the intended recipient. The intended recipient can be either a land line based customer or another wireless customer. The transceiver  10  provides a wireless link from a network or private phone line to the PSTN and eliminates the need for a lengthy network of land lines to connect many individual customers to the PSTN. Alternately, the transceiver  10  is itself a base station and communicates directly with a PSTN.  
     [0037] When installed, the transceiver  10  is hard wired into a home or business via the cable  24  and the power cable  22 . Alternately, the transceiver  10  can receive power from an independent battery pack or other rechargeable power supply mounted in close proximity to the transceiver  10  or incorporated into the transceiver itself. The transceiver  10  is also preferably formatted to include features such as remote meter reading and programming capabilities. The details of such a programmable transceiver can be found in Lyon &amp; Lyon docket No. 243/150, entitled “Data Terminal Apparatus”, the entirety of which is incorporated by reference into this disclosure.  
     [0038] In order to complete the functionality of the transceiver  10 , an antenna  100  is incorporated into its structure. Since the transceiver  10  is preferably mounted on a wall or pole, certain characteristics of the antenna  100  must be maintained in order to allow efficient communication with the base station or network which it communicates with. In particular, the radiation pattern produced by the antenna system must be formatted to transmit and receive information efficiently while taking into account the location where the transceiver may be mounted, as well as the design of the transceiver itself. Most notably, when mounted against a large flat surface, the transceiver antenna must provide a hemispherical radiation pattern which maximizes radiation in the directions away from the mounting surface. Similarly, the antenna design should minimize the radiation directed toward the mounting surface. FIGS.  14 - 19  illustrate the radiation patterns associated with a preferred embodiment of a wide beamwidth folded patch antenna system constructed in accordance with the present invention.  
     [0039] FIGS.  2 - 5  show a wide beamwidth folded patch antenna  100  constructed in accordance with the present invention. An antenna element  120  is formed into a folded shape. The radiating portion of the antenna element  120  is substantially L shaped and includes a first radiating component  122  and a second radiating component  124 . Preferably, the antenna element  120  also includes a mounting flange  126  attached to a distal edge of the first radiating component  122 . The mounting flange  126  allows the entire antenna element  120  to be connected to another surface. The two radiating components  122  and  124 , along with the mounting flange  126  together form a folded or “step” shaped element. The mounting flange  126  is for electrically grounding the radiating components  122  and  124  to a ground plane  150  and for mechanically attaching and aligning the radiating components  122  and  124  to a substrate  140 . The mounting flange  126  includes at least one aperture  128 , but two or more apertures  128  are preferred in order to more effectively align the radiating element  120  prior to connecting it to the groundplane  150 . Each of the apertures  128  are adapted to receive screws, rivets, bolts, or another type of suitable fastening device. In addition to using the apertures  128  to attach the antenna element to the ground plane, the mounting flange is also preferably soldered to the groundplane in order to ensure that a consistent electrical ground is maintained.  
     [0040]FIG. 6 illustrates in more detail, the construction and orientation of the antenna components, including the first radiating component  122 , the second radiating component  124 , and the mounting flange  126 . The first radiating component  122  is preferably a thin rectangular element formed from a metallic material such as copper, silver, gold, or another material which is conducive to antenna applications. The first radiating component  122  has a first lengthwise edge  122 - a  and a second lengthwise edge  122 - b,  consistent with the geometry of a rectangle. The first radiating component  122  is positioned so that the first lengthwise edge  122 - a  is in contact with or otherwise attached to a first lengthwise edge  126 - a  of the mounting flange  126 . When attached to the mounting flange  126 , the first radiating component  122  projects away from and is substantially perpendicular to the mounting flange  126 .  
     [0041] The second radiating component  124  is also preferably a thin rectangular element formed from a metallic material such as copper, silver, gold, or another material which is conducive to antenna applications. The second radiating component  124  has a first lengthwise edge  124 - a  and a second lengthwise edge  124 - b,  consistent with the geometry of a rectangle. The second radiating component  124  is positioned so that the first lengthwise edge  124 - a  is in contact with or otherwise attached to the second lengthwise edge  122 - b  of the first radiating component  122 . When attached to the first radiating component  122 , the second radiating component  124  projects away from and is substantially perpendicular to the first radiating component  122 . The second radiating component  124  is spaced from and is substantially parallel to the substrate  140 .  
