Abstract:
Multi-frequency, low-profile, capacitively loaded magnetic dipole antennas to be used in wireless communications. Each antenna comprises one to n antenna elements and each element having one to n arms. The various antenna embodiments can cover a range of frequencies to be determined by the shape, size, and number of elements in the physical configuration of the antenna. The antenna configuration can also be adapted to expand frequency bands covered by the antenna or to fit within space restrictions dictated by specific antenna applications.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application relates to co-pending application Ser. No. 09/892,928, filed on Jun. 26, 2001, now U.S. Pat. No. 6,456,243, entitled “Multi Frequency Magnetic Dipole Antenna Structure and Methods Reusing the Volume of an Antenna” by L. Desclos et at., owned by the assignee of this application and incorporated herein by reference. 
     This application relates to co-pending application Ser. No. 10/076,922, now pending entitled “Multi Frequency Magnetic Dipole Antenna Structures with a New E-Field Distribution for Very Low-Profile Antenna Applications” by G. Poilasne et al., owned by the assignee of this application and incorporated herein by reference. 
    
    
     BACKGROUND INFORMATION 
     1. Field of the Invention 
     The present invention relates generally to the field of wireless communications, and particularly to multi-band antennas used in wireless communications. 
     2. Background 
     Certain applications such as the Global System for Mobile Communications (GSM) and Personal Communications Service (PCS) require that multiple bands be accessible, depending upon the local frequency coverage available from a service provider. Because applications such as GSM and PCS are used in the context of wireless communications devices that have relatively small form-factors, a low profile is also required. 
     A magnetic dipole antenna (MDA) is a loop antenna that radiates electromagnetic waves in response to current circulating through the loop. The antenna element of an MDA is designed so that it resonates at the frequency required by the ultimate application for which the antenna is intended. The antenna&#39;s resonant frequency is dependent on the capacitive and inductive properties of the antenna elements, which in turn are controlled by various dimensions of the antenna elements. 
     For some applications, it is desirable to expand the frequency range of an antenna to cover a wider band of frequencies. However, size constraints often make it difficult to design an antenna with a frequency band wide enough to meet these applications needs. The present invention addresses the requirements of certain wireless communications applications by providing configurations for tow profile, multi-frequency, multi-band, magnetic dipole antennas. 
     SUMMARY OF THE INVENTION 
     The present invention discloses a myriad of physical arrangements of antenna elements configured to cover one to n number of frequencies or bands of frequencies. In the present invention, the antenna elements include both inductive and capacitive parts. Each element provides frequencies or bands of frequencies. The physical design of each element can vary, but always allows for multi-frequencies by using a plurality of antenna elements to produce a multi-frequency antenna. Furthermore, the arrangement of a plurality of antenna elements allows the frequency coverage of the antenna to be enlarged. 
     Each antenna element is cut, folded, and/or arranged to meet both the frequency and space requirements of the specific application. In one embodiment, each antenna element comprises three arms arranged to produce multiple frequency bands. Multiple elements of relatively the same size can be arranged in various fashions such that the frequency bands produced by each element combine to enlarge each frequency band produced by each element. Alternatively, the multiple elements can be of varying sizes to increase the number of frequency bands produced by the antenna. 
     The ground and feed points of the antenna can be arranged in various fashions to meet the needs of a specific antenna application. In addition, filters can be added to or incorporated into the antenna elements in a variety of ways for frequency matching or to reject unused frequency bands. For example, in one embodiment the filter is formed by attaching a matching element, which can be a piece of conductive material, to the antenna element. In another embodiment, the filter can be formed by removing material from the antenna element. 
