KAAY would detune two of their three antennas to get their circular daytime pattern and bypass the tuning for their nighttime figure-eight pattern. There was also a water tower, shown in the pictures, which had to have a detuning network to stop it from being resonant (working like an antenna) on 1090. Click on the picture(s) and look close and you'll see the wires and stand-offs holding them away from the water tower's legs:
Dave says this is a view of the water tower in Wrightsville at the corner of 2nd and Locust Streets, and KAAY is about 1/2 to 3/4 mile to the left.
Here is another picture of the water tower and a satellite view of KAAYs antenna array:
Thank you, Dave! Dave also sent in an excellent paper on detuning; I'd be glad to forward it on to anyone who would like a copy.
Bud S. (firstname.lastname@example.org)