Interesting experiment and thank you for sharing.
1) I would note that the loop's null would be deeper if a shielded (or choked)
pickup loop were used. I could not determine from pictures the exact
construction, but have seen responses from unshielded loops before (currents on
feedlines become a factor.).
2) I worked out an E-field xmit antenna a few years back and noted response of
the ends, with unexpected nulls off the *broadside*. A very quick backyard
test of the pattern here; listen to the audible null at broadside from the test
receiver (ignore all the noisy birds): (Also recommend playing at half speed)
https://www.youtube.com/watch?v=TxxosnZo0i4
When I first constructed this oddity of nature I noticed that the usual noise
sources nulled off the *broadside*, instead of off the ends as the usual 1/2
wave dipole characteristically exhibits
de Jim WB5WPA
PS fo = 7 MHz in above test
From: Tom Thompson <w0ivj@tomthompson.com>
To: Rfi List <rfi@contesting.com>
Sent: Tuesday, June 13, 2017 12:49 PM
Subject: [RFI] Polarity Tests
Some of you have mentioned in the past about using a tuned loop for
tracking RFI. A question has sometimes arose about the direction of the
null of the loop. Larry Benko, W0QE, and I did some polarity tests
using various orientations of both the transmitting short dipole and a
receiving loop and a receiving short dipole. The results are shown here:
http://tomthompson.com/radio/Antenna_Polarity/Antenna%20Polarity%20Measurements.html
73, Tom W0IVJ
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