At 06:53 AM 7/2/2008, Pat Rundall wrote:
>I am contemplating the construction of a dual band sloping inverted L
>for 160 and 80 meters. It would be a quarter wave design with a
>sloping top and mounted off of the side of my self supporting tower.
Good Morning Pat & all:
Pat, I am using an Inverted L very similar to what you describe, on
160 only. The vertical portion goes up to 65 feet, and the horizontal
portion slopes down to about 30 feet. The proximity to the tower is
much like you describe. I modeled the antenna in EZ-Nec, including
the tower, and was surprised to find that rather than the usually
expected 35 ohms or so at the feed point, it came out to around 4.5-5 ohms.
I built a T network to match it, and it tunes the antenna well. The
antenna works well, and I have been able to work a respectable number
of DX stations with the antenna and 500 watts over two seasons. The
ground system consists of 65 radials of lengths varying from 30 feet
to 130 feet. There are only 4 of the longer radials that are in the
130 foot range that bend around the corner of the house and out to
the front. The rest are 30 to 60 feet depending on where they go out
into the yard surrounding the tower.
Modeling the antenna on 80 meters shows very poor results. Good luck
with the project.
73,
Mike, W5UC
**age & treachery will overcome youth & skill**
**Management is the cesspool of life.
It's the place where the big chunks float to the top.**
** http://www.suddenlink.net/pages/w5uc/ **
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