VE3PCP Double Delta Loop Array

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VE3PCP
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VE3PCP Double Delta Loop Array

Post by VE3PCP » Sat Sep 23, 2017 12:25 am

Hi folks:
When I was first getting in to Ham radio back in the 80s with all kinds of gusto and enthusiasm, I constructed many antenna systems from verticals to yagis to log yagis to loops and so on.
One that I constructed as a brain child i=of my own making was a 20M Double Delta Loop Array. I constructed it for field day one year and remembered it working quite well. I recently came across it while looking through all the various wire antennas I have coiled up.
I spoke with Dave Casler about is, KE0OG. He has a significant Youtube channel with many antenna tests he has done. I just wanted to see if he had seen anything like it and he had not. He suggested that I download an antenna analysis software, so I did. It's cal 4nec2.
After a few days of getting to know the software, I input my "as built" design and was actually quite shocked at the results. I tried optimising it but it ended up really not making much more gain but made it more difficult to erect and use.
The original design intent was to be able to string it up between 2 points that were in the 20' to 25' high range, typical of a rock over a tree limb on field day height. One thing I did add those thru my testing was a ground connection at the bottom of each loop. I saw around 1 dB gain by doing that.
I am going to be setting up a "antenna test range" in my back yard so my son Justin and I can spend time designing and testing antennas. I wil be doing some field testing the the Double Delta Loop hopefully before snow flies.
In the mean time, here are the test results from the 4nec2 program.
Looking forward to questions and comments.
Thanks!
Rob
VE3PCP

There are many more charts and graphs I can add if anyone is interested. Things like freq scan to show swr, gain and impedance over a range of freq. etc.
Attachments
20M DD Loop Test Sheet.png
20M DD Loop Antenna.png
20M DD Loop Hor Pattern Graph.png
20M DD Loop Vert Pattern Graph.png
20M DD Loop 3D Pattern.png
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VE3PCP
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Re: VE3PCP Double Delta Loop Array

Post by VE3PCP » Sat Sep 23, 2017 12:29 am

A few more graphs.
Attachments
20M DD Loop SWR Graph.png
20M DD Loop Gain Graph.png
20M DD Loop Imp Graph.png
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ve3efq
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Re: VE3PCP Double Delta Loop Array

Post by ve3efq » Sat Sep 23, 2017 2:01 pm

Dave Casler, KE0OG, his videos are some of the best. I've watched a bunch of his stuff.

I tried using EZNEC one time; but never made much head way. Perhaps I'll give that software you mentioned a try.

I was thinking of trying to build a phased vertical array for portable use: I made a vertical for 20m out of 26 gauge wire; it is so small it will fit in my jeans' pant pocket; so, I thought, why not make a few then set up a phased array when out operating portable. Maybe this software will be easier to model with than EZNEC? But for want of a t-connector and a large coil of coax to cut for the feed-lines to the right size for the phase delay I would be building my portable vertical phased array: it looks like there is a fair bit of gain and directivity, if I create a reversing switch on a relay, that can be had with such a system if one can get it working properly. I even thought of writing Casler to see if he would make a video about phased arrays.

Since I don't have the parts to make a phased array I was looking around for some models and details about a simple parasitic array for 20m; but I have yet to try to set that up yet, mostly for lack of well-defined research about how to set it up - some say .18 Lamda, other .25 L, and I could not find EZNEC models of such a system online; I should try and model one myself I suppose.

I have noticed that the ground characteristics can be modelled in that software you used, i.e.: mhos/meter. I always wondered about the ground at the places I go and I was wondering how I could measure its actual conductivity. I am not sure how good the ground here will be given that the soil is so thin and the underneath is solid rock; though I have read that moisture content is important for conductivity - at least this summer that variable has been optimized.

'EFQ
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VE3PCP
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Re: VE3PCP Double Delta Loop Array

Post by VE3PCP » Mon Oct 30, 2017 8:30 am

So I finally got things in place to put this antenna up yesterday and do some tetsing.
I did a video of it.
Enjoy!
Rob, VE3PCP
https://youtu.be/hMi6aKXPqCk
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VE3PCP
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Re: VE3PCP Double Delta Loop Array

Post by VE3PCP » Wed Nov 22, 2017 8:11 pm

Had a chance to do more testing and another short video.

https://youtu.be/aSHWw0kOXLQ
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Re: VE3PCP Double Delta Loop Array

Post by va3ts » Wed Nov 22, 2017 8:19 pm

Nice video, thanks for sharing
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VE3PCP
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Re: VE3PCP Double Delta Loop Array

Post by VE3PCP » Wed Nov 22, 2017 9:11 pm

It also seems to work well on 17M too. Had a number of FT8 contact using it.

It loads up nice on 10M but with no signals, hard to see how it works.

Doesn't seem to work all that great on 15. The 4NEC2 model shows an odd pattern on 15 as well.
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