Abstract:
A balun component or structural subassembly, for use in conjunction with an antenna radome assembly, comprises a two-sided printed circuit board substrate having a longitudinal axis, wherein each side of the two-sided printed circuit board substrate is asymmetric with respect to itself but is in effect anti-symmetric with respect to the opposite side of the two-sided printed circuit board substrate in a 180° out-of-phase manner such that the entire two-sided printed circuit board balun component or structural subassembly exhibits diametrical symmetry with respect to the longitudinal axis of the overall two-sided printed circuit board substrate. Such diametrical symmetry with respect to the longitudinal axis of the overall two-sided printed circuit board substrate enables operatively associated antenna sensor amplitude and phase comparison assemblies or systems to achieve well-behaved and unsquinted amplitude and phase patterns regardless or independent of polarization in order to reduce angle of arrival (AOA) errors. In addition, the balun component or structural subassembly comprises tapered transformer structure which effectively converts the coaxial feed point impedance values of incoming signals to signals having impedance values at the output or downstream end which are able to achieve good impedance matching with the aforenoted spiral circuit component or assembly of the radome elements or components of the overall antenna structure. Still further, such tapered transformer structure positively affects or enhances the range of bandwidth frequencies over which the balun component or structural subassembly is capable of operating.

Description:
STATEMENT OF GOVERNMENT INTERESTS 
     The United States Government has a paid-up license in connection with the present invention and accordingly has the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by means of the terms of United States Government Contract Number N00019-97-C-0147 which was awarded by means of the United States Navy. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to balun components or structural subassemblies utilized in conjunction with antenna radome assemblies, and more particularly to a new and improved balun component or structural subassembly which comprises a two-sided printed circuit board substrate having a longitudinal axis, and wherein each side of the two-sided printed circuit board substrate is asymmetric with respect to itself but is in effect anti-symmetric with respect to the opposite side of the two-sided printed circuit board substrate in a 180° out-of-phase manner such that the entire two-sided printed circuit board balun component or structural subassembly exhibits diametrical symmetry with respect to the longitudinal axis of the overall two-sided printed circuit board substrate. 
     BACKGROUND OF THE INVENTION 
     Most direction finding systems utilize antenna sensor amplitude and phase comparison techniques in order to necessarily determine angle of arrival (AOA) information or data with respect to a distant emitter. Such antenna sensor amplitude and phase comparison assemblies or systems must exhibit well-behaved amplitude and phase patterns regardless or independent of polarization in order to reduce angle of arrival (AOA) errors. Some prior art balun components, devices, or structural subassemblies have in fact been developed for utilization within such antenna sensor amplitude and phase comparison assemblies or systems in an attempt to provide such well-behaved and unsquinted amplitude and phase patterns, however, their performance has unfortunately been limited to narrow frequency bandwidth parameters. Other prior art balun components or subassemblies comprise broadband devices, however, they require cumbersome coaxial implementation which renders the antenna sensor amplitude and phase comparison assembly or system unnecessarily and undesirably large. Still other prior art balun components or subassemblies are desirably small and light in weight but are not symmetrical and therefore do not provide the required well-behaved and unsquinted amplitude and phase patterns regardless or independent of polarization. 
     Still further, the balun components or subassemblies are often particularly adapted for cooperative use in conjunction with spiral circuit components or assemblies which are, in turn, operatively associated with radome elements or components of overall antenna radome assemblies. Such balun components or subassemblies conventionally comprise parallel strip transmission lines, however, such parallel strip transmission lines are known to have high impedance values on the order of 200 ohms due to their inherently low capacitance characteristics which renders impedance matching difficult to achieve. As a result, antenna efficiency and operating bandwidth are compromised within the printed circuit board line width and spacing tolerances. 
     A need therefore exists in the art for a new and improved balun component or structural subassembly which can be utilized within antenna sensor amplitude and phase comparison assemblies or systems wherein such balun component or structural subassemblies can provide well-behaved and unsquinted amplitude and phase patterns regardless or independent of polarization in order to reduce angle of arrival (AOA) errors, and wherein further, such balun components or structural subassemblies will exhibit broad frequency bandwidth parameters as well as good antenna radome assembly impedance matching characteristics. 
