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Author Topic: New Shared Apex Loop Receiving Arrays  (Read 66692 times)
K0OD
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« on: September 14, 2013, 08:48:44 AM »

Two new antennas from Array Solutions would seem to be the ultimate receiving antennas for listeners and many hams. The AS-SAL-20 covers VLF, BCB, and shortwave to 15 MHz  Can be switched remotely and instantly in 8 directions (or omni)  and offers high f/b and f/side. No radials required.

A smaller version covers BCB to 30 MHz.

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

Are these being shipped now?  Thoughts?  Price (from what I can tell) is under $800.

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KZ1X
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« Reply #1 on: September 21, 2013, 03:10:04 PM »

I actually asked to the eHam gurus to put up a new review category for such items, especially this one, to encourage reviews to be posted.  Hasn't happened yet that I know of.

The antenna you mention is supposedly shipping.  There are many articles written and YouTube videos of it in operation.  So I am certainly intrigued.

I want to buy one, like soon, but I do not want to be an early adopter.  Hopefully Jay will ask some of his customers to post reviews.
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KD8IIC
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« Reply #2 on: September 21, 2013, 05:34:06 PM »

 I believe the antenna in question is the K9AY designed by Gary Breed. It has been around for some time. If you were going to make such an investment, and take the hours needed to install, I would rather encourage one to look into the Pixel Pro 1 Loop of which I have two installed at my QTH. Quite the good investment and it takes up so much less room. All that is needed is a 4 foot mast out of the ground and a low priced TV antenna rotator.The very low noise pre-amp is built in and you also get a TR switch built in to mute the pre-amp and rf to your receiver when transmitting. 
 All stated, I did build a K9AY and was not impressed with the performance compared to what I bought from Pixel in 2010.
  73 from Lane in Ohio  de n8aft  sk  ..
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K0OD
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« Reply #3 on: September 21, 2013, 07:37:00 PM »

It resembles the old K9AY antenna physically. But K9AYs have a broader pattern and reduced bandwidth. 

The Shared Apex Loop Array pattern resembles that of a 4-square phased vertical array. The Array Solutions system can be instantly switched in eight directions, or made omnidirectional or bi-directional. The direction can even be flipped to see front to back or to check long path. No conventional mechanical rotator is used. No separate control cable is required. 

This would appear to be far superior to Pixel or Wellbrook type loops which are fairly omnidirectional except for reduced pickup off each end. Those nulls, I believe, are mainly effective for reducing local noise from power-lines, nearby home appliances and such. Local crud. They can be useful for reducing problems caused by local high power transmitters. But they won't null skywave signals. Steering a Pixel loop can be done by hand or by slow mechanical means.

The Shared Loop should lower skywave AND ground wave interference.  In fact it can reduce interference from atmospheric noise or distant radio signals over about 80% of the azimuth at a time.

I've used a 4 element phased vertical array on 40 meters years ago for both transmitting and receiving. It worked fabulously especially on receive but it required a lot of space and a full radial field for each of the four verticals. No radial system is required for a Shared Loop Array.

Main caveat I see is that the array should be located in the clear. Array Solutions suggests that it should be >100 feet from homes.  I wondered whether the vertical center support can be hidden in a tree, or can be a tree. Cutting the lawn under the array could be a problem. In my location, deer would be a concern.   

Article from QEX:
http://www.arraysolutions.com/Products/SAL_shared%20apex%20loop/PDF%20Files/Bauman%20Sept%202012.pdf 

 
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W4OP
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« Reply #4 on: September 21, 2013, 08:48:17 PM »

I use the Pixel loop and remotely rotate it in azimuth and elevation achieving good night time nulls as well as daytime. Working on an Arduino micro to auto null.
A lot smaller than the K9AY and less expensive.
Dale W4OP
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K5RT
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« Reply #5 on: September 22, 2013, 07:42:36 AM »

This antenna is not, or anything like, the K9AY antenna. The Shared Apex Loop Array operates on a totally different principle.

Recent testing indicates the Shared Apex Loop Array has proven the antenna pattern is not terribly affected by nearby objects.

Mine is about 30 feet from overhead power lines, it's about 60 feet away from the tower, 75 feet away from the 160 meter vertical and about 120 feet from the 80 meter ground plane. The pattern is very good and F/B is exceptional.

The concern about locating in close proximity to nearby metal objects, houses and such is due to re-radiation of very strong signals, man made noise from plasma TVs and what have you.

Don't forget, your transceiver needs to be properly configured to use an external recieve antenna.

Guys, this is the antenna you want if you are unable to install Beverages. The Shared Apex Loop Array performs as well as the Hi-Z antennas at a much lower price. It runs rings around the K9AY, EWE, Pennant/Flag, BOGS or Small magnetic loops. It's the real deal.

At my station, the ambient noise on 80 and 160 is S8 to S9. The SAL solves that problem! It won't fix bad band conditions, but it enables me to copy 3 or 4 layers of stations during a contest that I couldn't copy otherwise.

Call or email Array Solutions for availability, they should start shipping very soon.

Vy 73
Paul
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KB7GF
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« Reply #6 on: September 22, 2013, 07:57:24 AM »

Good Morning Guys,

Just wanted to clarify a few points on this thread and it is a good discussion.  The Shared Apex Loop Array (SALA) is quite different from the K9AY in operating principle and performance.  It utilizes broadband loops (each loop being similar, although physically larger, than the Pixel Tech or Wellbrook loops).  It differs from a foursquare array in that it uses broadband loops rather than vertical elements.

