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[TowerTalk] optimum height

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Subject: [TowerTalk] optimum height
From: (Pete Smith)
Date: Sat, 28 Jul 2001 13:22:16 -0400
At 04:18 PM 7/28/01 +0000, alsopb wrote:
>As stated originally the boom length in the formula is in wavelengths.
>A 47' boom is about .7 wavelength on 40 meters.  The formula predicts
>a spacing of .84 wavelenth or about 56 feet.

I think it's fairly well understood that stack spacing for HF (with real
ground a couple of wavelengths below the stack) is quite a different matter
than VHF/UHF.  What intrigues me are the "sweet spots" in HF stacking --
for example, 1X/2X spacing, such as 50 and 100 feet, or 1X/2X/3X
(50/100/150 ft)for that matter.  It appears from modeling that these
spacings redistribute power out of high-angle minor lobes and into the
first forward lobe.  This is even the case where inter-yagi spacings are
far from optimum, as for example with 8.5 dBi yagis spaced 30/60/90.
Suppression of high-angle lobes is quite evident on all 3 bands of
interest, even though the spacing varies from <1/2 wl to almost one full wl.

73, Pete N4ZR

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