     OBJECTS OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a new and improved balun component or structural subassembly for use within antenna sensor amplitude and phase comparison assemblies or systems. 
     Another object of the present invention is to provide a new and improved balun component or structural subassembly for use within antenna sensor amplitude and phase comparison assemblies or systems which effectively overcome the various operational drawbacks or disadvantages characteristic of PRIOR ART antenna sensor amplitude and phase comparison assemblies or systems. 
     An additional object of the present invention is to provide a new and improved balun component or structural subassembly for use within antenna sensor amplitude and phase comparison assemblies or systems which can provide well-behaved and unsquinted amplitude and phase patterns regardless or independent of polarization in order to reduce angle of arrival (AOA) errors. 
     A further object of the present invention is to provide a new and improved balun component or structural subassembly for use within antenna sensor amplitude and phase comparison assemblies or systems which will exhibit broad frequency bandwidth parameters as well as good antenna radome assembly impedance matching characteristics. 
     SUMMARY OF THE INVENTION 
     The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved balun component or structural subassembly, for use within antenna sensor amplitude and phase comparison assemblies or systems, which comprises a two-sided printed circuit board substrate having a longitudinal axis, and wherein each side of the two-sided printed circuit board substrate is asymmetric with respect to itself but is in effect anti-symmetric with respect to the opposite side of the two-sided printed circuit board substrate in a 180° out-of-phase manner such that the entire two-sided printed circuit board balun component or structural subassembly exhibits diametrical symmetry with respect to the longitudinal axis of the overall two-sided printed circuit board substrate. 
     As a result of the aforenoted asymmetric, anti-symmetric structural characteristics of the new and improved balun component or structural subassembly, the aforenoted diametrical symmetry with respect to the longitudinal axis of the overall two-sided printed circuit board substrate enables the operatively associated antenna sensor amplitude and phase comparison assemblies or systems to achieve well-behaved and unsquinted amplitude and phase patterns regardless or independent of polarization in order to reduce angle of arrival (AOA) errors. In addition, the anti-symmetric structure of the new and improved balun component or structural subassembly exhibits balanced output characteristics for operative cooperation with spiral circuit components or assemblies of radome elements or components of overall antenna radome assemblies. Still further, the new and improved balun component or structural subassembly lastly comprises tapered transformer structure which effectively converts the coaxial feed point impedance value to an impedance value at the output or downstream end which is able to achieve good impedance matching with the aforenoted spiral circuit component or assembly of the radome elements or components of the overall antenna structure. In addition, such tapered transformer structure positively affects or enhances the range of bandwidth frequencies over which the new and improved balun component or structural subassembly is capable of operating. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other objects, features, and attendant advantages of the present invention will be more fully appreciated from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views, and wherein: 
     FIG. 1 is a top plan view of a new and improved balun component or structural subassembly constructed in accordance with the principles and teachings of the present invention and showing the cooperative parts thereof; 
     FIG. 2 is a bottom plan view of the new and improved balun component or structural subassembly as shown in FIG. 1, and corresponding to the new and improved balun component or structural subassembly as shown in FIG. 1 when the new and improved balun component or structural subassembly as shown in FIG. 1 is rotated around the longitudinal axis thereof, thereby illustrating the anti-symmetric structure of the new and improved balun component or structural subassembly constructed in accordance with the principles and teachings of the present invention; 
     FIG. 3 is a bottom plan view of the new and improved balun component or structural subassembly as shown in FIG. 1, and corresponding to the new and improved balun component or structural subassembly as shown in FIG. 1 when the new and improved balun component or structural subassembly as shown in FIG. 1 is rotated around the left end edge portion thereof, thereby illustrating, from a somewhat different perspective than that of FIG. 2, the anti-symmetric structure of the new and improved balun component or structural subassembly constructed in accordance with the principles and teachings of the present invention; 
     FIG. 4 is an exploded, front perspective view of an antenna assembly in connection with which the new and improved balun component or structural subassembly, constructed in accordance with the principles and teachings of the present invention, is to be utilized in order to in fact achieve well-behaved and unsquinted amplitude and phase patterns regardless or independent of polarization in order to reduce angle of arrival (AOA) errors; 
