Chris Warren at Off Grid Ham talks about Cheap & Easy Portable Antenna Hacks in the article below. When I run off battery power or away from home, I tend to use a Buddipole portable antenna system. The first time I set it up, I was able to tune into a pileup on an operator in Ukraine, and I’ve been pretty happy with it since then. However, you need to think about how and why you’ll be using your radio off grid. My Buddipole antenna is portable, but not so portable that I’d want to backpack it in somewhere with my radio and camping gear. Additionally, unless you are most worried about an EMP taking out North America, in most situations you don’t need to be able to talk halfway around the world.
Wire and wire dipole antennas can be cheap and light. If you only want to talk to radio operators in your state or couple of hundred mile around, you don’t need to mount the antenna very high. And if you only want to listen, you can lay your wire right on the ground. There is also a ton of information on the internet about building wire antennas. I’ll put a YouTube video at the bottom.
It’s a little unclear the way Chris wrote about baluns and ununs, but the need for either is based on both the feedline to the antenna system and the antenna itself. Chris is writing about using coaxial cable as the feedline, which is unbalanced. If you were using ladder line, that would be a balanced line. So feeding a dipole, which is balanced, from Coax, which is unbalanced, would be aided by a balun (balanced to unbalanced). Feeding dipole, again balanced, using ladder line, which is balanced would not need either. Feeding a random wire, which would be unbalanced, using coax, which is unbalanced, could use an unun (unbalanced to unbalanced). And feeding an unbalanced random wire antenna with balanced ladder line could be aided by a balun.
All that said, if your radio itself isn’t putting out balanced output, then a balun or unun may still improve things for you. Additionally, just because you’re going from coax to a dipole doesn’t mean that you have to have a balun to talk to anyone. Having a balun may reduce noise and keep unwanted RF out of your operating shack (if you’re using one), but not having one may not impede your ability to communicate as needed. These kinds of things are part of the reason why people who use radios a lot continually tell preppers not to just buy a radio thinking that they’ll be able to unbox it and use it perfectly when the emergency happens. Yes, you may be able to unpack your Baofeng HT, and it may work properly out of the box, but it may not perform the way you need it to if you haven’t tested it and made adjustments.
I don’t do a lot of antenna articles because there is already so much information in circulation I can’t see much ground left to cover, at least that’s what I thought until new Off Grid Ham reader Rick sent a nice email that inspired this article. What are some cheap and easy ideas to make a portable antenna better, from an off grid perspective?
The off grid niche. portable antenna
To rehash the obvious, running off grid radio does not require a “special” antenna. Whatever works for conventionally-powered stations will also work off grid. However, off gridders tend to have different needs and operating goals. Some antennas fit these needs and goals better than others. portable antenna
I know from my own operating experience, running this blog for over seven years, and talking with other hams, that off grid amateurs disproportionally use QRP, lean towards portable operations (outdoors), and are less focused on having a big signal for the purpose of DX, contests, & awards. They also, by a very large margin, are involved with the survivalist/prepper movement and/or EMCOMM on some level.
If you are into amateur radio in whole or in part because you want communications when SHTF, then your equipment choices are going to be different from the guy who is a contester, DXer, or thinks it’s just a fun hobby. An analysis of those two demographics might itself be worthy of an entire Off Grid Ham article.
From the abstract to the real.
Now that we’ve lightly touched on the sociology and psychology of why operators may choose different equipment, the next question is “what are my options?” Your options as an off gridder are are for the most part the same as they are for everyone else. You’ll just have to make a few adaptations. As we have discussed many, many times on this blog, there will be tradeoffs and compromises. Here are a few ideas with a “cheap & easy” goal in mind:
The wire antenna. portable antenna
Perhaps the most fundamental of all antennas, the dipole has been around almost as long as radio itself. There are a few things an operator can do to make it more off-grid friendly. These ideas can apply to all other wire antennas too:
Lose some weight!
If you are running QRP power levels, there is no compelling reason to have a dipole with heavy gauge (16 or less) wire. Wire sizes between 18-22 gauge are perfectly acceptable for QRP. It’s less expensive, easy to work with, and coils nicely for easy transport.
Speaker wire is a popular material for light weight antennas. It’s easy to find and not particularly expensive. It would be a great choice. But there is something better. Much better.
The “holy grail” of off grid antenna wire.
The top of the QRP antenna wire pyramid is 22 gauge central office frame wire (sometimes referred to as cross connect wire). CO frame wire is incredibly strong for its size and does not easily stretch. It comes in a twisted pair. There is no need to separate the pair. Simply strip the insulation and terminate the bare wires together at each end. This turns the twisted pair into what is effectively one single conductor. The twist will have no meaningful effect on your send or receive signal.
Unfortunately, CO frame wire is used only by the telecommunications industry and is very hard to find for sale to the public. It can occasionally be found at swap meets. I was able to source this wire through my professional affiliations and can confirm that it makes a fantastic light weight antenna material.
The photo below is a 20 meter central office frame wire dipole with balun, rolled up for transport. It weighs 9.6 ounces (0.272 kg) including the balun and fits in a plastic sandwich bag.
Many hams work for the phone company, or have connections. Ask around. If all else fails, you’ve got nothing to lose by knocking on the door of your local central office and simply asking the tech if you can have some frame wire. He/she will know what you are talking about. Every year they pay contractors to haul away thousands of feet of the stuff to the scrap yard, so it’s not a big deal to give some away. Many telephone central offices are not manned full time so you may have to make a few attempts to catch someone while they are there. Since techs set aside unwanted wire for recycling, “dumpster diving” will not likely produce any results. In any case, it will be well worth your effort if you can find some.
If you cannot source central office frame wire, light gauge speaker or doorbell wire will work just fine but will not be as strong and stretch resistant.
Baluns and ununs.
Almost any antenna fed by coax can be improved by adding a balun or a unun. These devices are essentially transformers that manage the impedance difference between your feedline and the antenna and prevent common mode current. Common mode current is undesirable RF energy that flows along the outer braid or shield of the coax; it contributes to inefficiency and poor antenna performance.
A balun is used on antennas where all elements are the same length, such as a dipole. A unun is used on antennas where the elements are not the same length, such as a random long wire…(article continues)
And here’s a video on building a 20m dipole antenna.