Abstract:
A compact single or multiple band antenna assembly for wireless communications devices. One multi-band embodiment includes a high frequency portion and a low frequency portion, both fed at a common point by a single feed line. Both portions may be formed as a single stamped metal part or metallized plastic part. The overall size is suitable for integration within a wireless device such as a cell phone. The low frequency portion consists of two resonant sections which are stagger tuned to achieve a wide resonant bandwidth, thus allowing greater tolerance for manufacturing variations and temperature than a single resonant section, and is useful for single band antennas as well as multi-band antennas where it may be used to enhance bandwidth for both sections of a dual band antenna as well. The resonant sections for single or multi-band antennas operate in conjunction with a second planar conductor, which may be provided by the ground trace portion of the printed wiring board of a wireless communications device. The antenna assembly provides a moderate front-to-back ratio of 3-12 dB and forward gain of +1 to +5 dBi. The front to back ratio reduces the near field toward the user of a hand held wireless communications device, thus reducing SAR (specific absorption rate) of RF energy by the body during transmit. The antenna pattern beamwidth and bandwidth are increased for a handset during normal user operation, as compared to a half wave dipole.

Description:
This application claims the benefit of priority pursuant to 35 U.S.C. §119 of copending PCT application Ser. No. PCT/US00/30428 filed Nov. 4, 2000. 
     PCT application Ser. No. PCT/US00/30428 filed Nov. 4, 2000, claimed the benefit of U.S. Provisional Application No. 60/163,515 filed Nov. 4, 1999. 
     This application is a continuation-in-part application pursuant to 37 C.F.R. 1.53(b) of application Ser. No. 09/374,782, filed Aug. 16, 1999, now U.S. Pat. No. 6,215,447, which was a continuation-in-part of application Ser. No. 09/008,618 filed on Jan. 16, 1998, now U.S. Pat. No. 5,945,954. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an antenna assembly suitable for wireless transmission of analog and/or digital data, and more particularly to a parasitic element antenna assembly for single or multiple band wireless communications devices. 
     BACKGROUND OF THE INVENTION 
     There exists a need for an improved antenna assembly that provides a single and/or dual band response and which can be readily incorporated into a small wireless communications device (WCD). Size restrictions continue to be imposed on the radio components used in products such as portable telephones, personal digital assistants, pagers, etc. For wireless communications devices requiring a dual band response the problem is further complicated. Positioning the antenna assembly within the WCD remains critical to the overall appearance and performance of the device. 
     Known antenna assemblies for wireless communication devices include: 
     1. External single or multi band wire dipole: 
     Features of this antenna includes an external half wave antenna operating over one or more frequency range; a typical gain of +2 dBi; negligible front-to-back ratio; and minimal specific absorption rate (SAR) reduction (SAR 2.7 mw/g typ @ 0.5 watt transmit power level). Multiple band operation is possible with this antenna by including LC (inductor and capacitor) traps used to achieve multi band resonances. 
     2. External single or multi band asymmetric wire dipole: 
     Features of this antenna include an external quarter wave antenna operating over one or more frequency range; typical gain of +2 dBi; and minimal front-to-back ratio and SAR reduction. LC traps may also be used to achieve multi-band resonance. 
     3. Internal single or multi band asymmetric dipole: 
     Features of this antenna include a quarter wave resonant conductor traces, which may be located on a planar printed circuit board; typical gain of +1-2 dBi; slight front-to-back ratio and reduced SAR (2.1 mw/g.). This antenna may include one or more feedpoints for multiple band operation. A second conductor may be necessary for additional band resonance. 
     4. Internal or single multi band PIFA (planar inverted F antenna): 
     Features of this antenn include a single or multiple resonant planar conductor; typical gain of +1.5 dBi; and front-to-back ratio and SAR values being a function of frequency. A dual band PIFA antenna for 824-894/1850-1990 MHz operation may exhibit 2 dB gain and present minimal front-to-back ratio and reduced SAR of 2 mw/g in the lower frequency band. 
     SUMMARY OF THE INVENTION 
     A compact single or multiple band antenna assembly for wireless communications devices is described. One multi-band implementation includes a high frequency portion and a low frequency portion, both fed at a common point by a single feedline. Both portions may be formed as a single stamped metal part or metallized plastic part. The overall size is suitable for integration within a wireless device such as a cellphone. 
     Further, the low frequency portion consists of two resonant sections which are stagger tuned to achieve a wide resonant bandwidth, thus allowing greater tolerance for manufacturing variations and temperature than a single resonant section. This feature is useful for single band antennas as well as multi-band antennas. This feature may also be used to enhance bandwidth for both sections of a dual band antenna as well. 