     FIG. 5 is an exploded, rear perspective view of the antenna assembly illustrated in FIG. 4 showing, particularly in connection with FIG. 4, the mounting of the new and improved balun component or structural subassembly, constructed in accordance with the principles and teachings of the present invention, for use in connection with antenna assemblies for achieving well-behaved and unsquinted amplitude and phase patterns regardless or independent of polarization in order to reduce angle of arrival (AOA) errors; 
     FIG. 6 is a graphical plot of phase interferometer error as a function of frequency illustrating the enhanced performance achieved by means of the new and improved balun component or structural subassembly constructed in accordance with the principles and teachings of the present invention as compared to a PRIOR ART balun component or structural assembly; 
     FIG. 7 is a graphical plot of angle of arrival (AOA) error as a function of frequency illustrating the enhanced performance achieved by means of the new and improved balun component or structural subassembly constructed in accordance with the principles and teachings of the present invention as compared to a PRIOR ART balun component or structural assembly; and 
     FIG. 8 is a graphical plot of standing wave ratio (SWR) as a function of frequency illustrating the enhanced efficiency achieved by means of the new and improved balun component or structural subassembly constructed in accordance with the principles and teachings of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and more particularly to FIG. 1 thereof, a new and improved balun component or structural subassembly, constructed in accordance with the principles and teachings of the present invention, is disclosed in a top plan view of the same and is generally indicated by the reference character  10 . More particularly, the new and improved balun component or structural subassembly  10  constructed in accordance with the principles and teachings of the present invention is seen to comprise a printed circuit board substrate  12  which has a longitudinal axis  14  and a top or front surface portion  16 . A microstrip line  18  extends axially inwardly from a left end edge portion  20  of the printed circuit board substrate  12 , and it is seen that the microstrip line  18  is disposed at a radially offset position with respect to the longitudinal axis  14  of the printed circuit board substrate  12  so as to effectively be disposed upon a first lateral upper side portion  22  of the top or front surface portion  16  of the printed circuit board substrate  12  as considered with respect to the longitudinal axis  14 . The microstrip line  18  is copper-plated upon the top or front surface portion  16  of the printed circuit board substrate  12  and is integrally connected to a first anti-symmetric ground plane  24  by means of a radially or transversely extending electrical connector portion  26 . Both the first anti-symmetric ground plane  24  and the transversely or radially extending electrical connector portion  26  are also copper-plated upon the top or front surface portion  16  of the printed circuit board substrate  12 , and it is seen that the first anti-symmetric ground plane  24  is likewise disposed at a radially offset position with respect to the longitudinal axis  14  of the printed circuit board substrate  12  so as to effectively be disposed upon a second lower lateral side portion  28  of the top or front surface portion  16  of the printed circuit board substrate  12  as considered with respect to the longitudinal axis  14 . 
     The extreme left end portion of the microstrip line  18  is operatively connected to a coaxial feed point  30 , through which incoming signals are introduced by means of a suitable coaxial connector, not shown, and accordingly, the incoming signals are therefore capable of being conducted or transmitted along the microstrip line  18  and the radially or transversely extending electrical connector portion  26 . At the intersection  32  defined between the radially or transversely extending electrical connector portion  26  and the first anti-symmetric ground plane  24 , the incoming signal is effectively split into a first portion which is conducted in the leftward direction toward an RF short circuit point  34 , comprising a hole electrically connecting the top or upper surface portion  16  of the printed circuit board substrate  12  to a bottom or rear surface portion  36  of the printed circuit board substrate  12 , and into a second portion which is conducted in the rightward direction toward a first tapered transformer  38  which is integral with the first anti-symmetric ground plane  24 . It is to be noted that as a result of the transmission of the first portion of the signal toward the RF short circuit point  34 , that portion of the incoming signal is effectively bounced back or reflected by means of the RF short circuit hole  34  so as to in turn be 180° out of phase with respect to subsequently transmitted first portion signals, thereby effectively cancelling the same. This enables or facilitates enhanced transmission of the second portion signals toward and along the first tapered transformer  38 . Such second portions of the incoming signals are thus able to be transformed from signals having an impedance value of 50 ohms to signals having an impedance value of 120 ohms so as to facilitate impedance matching with a spiral circuit component  40  of an antenna radome assembly  42 , the structure of which will be discussed in greater detail in connection with FIGS. 4 and 5. It is also noted that an air gap region  43  is defined upon the top or front surface portion  16  of the printed circuit board substrate  12  between the microstrip line  18  and the first anti-symmetric ground plane  24 . 
