Patent Publication Number: US-2013249768-A1

Title: Multi-band monopole antennas for mobile communications devices

Description:
INTRODUCTION 
     This invention relates generally to the field of multi-band monopole internal and external antennas. More specifically, multi-band monopole antennas are provided that are particularly well-suited for use in mobile communications devices, such as Personal Digital Assistants, cellular telephones, and pagers. 
     BACKGROUND 
     Multi-band antenna structures for use in a mobile communications device are known in this art. For example, one type of antenna structure that is commonly utilized as an internally-mounted antenna for a mobile communication device is known as an “inverted-F” antenna. When mounted inside a mobile communications device, an antenna is often subject to problematic amounts of electromagnetic interference from other metallic objects within the mobile communications device, particularly from the ground plane. An inverted-F antenna has been shown to perform adequately as an internally mounted antenna, compared to other known antenna structures. Inverted-F antennas, however, are typically bandwidth-limited, and thus may not be well suited for bandwidth intensive applications. An example of an antenna structure that is used as an externally mounted antenna for a mobile communication device is known as a space-filling or grid dimension antenna. External mounting reduces the amount of electromagnetic interference from other metal objects within the mobile communication device. 
     SUMMARY 
     Antennas for use in mobile communication devices are disclosed. The antennas disclosed can include a substrate with a base, a top, a front side and a back side; a first conductor can be located on the first side of the antenna substrate; and a second conductor can be located on the second side of the antenna substrate. The conductors can have single or multiple branches. If a conductor is a singe branch it can, for example, be a spiral conductor or a conducting plate. If a conductor has multiple branches, each branch can be set up to receive a different frequency band. A conductor with multiple branches can have a linear branch and a space-filling or grid dimension branch. A conducting plate can act as a parasitic reflector plane to tune or partially tune the resonant frequency of another conductor. The first and second conductors can be electrically connected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of an exemplary multi-band monopole antenna for a mobile communications device; 
         FIG. 2  is a top view of an exemplary multi-band monopole antenna including one alternative space-filling geometry; 
         FIGS. 3-9  illustrate several alternative multi-band monopole antenna configurations; 
         FIG. 10  is a top view of the exemplary multi-band monopole antenna of  FIG. 1  coupled to a circuit board for a mobile communications device; 
         FIG. 11  shows an exemplary mounting structure for securing a multi-band monopole antenna within a mobile communications device; 
         FIG. 12  is an exploded view of an exemplary clamshell-type cellular telephone having a multi-band monopole antenna; 
         FIG. 13  is an exploded view of an exemplary candy-bar-style cellular telephone having a multi-band monopole antenna; and 
         FIG. 14  is an exploded view of an exemplary personal digital assistant (PDA) having a multi-band monopole antenna. 
         FIG. 15  shows one example of a space-filling curve; 
         FIGS. 16-19  illustrate an exemplary two-dimensional antenna geometry forming a grid dimension curve; 
         FIG. 20   a  is a perspective view of a double-sided, double-surface antenna with two spiral conductors in the absence of a substrate. 
         FIG. 20   b  is a front view of a double-sided, double-surface antenna with two spiral conductors with a substrate. 
         FIG. 20   c  is a back view of a double-sided, double-surface antenna with two spiral conductors with a substrate. 
         FIG. 21   a  is a perspective view of a double-sided, double-surface antenna with a dual branched conductor and a conducting plate in the absence of a substrate. 
         FIG. 21   b  is a front view of a double-sided, double-surface antenna with a dual branched conductor and a conducting plate with a substrate. 
         FIG. 21   c  is a back view of a double-sided, double-surface antenna with a dual branched conductor and a conducting plate with a substrate. 
         FIG. 22   a  is a front view of a Rogers-type double-sided, double-surface antenna showing a Hilbert-like space-filling conductor. 
         FIG. 22   b  is a back view of a Rogers-type double-sided, double-surface antenna showing a parasitic plate reflector. 
         FIG. 23   a  is a front view of a double-sided, double-surface antenna showing a modified Hilbert-like space-filling conductor. 
         FIG. 23   b  is a back view of a double-sided, double-surface antenna showing a parasitic plate reflector. 
         FIG. 24  is an example of an external antenna housing that might be fitted with one of the described antennas. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawing figures,  FIG. 1  is a top view of an exemplary multi-band monopole antenna  10  for a mobile communications device. The multi-band monopole antenna  10  includes a first radiating arm  12  and a second radiating arm  14  that are both coupled to a feeding port  17  through a common conductor  16 . The antenna  10  also includes a substrate material  18  on which the antenna structure  12 ,  14 ,  16  is fabricated, such as a dielectric substrate, a flex-film substrate, or some other type of suitable substrate material. The antenna structure  12 ,  14 ,  16  is preferably patterned from a conductive material, such as a metallic thick-film paste that is printed and cured on the substrate material  18 , but may alternatively be fabricated using other known fabrication techniques. 