     The resonant sections for single or multi-band antennas operate in conjunction with a second planar conductor, which may be provided by the ground trace portion of the printed wiring board of a wireless communications device. An antenna assembly so formed provides a moderate front-to-back ratio of 3-12 dB and forward gain of +1 to +5 dBi. The front to back ratio reduces the near field toward the user of a hand held wireless communications device, thus reducing SAR (specific absorption rate) of RF energy by the body during transmit. Antenna pattern beamwidth and bandwidth is increased for a handset during normal user operation, as compared to a half wave dipole. An antenna assembly according to the present invention may provide increase beamwidth when the WCD is near the user head in the talk position, by a factor of 1.5-2. 
     An object of the present invention is thus to satisfy the current trends which demand a reduction in size, weight, and cost for wireless communication devices. 
     Another object of the present invention is the provision of multiple stagger-tuned resonant elements to enhance operational beamwidth and bandwidth, and providing an improved margin for manufacturing tolerances and environmental effects. An improved beamwidth and bandwidth of the handset may translate into improved communication by increasing the number of illuminated cell sites during operation. 
     Another object of the present invention is the provision of an antenna assembly which is extremely compact in size relative to existing antenna assemblies. The antenna assembly may be incorporated internally within a wireless handset. A unique feed system without matching components is employed to couple the antenna to the RF port of the wireless handset. The antenna assembly requires three small-area RF ground lands for mounting, and is effectively a surface mount device (SMD). Beneficially, the antenna assembly may be handled and soldered like any other SMD electronic component. Because the antenna is small, the danger of damage is prevented as there are no external projections out of the WCD&#39;s housing. Additionally, portions of the antenna assembly may be disposed away from the printed wiring board and components thereof, allowing components to be disposed between the antenna assembly and the printed wiring board (PWB). 
     Another object of the present invention is an antenna assembly providing substantially improved electrical performance versus volume ratio, and electrical performance versus cost as compared to known antenna assemblies. Gain of the antenna assembly according to the present invention may be nominally equal to an external ¼ wave wire antenna, with SAR level less than 1.6 mw/g achieved at 0.5 watt input for an internally mounted antenna. The 3 dB beamwidths are significantly higher than a dipole antenna during normal user operation. The performance characteristics are found across a wide range of environmental operating conditions, e.g, at temperatures ranging from −40 to +60 degrees C. 
     Components of the antenna assembly may be manufactured in different ways. It is conceivable for example that the antenna can be formed from a punched or etched sheet. In a preferred embodiment, the antenna may be formed from a single-piece metal stamping adaptable to high volume production. Additionally, capacitor elements may be coupled to the antenna assembly through known high volume production techniques. 
     Another object of the present invention is to provide an antenna assembly having improved operational characteristics, including an increased front-to-back ratio and a decreased specific absorption rate of RF energy to the user of an associated wireless communications device. 
     Accordingly, it is the primary object of the present invention to provide an improved antenna assembly for communications devices including portable cellular telephones and PCS devices with improved directionality, broadband input impedance and increased signal strength. The present invention additionally reduces radio frequency radiation incident to the user&#39;s body and reduces the physical size requirements for a directional antenna assembly used on communications devices. 
     It is still an additional object of the present invention to provide a compact antenna assembly suitable for incorporation within the housing of a portable wireless communication device. The current invention provides compact, discrete antenna assembly without external appendages, such as provided by known external dipole antennas. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention. In the drawings: 
     FIG. 1 is a perspective view of a communication device incorporating an antenna assembly according to the present invention; 
     FIG. 2 is a perspective view of an antenna assembly according to the present invention; 
     FIG. 3 is a perspective view of an antenna assembly according to the present invention; 
     FIG. 4 is a perspective view of another embodiment of an antenna assembly according to the present invention; 
     FIG. 5 is a perspective view of yet another embodiment of an antenna assembly according to the present invention including a dual band antenna circuit with parasitically coupled stagger tuned sections for the lower frequency band, and a single resonant section for the higher frequency band; 