     It is to be noted that the transformation of the second signal portion being conducted or transmitted along the first tapered transformer  38  occurs as a result of the first tapered transformer  38  having a uniquely curved, arcuate, or tapered configuration, as disclosed within FIG. 1, which extends in the longitudinal axial direction from its integral connection with the first anti-symmetric ground plane  24  toward an opposite end edge portion  44  of the printed circuit board substrate  12 . The first tapered transformer  38  terminates in a balun tip antenna connection line or terminal wire  46  which extends a predetermined distance beyond the opposite end edge portion  44  of the printed circuit board substrate  12 . It is noted still further that the upper edge portion  48  of the first tapered transformer  38 , as disclosed or viewed in FIG. 1, is disposed above the longitudinal axis  14  so as to be effectively disposed upon the first lateral side portion  22  of the top or upper surface portion  16  of the printed circuit board substrate  12 . 
     With reference now being made to FIGS. 2 and 3, there are respectively disclosed bottom plan views of the new and improved balun component or structural subassembly  10  constructed in accordance with the principles and teachings of the present invention and corresponding to the top plan view of the same as disclosed within FIG. 1 but viewed from different perspective viewpoints. More particularly, in accordance with the new and improved balun component or structural subassembly  10  constructed in accordance with the principles and teachings of the present invention, it is seen that the bottom or rear surface portion  36  of the printed circuit board substrate  12  is structured so as to effectively be anti-symmetric with respect to the structure of the top or front surface portion  16  of the printed circuit board substrate  12  except for the fact that the microstrip line  18  and coaxial feed point  30  components, disposed upon the top or front surface portion  16  of the printed circuit board substrate  12 , are not present upon, or have been omitted from, a first lower lateral side portion  50  of the bottom or rear surface portion  36  of the printed circuit board substrate  12  as viewed in FIG.  3  and with respect to the orientation of the substrate  12  as shown in FIG.  1 . However, in accordance with the specifically developed structure uniquely characteristic of the new and improved balun component or structural subassembly  10  constructed in accordance with the principles and teachings of the present invention, it is seen that, in a manner similar to the top or front surface portion  16  of the printed circuit board substrate  12 , the bottom or rear surface portion  36  of the printed circuit board substrate  12  comprises a second anti-symmetric ground plane  52  which is copper-plated upon the bottom or rear surface portion  38  of the printed circuit board substrate  12  and which is disposed at a radially offset position with respect to the longitudinal axis  14  of the printed circuit board substrate  12  so as to effectively be disposed upon a second upper lateral side portion  54  of the bottom or rear surface portion  38  of the printed circuit board substrate  12  as considered with respect to the longitudinal axis  14  when the printed circuit board substrate  12  is disposed in a fixed position as would be the case when viewed in FIGS. 1 and 3. 
     As a result of the aforenoted presence or provision of the RF short circuit point  34 , and its connection to the bottom or lower surface portion  38  of the printed circuit board substrate  12 , or more particularly, as a result of the RF short circuit point or hole  34  electrically connecting the first top surface anti-symmetric ground plane  24  to the second bottom surface anti-symmetric ground plane  52 , the aforenoted first portions of the incoming signals are also now able to be transmitted or conducted by means of the RF short circuit point or hole  34  toward and along the second anti-symmetric ground plane  52  which, in turn, is electrically connected to a second tapered transformer  56 . In this manner, those portions of the incoming signals are likewise able to be transformed from signals having an impedance value of 50 ohms to signals having an impedance value of 120 ohms so as to likewise facilitate the impedance matching with the spiral circuit component  40  of the antenna radome assembly  42 , the structure of which will be discussed in greater detail in connection with FIGS. 4 and 5. As was the case with the first tapered transformer  38 , it is to be noted that the transformation of the first signal portion being conducted or transmitted along the second tapered transformer  56  occurs as a result of the second tapered transformer  56  likewise having a uniquely curved, arcuate, or tapered configuration, as disclosed within FIGS. 2 and 3, which extends in the longitudinal axial direction from its integral connection with the second anti-symmetric ground plane  52  toward the opposite end edge portion  44  of the printed circuit board subtrate  12  so as to terminate in a balun tip antenna connection line or terminal wire  58  which likewise extends a predetermined distance beyond the opposite end edge portion  44  of the printed circuit board substrate  12 . 
