On 11/29/2012 2:55 AM, Larry Gauthier (K8UT) wrote:
Especially on 160 meters, results varied widely from day-to-day; even
from hour-to-hour. You may find the same is true by looking back
through the history of spots for your old antenna as you compare it to
your new antenna.
I strongly agree. This spring, I used W6CQZ's JT65 RBN to try to compare
two 160M antennas in real time. I did so by calling CQ for one sequence
on one antenna, then the next sequence (2 minutes later) on the other
antenna, and repeating that for at least an hour. On a typical evening,
I got reports from receivers in MI, IN, and PA, (as well as some much
closer) with QSB that was at least 2-3 times the difference in dB of the
predicted difference between the two antennas. I put the numbers in a
spreadsheet and carefully averaged them, and even after six or eight
runs, was not able to establish that I was seeing the difference the
model predicted. Depending on how the timing of the sequences correlated
with the timing of the QSB, I could see the predicted 2dB advantage or not.
73, Jim K9YC
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