Hello Rob
The left hand scale is in dB, and is the correction which would need to be
applied to get a unity antenna factor. So the actual performance is the inverse
of the scale. One would expect the actual performance to decrease with
frequency.
So the actual antenna factor is ca. -7dB or 0.45 (ie 10^(-7/20)) over most of
the hf frequencies.
The cross check is the value of 0.5 which Andy Ikin gave in his article in
Medium Wave News in March 1998. See:
A. Ikin, Broadband Loop Aerials (part 1), Medium Wave News, Jan 1998, pp
13-16
A. Ikin, Broadband Loop Aerials (part 2), Medium Wave News, Mar 1998, pp 9-12
Medium Wave News is published by the Medium Wave Circle. See:
www.mwcircle.org
I have not checked, but suspect that these articles are not available online.
You will note that a couple of the other Wellbrook loops have a slightly
higher gain, with a quoted antenna facro of 1.0 and/or 0dB.
HTH and 73
John KC0G
In a message dated 5/15/07 1:54:28 PM Central Daylight Time,
rmoore5@... writes:
John,
At the bottom of the Wellbrook ALA-1530 information page, there is a
calibration chart which show the Aantenna factor vs frequency. It
indicates that the antenna factor is roughly 8 over most of the range.
How did you come up with a .45 factor?
Rob
--- In loopantennas@..., crabtreejr@... wrote:
The actual antenna factor is about -7dB, ie ca. 0.45, ie the antenna
output is ca. 0.45 volts for a field strength of 1 volt per meter. The
required antenna gain is then +33 - 7 = 26dB.
***
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