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## Re: [TowerTalk] Horizontal Loops

 To: "RICHARD BOYD" ,"Tim Makins, EI8IC" Re: [TowerTalk] Horizontal Loops "Tom Rauch" Tom Rauch Mon, 16 Aug 2004 10:54:43 -0400
 ```> Many people who have horizontal loops have them low, which is thought to be > good for a big signal close-in -- some of us have experienced having trouble > working close-in stations with antennas that are high -- but a horizontal > loop that's at least a half wavelength up should work fine for DX, and I > expect will be "quieter" (less QRN reception) than other antennas, at least > in some conditions. 73 - Rich, KE3Q > > > So, if the loop is big enough, and has the right angles, it becomes a > > useful > > DX antenna ? The next question would have to be: How do you work out the > > required angles ? I replied to Tim but probably should have CC'ed the reflector. There are many myths about loops. One myth is they are more immune to QRN or noise, another is the peak gain from multiple lobe patterns is useful or effective gain. Whenever we see one thing touted as the answer for everything, we better lookout. Long loops can be forms of Echelon arrays if they have correct spacing and stagger, like the receiving array at http://www.w8ji.com/echelon-log_beverages.htm We also have to remember gain always comes at the expense of removing energy from some other angle or direction. The small multiple sharp lobes from a loop do not produce useful gain, because immediately next to each lobe is a deep null. Unless you can rotate the loop, statistically some desired signal is just as likely to fall in a null as on a lobe. With narrow lobe antennas that cannot be rotated, we have to plan the location of nulls or lobes or play roulette. The signal might fall in a 20 dB hole just as likely as on a 6dB peak. Noise is a myth. HF noise rejection comes from the pattern of an antenna, not the family of antenna. If an antenna responds better in the direction, polarization, and angle of a signal than at the accumulated noise from all other directions, it will be quieter. That generally requires the antenna have a very narrow clean lobe with a high ratio of gain in the desired direction to average gain in all other directions http://www.w8ji.com/receiving.htm explains this. I think the "low noise" myth is a carry over from quads. Yagi's have sharp pointed elements protruding which produce corona in inclement weather. The corona is at the high impedance tips, and impedance at that point somewhat matches the low-current high-voltage element discharge for maximum noise transfer. A quad generally has blunt sides at the high impedance point, and with well-insulated elements that are compact it has less corona. As a matter of fact, the quad was popularized from use at station HCJB where it was used to reduce corona! This noise difference in one special situation (hissing and sizzling corona noise in inclement weather) gets pushed along by myth and wive's tales to include general applications where it is a total non-issue, like power line noise or lightning storm QRN. The primary advantage of loops, Rhombics, and such is wide bandwidth and simple construction. The disadvantage is they occupy a lot of real estate for the amount of useful gain. 73 Tom _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread Re: [TowerTalk] Rohn HDBX 48 use ladder as gin pole, K3vw [TowerTalk] Horizontal Loops, Tim Makins, EI8IC Re: [TowerTalk] Horizontal Loops, Tom Rauch Re: [TowerTalk] Horizontal Loops, Tim Makins, EI8IC Re: [TowerTalk] Horizontal Loops, jerryc Re: [TowerTalk] Horizontal Loops, Paul Carr RE: [TowerTalk] Horizontal Loops there was write up several yearsback, Kevin Adam Re: [TowerTalk] Horizontal Loops, RICHARD BOYD Re: [TowerTalk] Horizontal Loops, Joe Giacobello Re: [TowerTalk] Horizontal Loops, RICHARD BOYD Re: [TowerTalk] Horizontal Loops, Tom Rauch <= Re: [TowerTalk] Horizontal Loops, RICHARD BOYD Re: [TowerTalk] Horizontal Loops, Tim Makins, EI8IC Re: [TowerTalk] Horizontal Loops, John Kiesel