The array combines the signal of an electrically small loop with a delayed signal from an adjacent electrically small loop.  In this manner, two loops and a single delay line can provide both front to back rejection and front to side rejection - especially on vertically polarized signals - and can provide this directivity over a wide range of frequencies.

The array does not require an RF ground.  As far as distance to other objects, modeling shows that there is some interaction; however, my array is located 50 feet from my house and I have good directivity from 500 KHz to 10 meters.

73,

Mark KB7gf  
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K0OD
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« Reply #7 on: September 22, 2013, 08:28:15 AM »

We've hit the SALA information jackpot. Mark holds the patent on it. Welcome guys. www.widebandloop.com

What about using a tree for the center mast?
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KB7GF
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« Reply #8 on: September 22, 2013, 08:51:26 AM »

Hmm...a tree for the center mast.  It is non-conductive (that is good) ... the spacing is more than necessary, but wouldn't be a problem if it was modeled. The biggest problem would be keeping the loops the same size and shape...very critical, especially at low frequencies.

73,

Mark KB7GF
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K0OD
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« Reply #9 on: September 22, 2013, 10:51:39 AM »

Quote
Hmm...a tree for the center mast.  It is non-conductive (that is good) ... the spacing is more than necessary, but wouldn't be a problem if it was modeled. The biggest problem would be keeping the loops the same size and shape...very critical, especially at low frequencies.

Is the supplied wire insulated?

I'm thinking in terms of my 60' tall Pin Oak trees which have bare vertical trunks that go up about 30 feet to where the tree branches out. Trees aren't exactly non-conductive. In fact they have been used by themselves as verticals. Military did a lot of tests on that long ago. Drive a nail into the base of a 100 foot tree and you're on the air in 5 minutes!

I don't foresee problems (at my QTH) making the loops even. A few minutes with a tree saw will take care of that.  What about the loop bottoms? My yard, like many,  isn't perfectly flat.

Thoughts on grass mowing and critters... real world problems that a lot of buyers will wonder about?
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K5RT
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Posts: 129




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« Reply #10 on: September 22, 2013, 11:02:24 AM »

Some other points to note about the antenna. Or more like to all antennas. The pattern is three dimensional. For example, on the AM band, I notice different Front/Back values vary from station to station. This is due to the ground wave component, vs skywave component. Or to put it another way, angle of arrival of the incoming wave.

I had Beverages up for several years, until the pasture behind my QTH grew a bunch of McMansions. IMO, the SAL is a very close performer to what I remember my Beverages being.

It won't cure power line noise, or spurs from plasma TVs or the common cold, but it will open a new world of low band DXing for you. And looking at the sunspot cycle predictions, this is where you want to spend your hard earned consumer dollars.

Yes, the wire being supplied for the loops is insulated.

I've had a prototype up for over a year now and I'd rather be QRT on the lowlands than do without the SAL.

Mark is a genius.

Vy 73
Paul
« Last Edit: September 22, 2013, 11:15:32 AM by K5RT » Logged
K5RT
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Posts: 129




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« Reply #11 on: September 22, 2013, 11:05:44 AM »

Mowing isn't a big problem. I roll up the RG-6 feed line, and mow around the array with a push mower.

It adds a little time to the mowing chore, but it's a price I gladly pay.

Mark will have to speak to the effects of uneven ground, but I don't think it's a problem, as long as the base leg of each loop is at the same elevation.

Paul
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KB7GF
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« Reply #12 on: September 22, 2013, 04:59:52 PM »

We have been recommending that the ground be flat under the array because all of the installs to date have been on flat ground.  This may be overly conservative, however, because modeling of a single loop measured at various heights above ground (between 2 to 8feet) provide the same signal response, so this makes me optimistic that the array would work on uneven ground. 

The array will work fine if the loops are elevated.  I do recommend that the array not be tilted though, because this make the takeoff and null angles different depending on which side of the array you are pointing.

Good point on tree conductivity.  I know from testing and modeling that a SALA supported with a metal mast that is inserted into the ground several feet will not work.  Modelling does predict that a metal mast that isn't connected to the ground will work - although I have never tried this.  The model doesn't handle moderately conductive masts that are connected to the ground very well - so the only way to know would be to test it. 

73,

Mark
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K0OD
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« Reply #13 on: September 22, 2013, 08:29:50 PM »

Thanks guys.  Can the whole array be elevated to position the horizontal wires - the bases of the triangles - above head (and antler) level, about 7' above ground? Perhaps the diagonal wires could double as guys for the taller mast.

In other words, can your array be elevated in the same way a 4-square vertical array can be elevated? Elevated 4-squares work somewhat better than ground mounted ones.

 
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KB7GF
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« Reply #14 on: September 22, 2013, 09:57:45 PM »

Yes, modeling teaches that the loop bases can be elevated - above heads and antlers.  The limit seems to be around 1/4 wavelength base height at the highest frequency of interest.  So, if you have a small array and are interested in directivity all the way up to 29 MHz, then you should keep the loop bases below ~ 8 feet.  If you have a larger array and only interested up to 15 MHz, then you could put it as high as 16 feet.  If you only care about 1.8 MHz, then you could put it up to a height of 40 meters!  You would lose directivity, though on the bands above 160m.

73,

Mark KB7GF
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