    
    
     Further features and advantages of this invention as well as the structure and operation of various embodiments are described in detail below with reference to the accompanying drawings. This summary does not purport to define the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is a top view of one embodiment of an antenna element according to the present invention; 
     FIG. 1 b  is a graphical representation of the frequencies produced by the antenna element of FIG. 1 a;    
     FIG. 2 a  is a top view of an alternative embodiment of the antenna element of FIG. 1 a  including an inductive bridge between two arms of the element; 
     FIG. 2 b  is a top view of an alternative embodiment of the antenna element of FIG. 1 a  having slots inserted into one arm of the element; 
     FIG. 2 c  is a top view of another alternative embodiment of the antenna elements of FIG. 1 a  including an inductive bridge between two arms of the element; 
     FIG. 2 d  is a top view of another alternative embodiment of the antenna elements of FIG. 1 a including multiple inductive bridges between two arms of the element; 
     FIG. 2 e  is a graphical representation of one frequency band produced by the antenna element of FIG. 2 d;    
     FIG. 2 f  is a top view of another alternative embodiment of the antenna elements of FIG. 1 a showing an alternative feeding structure; 
     FIG. 2 g  is a side view of the antenna element of FIG. 2 f;    
     FIG. 3 a  is a perspective view of an alternative embodiment of the antenna of FIG. 3 including an external matching arm; 
     FIG. 3 b  is a perspective view of an alternative embodiment of the antenna of FIG. 3 a;    
     FIG. 3 c  is a top view of an alternative embodiment of the antenna element of FIG. 1 a;    
     FIG. 3 d  is a top view of an alternative embodiment of the antenna element of FIG. 3 c;    
     FIG. 3 e  is a top view of an alternative embodiment of the antenna element of FIG. 3 c;    
     FIG. 3 f  is a top view of an alternative embodiment of the antenna element of FIG. 3 c;    
     FIG. 4 is a top view of an antenna having multiple antenna elements according to the present invention; 
     FIG. 5 is a top view of an alternative embodiment of the antenna of FIG. 4 with a modified feeding structure; 
     FIG. 6 is a top view of an alternative embodiment of the antenna of FIG. 5; 
     FIG. 7 is a top view of an alternative embodiment of the antenna of FIG. 5; 
     FIG. 8 is a top view of an alternative embodiment of the antenna of FIG. 7; 
     FIG. 9 is a top view of an alternative embodiment of the antenna of FIG. 7; 
     FIG. 10 is a top view of an alternative embodiment of the antenna of FIG. 5; 
     FIG. 11 a  is a top view of an alternative embodiment of an antenna according to the present invention including matching elements and filters; 
     FIG. 11 b  is a perspective view of the antenna of FIG.  25 . 
     FIG. 12 is a top view of an alternative embodiment of the antenna of FIG. 4; 
     FIG. 13 a  is a top view of an alternative embodiment of the antenna of FIG. 12 with a modified feeding structure; 
     FIG. 13 b  is a graphical representation of the frequencies produced by the antenna of FIG. 13 a;    
     FIG. 14 is a perspective view of an alternative embodiment of an antenna according to the present invention; 
     FIG. 15 is a side view of the antenna of FIG. 14; 
     FIG. 16 is a perspective view of an alternative embodiment of an antenna according to the present invention; 
     FIG. 17 is a perspective view of an alternative embodiment of the antenna of FIG. 16 including an additional antenna element; 
     FIG. 18 is a perspective view of an alternative embodiment of the antenna of FIG. 17; 
     FIG.  19 . is a perspective view of an alternative embodiment of the antenna of FIG. 18 including an additional antenna element; 
     FIG. 20 is a top view of an alternative embodiment of the antenna of FIG. 5 including an additional antenna element; 
     FIG.  21 . is a top view of an alternative embodiment of the antenna of FIG. 20 with modified feeding structure; 
     FIG.  22 ,is a top view of an alternative embodiment of the antenna of FIG. 20 with additional antenna elements; 
     FIG. 23 is a top view of an alternative embodiment of the antenna of FIG. 12 with additional antenna elements; 
     FIG. 24 is a top view of an alternative embodiment of the antenna of FIG. 23 with antenna elements of varying size. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods and devices are omitted so as to not obscure the description of the present invention with unnecessary detail. 
