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[Articles Home]  [Add Article]  

$10 Delta Loop Antenna

Stephen (KE7WAV) on April 6, 2018
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$10 No Transmission Line Delta Loop
Article and art by: KE7WAV

Sometimes I am still that little boy who has to try a crazy idea just to see if it works.

I live in a mountain valley where my backyard is mountains and about 12 miles from my front yard are even more mountains. 45 degrees of my horizon to the back and 12 degrees to the front are nothing but mountains. In others words as beautiful as my valley is-- my poor little radio signals struggle to get out. To make matters worse I have electric lines about 30 feet from my front door!?! And because I am really sick I enjoy the idea and the practice of QRP work.

I can’t bring myself to drill a hole in the side of my drafty 117 year old house just yet so I usually open my window and pull the antenna coax into the shack to work on the radio. During the winter this means conscripting my wife’s hair dryer into service to thaw the aforementioned window, then jamming a towel under the window to stop the draft. Operating during -20 to -30 degrees F on winter nights it is a challenge and sacrifice.

I have tried a few antennas over the years including: fan dipoles, a doublet, and an off center fed 80 meter multiband dipole (aka OCF Dipole’), a random wire, and a few others. As I was preparing for this winter I read in W1FB’s QRP Notebook about his success with a low hanging full wave 40 meter delta loop. The information I read said it should help reduce the noise floor and help improve my signal getting out of my mountain valley. I read a few more articles and some Q&A on eham forums (thanks Dale WB6BYU, your answers are always awesome) and watched a great video by VK3YE. I did some math, and drew a couple of quick sketches to design where to hang my new cloud warmer.

My goals with this antenna included a few things:

1. It had to be able to go under the window frame so I could keep the window closed all winter, and not drill holes in my poor drafty old house.
2. It had to reduce the noise floor (S9 noise all winter stinks).
3. It had to have reception/transmission that is better or equal to my current antenna (an OCF dipole in an inverted V with the apex at about 20 feet and the ends at about 10 feet).
4. I wanted to avoid transmission line completely (yea-- I know I am crazy but that stuff is expensive!).
5. It had to be low cost. (Why would I pay more than $15 for a great antenna?)

It was time to stop reading and get to work.

Before racing out to buy wire I dug through my junk box, there I found some 22 guage insulated wire that went right under the window. I ran it out the window leaving both ends inside with just enough length to reach a tuner I purchased at a swap meet last year, and prompting closed the window. One corner of the loop was now carefully hung at the grandiose hieght of about 3 feet!

Outside I used a rubber mallet and some bailing twine to deploy a line to hoist my new loop up about 20 feet over a tree limb. (Only the most high tech stuff for me.) I attached the last corner of the loop to a piece of PVC pipe hooked to my fence and got it up to about 8 feet.

I adjusted the tension until I was happy and raced back inside. I plugged in my soldering iron, tinned the ends and hooked my new low hanging delta loop into my tuner. Switching from the OCF Dipole to the Loop my tests showed the Loop had an average of a 2 to 5 S units lower on the noise floor, and in most cases I could hear the ops more clearly one the loop. In some instances I heard ops on the loop I couldn’t even hear on the dipole. I even tried my 40 meter loop on 80 meters and the receive was about an S-Unit quieter than than my dipole but the noise floor was still better making copy easier. We were off to a good start.

Goal check: Better receive and lower noise floor – check & check. The wire fit nicly under the window and it will never have to be opened - check. The wire originally cost me about $10, and I had used it for a field antenna on a week long scout camp, and then “repurposed” it for this new antenna- Check. No transmission line – check. The only goal left to check was the transmit!

Right away I hopped in 40 meters and heard an op pounding my receiver all the way from South Africa, but couldn’t break through the huge pileup running 10 watts SSB. I even tried cranking it up to 30 watts and no luck (bummer). Later I got on again and running 30-50 watts in 15 minutes I made four quick SSB contactsall from 450-700 miles away with good reports (56, 57,+10, & +10). I compared my noise to signal ratio and on all but one contact the Loop out performed the OCF Dipole (the one was a tie). All up I am proud of my “junk-box-less-than-$10-no-transmission-line-multi-band-leave-the-window-closed-delta- loop-antenna.”

