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On Sep 14, 12:23*am, "Sal M. Onella"
wrote: NOTE: *This is a repost from my sent file. *It didn't appear 20 hours or so after I sent it. *Sorry if it's a dupe to anybody. ---------------------------------------------------------------------"Art Unwin" wrote in message news:7ce5bd71-d583-433d-88f0- snip The navy would not change to a antenna that was not resonant. Perhaps you are speaking of another country's Navy with which you are well-acquainted. Having been intimately involved with US Navy electronics for over 45 years (active duty 1962 -1982; civilian support in multiple capacities 1982 - 2007) *I can tell you that our Navy has numerous shipboard and shore-establishment antennas that are not resonant. *Since flexibility in frequency selection confers a tactical advantage, broadbanding is far more important. *Tuners and couplers of several designs allow non-resonant antennas to work well. The closest the Navy gets to resonant antennas is in some special fixed-frequency applications, like IFF. *Of course, antennas are sized for the application and will probably exhibit resonance within their band of operation, but that's not the design goal. These were shore based installations probably in Hawaii or some island. With respect to resonance, moving away from such as well as changing from 15 degrees (Frank's 30 degrees divided by two) would provide a pattern of distinct advantage which the navy is constantly looking for For a whip tipped at an angle of 15 degrees can provide a forward pattern of gain which can be a big deal I anticipate that the navy will gyrate towards helical design where the addition of a magnetic field will give a pattern of choice together with resonance the size of a shoebox to reduce the number of antennas on board. Thanks for the info, it certainly was not silly As an aside the 15 degrees is the same as found empirically by Kraus in the pitch angle of a helical, another example of the inclusion of the weak force in a system in equilibrium ! |
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