Abstract:
A compact SATCOM antenna is provided having an LNA integrated into the radiator body which may be mounted to a handheld satellite radio and articulated with respect to the radio to assume a wide variety of positions for communication with a geosynchronous satellite.

Description:
FIELD OF THE INVENTION 
   This invention relates to satellite communication (SATCOM) antennas, and, more particularly, to a compact SATCOM antenna having an integrated low noise amplifier (LNA) which may be directly connected to a satellite radio and articulated to a wide variety of positions. 
   BACKGROUND OF THE INVENTION 
   Handheld and other types of satellite radios require an antenna to transmit and receive signals, and must be provided with sufficient gain to communicate with geosynchronous satellites. A number of suitable antennas have been developed in the past but most are relatively large and bulky, they must be unloaded from a container, backpack or the like and then folded-out for use. In many situations, time is of the essence and it is desirable to communicate “on-the-move” without stopping to assemble an antenna for the radio. Moreover, in the case of a handheld radio, the antenna must be compact and lightweight if it is to be used on-the-move so as not to interfere with the operation or transport of the radio. 
   An LNA is typically employed to enhance receive performance while reducing out-of-band interference and achieving high dynamic range. LNAs are active devices and require DC power. When integrated within an antenna, the LNA is powered and switched by the radio. The LNA improves cascaded system performance in terms of system noise figure by overcoming system losses that occur after the LNA. 
   SUMMARY OF THE INVENTION 
   This invention is directed to a compact SATCOM antenna having an LNA integrated into the radiator body which may be mounted to a handheld satellite radio and articulated with respect to the radio to assume a wide variety of positions for communication with a geosynchronous satellite. 
   The antenna of this invention is preferably a dipole antenna comprising a coupler adapted to connect to a satellite radio, a top radiator section, and, a bottom radiator section including a housing and a linkage extending between the coupler and the bottom radiator section. The top radiator section is preferably joined by a threaded connection to the bottom radiator section so that the two sections may be disassembled, as desired. The housing of the bottom radiator section encloses a printed circuit board which incorporates an LNA. 
   The linkage is preferably a gooseneck or other length of flexible conductor or the like which may be readily moved within wide range of positions relative to its point of connection to the coupler. This permits the radio operator to articulate the bottom radiator section, and, hence, the top radiator section, into polarization alignment with a satellite to be used for communication. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure, operation and advantages of the presently preferred embodiment of this invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a front view of a handheld radio connection to the SATCOM antenna of this invention wherein articulation of the antenna is shown in dotted and solid lines; 
       FIG. 2  is a cross sectional view of the coupler and the bottom radiator section of the antenna; 
       FIG. 3  is an enlarged view of that portion of the bottom radiator section depicted in cross section in  FIG. 2 ; and 
       FIG. 4  is a cross sectional view taken generally along line  4 - 4  of  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring initially to  FIG. 1 , the SATCOM antenna  10  of this invention is shown connected to a handheld radio  12  by a coupler  14 . The antenna  10  is preferably a dipole antenna having a top radiator section  16 , and a bottom radiator section  18  which is formed by a circuit board housing  20  and a linkage  22 . The linkage  22  is preferably a gooseneck or other form of readily bendable length of metal or similar flexible conductor which may be moved to a particular position and remain there until moved again. The degree of articulation of the linkage  22  is partially illustrated in  FIG. 1  wherein the antenna  10  is depicted in both solid and phantom lines. It should be understood that the linkage  22  may also be moved in and out of the plane of the sheet on which  FIG. 1  is depicted, as well as toward the radio  12 , if desired. Further, the terms “top,” “bottom,” “inner” and “outer” as used herein refer to the position and/or direction of elements of this invention in the orientation in which they are shown in the Figs. 
   As best seen in  FIG. 2 , the coupler  14  includes a connector  24  and a balun  26  which are axially aligned with one another and coupled to one end of a coaxial cable  28 . The connector  24  is preferably a threaded Neill-Concelman (TNC) connector, or other connector suitable for coupling the coaxial cable to radio  12 . In order to form the coupler  14 , one end of the linkage  22  is placed in axial alignment with the connector  24  and balun  26 , and then all three components are encased within a non-conductive body  30  formed of epoxy or other suitable material which may be poured or injected over such components and thereafter cured to form a hardened structure which insures alignment of linkage  22  and connector  24 . The body  30  is then covered by an overwrap  32 , preferably in the form of a layer or layers of resilient material such as rubber or the like. 
   Referring now to  FIGS. 3 and 4 , the circuit board housing  20  of the bottom radiator section  18  of the antenna  10  is shown in detail. Housing  20  includes a casing  34  preferably formed in the shape of a cylinder cut in half along its longitudinal axis, thus defining one half section depicted in  FIG. 3  and a cover (not shown). The cover is connected by screws  36  to the other half of casing  34  in the locations illustrated in  FIG. 3 . The two halves of casing  34  define a side wall  38 , opposed end walls  40  and  42 , and, a cylindrical-shaped extension  44  which protrudes outwardly from the end wall  40 . The extension  44  is connected to one end of linkage  22 , such as by crimping or the like. 
   In the presently preferred embodiment, a printed circuit board  46  is mounted within the casing  34  in the position shown in  FIG. 4 . One end of the printed circuit board  46  connects to the end wall  40 , and its opposite end extends past the end wall  42  into engagement with a slot formed in a conical conductor nut  50  having an internally threaded bore  52 . The coaxial cable  28  from the coupler  14  extends through the hollow linkage  22  and connects to the printed circuit board  46  near the end wall  40 . As schematically depicted in  FIG. 4 , the printed circuit board  46  includes an LNA  54  which is therefore integrated into the bottom radiator section  18  of the antenna  10 . 
   The casing  34 , and, hence, printed circuit board  46 , as well as the nut  50  and a portion of the linkage  22 , are preferably encased within a non-conductive body  56  of the same material as body  30  described above. Initially, the two halves of the casing  34  of the housing  20  are assembled, and a sleeve  58  formed of plastic or the like is slipped over the inner end of the conical conductive nut  50 . The sleeve  58  prevents epoxy from entering the interior of casing  34  and contaminating the printed circuit board  46  as it is poured over the casing  34  and nut  50 . Once the epoxy has cured to form non-conductive body  56 , an overwrap  60  of the same type as overwrap  32  covers the body  56  and engages both the linkage  22  and nut  50 . The casing  34 , body  56  and overwrap  60  collectively form the housing  20  for the printed circuit board  46 . 
   The top radiator section  16  is formed with a threaded extension (not shown) which is received within the threaded bore  52  of the nut  50  in order to connector the two radiator sections  16  and  18  together. This forms the completed antenna  10  as illustrated in  FIG. 1 . With the coupler  14  connecting the antenna  10  to the radio  12 , the antenna  10  may be moved to essentially an infinite number of positions to align it with a satellite of interest. Because the LNA  54  is integrated into the bottom radiator section  18  of the antenna  10 , transmission line losses are reduced. The radio  12  supplies 12 volts DC to both switch and power the LNA  54 . 
   While the invention has been described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.