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Old February 17th 04, 09:28 PM
Crazy George
 
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And how does that help track a non - (frequency) - stationary signal? And
150 MHz two-way has nit to do with downcoming horizontally polarized sky
waves, I theenk.

By the way, Terman and Pettit got themselves into a heap o' grief with that
simplistic approach. I've sent them on to the archives now, but there is a
large volume of correspondence in Proc. IRE back about '47 about how that
doesn't work.
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Crazy George
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"Richard Harrison" wrote in message
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Crazy George wrote:
"I think Steve would be interested in hearing a methodology for DFing a
non-stationary signal, as would I."

Terman says on page 1050 of his 1955 edition:
"The errors in bearing caused by downcoming horizontally polarized sky
waves can be eliminated by replacing the loop antenna with an Adcock
antenna, which in its simplest form consists of two spaced vertical
antennas, connected as shown in Fig. 26-28."

The ARRL Antenna book also gives information and says construction is
not critical.

Best regards, Richard Harrison, KB5WZI





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Old February 18th 04, 05:11 AM
Richard Harrison
 
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Crazy George wrote:
"And how does that help track a non-frequency-stationary signal?"

It senses the line between the transmitter and receiver that contains
the path of the signal
by finding a null along that line.

You have a broadband antenna array in the Adcock which produces a null
simultaneously in horizontal and vertical polarizations.

You can have confidence in the null produced by the Adcock array.
Cross-polarized reception causes no error so long as the antenna remains
balanced regardless of the frequency of reception. The Adcock doesn`t
require self-resonance nor a definite spacing between elements. Its
bandwidth means the balance can be good throughout the 2-meter band if
that`s the design frequency.

The longest dimension can be about 40 inches which makes the antenna a
practical size for the 2-meter band.

Best regards, Richard Harrison, KB5WZI

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