My preference, as always, is to INVERT the Xmas-tree, with the 20m on
top, 15m below it, and 10m below that. Used that arrangement for many
years in the 1980's and early 90's.
Don
N8DE
KT2Q wrote:
> All:
>
> Thanks for the replies regarding the mounting of 15 and 20 meter monobanders
> on a single mast. Although there might be exceptions, the general agreement
> seems to be that there is a slight detuning effect in F/B with mounting
> distances no less than 8 to 10 feet between the 20m/15m antennas.
>
> John, KK9A / P40A explained that his 15 meter monobander shows a slight F/B
> loss with the antenna 8 feet above the 20m monobander. His 20 meter
> monobander seems unaffected from the 8 foot spacing.
>
> It would be interesting to model the effect to find the best spacing (within
> reason) for mounting monobanders on the same mast. I have a 20 foot mast and
> can mount 20m and 15m monobanders 10 feet apart and have enough room to
> mount my existing 10/12 meter Force12 Yagi about 10 feet above the 15m
> monobander. But the question is what effect the third antenna might have on
> the others? Which is the least effected etc.
>
> The 4 and 5 element M2 / Force12 monobanders for 20 meter and 15 meters seem
> like a good idea for improved performance over shorter-boom multi-band
> interlaced designs that utilize 2/3 or so of actual boom length. But there
> is the expense and tower loading to consider.
>
> Obviously, the improved F/B and forward gain would depend on how long a boom
> length you're willing to go with or can afford. When you look at the
> numbers, it's obvious that it takes quite a bit of additional boom length to
> add an extra 3db.
>
> Any additional suggestions on mast mounting distance for monobanders would
> be greatly appreciated. Comparisons between different monobanders would be
> appreciated as well.
>
> 73 Tony KT2Q
>
>
>
> _______________________________________________
>
> 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.
>
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>
_______________________________________________
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.
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