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On Mon, 02 Feb 2004 14:30:39 GMT, "Scott Gordon"
wrote: I seen in a recent article showing a Compact T Antenna for 160 Meters. Tophat is 80 ft long and the T is connected in the center and should be 40ft long with a 20uH to the feedpoint then the shield to ground. Has anyone used one of these antennas? I use a Inverted L right now and it is playing very well but the noise is S9 to 5 Over. I understand the the T Antenna is a much more quiet antenna? Thanks Scott A classic vertical antenna should indeed have a pretty deep overhead null. Perhaps also your T antenna might have this null- it probably depends on how symmetrical you can make the antenna. I can think of scenarios where the difference between an inverted L and a T antenna should be minimal, namely when the predominate noise source is man-made and local. OTOH your T antenna might discriminate better against atmospheric noise that originates fairly 'close by', but is beyond ground wave range. Certainly if your T has a good overhead null, there is one kind of noise that it will reject much better than your inverted L, namely the very loud close-in signals from your competition in a big pileup, and especially if the DX is working everyone transceive instead of QSX up/down. The DX is often puny weak and the pile more like 40+dB over S9. If your ham neighbor 50-100 miles up the road from you simply has to have the DX you are calling, his high-angle NVIS signal may be deafening on an inverted L but manageable on a vertical having a good overhead null. BTW the foregoing discussion assumes you are using your antenna to receive as well as to transmit. It certainly sounds that way from the way you posed your question. 73, David K3KY P.S. An interesting artifact of bobtail/ half square arrays is that often the ham who has just put one up becomes worried that the antenna is not working. The band sounds too quiet at first. But upon tuning around, he finds that there are good signals across the band standing out well from the background. Here we see a double treat in effect- good overhead null plus the nice, deep end nulls off the ends in line with the horizontal wire. It is a striking effect which I have heard myself at this QTH. Just a thought... |
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