Hello,
I'm new to the group and saw the thread - my ears were burning
. I have one of these antennas - but it will be hard to give an impartial review. However, I'm glad to answer any specific questions.
For starters, the antenna is very different from the K9AY is operating principle and performance. The K9AY uses a termination resistor to cause a cancellation on the loop itself.
In the Shared Apex Loop (SAL) a pair of identically sized electrically small loops are positioned a few inches apart. Signals are coupled from the base of each loop at an equal distance from the center of the array. The signal from one of the loops is routed through a delay line to a combiner. The signal from the opposite loop is routed directly to the combiner. The resultant signal is amplified and then sent along a feedline to the shack.
Performance-wise, the K9AY has a cardioid pattern. The SAL has somewhat better front-to-side rejection for many sky-wave signals and much better front-to-side rejection for local interference and some sky-wave signals (vertically polarized signals produce the tightest pattern).
The SAL has a wider operating frequency range. For a 12 foot radius array, it is directive from 500 KHz to at least 25 MHz. For a 20 foot radius array, the directivity is from ~300 KHz to at least 14 MHz. The downside for the smaller array is somewhat reduced sensitivity below 3 MHz.
73,
Mark KB7GF
Topic: Shared apex loop array antenna (Read 8661 times)
