Topband: New 160M high performance receiving antenna at W3LPL

Lee K7TJR k7tjr at msn.com
Wed Feb 6 00:06:58 EST 2013


>The "Wullenwever" antenna was never a low-noise high performance antenna.
 It was simply a system designed to find direction over a very wide frequency 
range. The multitude of elements increased bandwidth, but the physical width 
in wavelengths is the primary determinant of directivity.

    While I will agree that the Wullenweber antenna was never designed to be a
 low noise antenna, I fail to see why it is not. My copy of TM32-....... manual 
on the US version shows some pretty good directivity specs. On the low band
 starting at 2 MHZ the beamwidth was 11 degrees with the side lobes down a 
minimum of 18dB. The maximum elevation was 30 degrees. Also the range
 specified was 4000 nautical miles. And its outer element diameter was
 1116 feet. The 48 low band elements were 35 feet tall with a 120 foot tall 
reflecting screen. Each element had a 19dB gain semiconductor amplifier with 
a 7 dB noise figure. I agree also that not all the 48 elements were active
 however the ones that are in a given direction produce some outstanding specs.
      So if I compare usual high performance low noise RX antennas to this large
 antenna our directivity specs pale in comparison leading me to believe the RDF
 of the "W" system surely would be greater than anything we could imagine with
 our RX antennas. Nor does noise figure appear to be a concern.
     Or is my thinking corrupt?
Lee   K7TJR 


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