     [0042] The entire antenna element  120 , including the first radiating component  122 , the second radiating component  124 , and the mounting flange  126 , thereby forms a step shaped element where the step has two “landings”, represented by the mounting flange  126  and the second radiating component  124 , connected by a single “riser”, represented by the first radiating component  122 . When taken individually, the radiating components  122  and  124  form a substantially “L” shaped element.  
     [0043] Preferably, the step-shaped antenna element  120  is a unitary piece formed from a single piece of material. Mechanically joining the mounting flange  126 , the first radiating component  122  and the second radiating component  124  is therefore unnecessary during manufacturing. If formed separately, each of the antenna elements are preferably welded or soldered together so that a uniform and consistent connection is maintained.  
     [0044] Referring again to FIG. 2, the substrate  140  forms the structural base of the wide beamwidth folded patch antenna  100 . The substrate  140  plays a dual role. Electrically it is part of the transmission lines, circuits, and antenna. Mechanically, it supports the structure of the antenna. The construction of the substrate must therefore satisfy both electrical and mechanical requirements. The relevant electrical properties of the substrate are the relative permittivity ε r , the substrate thickness h, and the dielectric loss factor tan δ. In antenna applications, it is important to keep a constant permittivity across the substrate, as well as a uniform thickness. The dielectric losses of the substrate must be as small as possible in order to ensure a high circuit performance and a good overall efficiency. Typically tan δ should be smaller than 0.002.  
     [0045] Physically, the substrate must have a large enough mechanical resistance, a good shape stability, and an expansion factor close to that of the metal used for the conductors and ground plane. It should withstand high temperatures during soldering and present a smooth and flat surface to reduce losses. Many materials are commercially available for forming such substrates including alumina (Al 2 O 3 ), beryllia (BeO), teflon, polypropylene, silicon, and ferrite.  
     [0046] The substrate  140  has an first surface  144  (See FIG. 2)and a second surface  146  (See FIG. 4). A portion of the first substrate surface  144  is coated with the metalized ground plane layer  150 . Apertures  152  extend through both the ground plane layer  150  and the substrate  140 . The apertures  152  are adapted to receive a fastening device such as a screw, rivet or bolt. When positioned on the first surface  144  of the substrate  140 , the apertures  128  of the mounting flange  126  align with the apertures  152 , allowing the elements to be aligned and securely connected together with a mechanical fastening device. The elements can also be soldered together. The substrate  140  also includes additional apertures  142  which are similarly adapted to receive a fastening device. The apertures  142  allow a standoff  190  (described below) to be secured to the substrate  140 .  
     [0047] The metal ground plane layer deposited on the substrate must have a very low resistivity (small ohmic losses), a sufficient thickness, a good solderability, and a good adhesion to the substrate  140 . The metalized material must be resistant to oxidation during soldering processes and suitable for different contact making and bonding techniques. These requirements typically limit the choice of the metal to copper, silver, gold, and maybe aluminum. Certain other synthetic materials are also commercially available.  
     [0048] With the antenna element  120  mounted to the substrate  140 , a resonant cavity  220  is defined. More particularly, the resonant cavity  220  is the volume of space bordered by the second radiating component  124  on one side, bordered by the first radiating component  122  on a second side, and bordered by the substrate  140  or ground plane  150  on a third side. The remaining three sides of the resonant cavity  220  are open ended and do not have a solid surface defining their boundaries. The resonant cavity  220  is the volume of space within this region. FIGS. 7A and 7B further define the resonant cavity  220 , the open ended borders of which are represented by dashed lines. In operation, the maximum radiation occurs at the open end which is opposite to the first radiating component  122 . Secondary radiation occurs from the other two open sides.  