     The first radiating arm  12  includes a meandering section  20  and an extended section  22 . The meandering section  20  is coupled to and extends away from the common conductor  16 . The extended section  22  is contiguous with the meandering section  20  and extends from the end of the meandering section  20  back towards the common conductor  16 . In the illustrated embodiment, the meandering section  20  of the first radiating arm  12  is formed into a geometric shape known as a space-filling curve, in order to reduce the overall size of the antenna  10 . A space-filling curve is characterized by at least ten segments which are connected in such a way that each segment forms an angle with its adjacent segments, that is, no pair of adjacent segments define a larger straight segment. It should be understood, however, that the meandering section  20  may include other space-filling curves than that shown in  FIG. 1 , or may optionally be arranged in an alternative meandering geometry.  FIGS. 2-6 , for example, illustrate antenna structures having meandering sections formed from several alternative geometries. The use of shape-filling curves to form antenna structures is described in greater detail in the co-owned PCT Application WO 01/54225, entitled Space-Filling Miniature Antennas, which is hereby incorporated into the present application by reference. 
     The second radiating arm  14  includes three linear portions. As viewed in  FIG. 1 , the first linear portion extends in a vertical direction away from the common conductor  16 . The second linear portion extends horizontally from the end of the first linear portion towards the first radiating arm. The third linear portion extends vertically from the end of the second linear portion in the same direction as the first linear portion and adjacent to the meandering section  20  of the first radiating arm  14 . 
     As noted above, the common conductor  16  of the antenna  10  couples the feeding port  17  to the first and second radiating arms  12 ,  14 . The common conductor  16  extends horizontally (as viewed in  FIG. 1 ) beyond the second radiating arm  14 , and may be folded in a perpendicular direction (perpendicularly into the page), as shown in  FIG. 10 , in order to couple the feeding port  17  to communications circuitry in a mobile communications device. 
     Operationally, the first and second radiating arms  12 ,  14  are each tuned to a different frequency band or bands, resulting in a dual-band or multi-band antenna. 
     The antenna  10  may be tuned to the desired dual-band operating frequencies of a mobile communications device by pre-selecting the total conductor length of each of the radiating arms  12 ,  14 . For example, in the illustrated embodiment, the first radiating arm  12  may be tuned to operate in a lower frequency band or groups of bands, such as PDC (800 MHz), CDMA (800 MHz), GSM (850 MHz), GSM (900 MHz), GPS, or some other desired frequency band. Similarly, the second radiating arm  14  may be tuned to operate in a higher frequency band or group of bands, such as GPS, PDC (1500 MHz), GSM (1800 MHz), Korean PCS, CDMA/PCS (1900 MHz), CDMA2000/UMTS, IEEE 802.11 (2.4 GHz), IEEE 802.16 (Wi-MAX), or some other desired frequency band. It should be understood that, in some embodiments, the lower frequency band of the first radiating arm  12  may overlap the higher frequency band of the second radiating arm  14 , resulting in a single broader band. It should also be understood that the multi-band antenna  10  may be expanded to include further frequency bands by adding additional radiating arms. For example, a third radiating arm could be added to the antenna  10  to form a tri-band antenna. 
       FIG. 2  is a top view of an exemplary multi-band monopole antenna  30  including one alternative meandering geometry. The antenna  30  shown in  FIG. 2  is similar to the multi-band antenna  10  shown in  FIG. 1 , except the meandering section  32  in the first radiating arm  12  includes a different curve than that shown in  FIG. 1   
       FIGS. 3-9  illustrate several alternative multi-band monopole antenna configurations  50 ,  70 ,  80 ,  90 ,  93 ,  95 ,  97 . Similar to the antennas  10 ,  30  shown in  FIGS. 1 and 2 , the multi-band monopole antenna  50  illustrated in  FIG. 3  includes a common conductor  52  coupled to a first radiating arm  54  and a second radiating arm  56 . The common conductor  52  includes a feeding port  62  on a linear portion of the common conductor  52  that extends horizontally (as viewed in  FIG. 3 ) away from the radiating arms  54 ,  56 , and that may be folded in a perpendicular direction (perpendicularly into the page) in order to couple the feeding port  62  to communications circuitry in a mobile communications device. 
     The first radiating arm  54  includes a meandering section  58  and an extended section  60 . The meandering section  58  is coupled to and extends away from the common conductor  52 . The extended section  60  is contiguous with the meandering section  58  and extends from the end of the meandering section  58  in an arcing path back towards the common conductor  52 . 
