Abstract:
The present invention provides a printed circuit board omni directional antenna. The omni directional antenna includes power dissipation elements. The power dissipation elements reduces the impact the power feed to the radiating elements has on the omni directional antenna&#39;s radiation pattern.

Description:
CROSS REFERENCE To RELATED APPLICATIONS  
       [0001]    This application claims the benefit of United States Provisional Patent Application Serial No. 60/456,764, filed Mar. 21, 2003, titled Multi-Band Omni Directional Antenna, incorporated herein by reference. 
     
    
     
       BACKGROUND OF INVENTION  
         [0002]    Omni directional antennas are useful for a variety of wireless communication devices because the radiation pattern allows for good transmission and reception from a mobile unit. Currently, printed circuit board omni directional antennas are not widely used because of various drawbacks in the antenna device. In particular, cable power feeds to conventional omni directional antennas tend to alter the antenna impedance and radiation pattern, which reduces the benefits of having the omni directional antenna.  
           [0003]    Thus, it would be desirous to develop a printed circuit board omni directional antenna device having a power feed that does not significantly alter the antenna impedance or radiation pattern  
         FIELD OF THE INVENTION  
         [0004]    The present invention relates to antenna devices for communication and data transmissions and, more particularly, to a multi-band omni directional antenna with reduced current on outer jacket of the coaxial feed.  
         SUMMARY OF INVENTION  
         [0005]    To attain the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, an omni directional antenna is provided. The omni directional antenna includes a radiation portion and a power feed portion. The radiation portion includes a plurality of radiating elements. The power feed portion includes at least one power dissipation element. The at least one power dissipation element is coupled to a ground such that the impact on the antenna radiation pattern from the power feed is reduced.  
           [0006]    The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0007]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention, and together with the description, serve to explain the principles thereof. Like items in the drawings may be referred to using the same numerical reference.  
         [0008]    [0008]FIG. 1 is an illustrative block diagram of a printed circuit board omni directional antenna consistent with an embodiment of the present invention;  
         [0009]    [0009]FIG. 2 is an illustrative block diagram of a printed circuit board omni directional antenna consistent with another embodiment of the present invention; and  
         [0010]    [0010]FIG. 3 is an illustrative block diagram of a printed circuit board omni directional antenna consistent with still another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0011]    The present invention will be further explained with reference to the FIGS. Referring first to FIG. 1, a plan view of a printed circuit board omni directional antenna  100  is shown. Antenna  100  has a radiation portion  110  and a power feed portion  120  mounted on a substrate  130 . Substrate  130  can be a number of different materials, but it has been found that non conductive printed circuit board material, such as, for example, sheldahl comclad PCB material, noryl plastic, or the like. It is envisioned that substrate  130  will be chosen for low loss and dielectric properties. A surface  132  of substrate  130  forms a plane. Radiation portion  110  and power feed portion  120  are mounted on substrate  130 .  
         [0012]    Radiation portion  110  comprises multiple conductive prongs to allow radiation portion  110  to operate at multiple bands. In this case, radiation portion has radiating element  112  and radiating element  114 . As one of ordinary skill in the art will recognize on reading this disclosure, the operating bands can be tuned by varying the length L of radiating element  112 , the length L1 of radiating element  114 , or a combination thereof. While two radiating elements are shown, more or less are possible. Varying the thickness and dielectric constant of the substrate may also be used to tune the frequencies.  
         [0013]    Power feed portion  120  comprises multiple conductive prongs similar to radiation portion  110 . In this case, power feed portion  120  has power dissipation element  122 , power dissipation element  124 , and power dissipation element  126 . Power dissipation elements  122 ,  124 , and  126  may have identical lengths or varied lengths L2, L3, and L4 as shown. While three power dissipation elements are shown, more or less are possible.  
         [0014]    Radiating elements  112  and  114 , and power dissipation elements  122 ,  124 , and  126  can be made of metallic material, such as, for example, copper, silver, gold, or the like. Further, radiating elements  112  and  114 , and power dissipation elements  112 ,  124 , and  126  can be made out of the same or different materials. Still further, radiating element  112  can be a different material than radiating element  114 . Similarly, power dissipation elements  112 ,  124 , and  126  can be made out of the same material, different material, or some combination thereof.  
         [0015]    In this case, coaxial cable conductor  140  supplies power to antenna  100 . While the power feed is shown as coaxial cable conductor  140 , any type of power feed structure as is known in the art could be used. Coaxial cable conductor  140  has a center conductor  142  and an outer jacket  144 . center conductor  142  is connected to radiation portion  110  to supply power to radiating elements  112  and  114 . Outer jacket  144  is connected to power feed portion  120  to dissipate power from outer jacket  144 . Optionally, coaxial cable conductor  140  can be attached to the length of power dissipation element  124  or directly to substrate  130  to provide some strength. Generally, the connections are accomplished using solder connections, but other types of connections are possible, such as, for example, snap connectors, press fit connections, or the like.  
         [0016]    Another embodiment of the present invention is shown in FIG. 2. FIG. 2 shows a perspective view of an antenna  200  consistent with the present invention. Similar to antenna  100 , antenna  200  comprises a radiation portion  110  and a power feed portion  120 . Unlike antenna  100 , antenna  200  does not comprise a substrate  130  and has a different configuration. In particular, radiation portion  110  includes radiating element  202  and radiating element  204  arranged in a face-to-face or a broadside configuration (in other words, the broadsides of each radiating element are in different and substantially parallel planes). Similarly, power feed portion  120  includes power dissipation elements  206  and  208  arranged in a broadside configuration. As can be appreciated, radiating elements  202  and  204  are separated by a distance d. Altering distance d can assist in tuning antenna  200 . Radiating elements  202  and  204 , may angle towards or away from each other while still in a face-to-face, but non-parallel configuration. A coaxial cable power feed  140  is attached to antenna  200 . Coaxial cable power feed  140  includes a central conductor  142  and an outer jacket  144 . Central conductor is attached to radiation portion  110 , and outer jacket  144  is attached to power dissipation portion  120 , similar to the above.  
         [0017]    In this case, conductor  142  serves the additional purpose of coupling radiation portion  110  and power feed portion  120  together. Insulation is provided between portions  110  and  120  by outer jacket  144 . Instead of using coaxial cable, non-conducting posts  210  can be used.  
         [0018]    Referring now to FIG. 3, an antenna  300  is shown consistent with another embodiment of the present invention. Antenna  300  has identical components to antenna  100 , which components will not be re-described here. Unlike antenna  100 , antenna  300  has a non-flat substrate  302 . As shown, substrate  302  is a flexible substrate or a non-flexible substrate formed in an alternative shape, using fabrication technologies, such as, for example, injection molding. While shown as a wave shape, substrate  302  could take other configurations, such as, for example, a V shape, a arc shape, a U shape, a trough shape, an elliptical shape, or the like. In this configuration, the shape of substrate  302  will influence the frequency bands as well as the other tuning factors identified above.  
         [0019]    While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made without departing from the spirit and scope of the invention.