“Did you build that sloping Vee?” Team Daddy asked me.
“yeah Sa’rnt, the long whip wasn’t hitting the TOC from inside these walls.” I replied. The thick mud walls of the compound were hell on a signal, and the makeshift TOC the commo guys had set up on the next ridge was having a hard time hearing us. It was either hang out on the roof in 19 degree cold, exposed, or get out of the wind and put up an improvised Vee out the window.
“Damn dude, you’re good. I love it!”
Not only did it get us at least a little comfort and keep our butts from being out in the open, but it made me look good in the eyes of my betters. I used stuff I had been taught to our advantage- a rare thing these days. Anyway, it sparked a love for making and improvising that I carry on everyday and try to share with you.
A lot of you own an HT and not much else, signal-wise. And that’s ok, its what you can justify within the budgetary constraints we all live within. Generally, all of the HTs out there push between .5 and 5w, with a few doing a little more than that. The truth is this though; antenna makes all the world of difference as to how your signal ‘gets out’. So for that reason, you should work on building your own antennas. All antennas are compromises. The closer an antenna gets to resonance the more efficient it will be at radiating its energy. Theoretically speaking, this is measured by your Standing Wave Ratio (SWR). All antennas have a frequency which they are resonant on- along with a certain bandwidth, or distance between certain frequencies, where they perform best. This is what is meant by the terms Narrowband and Wideband. A wideband antenna will be resonant over more frequencies within a band, while a narrowband antenna will be more efficient on a single frequency. For homebrewing a purpose-built low power HT antenna, this doesn’t make a huge difference.
The most popular HTs out there (of any brand, Chinese, Japanese, dirty knees, whatever…) are at least dual band, working both VHF and UHF, containing the 2m Amateur Band, MURS, and Marine on VHF and 70cm Amateur, GMRS and FRS on UHF. That gives us a lot to work with, no matter what particular band or set of frequencies you rely on. Learning to make purpose driven antennas becomes a great compliment to that piece of equipment, allowing you to do much more with less power (and the satisfaction of building something yourself!).
Remember 936? Yep, still important. 936 is the constant for full-wave antenna length in feet.
936/frequency= antenna length in feet
And we know that each leg of a Dipole is Quarter-Wave (well, you know now) so,
936/4= 234, 234/freq= quarter wave antenna length in feet
Don’t skip steps in your math! It won’t turn out right.
Lets look at the parts we’re gonna use:
- Banana Post Adapter
- BNC to UHF adapter (for coax)
- Ring Terminals
- Two Egg insulators
- 16ga Insulated Stranded wire
Each of the parts aside from the banana post adapter and end-insulators were picked up at the hardware store. The connector and insulators came from a local hamfest.
Figure out your working frequency, and do the math. For this exercise I’m using the 2m National Simplex Frequency, 146.52mHz, which gives me a length of 1.597 ft, or multiplied by 12 to give me length in inches, coming out to 19.16. Give yourself around 21in to attach the end insulators.
Strip the ends, attach and crimp ring terminals so that the connections to the Banana Post will be clean and easy to manipulate.
Attaching the insulators and Banana Post, your antenna is now taking shape. Notice how small it really is? This will disappear into the background pretty easy.
Now let’s go string it up.
This is hard to see, and I’m standing right under it. With a run of coax to the radio and an SMA to UHF adapter, we’re ready to play. It makes a great SWL antenna as well, along with being able to transmit directionally.
So in doing this, we’ve built a homebrew antenna with just a couple cheap parts and a little know-how, as well as building our capabilities and our skills. It can be directional, it can be strung vertically for an omni-directional pattern, and it can be added to or re-configured if need be.
Homebrewing equipment can be some of the most rewarding activities a Survivalist can undertake. Not only does it render a sense of accomplishment not found in just buying something, its also the best teacher. And it might just score you some brownie points with somebody when it matters one day down the road.
23 thoughts on “The Versatile Dirt Cheap D-I-Y Dipole”
Mahalo to you too Brah!
What you described was the first home brew I built for my HT. It worked good but could only on occasion hit a repeater 30 miles away.
Then I read an article by you about a Moxon antenna. So in short I built one using on hand items.
– 1/2″ pvc
– 12 ga. Solid wire,
– some SS screws and bolts,
– A old hank of coax, and
– Some misc. Connectors.
Once completed, I could hit that 30 mile away repeater easily. Some folks thought I was using more power than the 5watts the HT puts out max.
Now granted, the redoubt is at 1,400 ft and the repeater is at 2,600 ft however I can hit repeaters out to ~50 miles when the conditions are right and I aim the moxon towards the repeater.
I would post a pic if I could.
All good stuff! Please keep it coming.
I’m glad you’re putting it to great use! With the last few posts I’m taking it to a ‘back to basics’ approach.
Great post G-money!
Reblogged this on Starvin Larry.
Other than what you post- what do you think is the best source of info on improvised antennas?
The USMC Field Antenna Book
FM 7-93 Long Range Surveillance Unit Operations
ARRL’s Wire Antenna Classics (1-3) and last but not least, John Hill’s “Portable Wire Antennas”.
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As always, most excellent, practical skills based on real world, less than ideal conditions…
I ordered Hills book, one for a buddy as well and downloaded both .mil manuals…Will have a buddy print em out and put in binder for me…
I thank you, and wish you and yours, Special K too, a most bountiful and relaxing Thanksgiving….
You too my Brother!
Henry, give my regards to Cindy Caswell and Uncle Max!
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Thanks. Reblogged at http://lowervalleyassembly.us
another good antenna to make yourself for an H/T is a ground plane made by soldering wires to a panel-mount UHF socket (SO-239). One going up for the radiator from the center conductor, four radials slightly longer and angled about 45 degrees down from level. It’s small enough to hang in the corner and the coax connects directly to the bottom of the SO-239. You can make them for each band.
You stole another post from me 🙂
I’ve built a few of those, and am planning on doing a post about them. This is the first in a short series of “DIY” antennas.
Totally agree Idahoser! I built one for my shack 2 meter HT this past summer. Like you wrote the secret is to bend down the radials 45 deg. Down towards the ground.
Being in NE PA. With an ugly winter coming, I also coated all of the screws on the 239 that hold the radials with liquid tape. So far so good.
Check out the post I did on the Jungle Antenna. It’s the same antenna, but made of wire. Basically it’s the dipole described here stretched vertically and with two (at least, but you can have as many as you want) more ground legs.
It’s another way to build the same antenna, depending on what spare parts you have laying around.
Great article! I want to build this, but I’ve got a few other projects in the works at the moment. I’ve also been practicing meatspace opns some – listening and not TX’ing. Thanks for the info!!
You’re very welcome!
Am I correct that making the dipole sloping, brings impedance to 50Ohms?
Yes, although impedance has to do with more than just the antenna design. Height, bandwidth, strength of resistors (if you’re using them, and they should be 500 ohm, but that’s another topic), quality of insulators, and soil composition all have a degree of changes to impedance as well.
If in doubt, especially with an unbalanced antenna such as a dipole of any type, put a few turns in the coax at the feedpoint to create an air choke balun.
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