For those of you in rentals, townhouses, or HOAs, this could be a great stealth low cost antenna to help you get on the air—though personally I would not recommend running more than 50 watts on such a small diameter wire.

Member Comments:
Add A Comment
 
$10 Delta Loop Antenna Reply
by W4FID on April 6, 2018 Mail this to a friend!
NICE! This restores the idea that you do what you can do and work who you can work and enjoy what you enjoy. A basic of ham radio that is lost too often these days. Is the total length of the wire about 120 feet? How well does it work on 75/80? On 30, 20, 17 meters? Have you worked enough QSOs to see if it has nulls and if so in what direction to the plane the wire is in?
 
RE: $10 Delta Loop Antenna Reply
by KE7WAV on April 6, 2018 Mail this to a friend!
Yes the antenna works better than I would have suspected on 80M. It does okay on 30M. I haven't tried 17M-sorry. And it is awesome on 20M. And I made mine about 134 feet.
 
RE: $10 Delta Loop Antenna Reply
by KE7WAV on April 6, 2018 Mail this to a friend!
I forgot your question about the nulls. SO far it seems to be omni-directional. I would assume this is because of how low to the ground it is located.
 
$10 Delta Loop Antenna Reply
by N1TA on April 6, 2018 Mail this to a friend!
Don't forget -- the Reverse Beacon Network is a great way to test your transmitted signal and even help determine nulls. I think you'll find this antenna is pretty omni, and also is likely a cloudwarmer. Being so close to and even inside the house, I'd suspect it's coupling to, well, everything. But if it works and it's fun, rock on!
 
$10 Delta Loop Antenna Reply
by K8YZK on April 6, 2018 Mail this to a friend!
Nice job, Wonder what tuner you are using?
 
RE: $10 Delta Loop Antenna Reply
by KE7WAV on April 6, 2018 Mail this to a friend!
MFJ -Deluxe Versa Tuner with the built in 4:1 Balun.
 
$10 Delta Loop Antenna Reply
by W8BFX on April 6, 2018 Mail this to a friend!
Enjoyed the article, the art, and your
sense of humor. Thanks
 
Success Story Reply
by VE3CUI on April 6, 2018 Mail this to a friend!
I just LOVE reading about all these "...MacGuyver-like" ad hoc antennas that end-up working so surprisingly well for the minimal amount of work that it might take in erecting them...!

Reminds me of the time back when I was still living at home, & ran a 33' piece of wire up the side of the family TV tower, & clipped the braid of my coax feeder to my Mom's plastic-covered steel clothes line that ran across the backyard, at the bottom of the tower...ta-da! INSTANT 1/4-WAVE ELEVATED GROUND PLANE ANTENNA FOR 40-METERS...!

And y'know what...? It worked GREAT for Europe, & even allowed me 2 QSOs with "ZL"-land one morning --- and all with nothing more elaborate than the output power of a 3rd hand Johnson Ranger-1 transmitter...

So who REALLY needs the likes of "EZ-NEC," anyway...?! :o)
 
RE: $10 Delta Loop Antenna Reply
by KG4RUL on April 6, 2018 Mail this to a friend!
I have to assume that your windows have wooden frames and sashes? Doesn't seem like it would work with my aluminum frame windows.
 
RE: $10 Delta Loop Antenna Reply
by KE7WAV on April 6, 2018 Mail this to a friend!
Yeah, my house is 117 years old. But that means I have a few really tall trees!?!
 
RE: $10 Delta Loop Antenna Reply
by WD5JFR on April 6, 2018 Mail this to a friend!
Looks to me like you could cut a small scrap of board or piece of plywood with a coax hole or two to fit a one or two inch opening in the frame as a solution...short or long term unless burglars are a problem.
73 Hank
 
$10 Delta Loop Antenna Reply
by K3ANG on April 6, 2018 Mail this to a friend!
Nice article and good job! You're doing well with your limited budget. Search the net for examples on how to build your own ladder line, either 600 ohm or 450 ohm. It's easier than you think! You probably have the tools and items near at hand.

73 from Maryland
de K3ANG
 
$10 Delta Loop Antenna Reply
by W8LV on April 6, 2018 Mail this to a friend!
Have you ever considered "coupling" capacitors, so to speak, to feed the antenna? I did this once for a receive long wire...