     [0049] Referring again to FIGS.  2 - 5  and located within the resonant cavity  220 , several additional antenna elements are present. These include a dielectric cylinder  160 , a parasitic element  170  and a pin  180 . The dielectric cylinder  160  includes a first dielectric surface  163 , a second dielectric surface  161 , and a passage  162  through its longitudinal axis. The dielectric cylinder  160  is positioned so that the passage  162  is aligned with an aperture  154  which extends through both the ground plane  150  and the substrate  140 . The parasitic element  170  is preferably wafer shaped, similar to that of a thin disk, and is positioned on the second dielectric surface  161 . The parasitic element  170  includes an aperture  172  extending through its longitudinal axis. When the parasitic element  170  is centrally mounted on the second dielectric surface  161 , the aperture  172  aligns with the cylinder passage  162  as well as the aperture  154 . The pin  180  extends though each of the parasitic disk aperture  172 , the dielectric cylinder passage  162  and the aperture  154 . On a first end  181  of the pin  180  is a thickening or ridge  182 . When the pin  180  is inserted through the passage  162 , aperture  172  and aperture  154 , the ridge  182  prevents the pin  180  from moving any further through the openings. The pin  180  therefore holds both of the dielectric cylinder  160  and the parasitic disk  170  attached to the substrate  140 . A second end  183  of the pin  180  is then soldered or otherwise secured or bonded to the substrate  140 . The parasitic element  170  and the dielectric cylinder  160  are thus permanently fixed to the substrate  140 . The pin  180  serves as a signal feed and connects the antenna elements to a microstrip transmission line  212  located on the second substrate surface  146 .  
     [0050] The location and dimensions of the dielectric cylinder  160 , parasitic disk  170  and pin  180 , in relation to the antenna element  120  are critical factors in the performance characteristics of the folded patch antenna  100 . A preferred embodiment of the folded patch antenna elements is shown in FIGS.  10 - 13 . All dimensions in FIGS.  10 - 13  are in inches.  
     [0051] A coaxial cable  200  provides a connection between the antenna elements and the transceiver circuitry mounted inside the housing  12 . A copper pad  210  and the microstrip transmission line  212  are located on the second substrate surface  146 . (See FIG. 4). The copper pad  210  and the microstrip transmission line  212  provide electrical connection and mechanical transition from the antenna elements to the coaxial cable  200 . More particularly, copper pad  210  and microstrip transmission line  212  provide a smooth transition from the larger leads of the coaxial cable  200  to the microstrip elements of the circuitry and the patch antenna.  
     [0052] The coaxial cable  200  preferably includes a center conductor  202  and an outer jacket  204 . The outer jacket  204  is soldered to the copper pad  210  which is in turn grounded to the ground plane  150 . The center conductor  202  is soldered to the microstrip transmission line  212 . On the free end of the coaxial cable, a fitting  206  is provided. The fitting  206  is preferably connected to its mate on the radio transceiver circuit board also mounted within the transceiver housing  12  (See FIG. 1A).  
     [0053] A standoff support structure  190  provides a partial enclosure as well as a mounting mechanism for the antenna. The standoff  190  includes apertures  192  which align with the apertures  142  on the substrate  140 . The apertures  192  are adapted to receive a fastening device such as a screw, rivet or bolt. The standoff  192  can therefore be firmly secured to the substrate  140 . Additionally, the standoff  190  includes recesses  194  which allow the standoff and antenna structure to be mounted within the transceiver housing  12  or to the lid  14 . (See FIGS. 1A and 1B).  
     [0054] Radiation Patterns of the Present Invention  
     [0055] Antenna transmission properties are measured according to the radiation patterns generated by the radiating elements. The radiation pattern defines the spatial distribution of the power radiated by the antenna and is normalized with respect to its maximum value. The distribution of the electromagnetic fields in the vicinity of an antenna results from the multiple contributions of the waves excited by the antenna. This distribution can become quite complex, including both radiated waves and local concentrations of the electric and magnetic fields, which give rise to reactive effects. Therefore in the context of the present invention, the combined effects of the transceiver housing  12 , the circuitry within the transceiver  10  and all of the other mechanical and electrical components, each contribute to the overall radiation pattern of the patch antenna. In particular, the size and shape of each of the antenna elements, the spacing between the second radiating component  124  and the ground plane  150 , the spacing between the second radiating component  124  and the cover  14 , and the feed point location, are all critical parameters that need to be customized for each specific application. The size of each of the radiating components  122  and  124 , the ground plane  150 , and the parasitic element  170  are also critical to the specific performance characteristics of the folded patch antenna.  