     FIG. 6 is a perspective view of yet another embodiment of an antenna assembly according to the present invention providing sections joined to facilitate construction as a single stamped part; 
     FIG. 7 is a perspective view of yet another embodiment of an antenna assembly according to the present invention; 
     FIG. 8 is a top plan view of an antenna assembly according to the present invention as represented in FIGS. 1-7; 
     FIG. 9 is a side elevational view of the antenna assembly of FIG. 8; 
     FIG. 10 is a perspective view of yet another embodiment of an antenna assembly according to the present invention; 
     FIG. 11 is a perspective view of yet another embodiment of an antenna assembly according to the present invention; 
     FIG. 12 is a perspective view of yet another embodiment of an antenna assembly according to the present invention; 
     FIG. 13 is a perspective view of yet another embodiment of an antenna assembly according to the present invention; 
     FIG. 14 is a perspective view of yet another embodiment of an antenna assembly according to the present invention; 
     FIG. 15 is a perspective view of yet another embodiment of an antenna assembly according to the present invention; and 
     FIG. 16 is a perspective view of a hand-held communications device according to another aspect of the present invention wherein the ground plane element of the antenna assembly is extended into a flip-portion of the communications device. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein like numerals depict like parts throughout, FIG. 1 illustrates a wireless communication device  8 , such as a cellular telephone, utilizing an antenna assembly  10  according to the present invention and operating over the cell band frequency range of 824-894 MHz. The antenna assembly  10  may be disposed within the communication device  8  at the rear panel  14  and proximate the upper portion of the handset (away from a user&#39;s hand), as illustrated in the embodiment of FIG. 1. A first embodiment of an antenna assembly  10  includes a driven conductor element  16  and a parasitic conductor element  18  each disposed relative to a ground plane element  20  of the wireless communication device  8  is illustrated in FIGS. 2 and 3. The ground plane element  20  may be defined as a portion of the printed wiring board (PWB)  22  of the communication device  8 . Driven conductor element  16  includes a conductive surface  24  with first and second leg elements  26 ,  28  and may be a singularly formed metallic member. Driven conductor element  16  may be a metallic chassis made, for example, of copper or a copper alloy. The driven conductor element  16  is approximately “C” shaped when viewed from its side and defines an interior region  30  disposed between the conductive surface  24  and the ground plane element  20 . Components of the communication device  8  may thus be disposed within the interior region  30  to effect a reduction in overall volume of the device. 
     The conductive surface  24  is disposed a predetermined distance above the ground plane element  20  and includes a plurality of sections having different widths for effecting optimal operation over the cell band frequency range (824-894 MHz.). A first rectangular section  32  is approximately 0.42 inch by 0.61 inch in size for a preferred embodiment. A second rectangular section  34  disposed at an upper edge of the first section  32  is approximately 0.1 inch by 0.42 inch in size. A third rectangular section  36  disposed at an upper edge of the second section  34  is approximately 0.2 inch by 0.25 inch in size. A fourth rectangular section  38  disposed at an upper edge of the third section  36  is approximately 0.15 inch by 0.13 inch in size. Other dimensions for a preferred embodiment of the present invention are disclosed in FIGS. 8-9 and Table 1. 
     Conductive surface  24  is electrically or operatively connected at an upper edge of the fourth section  38  to a downwardly-directed, perpendicular first leg element  26  which is shorted to the ground plane  20  at foot  40 . One or more feet  40  may be practicable to provide for stability of the driven element  16  or routing requirements of the printed wiring board  22  of the communication device. Preferably a single foot  40  is utilized to minimize the contact requirements to the ground plane  20  and otherwise minimize physical interference with other components of the printed wiring board  22 . 
     Conductive surface  24  is also coupled at a lower edge of the first section  32  to a downwardly-directed perpendicular second leg element surface  28 . Second leg element  28  includes a ‘T’ shaped profile to minimize the interference with other components of the printed wiring board  22 . Second leg element  28  includes a perpendicular foot  42  for capacitively coupling driven conductor  16  to the ground plane member  20 . One or more feet  42  may be practicable to provide for conductor stability or wire routing requirements of the printed circuit board  22  the communication device. Ground plane element  20  preferably has a minimum length in a direction of polarization ‘DP’ of approximately one-quarter wavelength (for a wavelength within the range of operation). Reference may be made to FIG. 16, wherein an approach to extending the ground plane member  20  of a small hand-held communication device is provided. Driven conductor element  16  may be a single metallic formed element having a thickness within the range of 0.005 to 0.09 inch. 
