Reasonable size of an AziLoop?

#21140

Hello from Austria,

I am an enthusiastic mediumwave BC-DXer and operate a small remote station outside Salzburg, which I have built up over the last 14 years. (  As I don't own the land, I can't set up endless antennas there. At the moment I use a 200 metre two-wire Beverage and a K9AY (circumference of 30 meter), but it only listens to Asia and South America and is much too close to a house wall. The cows want it that way. But everything can be controlled remotely from QRO.cz, I'm very happy with it.

I'm thinking about setting up the ingenious AziLoop, which I could erect a good distance from the houses. The coax there is already buried, so far everything is fine. However, I have two problems at my location: the antenna has to survive storms well, and there are often storms there. And it has to be able to be dismantled quickly, but maybe I can talk my farmer out of that.

So I come to the point: I should - although the opposite would be better - erect the antenna as compactly as possible, also because I have to do everything myself. Dave specified a circumference of only 10 meters in his AziLoop manual (page 104). He wanted to cover this topic in more detail in the forthcoming manual, which will be much more comprehensive, but it has not yet been published. In an exciting (and humorous) talk at the Norfolk Amateur Radio Club, he presented the antenna and his thoughts:  - starts at minute 20, the more technical part begins at minute 52.

In the presentation Dave showed a circumference of 15 meters, a picture is attached here. This size seems to me to be easily realisable, so my question is whether anyone here already has experience with a ‘relatively’ small AziLoop. My use is only intended from 500-1800 kHz. I have seen the perfect installation from Steve, VK5SFA, in the group - I don't know the exact size, but that seems ‘a size’ too big for me - even if I would do it exactly the same way. Then I would certainly hear AM stations from Australia better in Austria!

Thanks for your opinions.

73 Christoph, OE2CRM

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#21143

Hi Christoph,

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The image you uploaded from Dave's excellent presentation actually shows a circumference of 13.8m; close, but not quite the 15m you mentioned.

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I currently have an Azi-Loop in the construction process; it's been taking some months due to other commitments. I am designing it to be easily transportable to take it from home to DXpedition sites, and also so that it will be mostly free-standing (fewer stakes and structures for the local deer to trip over or damage :^)? ?Like you I want the Azi-Loop to resist storms; I live on a hill above Aberdeen, WA USA, and we are vulnerable to Pacific coastal weather. The self-supporting "arms" for the lower horizontal loop segments are made from 3/8-inch dia. fiberglass rods (so-called driveway flags or markers). My hope is that the semi-flexibility of the rods will let the structure bend but not break in the winds.

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As you've read, the Azi-Loop designer Dave recommends a modest 9.0m circumference. The dimensions of the Azi-Loop I'm building work out to a 10.56m circumference, so that's roughly similar to the size you are considering. Like you, my primary application will be the medium wave range.

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Unfortunately I cannot give any comments just yet on performance, but hopefully in 2-3 weeks! I have a DXpedition to a beach location planned for mid-April, so I definitely need to have the antenna ready by then.

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You are probably familiar with the name of my Pacific Northwest DXing pal, Dr. Walt Salmaniw. He has an Azi-Loop among his antennas for MW DXing, at his Haida Gwaii, BC Canada vacation home. If you contact him I'm sure he'd be happy to give you comments on the antenna's performance. However, his antenna is built considerably larger than 10-15m circumference we are discussing. He decided to go larger since he has nearly zero chance of overload at that remote location.

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73,

Guy KE7MAV

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#21150

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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#21152

I currently have an Azi-Loop in the construction process;Thanks Guy,

I know your and Walt's ambitions for AM-DX, your solution is already very perfect. I can see that the size (one meter up or down) will be a very good option, also the self-supporting structure is a perfect solution, especially because of animals. I'm already looking forward to a short report on the antenna from your upcoming DXpedtion. My plan is to erect the antenna in the summer, just in time before the first Asian signals can be heard in Central Europe in the fall. Thanks also for the photo, very helpful.

Good luck with the AziLoop on your DXpedtion!

73 Christoph, OE2CRM

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#21153

I can hardly rotate a 200m wire - !!?;-)

That reminds me of the note in the AziLoop manual, “To be clear, the antenna does not move”

Thanks for your explanation and assessment. Especially the reference to the earthing, which I will lay cleanly underground because of the animals. And you also mention the “small” size, so the 13.8 meter circumference mentioned by Dave and Guy with a solid grounding will be a good solution for me and my question here has been answered well.

Of course, the comparison with my 200 meter Beverage will be interesting, but the main reason for the installation is simply the flexibility of this system in all directions, which allows the advantages of K9AY and Loop in an actually very small space, and everything can be controlled via IP. This is already a very good job by Dave, who will soon be releasing a software update with some new features and improvements, and in the new guide he will also provide further antenna suggestions.

Now I'm thinking about how best to erect a self-supporting structure. Given the relatively small size, additional guy ropes may not even be necessary.

Thanks again John for your help.

73 Christoph, OE2CRM

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Reasonable size of an AziLoop?