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## [TowerTalk] Delta (Quad) Loop Polarization

 To: [TowerTalk] Delta (Quad) Loop Polarization W8JI@contesting.com (Tom Rauch) Mon, 10 Sep 2001 07:47:24 -0400
 ``` > I have modeled quad loops for dual polarization (H and V) and contrary > to W8JI claims and others, they have dual polarization components > nicely filling nulls in the pattern of the "other" polarization. I had > 3 el. dual polarization quad mounted over salt water on the boat ramp, > half wave up, 90% of the time beating 4 square over "salty beach > sand." Hi Yuri, The reason you see that "dual polarization" is because Eznec only considers the polarization as two pure distinct polarizations. When you have a tilted wave, it shows up as a mixture of V and H even though it is actually a plane wave of one pure polarization. If you stood out in front of the antenna with a small antenna and checked the radiation, what you would find is a peak at some angle other than flat or vertical, and a perfect null 90 degrees from that tilt. The only way to get two distinct polarizations at the same time is to excite two similar antennas mounted at right angles in the same physical location with 90 degree phase shift, to mount a small loop with a small complementary dipole running through the axis and feed them both in phase, or to stagger two right-angle antennas 90 degrees distance and feed them in phase. In those cases, you will generate a circular rotating wave. It is physically impossible to generate more than one polarization in any given direction at the same time without doing one of the above, and without a rotating wave (circular polarization). People wrongly think it happens because modelling programs display results as mixtures of pure V and pure H when the wave is actually just skewed. 90 degrees from that skew the field is zero, so you have a single polarized wave that is simply tilted. For example, a horizontal dipole has a perfectly horizontal electric field broadside. As we move off towards the ends, the wave starts to "tilt". Straight off the ends, the electric field is vertical. But it has ONLY one polarization in any point in space looking back at the antenna. A loop is no different, neither is a Carolina Windom, neither are a vertical and dipole that are centered and fed in-phase. 73, Tom W8JI W8JI@contesting.com List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems, Trylon Titan towers, coax, hardline and more. Also check out our self supporting towers up to 96 feet for under \$1500!! http://www.anwireless.com ----- FAQ on WWW: http://www.contesting.com/FAQ/towertalk Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com ```
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