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Author Topic: Shared apex loop array antenna  (Read 5988 times)

Offline ChrisSmolinski

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Shared apex loop array antenna
« on: August 05, 2013, 1610 UTC »
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
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Offline redhat

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Re: Shared apex loop array antenna
« Reply #1 on: August 06, 2013, 0043 UTC »
Looks feasible.  I'll add it to my 30 year projects list :)

This should give you some idea of its capabilities.
http://www.widebandloop.com/Documents/SALA_DRM_201103.pdf

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Offline glimmer twin

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Re: Shared apex loop array antenna
« Reply #2 on: August 06, 2013, 0444 UTC »
I seem to remember somebody in this group who lists this as one of their antennas. I found this link after viewing it listed in their setups.

http://www.arraysolutions.com/Products/sal_array.htm
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Offline Pigmeat

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Re: Shared apex loop array antenna
« Reply #3 on: August 06, 2013, 0610 UTC »
It looks like a a variation of the K9AY Loop. The K9AY Loop is a proven DX performer from MW well into the HF bands.

Offline ChrisSmolinski

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Re: Shared apex loop array antenna
« Reply #4 on: September 19, 2013, 2044 UTC »
Yes, I seem to recall someone here either had one or was going to get one. I'd love to see a review! :-)
Chris Smolinski
Westminster, MD
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Offline Markb

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Re: Shared apex loop array antenna
« Reply #5 on: September 25, 2013, 0142 UTC »
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