You attach the wire to a piece of sheet metal. You attach that directly to the window glass with tape. And you do the same thing to the inside. In your case? Two such attachments. I supposed a bit of inductance could match the capacitance that you get there.

73 and All the Best!
DE W8LV Bill
 
RE: $10 Delta Loop Antenna Reply
by K6CRC on April 7, 2018 Mail this to a friend!
Great, assuming no kids or deer will run into the wire.
I am always impressed when I have a QSO with a ham running simple wires and a transceiver they got for $200 at a swap and fixed. Gives me hope for the hobby.
I would also consider using an inverted L. You can wind a 9:1 unun for under $20, use chunks of house wiring found discarded at a construction site for radials or counterpoise. Someone can give you a bit of old coax they don't need.
Config works well. 30w will let you work the world with FT8 or CW.
 
RE: $10 Delta Loop Antenna Reply
by KE7WAV on April 7, 2018 Mail this to a friend!
Thanks for the inverted L suggestion, my dad ran one of those on his HW-8 in the 80's. I normally run only 5W on CW and so far this has been a fun antenna. Now that spring is almost here in my mountain valley I will try something else. I find I enjoy building a large variety of antennas. I enjoy experimenting and seeing what can make work for cheap- it's my current bug in the hobby. I even tried to make a duck style HF antenna, it was a terrible antenna, but it did work for some QSOs.
 
$10 Delta Loop Antenna Reply
by KF7ATL on April 7, 2018 Mail this to a friend!
Great article Steve! Thanks for the inspiration for the budget-minded.
 
$10 Delta Loop Antenna Reply
by NO6E on April 7, 2018 Mail this to a friend!
Terrific article and great illustrations!
 
RE: $10 Delta Loop Antenna Reply
by KW4JX on April 7, 2018 Mail this to a friend!
I've heard that a new and higher 'Superior Class' of ham is to be qualified. The first question on their test is,'Have you ever set any trees on fire?'
 
$10 Delta Loop Antenna Reply
by AE5NE on April 8, 2018 Mail this to a friend!
Leaving small-diameter rope or twine hung over a tree limb will eventually abrade the bark and kill the limb.

It's likely to fall off right were the line is hung over it.

 
RE: $10 Delta Loop Antenna Reply
by K0UA on April 8, 2018 Mail this to a friend!
I have had both ends of my 80 meter OCFD hung over fairly small tree limbs high up in oak trees. There are 10 lb weights on each end. While I don't doubt there is some abrading, they have been up for about 15 years and the limbs haven't died yet.
 
$10 Delta Loop Antenna Reply
by AB9TX on April 9, 2018 Mail this to a friend!
Nice, but that will not pass the QYL test. Also, decapitating birds.
 
RE: $10 Delta Loop Antenna Reply
by AB9TX on April 9, 2018 Mail this to a friend!
XYL, sorry - she would never approve this...
 
RE: $10 Delta Loop Antenna Reply
by N6JSX on April 9, 2018 Mail this to a friend!
This is an interesting method IF you have the right setup to do it.

Here is a window DIY.... Cut a piece of 3/4" by 6" plywood to fit into you window width - lower the window upon it trapping it. Get a piece of soft foam the width of the window and put it between the bottom window and top window killing cold/hot drafts and keepping bugs out.

Now using bulkhead barrels SO-239/BNC/N and three 1/4"-20 bolts - place them in the plywood. The bolts are for your wire antenna connections and Shack Ground feed-thru. The barrels are for your other antennas.

Need rain/snow cover - cut a rubber tire inner-tube the width of the window and screw to outside of window plywood to make a flap over the connections. Seal the plywood with same color window spray paint....
Cheap simple - KISS.

I really would hate to see you have a window fire with the trapped wires under the window breaking the wire insulation and rain creating a shorting path. I hope you have a full time Power/VSWR meter to this loop to alert you of fluctuations.

Actually, I'm a little surprised MFJ has not incorporated into their Tuners a settable VSWR Alert Alarm. Sounding an audible high pitch beep when TX is above a set-point or 3:1.
 
RE: $10 Delta Loop Antenna Reply
by KB6QXM on April 9, 2018 Mail this to a friend!
I would like to ask a few questions about your project goals:

My goals with this antenna included a few things:

1. It had to be able to go under the window frame so I could keep the window closed all winter, and not drill holes in my poor drafty old house.