     Referring now to the drawings, an antenna element which can be used according to the present invention is generally designed by reference numeral  10  in FIG. 1 a . The antenna element  10  comprises three antenna arms  12 ,  14 , and  16 . The antenna element  10  is fed through the feeding structure comprising feed line  18  and ground line  20 . The antenna arms  12 ,  14 , and  16  are configured to produce circulating current flows which cause the antenna element  10  to radiate at a low frequency (f 1 ) and a high frequency (f 2 ). 
     Arms  12  and  14  form a large u-shaped antenna element which is fed by feed line  18 . This structure produces a current flow indicated by line  22  causing the antenna element  10  to radiate at low frequency (f 1 ). Arms  14  and  16  form a small u-shaped antenna element which is fed through electromagnetic coupling with arm  12 , which is represented by dashed line  24 . This small structure produces a current flow which causes the antenna element  10  to radiate at high frequency (f 2 ). This antenna element design creates inductive and capacitive elements which create the antenna frequency bands. For example, arms  12  and  16  form a first capacitive part of antenna  10  and arms  14  and  16  form a second capacitive part. Corresponding inductive parts of the antenna  10  are created between the arms  12 ,  14  and  16  and a ground plate (not shown except in FIG.  15 ). 
     Antenna element  10  can be modified for different applications. For example, FIGS. 2 a ,  2   b  and  2   c , illustrate various ways to modify the inductance of antenna element  10 . FIG. 2 a  shows adding an inductive bridge  26  between arms  12  and  16 . The inductive bridge  26  can be used to widen the tow frequency band (f 1 ) of antenna element  10 . The inductive bridge  26  can also be used to widen the high frequency band (f 2 ) of antenna element  10  by adjusting its placement and width. The effect the inductive bridge  26  has on antenna performance can be controlled to suit many different antenna applications. For example, some of the factors which determine the effect the inductive bridge  26  has on antenna  10  are the width of element  12 , the width of the inductive bridge  26 , the position of the inductive bridge  26  along the length of element  12 , and the width of the gap between elements  12  and  16 . 
     FIG. 2 c shows adding an inductive bridge  30  between arms  14  and  16 . This inductive bridge  30  can be used to widen the high frequency band (f 2 ) of antenna element  10 . Similar to inductive bridge  26 , inductive bridge  30  can be used to widen the low frequency band (f 1 ) of antenna element  10  by adjusting its placement and width. 
     FIG. 2 d  show adding multiple inductive bridges  31  between arms  12  and  16 . The additional inductive bridges  31  can be used to further widen the low (or high) frequency band of antenna element  10 . For example, the embodiment shown in FIG. 2 d  can be configured to produce an expanded low frequency band (f 1 ) like the one shown in FIG. 2 e.    
     FIG. 2 b shows inserting slots  28  into arm  12 . Slots  28  allow the length of element  12  to be shortened without effecting antenna performance. FIG. 2 c shows placing an inductive bridge  30  between arms  14  and  16  to widen the bandwidth at the high frequency (f 2 ), similar to the way inductive bridge  26  operates. Various other modifications can be made to antenna element  10  and various other antenna element configurations can be used for the purposes of the present invention. For example, various other suitable antenna element configurations are set forth in co-pending application Ser. No. 10/133,717 entitled “Low-profile, Multi-Frequency, Multi-Band, Capacitively Loaded Magnetic Dipole Antenna” which is incorporated herein by reference. 
     FIGS. 2 f - 2   g  show an alternative feeding structure arrangement in which the feed line  18  cut away from arm  12 . As shown, the feed line  18  formed from a piece of arm  12  which is cut away and folded down. The ground line  20  is attached to the end of arm  12 . 
     As shown in FIGS. 3 a  and  3   b , a matching element  21  can be added to the antenna element  10  enabling additional control over the antenna element environment through frequency matching. Matching element  21  capacitively couples with arm  12  of the antenna element  10 . In FIG. 3 a , matching element  21  is connected to arm  12 . In FIG. 3 b , matching element  21  is connected to feed line  18 . Whether the matching element  21  is attached to arm  12  of feed line  18  can be dictated by size considerations of the antenna application. The matching element  21  can be configured to widen the frequency bands produced by antenna element  10 . Some of the factors which dictate the effect the matching element  21  has on the antenna element  10  include the length of the matching element  21  and the gap between matching element  21  and the antenna element arm  12 . For example, the longer the length of the matching element  21 , the more it affects the low frequency (f 1 ) component. Conversely, the shorter the length the more it affects the high frequency (f 2 ) component. With respect to the gap, generally the smaller the gap between the matching element  21  and arm  12 , the more the high frequency (f 2 ) component is affected and the larger the gap, the more the low frequency (f 1 ) component is affected. 