     Second leg element  28  includes a foot  42  which defines one side or plate of a two plate capacitor  46 . Foot  42  is spaced away from the ground plane element  20  by a dielectric element  48  so as to form a capacitor. Dielectric element  48  may have a dielectric constant of between 1-10, and preferably approximately 3.0. 
     The parasitic element  18  of antenna assembly includes a ‘C’-shaped element which is spaced away from the driven element  16 . Parasitic element  18  includes a conductive portion  50  with first and second leg portions  52 ,  54 . The conductive leg portions  50 ,  52 ,  54  of the parasitic element are substantially parallel with and correspond to conductive surfaces and the first and second leg elements  24 ,  26 ,  28  of the driven element  16 . Parasitic element  18  is supported above ground plane  20  by the second leg portion  54  which is capacitively coupled to the ground plane  20  via foot  56  and dielectric member  58 . As with the foot  42  and the dielectric element  48  of the driven element  16  forming a two plate capacitor  46 , the foot  56  and the dielectric element  58  of the parasitic element  18  form a two plate capacitor  60 . The parasitic element  18  is further supported by a first leg portion  52  which is electrically or operatively connected to the ground plane element  20  via foot  40 . Note that the parasitic element  18  includes an interior region  68  similar to the interior region  30  of the driven element. 
     FIG. 4 illustrates another embodiment of an antenna assembly  10  according to the present invention. The driven element  16  and the parasitic element  18  are coupled together via a coupling element  62 . The coupling element  62  includes a foot  64  for operatively coupling both the driven element  16  and the parasitic element  18  to the ground plane  20  of the communication device. The driven element  16 , parasitic element  18 , and coupling element  62  may be formed from as a single metal part and be fabricated, for example, using high-speed metal stamping processes. In this manner, a compact antenna assembly is provided which is suitable for incorporation within efficient, high volume production of communication devices. The antenna element may thus be utilized in conjunction with surface mount device (SMD) production techniques. 
     FIG. 5 illustrates another embodiment of an antenna assembly according to the present invention. The antenna of FIG. 5 optimally operates over a pair of frequency ranges, for example, such as cell band (824-894 MHz.) and PCS band (1850-1990 MHz.) ranges. Operation over a higher frequency range is attained by addition of an extension element  66  to the driven conductor element  16 . Preferably, extension element  66  is disposed at a left side edge of the third portion  36  of the driven element  16 . Dimensions of the extension element  66 , which are sized to effectuate resonance at the higher frequency range, are provided in FIG.  8  and Table 1. 
     FIG. 6 illustrates another embodiment of an antenna assembly according to the present invention. Similarly to FIG. 4, the driven element  16 , parasitic element  18 , and coupling element  62  are formed as a single unit and operatively connected to the ground plane member  20  at a single ground location via foot  64 . 
     FIG. 7 illustrates yet another embodiment of an antenna assembly according to the present invention. The driven element  16 , parasitic element  18 , and coupling element  62  are disposed upon a dielectric block or substrate  72 . The driven element  16 , parasitic element  18 , and coupling element  62  may be a metal deposition upon the dielectric substrate  72  or formed using other known metal deposition or metal etching processes as those skilled in the relevant arts may appreciate. 
     FIGS. 8 and 9, in conjunction with Table 1, disclose dimensions for preferred embodiments of an antenna assembly according to the present invention. 
     FIG. 10 illustrates another embodiment of an antenna assembly according to the present invention, in particular a dual band antenna assembly suitable for operation over the cell band (824-894 MHz.) and PCS band (1850-1990 MHz.) frequency ranges. This antenna assembly includes low frequency and high frequency driven elements  16 ,  17  and low frequency and high frequency parasitic elements  18 ,  19 , and for example, all elements being formed as a single stamped metal part. A coupling element  62  operatively connects the driven elements  16 ,  17  to the parasitic elements  18 ,  19  and is formed as a portion of the stamped metal part. Coupling element  62  is, in turn, operatively connected to the ground plane member  20  of the communication device  8  at an upper edge thereof. Low frequency driven element  16 , low frequency parasitic element  18 , and high frequency parasitic element  19  are each defined by a substantially rectangular planar top surface  74 ,  76 ,  78 . The top surfaces  74 ,  76 ,  78  are substantially co-planar. The high frequency driven element  17  is defined by a substantially rectangular element  80  disposed at a side of the low frequency driven element  16  and downwardly angled toward a foot  82 . Foot  82  is disposed upon a dielectric element  84  to capacitively couple the high frequency driven element  17  to the ground plane member  20  of the communication device. Dielectric member  84  may be a {fraction (1/32)} inch thickness dielectric substrate having a dielectric constant between 1 and 10, and preferably about 3.0. Dielectric member  84  may be a dielectric substrate such as used for printed circuit boards, having a dielectric constant in the range of 1-10, or dielectric member  84  may be a chip capacitor. 
