>OK another one of those what do you think questions..Here is my problem.
>I have two towers. I need to put the following antennas on them.
Hygain DB-1217 (dual bander for 12/17 meters)
>What would you think would be the best configuration? I am inclined to
>place 40/20 on one with 12 foot separation and the rest on the second
>tower on a mast 16 foot out of the tower.
First of all, what 40 meter antenna will you be using? Some 40 meter
loaded beams have a resonance on 17 meters, so be carefull when stacking
with another 17m antenna.
Usually you can stack 20m and 40m beams fairly close, within 5 to 6 feet,
without VSWR or pattern problems. Same goes for the 10m and 15m at approx.
7 feet, and 15m and 20m at approx. 9 feet.
I would not recommend stacking 20m with 17m, 17m with 15m, 15m with 12m, or
12m with 10m. The 20m directors are close enough in frequency to act like
17m reflectors. Same for the other bands. Especially 12m and 10m, where
the 12m director is exactly the same as a 10m reflector. Stacking these
bands result in a skewing of the radiation pattern in the elevation plane,
up to 50-60 degrees at close spacing and 30-45 degrees even at 15' spacing.
I can supply you with either YO, AO or NEC/Wires models of any of these
monobanders and a NEC/Wires model of the DB-1217 on either the standard
12/17m setting or the optional 10/15m setting. I can also supply measured
E-plane radiation patterns of these antennas.
Also, I would recommend the newer CA settings for the 155 and 105 antennas,
and the QHS modified setting for the 204BA. I can send you these or you
can find them on our web site at
http://ourworld.compuserve.com/homepages/hygain. There is also a link to
our site from http://www.telex.com.
73 Roger WB0DGF
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