Hi Christoph,
I use 16m (50ft) circumference (W=20ft, top H=15ft, bottom H=4ft) .? I decided on this size for 9dB or 10dB noise over-ride from the antenna on 160m. using only 4 x 3.5m elevated radials (H=3ft) as a counterpoise.
In K9AY loop mode, the antenna works very well on MW as well as 160m and 80m., with measured groundwave f/b in the region of 30dB, degrading considerably on 7 and 10MHz..
The sensitivity of the antenna models just over -40dBi with the counterpoise, and -35dBi if a good conventional earth is used.
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So with a good conventional earth you may be able to go considerably smaller than 16m. which will help the antenna performance on higher frequencies where the K9AY cardioid pattern degrades. Quickly modelling a size reduction for near -40dBi on 1.8MHz indicates about 10.5m circumference. However, there is considerable difference in back-lobe pattern using the two earth systems, with a high null (around 45 degrees) using the conventional earth but less groundwave null.
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In performance, the Aziloop is up to a few dB down in s/n on my beverages in their optimum directions on some days, as we might expect from their comparative RDFs, but this depends on direction and conditions of course. I can hardly rotate a 200m wire - !!? Also when the ionoshere favours higher angles then the Aziloop is just as good, again as you might expect from the comparitive patterns.
73
John
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