     Low frequency driven element  16  and low frequency parasitic element  18  are each operatively coupled at one end to the ground plane member  20  of the communication device via a capacitive coupling  86 ,  88  defined between a foot member  90 ,  92  and the ground plane  20 . A dielectric element  94  may be disposed within each capacitive coupling  86 ,  88 . In comparison, high frequency parasitic element  19  includes a free end. 
     The antenna assembly of FIG. 10 includes a feed point  12  at which a single conductor from the communication device may be coupled thereto. Operation at alternative frequency ranges may be practicable utilizing the concepts of this embodiment by scaling the relevant dimensions provided herein as those skilled in the arts will appreciate. 
     FIG. 11 illustrates another embodiment a multiple band antenna assembly of the present invention. Driven element  16  is coupled at feed point  12  to the communication device via a single conductor. Driven element  16  is approximately ‘C’ shaped when view in profile and includes a top planar surface including the feed point  12 , a first leg element  26  operatively connected near the upper edge of the ground plane element  20  of the printed wiring board via foot member  40 , and a second leg element  28  capacitively coupled to the ground plane element  20  via foot  92  and capacitor element  94 . A parasitic element  18  is disposed relative the driven element  16  and is similarly shaped. Parasitic element  18  is directly or operatively connected at one end near the upper edge of the ground plane element  20 , and capacitively coupled at another end to the ground plane element  20 . A perpendicular coupling section  98  is disposed between the driven element  16  and the low frequency parasitic element  18 . Coupling section  98  is capacitively coupled to the driven element  16  and the low frequency parasitic element  18  via capacitor elements  96 . The dielectric constant of the capacitor elements  96  may range from 1 (air) to approximately 10. 
     Antenna assembly of FIG. 11 further includes a high frequency parasitic element  19  directly or operatively connected at one end to the ground plane element  20  of the telecommunication device. High frequency parasitic element  19  may be a conductive wire element having a nominal 0.05 inch thickness and including an upper portion substantially aligned with the conductive surface and conductive portion  24 , 50 , respectively, of the driven element  16  and low frequency parasitic element  18 . Note that high frequency parasitic element  19  is angled relative to the low frequency parasitic element  18  by an angle “α” of between approximately 5-25 degrees. 
     FIG. 12 illustrates yet another embodiment of an antenna assembly  10  according to the present invention. The low frequency driven element  16  is directly or operatively connected at a first end to an upper portion  102  of the printed wiring board  22 , and at a lower portion  104  of the printed wiring board  22  through capacitive coupler  86 , and at feed point  12 . Low frequency driven element  16  includes a top planar surface  106  including first and second portions  108 ,  110 , the first portion  108  defined by a substantially rectangular area and the second portion  110  defined by a relatively smaller rectangular area. Feed point  12  is disposed within the second portion  110  of the top planar surface  106 . High frequency driven element  80  is directly coupled at an edge of the low frequency driven element  16  (at the second portion  110 ) and is capacitively coupled at the other end to the ground plane  20  of the printed wiring board via foot element  82  and dielectric element  84 . High frequency parasitic element  19 , which is defined by a substantially rectangular area, is also capacitively coupled to the ground plane member  20  through common foot element  82  and dielectric element  84 . 
     Still referring to FIG. 12, the low frequency parasitic element  18 , which is disposed on the opposite side of the low frequency driven element  16 , is capacitively coupled at a first end to the ground plane element  20  of the printed wiring board and at the opposite end to a coupling element  62  directly connected to the ground plane element  20 . Low frequency parasitic element  18  includes a top planar surface  112  having a plurality of portions defined by varying width dimension. Coupling element  62  electrically connects the low frequency parasitic element  18  to the low frequency driven element  16 . 