     The second radiating aim  56  includes three linear portions. As viewed in  FIG. 3 , the first linear portion extends diagonally away from the common conductor  52 . The second linear portion extends horizontally from the end of the first linear portion towards the first radiating arm. The third linear portion extends vertically from the end of the second linear portion away from the common conductor  52  and adjacent to the meandering section  58  of the first radiating arm  54 . 
     The multi-band monopole antennas  70 ,  80 ,  90  illustrated in  FIGS. 4-6  are similar to the antenna  50  shown in  FIG. 3 , except each includes a differently-patterned meandering portion  72 ,  82 ,  92  in the first radiating arm  54 . For example, the meandering portion  92  of the multi-band antenna  90  shown in  FIG. 6  meets the definition of a space-filling curve, as described above. The meandering portions  58 ,  72 ,  82  illustrated in  FIGS. 3-5 , however, each include differently-shaped periodic curves that do not meet the requirements of a space-filling curve. 
     The multi-band monopole antennas  93 ,  95 ,  97  illustrated in  FIGS. 7-9  are similar to the antenna  30  shown in  FIG. 2 , except in each of  FIGS. 7-9  the expanded portion  22  of the first radiating arm  12  includes an additional area  94 ,  96 ,  98 . In  FIG. 7 , the expanded portion  22  of the first radiating arm  12  includes a polygonal, portion  94 . In  FIGS. 8 and 9 , the expanded portion  22  of the first radiating arm  12  includes a portion  96 ,  98  with an arcuate longitudinal edge. 
       FIG. 10  is a top view  100  of the exemplary multi-band monopole antenna  10  of  FIG. 1  coupled to the circuit board  102  of a mobile communications device. The circuit board  102  includes a feeding point  104  and a ground plane  106 . The ground plane  106  may, for example, be located on one of the surfaces of the circuit board  102 , or may be one layer of a multi-layer printed circuit board. The feeding point  104  may, for example, be a metallic bonding pad that is coupled to circuit traces  105  on one or more layers of the circuit board  102 . Also illustrated, is communication circuitry  108  that is coupled to the feeding point  104 . The communication circuitry  108  may, for example, be a multi-band transceiver circuit that is coupled to the feeding point  104  through circuit traces  105  on the circuit board. 
     In order to reduce electromagnetic interference or electromagnetic coupling from the ground plane  106 , the antenna  10  is mounted within the mobile communications device such that 50% or less of the projection of the antenna footprint on the plane of the circuit board  102  intersects the metalization of the ground plane  106 . In the illustrated embodiment  100 , the antenna  10  is mounted above the circuit board  102 . That is, the circuit board  102  is mounted in a first plane and the antenna  10  is mounted in a second plane within the mobile communications device. In addition, the antenna  10  is laterally offset from an edge of the circuit board  102 , such that, in this embodiment  100 , the projection of the antenna footprint on the plane of the circuit board  102  does not intersect any of the metalization of the ground plane  106 . 
     In order to further reduce electromagnetic interference or electromagnetic coupling from the ground plane  106 , the feeding point  104  is located at a position on the circuit board  102  adjacent to a corner of the ground plane  106 . The antenna  10  is preferably coupled to the feeding point  104  by folding a portion of the common conductor  16  perpendicularly towards the plane of the circuit board  102  and coupling the feeding port  17  of the antenna  10  to the feeding point  104  of the circuit board  102 . The feeding port  17  of the antenna  10  may, for example, be coupled to the feeding point  104  using a commercially available connector, by bonding the feeding port  17  directly to the feeding point  104 , or by some other suitable coupling means, such as for example a built-in or surface-mounted spring contact. In other embodiments, however, the feeding port  17  of the antenna  10  may be coupled to the feeding point  104  by some means other than folding the common conductor  16 . 
       FIG. 11  shows an exemplary mounting structure  111  for securing a multi-band monopole antenna  112  within a mobile communications device. The illustrated embodiment  110  employs a multi-band monopole antenna  112  having a meandering section similar to that shown in  FIG. 2 . It should be understood, however, that alternative multi-band monopole antenna configurations, as described in  FIGS. 1-9 , could also be used. 
     The mounting structure  111  includes a flat surface  113  and at least one protruding section  114 . The antenna  112  is secured to the flat surface  113  of the mounting structure  111 , preferably using an adhesive material. For example, the antenna  112  may be fabricated on a flex-film substrate having a peel-type adhesive on the surface opposite the antenna structure. Once the antenna  112  is secured to the mounting structure  111 , the mounting structure  111  is positioned in a mobile communications device with the protruding section  114  extending over the circuit board. The mounting structure  111  and antenna  112  may then be secured to the circuit board and to the housing of the mobile communications device using one or more apertures  116 ,  117  within the mounting structure  111 . 
