K3GM wrote:
> I used one previously, ground mounted, a couple inches off the soil, and
> over a very large radial field. The antenna feedpoint impedance is around
> 50 ohms when mounted only on a pipe. Adding radials will cause the
> feedpoint impedance to drop, and when you get enough of them around the
> antenna, it will no longer resonate within the available bands. It becomes
> necessary to retune the traps. If this is the direction you're going (lots
> of radials), mark the traps before messing with them. Start from the bottom
> up. A little movement goes a long way!.....and resist the urge to trim the
> tubing even though it seems to make sense to do so..
>
>
or put something like a SGC tuner at the base... the mismatch it's
dealing with is small, so the losses in the tuner are small, but it
saves you having to worry about dialing in the traps just so. AND, you
get the advantage of the radiator length shortening as the band goes
higher, so you don't have the weird pattern you'd have from a 30 ft
antenna on 10m.
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