     It is noted still further that the upper edge portion  60  of the second tapered transformer  56 , as disclosed or viewed in FIG. 2, or the lower edge portion  60  of the second tapered transformer  56 , as disclosed or viewed in FIG. 3, is respectively disposed above or beneath the longitudinal axis  14  so as to be effectively disposed upon the first lower lateral side portion  50  of the bottom or rear surface portion  38  of the printed circuit board substrate  12 . In a manner similar to the disposition of the upper edge portion  48  of the first tapered transformer  38 , as viewed or disclosed in FIG. 1, with respect to its position above the longitudinal axis  14  so as to be effectively disposed upon the first upper lateral side portion  22  of the top or front surface portion  16  of the printed circuit board substrate  12 , the disposition of the edge portion  60  of the second tapered transformer  56  upon the first lower lateral side portion  50  of the bottom or rear surface portion  38  of the printed circuit board substrate  12  is critically important in that there is in effect defined an overlap of the two edge portions  48  and  60  of such tapered transformers  38  and  56  whereby the aforenoted resultant impedance values of 120 ohms for antenna impedance matching are able to in fact be achieved. It is critically important to appreciate still further the fact that all of the structural components respectively defining or disposed upon each one of the upper or front and lower or rear surface portions  16  and  38  of the printed circuit board substrate  12  are respectively asymmetrically located with respect to the longitudinal axis  14  of the balun component or structural subassembly  10  and are anti-symmetric with respect to each other from an overall viewpoint of the balun component or structural sub-assembly  10 . 
     The aforenoted asymmetric and anti-symmetric characteristics of the balun component or structural subassembly  10  enables or facilitates improved operative cooperation with the antenna radome assembly  42  as disclosed more in detail in FIGS. 4 and 5. More particularly, an antenna radome assembly, similar to the antenna radome assembly  42  disclosed within FIGS. 4 and 5, is disclosed, for example, in more detail within U.S. patent application Ser. No. 09/759,851 which was filed in the name of Jeffrey T. Butler on Jan. 12, 2001 and is entitled LOW PROFILE ANTENNA RADOME ELEMENT WITH RIB REINFORCEMENTS, the disclosure of which is incorporated herein by reference. Briefly, however, for the purposes of the present patent application and the invention embodied herein, it is seen that the antenna radome assembly  42 , in connection with which the new and improved the balun component or structural subassembly  10  of the present invention is to be operatively used, comprises an antenna radome element or component  62 , the spiral circuit element or member  40  upon which a pair of spiral circuits, arrays, or arrangements are disposed, a spiral circuit support member or component  64  which together with the spiral circuit element or member  40  comprises a spiral circuit support assembly, and a housing member or component  66 . 
     The spiral circuit element or member  40  comprises a printed circuit board assembly which has the configuration of a substantially flat disk, which may be fabricated from a suitable dielectric material, similar to the material from which the balun printed circuit board substrate  12  is fabricated, such as, for example, polytetrafluoroethylene or TEFLON®, and which has a pair of copper circuits, not shown, provided thereon as is conventional. The spiral circuit element or member  40  is adapted to be mounted upon the front face of the spiral circuit support member or component  64  and is preferably bonded thereto by means of a suitable adhesive so as to form the aforenoted integral spiral circuit support assembly. The spiral circuit support member or component  64  is further noted as comprising a honeycomb core structure  68 , as best seen in FIG. 5, and an annular reinforcing peripheral wall  70  is integrally secured around the honeycomb core structure  68 . In order to facilitate the mounting and bonding of the spiral circuit element or member  40  upon the front face of the spiral circuit support member or component  64 , the front end of the spiral circuit support member or component  64 , and more particularly, the front edge portion of the annular reinforcing peripheral wall  70 , is provided with a radially outwardly extending or projecting flange portion  72  which, in addition to the front face or surface of the honeycomb core structure  68  of the spiral circuit support member or component  64 , effectively defines a seat upon which the spiral circuit element or member  40  is able to be mounted and bonded. As may best be seen from FIG. 5, the housing member or component  66  comprises a substantially hollow structure which has a substantially cup-shaped configuration as defined by means of an open forward end, a base or rear end wall member  74 , and a peripheral side wall  76 . 