       FIG. 12  is an exploded view of an exemplary clamshell-type cellular telephone  120  having a multi-band monopole antenna  121 . The cellular telephone  120  includes a lower circuit board  122 , an upper circuit board  124 , and the multi-band antenna  121  secured to a mounting structure  110 . Also illustrated are an upper and a lower housing  128 ,  130  that join to enclose the circuit boards  122 ,  124  and antenna  121 . The illustrated multi-band monopole antenna  121  is similar to the multi-band antenna  30  shown in  FIG. 2 . It should be understood, however, that alternative antenna configurations, as describe above with reference to  FIGS. 1-9 , could also be used. 
     The lower circuit board  122  is similar to the circuit board  102  described above with reference to  FIG. 10 , and includes a ground plane  106 , a feeding point  104 , and communications circuitry  108 . The multi-band antenna  121  is secured to a mounting structure  110  and coupled to the lower circuit board  122 , as described above with reference to  FIGS. 10 and 11 . The lower circuit board  122  is then connected to the upper circuit board  124  with a hinge  126 , enabling the upper and lower circuit boards  122 ,  124  to be folded together in a manner typical for clam-shell-type cellular phones. In order to further reduce electromagnetic interference from the upper and lower circuit boards  122 ,  124 , the multi-band antenna  121  is preferably mounted on the lower circuit board  122  adjacent to the hinge  126 . 
       FIG. 13  is an exploded view of an exemplary candy-bar-type cellular telephone  200  having a multi-band monopole antenna  201 . The cellular telephone  200  includes the multi-band monopole antenna  201  secured to a mounting structure  110 , a circuit board  214 , and an upper and lower housing  220 ,  222 . The circuit board  214  is similar to the circuit board  102  described above with reference to  FIG. 10 , and includes a ground plane  106 , a feeding point  104 , and communications circuitry  108 . The illustrated antenna  201  is similar to the multi-band monopole antenna shown in  FIG. 3 , however alternative antenna configurations, as described above with reference to  FIGS. 1-9 , could also be used. 
     The multi-band antenna  201  is secured to the mounting structure  110  and coupled to the circuit board  214  as described above with reference to  FIGS. 10 and 11 . The upper and lower housings  220 ,  222  are then joined to enclose the antenna  212  and circuit board  214 . 
       FIG. 14  is an exploded view of an exemplary personal digital assistant (PDA) or gaming device  230  having a multi-band monopole antenna  231 . The PDA  230  includes the multi-band monopole antenna  231  secured to a mounting structure  110 , a circuit board  236 , and an upper and lower housing  242 ,  244 . Although shaped differently, the PDA circuit board  236  is similar to the circuit board  102  described above with reference to  FIG. 10 , and includes a ground plane  106 , a feeding point  104 , and communications circuitry  108 . The illustrated antenna  231  is similar to the multi-band monopole antenna shown in  FIG. 5 , however alternative antenna configurations, as described above with reference to  FIGS. 1-9 , could also be used. As discussed above with respect to  FIG. 10 , preferably 50% or less of the antenna footprint on the plane of the circuit board  236  intersects the metalization of the ground plane. 
     The multi-band antenna  231  is secured to the mounting structure  110  and coupled to the circuit board  214  as described above with reference to  FIGS. 10 and 11 . In slight contrast to  FIG. 10 , however, the PDA circuit board  236  defines an L-shaped slot along an edge of the circuit board  236  into which the antenna  231  and mounting structure  110  are secured in order to conserve space within the PDA  230 . The upper and lower housings  242 ,  244  are then joined together to enclose the antenna  231  and circuit board  236 . 
     An example of a space-filling curve  250  is shown in  FIG. 15 . As mentioned above, space-filling means a curve formed from a line that includes at least ten segments, with each segment forming an angle with an adjacent segment. When used in an antenna, each segment in a space-filling curve  250  should be shorter than one-tenth of the free-space operating wavelength of the antenna. 
     In addition to space-filling curves, the curves described herein can also be grid dimension curves. Examples of grid dimension curves are shown in  FIGS. 16 to 19 . The grid dimension of a curve may be calculated as follows. A first grid having square cells of length L 1  is positioned over the geometry of the curve, such that the grid completely covers the curve. The number of cells (N 1 ) in the first grid that enclose at least a portion of the curve are counted. Next, a second grid having square cells of length L 2  is similarly positioned to completely cover the geometry of the curve, and the number of cells (N 2 ) in the second grid that enclose at least a portion of the curve are counted. In addition, the first and second grids should be positioned within a minimum rectangular area enclosing the curve, such that no entire row or column on the perimeter of one of the grids fails to enclose at least a portion of the curve. The first grid should include at least twenty-five cells, and the second grid should include four times the number of cells as the first grid. Thus, the length (L 2 ) of each square cell in the second grid should be one-half the length (L 1 ) of each square cell in the first grid. The grid to dimension (D g ) may then be calculated with the following equation: 
     
