I mentioned in a Ham Radio Workbench podcast episode a few months ago that I planned to build a field-portable delta loop antenna and that led to a mini discussion about configurations, feed points, height off the ground, etc. and how all of those factors can influence the characteristics and dynamics of the antenna.
Vertical loops are pretty fascinating and incredibly effective.
Delta loops are super easy to build (no more difficult than an EFHW) but this summer has been insanely busy for me and I simply hadn’t gotten around to it yet.
Then my good friend Joshua (N5FY) who runs tufteln.com sent me a prototype 20M delta loop in the mail. We’d been talking delta loops and he couldn’t help but build one. He asked that I take it to the field and put it on the air, then give him any feedback and notes I might have.
Joshua’s design incorporates a 4:1 transformer and was cut to be resonant on 20 meters. I’d actually planned to build one identical to this because the type of loops I’ve deployed at home have been fed with ladder/window line which isn’t as portable as something I could feed with RG-316.
Holmes Educational State Forest (K-4856)
After a little scouting, I found a great site to set up the antenna.
I planned to set up this antenna as close as I could to an equilateral triangle with the apex up about 30 feet and the feedpoint in the middle of the base of the delta.
Deploying the antenna in this configuration meant that I only needed one line in a tree to hoist the apex of the delta and two lines to pull out the corners of the base.
I brought along some paracord with tent stakes to secure the base corners of the loop. In the end, though, I simply attached the paracord to trees instead of using the stakes.
I (somewhat reluctantly) made a video of the entire activation including the antenna deployment. I wanted to take my time deploying this antenna for the first time, so the antenna deployment section of the video is much longer than usual.
In the end though? It wasn’t as difficult as I thought it would be. The last vertical delta loop I deployed was a 40 meter loop which is roughly double the size–in my head I was expecting the aperture to be larger than it was.
The 20 meter loop is actually pretty compact and almost as easy as setting up as an inverted vee.
With my loop properly deployed, it was time to hit the air!
- Elecraft KX2
- Elecraft ES60 Pack (Note that mine is a discontinued LowePro CS60 pack, the ES60 is identical and Elecraft branded)
- Tufteln 20M Delta Loop (Not Yet in Production)
- ABR Industries 25’ RG-316 cable assembly with three in-line ferrites (Use Coupon Code ABR10QRPER for 10% Discount!)
- CW Morse SP4 N0SA SOTA Paddles
- Blue Ridge Overland Gear Gadget Bag
- GoRuck GR1 USA
- Elecraft KXBT2 Li-Ion Battery Pack
- Weaver arborist throw line/weight and storage bag
- GraphGear 0.9mm 1000 Automatic Drafting Pencil
- Rite In The Rain Top Spiral Notebook
- Camera: original OSMO Action Camera (the OSMO 3 is the current version) with Sensyne Phone Tripod
On The Air
I continued working stations on the 20 meter band until I logged all of the hunters who were calling. All in all, I worked 24 stations in 33 minutes on the 20 meter band.
Next–just for kicks–I moved up to the 17M band to see if the KX2 internal ATU could match the loop on 18 MHz. Sure enough it could.
Even though 17 meters was pretty dead, I did manage to work two stations.
I then discovered that the 20M loop could be tuned/matched from 17 meters to 12 meters via the KX2’s internal ATU.
But the biggest surprise? I moved up to the 10 meter band where I discovered that the loop was 1:1 resonant without needing an ATU! What!?!
I’ve always been under the impression that vertical loops are essentially mono band, so this was a very welcome surprise indeed!
Ten meters was completely dead that day, but it’s brilliant to know that it’s a proper option with this antenna!
Here’s what this five watt activation looked like when plotted out on a QSO Map:
Here’s my real-time, real-life video of the entire activation. As with all of my videos, I don’t edit out any parts of the on-air activation time. In addition, I have monetization turned off on YouTube, although that doesn’t stop them from inserting ads before and after my videos.
Loving the loop!
So loops aren’t the quickest to deploy and they need a bit of clear space along the plane of their profile.
That said, I will be taking the time to deploy this antenna many more times this year. I’m especially interested in how it might perform on a summit!
Keep in mind that this antenna is truly a prototype, but I think it’s possible Joshua may build a few to sell via tufteln.com later in the year if there’s interest. You might drop him a line or comment here if you like that idea.
Of course, like I said earlier, building a loop antenna is as easy as building an end-fed half-wave or random wire antenna. Consider homebrewing one! The internet is chock-full of info about building and trimming them for resonance.
I hope you enjoyed the process of testing this cool little antenna as much as I did.
Of course, I’d also like to send a special thanks to those of you who have been supporting the site and channel through Patreon and the Coffee Fund. While certainly not a requirement as my content will always be free, I really appreciate the support.
As I mentioned before, the Patreon platform connected to Vimeo make it possible for me to share videos that are not only 100% ad-free, but also downloadable for offline viewing. The Vimeo account also serves as a third backup for my video files.
Thanks for spending part of your day with me.
Have an amazing week ahead!
Cheers & 72,