     FIG. 13 illustrates yet another embodiment of an antenna assembly  10  according to the present invention. The driven element  16  is directly or operatively connected at a first end to an upper portion  102  of the printed wiring board  22 , and at a lower portion  104  of the printed wiring board  22  through capacitive coupler  86 . The driven element  16  includes a top planar surface including first and second portions  108 ,  110 , the first portion  108  defined by a substantially rectangular area and the second portion  110  defined by a relatively smaller rectangular area. Driven element  16  further includes a downwardly directed conductive surface  16   a  which is coupled at a lower foot surface to a feed point  12 . Operation over a higher frequency range is attained by addition of an extension element  66  to the driven conductor element  16 . Preferably, extension element  66  is disposed at a side edge away from the parasitic element  18 . Extension element  66  includes a downwardly directed conductive surface  66   a  which is coupled at a lower foot surface to the feed point  12 . The feed point  12  is preferably disposed a predetermined distance above the surface of the printed wiring board  22 . The foot surface defining the feedpoint  12  is illustrated as a planar surface, though alternatively, the pair of downwardly directed surfaces  16   a ,  66   a  could be joined without the planar foot surface. 
     Still referring to FIG. 13, the parasitic element  18 , which is disposed on the side of the driven element  16  opposite the extension element  66 , is capacitively coupled at a first end to the ground plane element  20  of the printed wiring board  22  and at the opposite end to a coupling element  62  directly connected to the ground plane element  20 . Parasitic element  18  includes a top planar surface having a plurality of portions defined by varying width dimension. Coupling element  62  electrically connects the parasitic element  18  to the low frequency driven element  16 . 
     Referring now to FIG. 14, another embodiment of an antenna assembly according to the present invention is provided. A dual band antenna includes a driven element  16  for the lower frequency band and a high frequency driven element  17  disposed away therefrom. The high frequency and low frequency driven elements  16 ,  17  are each defined by substantially planar rectangular portions which are coupled via a conductive spacer portion  114 . A feed point  12  is provided between the driven elements  16 ,  17  and a signal conductor from the printed wiring board  22 . A low frequency parasitic element  18  is disposed further away from the low frequency driven element  16  as indicated. 
     FIG. 15 illustrates another preferred embodiment of an antenna assembly according to the present invention wherein the driven elements  16 ,  17  and the parasitic element  18  are disposed upon an upper major surface  118  of a dielectric block element  120 . The driven elements  16 ,  17  and parasitic element  18  may be made as metal depositions upon the dielectric block or otherwise patterned from a plated dielectric stock material. Dielectric block element  120  has a dielectric constant of between 1 and 10, and more preferably approximately 3.0. The dielectric block  120  is supported a distance away from the printed wiring board  22  of the communication device by conductive spacer elements  124 . The spacer elements  124  additionally operatively or directly connect the driven elements  16 ,  17  and parasitic elements  19  to the ground plane member  22  at attachment points  134 . Low frequency driven element  16  and the parasitic element  18  are each capacitively coupled at respective ends to the ground plane  20 . Note that bottom plate elements  126  are disposed upon the opposite major surface  128  of the dielectric substrate  120  and are electrically coupled to the ground plane member  20  via truncated conductive spacer elements  124 . A tuner element  130  is disposed at one end of high frequency driven element  17  and may be adjusted relative to the ground plane element  20  to adjust the resonant frequency of the higher frequency antenna. 
     FIG. 16 illustrates another aspect of the present invention which provides for an extended ground plane element  140  for use in conjunction with the antenna assemblies disclosed herein. The overall length of the ground plane member  20 ,  140  (the electrical length) is preferably greater than one-quarter wavelength for a preselected wavelength in the operational frequency band. Applicants have determined that the electrical length of the ground plane  20 ,  140  in large part determines the gain of the antenna assembly. One limitation of smaller hand held communication devices is that the ground plane  20 ,  140  has an electrical length which is less than optimal. For communication devices having a lower flip panel portion  142 , the ground plane length  20 ,  140  may be extended by coupling a conductive panel  144  of the flip panel portion  142  to the main ground plane  20  of the printed wiring board  22 . The conductive panel  144  may be a separate conductor element or a conductive layer disposed upon an existing surface of the flip panel portion  142 . The coupling device  146  may be selected from among a group of known electrical coupling techniques as appreciated by those skilled in the relevant arts. 
     Particular dimensions for preferred embodiments according to the present invention are included as Table 1. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Dimension 
                 Inch 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 i. 
                 1.600 
               