       
         
           
             
               D 
               g 
             
             = 
             
               - 
               
                 
                   
                     log 
                      
                     
                       ( 
                       
                         N 
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                         2 
                       
                       ) 
                     
                   
                   - 
                   
                     log 
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                       ( 
                       
                         N 
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                          
                         1 
                       
                       ) 
                     
                   
                 
                 
                   
                     log 
                      
                     
                       ( 
                       
                         L 
                          
                         
                             
                         
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                         2 
                       
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                       ( 
                       
                         L 
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     For the purposes of this application, the term grid dimension curve is used to describe a curve geometry having a grid dimension that is greater than one (1). The larger the grid dimension, the higher the degree of miniaturization that may be achieved by the grid dimension curve in terms of an antenna operating at a specific frequency or wavelength. In addition, a grid dimension curve may, in some cases, also meet the requirements of a space-filling curve, as defined above. Therefore, for the purposes of this application a space-filling curve is one type of grid dimension curve. 
       FIG. 16  shows an exemplary two-dimensional antenna  260  forming a grid dimension curve with a grid dimension of approximately two (2).  FIG. 17  shows the antenna  260  of  FIG. 16  enclosed in a first grid  270  having thirty-two (32) square cells, each with length L 1 .  FIG. 18  shows the same antenna  260  enclosed in a second grid  280  having one hundred twenty-eight (128) square cells, each with a length L 2 . The length (L 1 ) of each square cell in the first grid  270  is twice the length (L 2 ) of each square cell in the second grid  280  (L 2 =2×L 1 ). An examination of  FIGS. 17 and 18  reveals that at least a portion of the antenna  260  is enclosed within every square cell in both the first and second grids  270 ,  280 . Therefore, the value of N 1  in the above grid dimension (D g ) equation is thirty-two (32) (i.e., the total number of cells in the first grid  270 ), and the value of N 2  is one hundred twenty-eight (128) (i.e., the total number of cells in the second grid  280 ). Using the above equation, the grid dimension of the antenna  260  may be calculated as follows: 
     
       
         
           
             
               D 
               g 
             
             = 
             
               
                 - 
                 
                   
                     
                       log 
                        
                       
                         ( 
                         128 
                         ) 
                       
                     
                     - 
                     
                       log 
                        
                       
                         ( 
                         32 
                         ) 
                       
