A method to align an antenna to a particular azimuth by using the Sun
In the Winter of 2022 I wanted to verify that a directional antenna I was using for TV reception was aligned to a particular station. I had previously set the azimuth for the antenna by eye, and then had made minor adjustments to its azimuth while checking on the strength and quality of the received ATS 1.0 television signal. Normally I would have used a small hand bearing compass to set the azimuth. I have owned an excellent hand bearing compass for many years due to my boating activities, but that compass was not handy. I noticed that since the desired heading for the antenna was in the southeast from my location, I could use the Sun to find the exact azimuth
By using the "signal search map" feature of the excellent website RABBITEARS.COM, I already knew the true heading from my location to the desired signal: 146-degrees-True to CBET in Windsor, Ontario, Canada. Next, I needed to find the exact time of day when the azimuth to the sun from my location would be 146-degrees.
To determine when the Sun's azimuth for my observation would be 146-degrees-True, I used the excellent NOAA SOLAR CALCULATOR website. By varying the input value for time of day, I was easily able to determine that on the particular day I was planning to re-orient the antenna, the Sun's azimuth observed from my location would be precisely 146-degrees-True at 10:50 a.m. that morning. Because I was observing in Winter, the Sun's elevation would also be quite low, only 30-degrees. This would make observation for azimuth even easier.
At the appointed time, I noted the Sun's azimuth, and establish a local fixed landmark to use as a reference point for aiming the antenna. Before adjusting the antenna, I had tuned my TV receiver to CBET and set up a diagnostic signal function. The signal was was not producing useful reception, with a signal-to-noise ratio (SNR) of 15 dB and with with picture and sound filled with drop outs and errors. For an ATS 1.0 signal, the theoretical threshold for solid signal lock and reception is right at 15 to 16 dB SNR. (This marginal signal was the reason for the decision to realign the antenna.)
After adjusting the antenna orientation to match the Sun's azimuth at 146-degrees, I was very pleased to see the receiver signal diagnostic screen show the SNR had increased to 19 dB. Over the next hour I observed the diagnostic screen indicate a SNR from 17 to 19 dB, which resulted in error-free reception of the desired signal from CBET.
There are some limitations to the method described, and foremost is the need for the path of the Sun in the sky to cross the desired azimuth. This is entirely determined by the relationship between the observer's location, the Sun, and the desired azimuth to be found. However, in some instances it may be possible to use the Sun's azimuth when 180-degrees opposite to the desired azimuth as a means of finding that direction, or to wait for a different time of year when the Sun's path more conveniently crosses the desired azimuth.
Copyright © 2022 by James W. Hebert. Unauthorized reproduction prohibited.
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Author: James W. Hebert
