We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissible in your locale.

Author Topic: Shared apex loop array antenna  (Read 8132 times)

Offline ChrisSmolinski

  • Administrator
  • Marconi Class DXer
  • *****
  • Posts: 31106
  • Westminster, MD USA
    • View Profile
    • Black Cat Systems
Shared apex loop array antenna
« on: August 05, 2013, 1610 UTC »
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline redhat

  • DX Legend
  • ******
  • Posts: 1585
  • USA
  • Music is my drug.
    • View Profile
    • Email
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

+-RH
Somewhere under the stars...
Airspy HF+, MLA-30/Mini-whip/Chi-Town Loop
Please send QSL's and reception reports to xfmshortwave [at] proton [d0t] me

Offline glimmer twin

  • DX Legend
  • ******
  • Posts: 1089
  • "I found my way to heaven , I did my time in hell"
    • View Profile
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
KCMO  Icom R 75 , SDR-IQ, Grundig Satellit 750 ,Tecsun PL 880, Tecsun PL660 , Tecsun PL380 & PL360  10 meter random wire  w/ RF systems MLB    Alpha Delta SWL DX sloper  
qsl   keithglimmer810@gmail.com

gentlemen,you can not fight in here, this is the war room

Offline Pigmeat

  • Marconi Class DXer
  • ********
  • Posts: 6684
    • View Profile
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

  • Administrator
  • Marconi Class DXer
  • *****
  • Posts: 31106
  • Westminster, MD USA
    • View Profile
    • Black Cat Systems
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
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline Markb

  • Newbie
  • *
  • Posts: 1
    • View Profile
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     

 

HFUnderground T-Shirt
HFUnderground Garden Flag
by MitchellTimeDesigns