                     
                   
                   
                     
                       log 
                        
                       
                         ( 
                         
                           2 
                           × 
                           L 
                            
                           
                               
                           
                            
                           1 
                         
                         ) 
                       
                     
                     - 
                     
                       log 
                        
                       
                         ( 
                         
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                            
                           1 
                         
                         ) 
                       
                     
                   
                 
               
               = 
               2 
             
           
         
       
     
     For a more accurate calculation of the grid dimension, the number of square cells may be increased up to a maximum amount. The maximum number of cells in a grid is dependent upon the resolution of the curve. As the number of cells approaches the maximum, the grid dimension calculation becomes more accurate. If a grid having more than the maximum number of cells is selected, however, then the accuracy of the grid dimension calculation begins to decrease. Typically, the maximum number of cells in a grid is one thousand (1000). 
     For example,  FIG. 19  shows the same antenna  260  enclosed in a third grid  290  with five hundred twelve (512) square cells, each having a length L 3 . The length (L 3 ) of the cells in the third grid  290  is one half the length (L 2 ) of the cells in the second grid  280 , shown in  FIG. 18 . As noted above, a portion of the antenna  260  is enclosed within every square cell in the second grid  280 , thus the value of N for the second grid  280  is one hundred twenty-eight (128). An examination of  FIG. 19 , however, reveals that the antenna  260  is enclosed within only five hundred nine (509) of the five hundred twelve (512) cells in the third grid  290 . Therefore, the value of N for the third grid  290  is five hundred nine (509). Using  FIGS. 18 and 19 , a more accurate value for the grid dimension (D g ) of the antenna  260  may be calculated as follows: 
     
       
         
           
             
               D 
               g 
             
             = 
             
               
                 - 
                 
                   
                     
                       log 
                        
                       
                         ( 
                         509 
                         ) 
                       
                     
                     - 
                     
                       log 
                        
                       
                         ( 
                         128 
                         ) 
                       
                     
                   
                   
                     
                       log 
                        
                       
                         ( 
                         
                           2 
                           × 
                           L 
                            
                           
                               
                           
                            
                           2 
                         
                         ) 
                       
                     
                     - 
                     
                       log 
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                         ( 
                         
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                            
                           
                               
                           
                            
                           2 
                         
                         ) 
                       
                     
                   
                 
               
               ≈ 
               1.9915 
             
           
         
       
     