     FIGS. 3 c - 3   f  show alternative embodiments of matching element  21 . FIG. 3 c  shows matching element  21  extending vertically downward from the outside edge of arm  12 . FIG. 3 d  shows matching element  21  attached to the outside edge of arm  12  and extending perpendicular under arm  12  to under arm  16  where it extends parallel under arm  16 . FIG. 3 e  shows matching element  21  attached to the outside edge of arm  12  and extending perpendicular under arm  12  to under arm  14  where it extends parallel under arm  14 . FIG. 3 f  shows matching element  21  attached to the outside edge of arm  12  and extending under arm  12  at one diagonal to under arm  16  where it extends at another diagonal to under arm  14 . 
     The antenna  32  shown in FIG. 4 comprises two antenna elements  34  and  36  fed through a signal feeding structure using feed line  38  and ground line  40 . In the embodiment shown in FIG. 4, antenna elements  34  and  36  are arranged perpendicular to each other and are connected at their open ends. Both feed line  38  and ground line  40  are attached to element  34  but are configured to power both element  34  and element  36 . This 90 degree arrangement between elements  34  and  36  minimizes coupling between the elements and thus maximizes the bandwidth of antenna  32 . 
     As described above, antenna elements  34  and  36  are each configured to radiate a high frequency and a low frequency, thus producing four separate frequency bands (f 1 , f 2 , f 3 , and f 4 ). The structure of the antenna elements  34  and  36  and their arrangement with respect to each other can be designed such that the low frequencies (f 1  and f 3 ) of both elements are near enough on the frequency spectrum to partially combine to form a single, enlarged low frequency band. Similarly, the antenna  32  can be designed such that the high frequencies (f 2  and f 4 ) of both elements  34  and  36  are also near enough on the frequency spectrum to partially combine to form a single, enlarged high frequency band. Generally, in order for the antenna elements  34  and  36  to produce frequency bands that combine, antenna elements  34  and  36  should be similarly sized. However, even if elements  34  and  36  are not similarly sized, they can be configured to produce overlapping frequency bands by adjusting the arm lengths and gaps between the arms. Alternatively, the antenna  32  can be configured so that the four frequency bands (f 1 , f 2 , f 3 , and f 4 ) do not overlap allowing them to be used as in a communication system with two separate transmit and receive frequencies. Conversely to the situation described about, generally elements  34  and  36  should be different sized elements in order to produce frequency bands that do not overlap. However, even if elements  34  and  36  are similarly sized, they can be designed to produce non-overlapping frequency bands such as by adjusting the arm lengths and gaps between the arms. 
     FIG. 5 illustrates an alternative feeding structure for the antenna of FIG.  4 . In FIG. 5, ground line  40  is connected to element  36  while feed line  38  is connected to element  34 . This feeding structure can be used to power both elements  34  and  36 . This and other alternative feed structure arrangements can be made to accommodate size constraints imposed by various antenna applications. 
     FIG. 6 illustrates an alternative embodiment of the antenna shown in FIG.  5 . In FIG. 6, elements  34  and  36  are arranged at an angle  42  less than 90 degrees. This allows the overall structure of the antenna  32  to be more compact allowing it to be used for applications in which space of limited. However, because the elements  34  and  36  are no Longer perpendicular, coupling occurs between the elements which can reduce the bandwidth of antenna  32 . This coupling can be compensated for in a variety of ways such as, among other ways, adjusting the arm lengths of each element  34 ,  36  and/or adjusting the gaps between the arms. 