     [0056] The gain of an antenna, in a given direction, is defined by the ratio of the power radiated by the antenna to that radiated by a hypothetical lossless omni-directional antenna (called an isotropic radiator), which is fed with the same input signal. To determine the gain, one measures the power fed to the transmitting antenna and the power collected by the receiving antenna and then uses the Friis transmission formula:  
       P   r   =P   in   G   t   G   r (λ/4 πR ) 2    
     [0057] where P r  is the received power, P in  is the power fed to the input of the transmitting antenna, G t  is the gain of the transmitting antenna, G r  the gain of the receiving antenna, λ is the free-space wavelength, and R is the distance between the two antennas. The ratio P r /P in  is measured, and since λ and R are known, the product G t G r  can be deduced. Three different possibilities can then be considered:  
     [0058] (1) One may already know the gain of the source antenna, either from previous measurements or because the antenna is a high-accuracy antenna that was originally calibrated in a standards laboratory.  
     [0059] (2) The two antennas used for the measurement are identical, in which case one has G t =G r  and takes the square root of the product.  
     [0060] (3) One has three antennas with unknown gains. The transmission between two of them is measured successively for the three different couples of antennas. The determination of the gains of the three antennas is then straightforward.  
     [0061] The radiation patterns of antennas, particularly patch antennas, are typically measured along a vertical plane (E-plane), along a horizontal plane (H-plane) and along a polarized plane defined as an angle from the vertical (−45°, +45°, etc.). FIGS. 8 and 9 illustrate the definitions of these planes in relation to a folded patch antenna constructed in accordance with the present invention.  
     [0062] As described above, the presence of microelectronics, rigid enclosures, fasteners, solder material and other hardware in the transceiver, each affect the radiation pattern and performance of the antenna. A preferred embodiment of a wide beamwidth folded patch antenna constructed in accordance with the present invention with dimension as described in FIGS.  10 - 13 , achieves the necessary performance requirements for operation in the 1850 MHz-1990 MHz PCS band as well as the 1710 MHz-1880 MHz DCS band. Namely, the coverage and impedance match requirements are met even in the presence of the transceiver and micro-circuitry environment. Additionally, the antenna achieves low gain (4 Db), wide beamwidth hemispherical coverage, and minimal polarization discrimination in the above frequency bands.  
     [0063] FIGS.  10 - 13  show the dimensional details of a printed circuit board (FIG. 10), a folded antenna element (FIGS. 11A and 11B), a parasitic element (FIGS. 12A and 12B), and a cylindrical dielectric element (FIGS. 13A and 13B), in a preferred embodiment, and for use as a PCS transceiver antenna system. The several components of a folded patch antenna constructed in accordance with the present invention were optimized to the dimensions in FIGS.  10 - 13 . All dimensions are shown in inches.  
     [0064] Referring to FIG. 10 the substrate  140  has a length of approximately 3.6 inches and a width of approximately 2.19 inches. Apertures  154 ,  152 , and  142  are also shown in FIG. 10, and particularly their relative locations on the substrate  140 .  
     [0065] Referring to FIGS. 11A and 11B, the preferred dimensions of the antenna element  120  are shown. Apertures  128  are positioned so that they will align with the apertures  152  on the substrate  150 .  
     [0066] Referring to FIGS. 12A and 12B, the preferred dimensions of the parasitic element  170  are shown. The parasitic element  170  is preferably a disk shaped element with a diameter of approximately 0.54 inches, a thickness of approximately 0.031 inches and a central aperture  172  with a diameter of approximately 0.038 inches.  
     [0067] Referring to FIGS. 13A and 13B, the preferred dimensions of the dielectric cylinder  160  are shown. The cylinder  160  preferably has a height of approximately 0.309 inches, a diameter of approximately 0.188 inches. The central passage  162  has a diameter of approximately 0.029 inches.  
     [0068] FIGS.  14 - 19  show the radiation patterns for an assembled transceiver  10  with all of the electronics installed and all mechanical hardware in place, including mounting screws and transmission cables. The radiation patterns shown in FIGS.  14 - 19  correspond to a folded patch antenna system built to the dimensions described in FIGS.  10 - 13 . The radiation patterns are shown for the E-plane, H-plane, −45° polarization and +45° polarization at frequencies of 1850, 1920 and 2000 MHz. In each of the radiation patterns a substantially hemispherical pattern is produced, with little amplitude reduction at the extremities of the antenna elements (i.e. approaching 90° and approaching 270°). This radiation pattern provides the wide beamwidth hemispherical coverage pattern required in transceivers used for PCS and DCS communication systems.  
     [0069] Although the invention has been described and illustrated in the above description and drawings, it is understood that this description is by example only and that different embodiments may be made without departing from the true spirit and scope of the invention. The invention therefore should not be restricted, except within the spirit and scope of the following claims.