     The multi-band monopole antennas disclosed herein also include multiple conductor, double-sided, double-surface antenna arrangements. These multiple conductor, double-sided, double-surface antenna arrangements include all the aspects of the multi-band monopole antennas discussed above including, but not limited to, the physical properties of the substrate and conductive materials. In such double-sided, double-surface antenna arrangements, conductors are located on different surfaces of an antenna substrate. Each of the conductors can have the same or different geometry. Conductors on different sides of an antenna substrate can be physically, electrically connected or they may not be connected. Conductors on different sides of an antenna substrate can be connected by a coupling mechanism, e.g., an internal passage or via containing a conductor or an external conductor. Options for conductors include, but are not limited to, conductors with space-filling or grid dimension curves as discussed above, conductors with multiple arms as discussed above, and conducting plates that acts as parasitic reflector planes to tune the resonant frequency of a second band of another conductor. 
       FIGS. 20   a ,  20   b  and  20   c  show an example of a double-sided, double-surface antenna  300  with two spiral conductors ( 302  and  304 ).  FIG. 20   a  is a perspective view of the conductors of the double-sided, double-surface antenna  200 . An antenna substrate, may be included between the spiral conductors  302  and  304 . Suitable antenna substrate materials are well known and may include, for example, plastic, FR4, teflon, Arlon®, Rogers®, and fiberglass.  FIGS. 20   b  and  20   c  are views of the front and back of the double-sided, double-surface antenna  300  including a substrate  306 . Referring to  FIGS. 20   a ,  20   b , and  20   c , spiral conductor  302  may be located on the front face of antenna substrate  306  and spiral conductor  304  may be located on the back face of antenna substrate  306 . Spiral conductor  302  is connected to a feeding port  308  and spiral conductor  302  is connected to spiral conductor  304  by connector  309 . Connector  309  electrically connects spiral connectors  302  and  304  and passes through an internal passage of the antenna substrate  306 . 
       FIGS. 21   a ,  21   b  and  21   c  show an example of a double-sided, double-surface antenna  310  with a dual branched antenna  312 , a feeding port  314 , and a conducting plate  316 .  FIG. 21   a  is a perspective view of the conductors of the double-sided, double surface antenna  310 . Similar to double-sided, double-surface antenna  300 , an antenna substrate may be located between the dual branched antenna  312  and the conducting plate  316 .  FIGS. 21   b  and  21   c  are views of the front and back of the double-sided, double surface antenna  310  including a substrate  318 . The dual branched antenna  312  comprises two conductors: a space-filling or grid dimension section  320  and a linear section  322  (further examples of dual and multi-band antennas are discussed above). 
     Conducting plate  316  can either be an extension of the space-filling or grid dimension section  320  of the dual branched antenna  312  if electrically connected to space-filling or grid dimension section  320  or a parasitic plane reflector if not electrically connected to space-filling or grid dimension section  320 . If the plane  324  is used to represent a conductor electrically connecting the end of the space-filling or grid dimension section  320  of the dual branched antenna  312  to the conducting plate  316 , then the conducting plate acts as an extension of the space-filling or grid dimension section  320  of the dual branched antenna  312  and will also provide some of the tuning properties of a parasitic plane reflector. If the plane  324  is not a conductor connecting the end of the space-filling or grid dimension section  320  to the conducting plate  316 , then the conducting plate acts as a parasitic plane reflector. Conductors connecting the space-filling or grid-dimension section  320  to the conducting plate  316  can be any type of electrical connection and the electrical connection can occur at any points along their common length. The electrical connection also can be located in any orientation such as, for example, over the substrate surface or through an internal passage of the substrate. 
     Another antenna example is shown in  FIGS. 22   a  and  22   b . The antenna shown in  FIGS. 22   a  and  22   b  is an example of a double-sided, double-surface antenna  330  with a conductor  332  and reflector  334  located on an antenna substrate  336 . Antenna  330  is a Rogers-type antenna. The conductor  332  of antenna  330  has a Hilbert-like space-filling antenna that is located on the front face of substrate  336 . The reflector  334 , which is located on the back face of substrate  336 , acts as a parasitic plane reflector that helps to tune the resonant frequency of the conductor  332  located on the front face of substrate  336 . 
       FIGS. 23   a  and  23   b  show another example of a double-sided, double-surface antenna  350 . Antenna  350  is a modification of antenna  310  shown in  FIGS. 21   a ,  21   b  and  21   c . The first difference between antenna  350  and antenna  310  is that linear section  320  of antenna  310 , i.e., linear section  352  of antenna  350 , is now connected to the Hilbert-like space-filling section  354  of antenna  350  at the distal end  356  of the Hilbert-like space-filling section  354  rather than at the proximal end  358 . The Hilbert-like space filling section  354  of antenna  350  can, for example, be tuned to the GSM900 frequency band and the modification to linear section  352  could help to reduce the resonant frequency of the GSM900 band. The second difference between antenna  350  and antenna  310  is that a conducting plate  360  has been added to the back face of the antenna substrate to create a parasitic plane reflector. The linear portion  352  of antenna  350  can, for example, be tuned to the GSM1800 band and the parasitic plane reflector could help tune the frequency of the GSM1800 band. 
     Many modifications to the antennas described above are possible. For example, the linear portions of antennas  310  or  350  could be lengthened or shortened or the electrical connection relationship with a space-filling or grid dimension conductor can be adjusted. For further example, the space-filling or grid dimension portions of antennas  310 ,  330  or  350  could have various curves removed or replaced by solid conductor portions. The space-filling or grid dimension portions of these antennas can also adopt any of the configurations defined above. By way of an additional example, conductor plates/parasitic plane reflectors of antennas  310 ,  330  or  350  can be decreased in width or height or both. Further, the shape of a conductor plate/parasitic plane reflector could be modified in other ways, such as by removing various portions of the conductor/reflector or simply creating differing shapes. 
       FIG. 24  shows an example of an antenna housing that any one of the antennas described above could be fitted within. Such an antenna housing could be affixed, for example, to a candy bar type mobile communication device, to a clam-shell type mobile communication device, to a gaming device, or to a PDA. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable a person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples, which may be available either before or after the application filing date, are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.