     FIGS. 7-9 illustrate various embodiments in which elements  34  and  36  are arranged parallel to each other. In these embodiments, feed line  38  is connected to element  34  and ground line  40  is connected to element  36 , however the feed line  38  and ground line  40  could be reversed or both be attached to either element  34  or  36 . In this configuration, the coupling between the elements  34 ,  36  is very high since the magnetic fields created by each element are parallel to each other. In the embodiment shown in FIG. 7 the elements  34  and  36  are connected. In FIG. 8, the elements  34  and  36  are separated by a distance (d) which can be used to match the elements  34  and  36  return loss and efficiency. The coupling created between elements  34  and  36  decreases as the distance (d) between the elements increases. Conversely, the coupling is increased as the distance (d) decreases. Indirectly, the return loss of the elements  34  and  36  is proportional to the magnetic coupling between the elements  34  and  36 . In FIG. 9, a matching element  44  is added between elements  34  and  36 . Matching element  44  can be used for frequency matching for all frequency bands produced by antenna  32 . Thus, matching element  44  can be used to increase the bandwidth of antenna  32 . Also, as with the previously described embodiments, the Length of the antenna element arms and the gaps between the arms can be adjusted to compensate for coupling and to increase the bandwidth of antenna  32 . 
     FIG. 10 illustrates an alternative embodiment of FIG. 5 in which the angle between elements  34  and  36  is  180  degrees. In this embodiment, the feed line  38  is moved to the side (rather than the end) of element  34  in order to accommodate the connection between elements  34  and  36 . In this embodiment, there is only minimal coupling at the ends of the elements  34  and  36  but little or no magnetic coupling that would affect the bandwidth of antenna  32 . This arrangement can be used in antenna applications in which the a long, narrow piece of real estate is available for the antenna. 
     FIGS. 11 a  and  b  illustrate one embodiment of the invention that includes various filters and matching elements to customize and optimize operation of the antenna  46  for a particular application. This embodiment shows various filters  48  cut into antenna element  46 . Filters of this type, which allow element  46  to produce multiple frequency bands, are described in more detail in the co-pending applications mentioned above which have been incorporated by reference. Antenna  46  also includes a second antenna element  52  and a matching element  54  attached to the sides of antenna element  46 . An additional parasitic element  56  can also be included inside antenna  46 . Parasitic element  56  is feed through magnetic coupling and is configured to general additional frequency bands. As with the other antenna elements described herein, parasitic element  56  can be configured to produce overlapping frequency bands which combine with the frequency bands produced by the other antenna elements  46 ,  52  or can be configured to produce non-overlapping frequency bands. Feed line  18  and ground line  20  are shown attached to element  46 . 
     As shown in FIG. 12, antenna elements  34  and  36  can also be different sizes. The size of an antenna element  34 ,  36  largely dictates its resonant frequency band, i.e. the smaller the antenna element the higher the resonant frequency band. Thus, by making element  36  smaller than element  34 , the embodiment of antenna  32  shown in FIG. 12 is configured to produce four separate frequency bands, which could be configured as the send and receive bands for two distinct systems such as 800 MHz and 1900 MHz. Alternatively, the different sized antenna elements  34  and  36  shown in FIG. 12 could be designed to produce overlapping frequency bands by adjusting various attributes of the antenna elements such as, among other things, the length of the antenna elements arms and/or the gaps between the arms. In this embodiment, the feed line  38  and ground line  40  are both connected to element  36 . 
     Alternatively, as shown in FIG. 13 a , each antenna element  34  and  36  can be configured with its own feed line  38  and ground line  40 . Designing antenna  32  with separate feeding structures for element  34  and  36  may be desirable in situation in which the device that incorporates antenna  32  has more than one module. For example, the device may have separate Bluetooth™ and GSM modules. In this case, it may be desirable to separate each antenna element&#39;s feeding structure to take advantage of these separate modules. FIG. 13 b  illustrates the frequencies (f 1 , f 2 , f 3  and f 4 ) which could be produced by the embodiment of antenna  32  shown in FIG. 13 a  . As is shown, antenna element  34  could be configured to produce the lower frequency send and receive bands (f 1 , f 2 ), in the 800 MHz range and antenna element  36  could be configured to produce the higher frequency send and receive bands (f 3 , f 4 ) in the 1900 MHz range. 
