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## Topband: NE Dipole vs Vertical with Coupling Effects

 To: Topband: NE Dipole vs Vertical with Coupling Effects john.w1fv@telocity.com (John Kaufmann) Fri, 10 May 2002 15:05:15 -0700 (PDT)
 ```On Fri, 10 May 2002, Bill Tippett wrote > I'm surprised the 80 meter data Bob provided is so close > to 160 since my experience has been that high 80M dipoles work > very well compared to verticals. I think the consensus in New England is that high horizontals, up 1/2 wave or more, outperform verticals on 80, at least for inland locations. My vertical array (located right next to a swamp, with an extensive radial system) works well against most of the competition on 80 but just can't match the high horizontals. Verticals over salt water are a different story, although there aren't many in W1 land. Like Bill, I find it surprising the 80 and 160 coupling numbers are so similar for horizontal polarization. Here's a quick and dirty numbers comparison for horizontal vs. vertical on 80. Since I'm lazy, I'm just recalling some of the gain numbers from memory, and I could be off by a dB or so. A single vertical over "mediocre" ground, typical of New England, has about 0 dBi gain at 20 degrees elevation angle. A 2-element Yagi at a height of, say, 150 feet on 80 has about 12 dBi gain. The Yagi numbers are similar for a 2-element quad. Let's use -1 dB of coupling loss to the NE for the vertical, assuming 80 is like 160, and -9 dB for the horizontal, extrapolating just a bit from Bob's data for 20 degrees. Then the "effective" gain of the single vertical, taking coupling into account, is -1 dBi and the Yagi is 3 dBi. In other words, there is less than 1 S-unit (assuming 5 dB change per S unit) of advantage for the Yagi over the simple vertical. This, I think, would come as a surprise to the people using those big horizontal arrays on 80. If we convert the vertical to a 4-square, which picks up about 5 dB of gain, then the advantage shifts to the vertical array. Anyone else with 80 meter experience find this surprising? Are there other factors which make this analysis too simplistic? Another question: Bob has said that his coupling numbers "only apply to the first and last transits of the lower ionosphere". If we assume the ionosphere randomizes the polarization (true?), are any additional losses incurred in multiple hops (and therefore multiple exits and entries) more or less independent of the initial transmit polarization and therefore random? 73, John W1FV ```
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