[Antennas] Elevated 60 foot vertical

2002年8月18日 20:55:32 -0500

I have a 60 foot vertical (laying on the ground right now) that is 5 inches
in diameter that I would like to mount (insulated at base) on top of my 50
foot x 90 foot metal barn roof (14 foot high) as the ground plane. There is
a slight pitch to the roof of 1:12 to the North and South. The remainder of
the barn is also metal sheeting. This is a hilltop location 400 foot above
Fort Worth, and the soil contains a lot of rock, although it is typical
North Texas conductivity.
Is it possible to use this configuration as a 1/4 wave on 80, 5/8 wave on 40
(with base tapped coil), and hopefully baseload it for 160 meters? Would it
be of any use on the 30 meter band? The coax run to the house is over 250
feet, so all matching will need to be done at the base of the antenna and
then relays will be used to select the bands. Are there any particular
requirements on this home-brewed switchbox?
The only analysis program that I have is MMANA which is free and mini-nec
based. I have not seen any analsysis for any similar multi-band (switched)
antenna. Any assistance, suggestions, or comments will be sincerely
appreciated as I really need some good low band antennas.