     FIGS. 14 and 15 illustrate an embodiment of antenna  32  in which elements  34  and  36  are stacked in a vertical manner. Size constraints of an antenna application may require that the separate antenna elements  34  and  36  be stacked in this vertical manner. While there is come magnetic coupling between elements  34  and  36  in this arrangement, the coupling can be controlled and minimized by, among other ways, adjusting the gap between the elements  34 ,  36  and their alignment with respect to each other. In this embodiment, both elements  34  and  36  have their own feed line  38  and ground line  40 . However, the antenna  32  could be designed with one feeding structure by making one of the elements  34  or  36  parasitic as described herein with respect to other embodiment of the invention. In FIG. 15, the elements  34  and  36  are shown attached to a ground plane  58 . Similar to the embodiment illustrated in FIG. 13 a , elements  34  and  36  are different sizes and thus can be configured to produce multiple frequency bands across the spectrum. It should be noted that one advantage to the various antenna arrangements discussed herein is that antenna  32  can be designed to fit within the space constraints of various applications. 
     FIG. 16 illustrates still another embodiment of antenna  32 . In this embodiment, antenna element  36  is attached to the side of element  34  facing the same direction but at a  90  degree angle with element  34 . This arrangement minimizes coupling between elements  34  and  36  similar to the embodiment illustrated in FIGS. 4 and 5. Element  36  can be attached to any arm of element  34 , facing any direction, in order to accommodate size constraints placed on the antenna  32  by particular antenna applications. Similar to the embodiment illustrated in FIG. 12, element  36  is smaller than element  34 . Feed line  38  and ground line  40  are attached to element  34 . 
     FIG. 17 illustrates an alternative embodiment of the antenna of FIG.  16 . The antenna  60  shown in FIG. 17 includes three antenna elements  62 ,  64  and  66 . Antenna elements  64  and  66  are attached to the sides of element  62  at a 90 degree angle with element  62 . Elements  62 ,  64  and  66  are all different sizes. Thus, each antenna element  62 ,  64 , and  66  can be configured to produce two frequency bands at different places on the frequency spectrum. Similar to how the antenna embodiments shown in FIGS. 12-16 can be configured to operate with two separate communication systems at different frequency bands, the antenna  60  can be configured to operate with three separate communications each at a different frequency band. FIG. 17 shows element  66  facing in a direction opposite to elements  62  and  64 , however element  66  can be arranged in the same direction as elements  62  and  64  as shown in FIG.  18 . In embodiments shown in both FIGS. 17 and 18, the feed line  68  and ground line  70  are attached to element  62 . 
     FIG. 19 illustrates an alternative embodiment of the antenna  60  shown in FIG.  18 . The antenna  60  shown in FIG. 19 includes still another antenna element  72  attached to element  62 . Element  72  is arranged in a semi-circular way with elements  64  and  66  in the direction of current flow in element  62 . Alternatively, element  72 , or elements  64  or  66 , could also be arranged in the opposite direction or any combination thereof to accommodate the size constraints placed on the antenna  60  by the particular antenna application. In this embodiment, elements  62 ,  64 ,  66 , and  72  are all different sizes and are configured to produce eight separate frequency bands in four distinct sections on the frequency spectrum (each element producing a high and low frequency in its respective section of the spectrum). However, as described herein with respect to other embodiments of the invention, the characteristics of the antenna elements  62 ,  64 ,  66 , and/or  72  can be designed to allow the different-sized antenna elements to produce overlapping frequency bands. Alternatively, one of more of elements  62 ,  64 ,  66 , or  72  could be configured to be about the same size as another element thus acting to produce frequencies bands in the same section which combine to expand to the high and low frequency bands produced by the respective elements as described above. In this embodiment, the feed line  68  and ground line  70  are both attached to element  62 . 