     It is seen that the inner diametrical dimension of the housing side wall  76  is just slightly larger than the outer diametrical dimension of the annular peripheral wall  70  of the spiral circuit support member or component  64 , and in this manner, the annular peripheral wall portion  70 , and the operatively associated honeycomb core structure  68 , of the spiral circuit support member or component  64  is adapted, and is therefore able, to be mounted and seated internally within the forward open end of the housing  66 . In conjunction with the internal disposition of the honeycomb core structure  68  and the annular peripheral wall portion  70  of the spiral circuit support member or component  64  within the forward open end of the housing  66 , the rear side of the radially outwardly projecting flange portion  72  of the annular peripheral wall portion  70  of the spiral circuit support member or component  64  is seated upon the forward annular edge portion  78  of the side wall  76  of the housing  66  so as to ensure the proper and secure disposition and mounting of the spiral circuit support assembly upon or within the housing  66 . Continuing further, a pair of frequency absorber foam members, only one of which is shown at  80 , are disposed within the housing  66 , and it is seen that the balun component or structural subassembly  10  is disposed coaxially within the housing  66 . 
     More particularly, the rear end portion of the balun component or structural subassembly  10  is suitably secured within an axially protruding, rearwardly disposed stepped portion  82  of the housing  66 , and the balun component or structural subassembly  10  is adapted to pass coaxially through the frequency absorber foam members  80  such that the forward end of the balun component or structural subassembly  10  projects coaxially outwardly from the front surface of the forward one of the pair of frequency absorber foam members  80 . In addition, it is also to be appreciated that when the integral spiral circuit support assembly, comprising the spiral circuit element or member  40  and the spiral circuit support member or component  64 , is mounted or assembled within the forward open end of the housing  66 , the forward end of the balun component or structural subassembly  10  will likewise be disposed coaxially within the honeycomb core structure  68  of the spiral circuit support member or component  64 . It is also to be appreciated that the axial thickness or depth dimension of the pair of frequency absorber foam members  80  is less than that of the housing  66  such that the front surface of the forward one of the pair of frequency absorber foam members  80  is effectively disposed in a recessed mode set axially backwardly from the forward annular edge portion  78  of the side wall  76  of the housing  66 . In this manner, the integral spiral circuit support assembly, comprising the spiral circuit element or member  40  and the spiral circuit support member or component  64 , is able to be completely and properly mounted or accommodated within the housing  66  with the radially outwardly projecting flange portion  72  of the annular peripheral wall portion  70  of the spiral circuit support member or component  64  being seated upon the forward annular edge portion  78  of the side wall  76  of the housing  66  as has been noted hereinbefore. 
     With the various components being so mounted or assembled, it can be further appreciated that the terminal wires  46 , 58  of the balun component or structural subassembly  10  are adapted to project axially through the spiral circuit element or member  40  so as to be able to be electrically connected to the forward face of the spiral circuit element or member  40  by any suitable means, such as, for example, solder connections or the like, not shown, for electrical connection to the pair of spiral circuits formed upon the spiral circuit element or member  40 . As has been noted within the previously referenced, previously filed U.S. patent application Ser. No. 09/759,851 entitled LOW PROFILE ANTENNA. RADOME ELEMENT WITH RIB REINFORCEMENTS, the terminal wires  46 , 58  of the balun component or structural subassembly  10  must also be accommodated within the antenna radome element or component  62 . Accordingly, it is further seen that the antenna radome element or component  62  has a substantially cup-shaped configuration as defined by means of a forwardly disposed wall member  84  from which a rearwardly disposed annular or peripheral side wall member  86  projects, and a plurality of concentrically arranged reinforcing rib members  88  are provided upon the interior surface of the wall member  84 . The centralmost one of the concentrically arranged rib members  88  defines a pocket or recess within which the terminal wires  46 , 58  of the balun component or structural subassembly  10  are in fact accommodated. 
