John,
The antenna will radiate at low angles like a standard monopole. The helical
arrangement is just a way of loading the antenna so that it is resonant at a
lower frequency. The base area (before the spiralling wire emerges) could
contain a solenoid base loading coil. In that case the helical wire is used
to add a bit more capacitance - top loading.
Dave Cuthbert
From: [email protected] [mailto:[email protected]] On Behalf Of John
Woodgate
Sent: Tuesday, April 10, 2007 11:24 AM
To: [email protected]
Subject: Re: Unknown Antenna
In message <[email protected]>, dated
Tue, 10 Apr 2007, David Cuthbert <[email protected]> writes:
>This looks like a helical vertical. Given the spiral pitch it is
>resonant around 5 MHz.
Why would anyone want to squirt 5 MHz vertically upwards? E-layer height
measurement?
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
There are benefits from being irrational - just ask the square root of 2.
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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