>
>
>I tried to use a halfwave vertical with a parasitic reflector on the beach
>in Grand Cayman (ZF) two years ago. I fed my vertical in the center
>as a vertical dipole. I modeled it with AO, but when I put it up the SWR
>was terrible. I changed it to 1/4 wave verticals and they worked great
>being only 1 meter from the ocean. I never did figure out why the vertical
>dipole didn't work. When I took the vertical down and layed it on a
>chair the SWR was good. I later suspected the coax running down side
>of the vertical may have been the problem and I wish I tried pulling it out
>horizontally from the antenna. I'd like to try it again sometime when I'm
>on a Caribbean vacation.
>
// A 50 - approximately 1000-ohm L-network can be used to match coax to
an end-feed a half-wave (Hertz) antenna. If one uses DC gear motors to
drive the L and C from the shack, the SWR will be 1 to 1.
cheerio, John
>
>-----Original Message-----
>From: David Douglass
>To: towertalk@contesting.com
>Sent: 8/29/2001 8:11 AM
>Subject: [TowerTalk] halfwave verticals
>
>
>
>
>
>Hi all,
>
>I'm in the process of building some halfwave verticals to use portable
>on HF
>with the aid of a DK9SQ telescoping fibreglass pole.
>
>I am building the LC matching system to convert the high impedance at
>the
>end of the halfwave down to the 50ohms to match the coax.
>
>My question is this! I'm sure in the past I have seen a computer program
>that allows you to key in the frequency and it will give you the length
>required and the values of inductance and capacitance required.
>
>Does anyone know were I can locate this program or if there is a manual
>calculation I can use for the LC values.
>
>Regards
>
>David, VK2DPD
>vk2dpd@qsl.net
>vk2dpd@bigpond.com
>
>
>
>
>List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
>Trylon Titan towers, coax, hardline and more. Also check out our self
>supporting towers up to 96 feet for under $1500!!
>http://www.anwireless.com
>
>-----
>FAQ on WWW: http://www.contesting.com/FAQ/towertalk
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>
>
>
>List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
>Trylon Titan towers, coax, hardline and more. Also check out our self
>supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
>
>-----
>FAQ on WWW: http://www.contesting.com/FAQ/towertalk
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>
>
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|