     It is further noted that the housing  66  is also provided with a radially outwardly projecting annular flange portion  90  at an axial position which is adjacent to, but axially set back from, the forward annular edge portion  78  of the side wall  76  of the housing  66 , and in this manner, when the antenna radome element  62  is bonded to and upon the spiral circuit element or member  40 , and when the spiral circuit support assembly, comprising the spiral circuit element or member  40  and the spiral circuit support member or component  64 , is in turn mounted within housing  66 , the annular or peripheral edge portion  92  of the antenna radome element side wall  86  will be seated upon the annular flange portion or member  90  of the housing side wall  76 . This effectively completes the assembly of the antenna radome assembly  42  and clearly illustrates the operative cooperation defined between the new and improved balun component or structural subassembly  10  constructed in accordance with the principles and teachings of the present invention and the antenna radome assembly  42 . 
     Thus, it may be seen that in accordance with the principles and teachings of the present invention, there has been provided a new and improved balun component or structural subassembly  10  which achieves various operational parameters or characteristics which have not heretofore been able to be achieved or accomplished by means of conventional or PRIOR ART balun component or structural subassemblies. More particularly, the asymmetric structure of each side of the balun component or structural subassembly  10 , and the anti-symmetric structure of the overall or two-sided balun component or structural subassembly  10 , provides enhanced phase error and angle of arrival (AOA) error characteristics, in degrees and as functions of frequency, as graphically illustrated in FIGS. 6 and 7. The phase error data, for example, is derived from well-known phase interferometer amplitude comparison direction finding techniques employed in connection with two antenna assemblies or installations which are spaced a predetermined distance apart, and as seen from FIG. 6, a conventionally used balun exhibited an average phase error of 4.80 degrees RMS (root mean square) over the frequency range of 6-18 GHz, whereas the new and improved balun component or structural subassembly  10 , constructed in accordance with the principles and teachings of the present invention, exhibited an average phase error of only 4.02 degrees RMS (root mean square). In a similar manner, the angle of arrival (AOA) error data, for example, is derived from well-known measurements involving predetermined azimuth polarization angular orientations of the antenna assemblies or installations, and as seen in FIG. 7, a conventionally used balun exhibited an average angle of arrival (AOA) error of 2.53 degrees RMS (root mean square) over the frequency range of 6-18 GHz, whereas the new and improved balun component or structural subassembly  10 , constructed in accordance with the principles and teachings of the present invention, exhibited an average angle of arival (AOA) error of only 2.03 degrees RMS (root mean square). 
     With reference now being directed to FIG. 8, wherein the standing wave ratio (SWR) characteristics of the balun component or structural subassembly  10  are plotted as a function of frequency, it is further seen and appreciated that the new and improved balun component or structural subassembly  10 , constructed in accordance with the principles and teachings of the present invention, exhibits maximum standing wave ratio (SWR) values of approximately 1.5:1, whereas, as is known in the art, a standing wave ratio (SWR) of 1:1 is considered perfect or ideal. This data is indicative of the efficiency of the balun component or structural subassembly  10  as implemented by means of, for example, its impedance matching characteristics with respect to the antenna radome assembly  42 . 
     It is lastly noted that as a result of the particular structure of the new and improved balun component or structural subassembly  10 , constructed in accordance with the principles and teachings of the present invention, the new and improved balun component or structural subassembly  10  of the present invention also exhibits broad frequency bandwidth operating capabilities. These broad frequency bandwidth operating capabilities are derived from the fabrication or implementation of the pair of first and second tapered transformers  38  and  56  and the respective use or disposition of the same at their relatively anti-symmetric locations upon the oppositely disposed top or front, and bottom or rear, surfaces portions or regions  16  and  36  of the balun component or structural subassembly  10  whereby, as has been noted hereinbefore, such tapered transformers  38 , 56  transform the impedance values of the incoming or transmitted signals from 50 ohms to 120 ohms. In addition, it is also noted that in conjunction with such tapered transformers  38 , 56 , the presence or provision of the air gap  43  as defined between the microstrip line  18  and the first anti-symmetric ground plane  24  upon the top or front surface  16  of the balun component or structural subassembly  10  likewise serves to provide, establish, or affect, in a well-known manner, advantageous inductance, capacitance, and impedance values or parameters which together with the tapered transformers  38 , 56  generate or facilitate the broad frequency bandwidth operating capabilities of the balun component or structural subassembly  10  of the present invention. 
     Obviously, many variations and modifications of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.