               
                   
                 j. 
                 1.260 
               
               
                   
                 k. 
                 .925 
               
               
                   
                 l. 
                 .775 
               
               
                   
                 m. 
                 .725 
               
               
                   
                 n. 
                 .400 
               
               
                   
                 o. 
                 .200 
               
               
                   
                 p. 
                 .395 
               
               
                   
                 q. 
                 .200 
               
               
                   
                 r. 
                 1.330 
               
               
                   
                 s. 
                 .100 
               
               
                   
                 t. 
                 .640 
               
               
                   
                 u. 
                 .420 
               
               
                   
                 v. 
                 .360 
               
               
                   
                 w. 
                 .610 
               
               
                   
                 x. 
                 .530 
               
               
                   
                 y. 
                 .950 
               
               
                   
                 z. 
                 1.080 
               
               
                   
                 AA. 
                 1.200 
               
               
                   
                   
               
             
          
         
       
     
     In operation and use the antenna assemblies according to the present invention are extremely efficient and effective. The antenna assemblies provide improved directivity, broadband input impedance, increased signal strength, and increased battery life. The antenna of the present invention reduces radio frequency radiation incident to the user&#39;s body, and reduces the physical size requirements of directional antenna used in cell phone handsets, PCS devices and the like. The disclosed antenna also increases front-to-back ratios, reduces multipath interference, and is easily integrated into the rear panel portion of a cellular transceiver device to minimizes the risk of damage or interference. Additionally, beamwidth and bandwidth enhancement in the direction away from the user is achieved particularly when the antenna assembly is used in conjunction with hand-held wireless communication devices. Beamwidths of 1.5-2 times greater than for a dipole antenna have been recognized. 
     Additional advantages and modification will readily occur to those skilled in the art. The invention in its broader aspects is, therefore, not limited to the specific details, representative apparatus and illustrative examples shown and described. Accordingly, departures from such details may be made without departing from the spirit or scope of the applicant&#39;s general inventive concept.