Why not build a simple window feedthrough? Many hams build window feedthroughs. They are inexpensive to build and do not take that much time to build. If you do not want to do it or know how, how about asking a fellow ham to help?

2. It had to reduce the noise floor (S9 noise all winter stinks).

Why not use filtering or DSP or a item to shift noise phase from one antenna to another?

3. It had to have reception/transmission that is better or equal to my current antenna (an OCF dipole in an inverted V with the apex at about 20 feet and the ends at about 10 feet).

How was the comparison measurements done?


4. I wanted to avoid transmission line completely (yea-- I know I am crazy but that stuff is expensive!)

What about getting the feedline at a swap meet or have some ham friend give you some surplus? This is a technical hobby and it is not free.


5. It had to be low cost. (Why would I pay more than $15 for a great antenna?)

Because there is a lot of engineering and testing that go into a high performing antenna.

Is this article a "April Fools joke"?
 
RE: $10 Delta Loop Antenna Reply
by AJ4SN on April 9, 2018 Mail this to a friend!
I enjoyed the article. It is well-written. You are very resourceful!

73

Stan
 
RE: $10 Delta Loop Antenna Reply
by KE7WAV on April 9, 2018 Mail this to a friend!
KB6QXM, sorry no joke for April.
I have built probably 30-40 antennas in the last 10 years. I like to tinker and I like the challenge of building a functional antenna from next to nothing. Right now that is my joy in the hobby. It gives me something to play with and experiment with. Some of my antennas have been terrible performers while others have been astoundingly powerful. My prerequisites for this build were simply part of the challenge to make the build fun for me.

Your right a simple window pass through is easy to build and I have used them before. But at -20 degrees F in the winter it's never worked as well as my current setup. I only have older radios so I have built a filter, but I still like to listen without it sometimes, if I can reduce the noise---why not? As for the feed-line; because I build so many antennas yes I do buy feed-line at the local swap meet, but sometimes I like to get rid of that aspect of the antenna. Part of the fun. Yes there is a lot of engineering in great antenna design, but it doesn't have to cost a lot. It does require research, testing, and work.
 
$10 Delta Loop Antenna Reply
by K2PI on April 10, 2018 Mail this to a friend!
Nice article and art. It works well for you, so all the better. If the slope of the wires is towards your house as is shown in the article, make sure you have some way to block or counter water which will roll down the wires towards your house and to your window frame. Water is sure to damage your window frame or enter your home otherwise.

Enjoy the new antenna!

 
RE: $10 Delta Loop Antenna Reply
by KE7WAV on April 10, 2018 Mail this to a friend!
I added some quick drip lines that have worked great. Thanks for the thought.
 
$10 Delta Loop Antenna Reply
by KD8NGE on April 11, 2018 Mail this to a friend!
I'm with W8BFX.
Love the humor and the artwork!
I had to belt my forehead with the heel of my hand when you described starting and ending the loop connected directly to the tuner: "Why didn't I think of that! WHAP!"
You see, that'll solve a quandary ... portable (field ops) antenna, have a 30 ft fiberglass telescoping pole that I've fabricated a pipe nipple socket to hold ... I'm thinking a magnet wire delta loop, apex at the top of the pole, left angle and right angle (which are actually acute angles, just on my left and my right) tied off to something convenient with, oh, say, nonconductive nylon string ... in a place where passing pedestrians won't run into the horizontals, run the ends back and connect to the tuner ... field expedient antenna!
 
RE: $10 Delta Loop Antenna Reply
by W4WDM on April 12, 2018 Mail this to a friend!
I’ve killed more than one tree, some deserved it and others didn’t...
 
$10 Delta Loop Antenna Reply
by KD6NRP on April 13, 2018 Mail this to a friend!
You might want to consider running an insulated wire along the ground to form another side of your antenna.

If my 129.4 foot (42.4 meter) circumference vertical loop is elevated off of the ground, it will work well down to 7 MHz.

However, with one side of my loop running along the ground, it works well down to 3.5 MHz.

I've been using my vertical loop with one side along the ground since last December and the results have been quite good.

73

Brian
 
$10 Delta Loop Antenna Reply
by K5BEZ on April 15, 2018 Mail this to a friend!
Great job!
I love experimenting with antennas.
Thanks for sharing your experience

 
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