     FIG. 20 illustrates an alternative embodiment of the antenna shown in FIG.  5 . The antenna  60  shown in FIG. 20 includes three antenna elements  62 ,  64 , and  66  connected together. Elements  62  and  64  are arranged perpendicular to each other and element  66  is arranged between elements  62  and  64  at an angle of less than  90  degrees from element  62 . Because element  66  is not perpendicular to elements  62  and  64 , come magnetic coupling is likely to occur between elements. However, this coupling can be controlled and minimized, as described herein with respect to other embodiments of the invention, by altering various characteristics of the antenna elements or by adding matching elements. In this embodiment, elements  62 ,  64 , and  66  are approximately the same size and thus could be configured to produce frequency bands that combine to expand the frequency bands produced by a single antenna element. In this embodiment, feed Line  68  is attached to element  62  and ground line  70  is attached to element  64 . Alternatively, as shown in FIG. 21, ground line  70  could be attached to element  66 . It is contemplated that other feed line/ground line arrangements are possible and within the scope of this invention. 
     FIG. 22 illustrates an alternative embodiment of the antenna  60  shown in FIG.  21 . This embodiment of antenna  60  includes six antenna elements  62 ,  64 ,  66 ,  72 ,  74 , and  76  attached together. While feed line  68  is shown attached to element  62  and ground Line  70  is shown attached to element  66 , the feed line  68  and ground line  70  could be attached to other elements. In this embodiment, the antenna elements  62 ,  64 ,  66 ,  72 ,  74 , and  76  are approximately the same size. Thus, as with the embodiment shown in FIGS. 20 and 21, the antenna elements  62 ,  64 ,  66 ,  72 ,  74 , and  76  can be configured to produce frequency bands that combine to expand the overall frequency bands produced by antenna  60 . Alternatively, the elements  62 ,  64 ,  66 ,  72 ,  74 , and  76  could be configured to be different sizes thus producing frequency bands in distinct sectors of the frequency spectrum as previously described for other antenna embodiment discussed herein. In addition, a combination of same-sized and different-sized elements could be designed to produce expanded frequencies (caused by same-sized elements) in distinct sectors of the frequency spectrum (caused by different-sized elements). Additional elements can also be added in different planes (as previously discussed) or elements  62 ,  64 ,  66 ,  72 ,  74 , and  76  could be arranged in different planes in order to meet the space requirements of a specific application. 
     FIG. 23 illustrates an alternative embodiment of the antenna shown in FIG.  12 . The antenna  78  shown in FIG. 23 includes one Large antenna element  80  and three, same-sized, smaller antenna elements  82 ,  84  and  86 . Feed line  88  and ground line  90  are attached to element  80 . Large element  80  can be configured to produce a high and low frequency band in one sector of the frequency spectrum, while the three, same-sized, smaller antenna elements  82 ,  84 , and  86  produce an expanded high and low frequency band in a higher sector of the frequency spectrum than that of the large element  80 . As described above, the frequency bands produced by elements  82 ,  84  and  86  combine to produce the expanded high and low frequency bands in the higher sector. 
     FIG. 24 illustrates an alternative embodiment of the antenna  78  shown in FIG.  23 . In this embodiment, elements  82 ,  84 , and  86  are different-sized, smaller antenna elements. Thus, each of elements  82 ,  84  and  86  produce a high and low frequency band in a different sector of the frequency spectrum. In this manner, because each element  80 ,  82 ,  84 , and  86  produces a high and Low frequency band in a distinct sector of the frequency spectrum, the embodiment of the antenna  78  shown in FIG. 24 can be configured to operate in four different communication systems which operate at different frequencies. As with other embodiment of the invention described herein, coupling between the elements in the antennas shown in FIGS. 22-24 can be controlled and/or minimized in a variety of ways and various aspects of the antenna element&#39;s design and arrangement can be altered to fit the needs of particular antenna applications. 
     It can be readily appreciated that various other combinations of the above described concepts can be used to adapt an antenna to particular applications. These various combinations are considered within the spirit and scope of the invention described herein. The invention should not be considered limited expect as required by the attached claims.