I first became interested in operating amateur radio in the great outdoors (aka the Big Blue Sky Shack) over 20 years ago and since that time it has become a passion. The passion is partly inspired by the exploits of secret agents behind enemy lines during the Second World War. These people didn’t have to buy a radio at a high street store; it was delivered to them by parachute. Their antennas were simple end-fed wires supported by trees outside a covert farmhouse radio shack. Their transmissions were only as long as necessary to complete sending a short cryptic message in Morse Code. Rag chewing was discouraged by heavily armed enemy soldiers with sensitive radio direction finding equipment who could locate the clandestine operator in as little as a few minutes then enforce QRT and create a Silent Key with a few rounds of ammunition.
Semper Fi
I am equally inspired by the United States Marine Corps who have published extensive information – available online – on field expedient antennas and techniques for tactical HF communication during the Vietnam War era. Great credence should be given to the advice offered by those whose lives depend on the efficiency and safety of their radio communication equipment and operating procedures.
T O R T U R E
Perhaps the key consideration is “field expediency”. Imagine you are restricted from buying your equipment – by oh, let’s say a pandemic lockdown – could you improvise? Going back to WW2 for a moment; allied prisoners of war in Europe were able to build radio receivers using rusty razor blades. In Vietnam, P.O.W. Admiral Jeremiah Denton managed to send a covert Morse Code message during a televised propaganda interrogation by famously blinking his eyes. With these examples of what human ingenuity can achieve, how can anybody not be inspired to explore the skill of using whatever is available to communicate?
That story underpins how I turned out to be an amateur radio operator who enjoys operating in the field using (wherever possible) improvised or home made equipment. Along the way I devised some techniques that have served me well; I hope you will find them interesting.
The best place to start is with antennas. I have never bought an HF antenna. They are so simple to construct that it just doesn’t make sense to blow precious dollars buying one. And, you learn a lot about how they work, what doesn’t work and why. All you need is a reel of wire, some connectors and a willingness to experiment. It also helps to own an antenna analyzer. I avoided buying an analyzer for many years on the assumption that it was an expensive item that I would rarely use. Wrong! Barely a day goes by now without my RigExpert Zoom getting a workout.
The posts here on Ham Radio Outside the Box contain plentiful examples of antenna experimentation – including the day I arrived at a park intending to do a POTA activation only to discover I had left my antenna at home. Fortunately I had 33 feet of wire in my truck from which I improvised a 20m dipole. The antenna was ugly and horribly inefficient but the activation was successful and even yielded some DX.
Tip: always carry a spare reel of wire in your vehicle when you are out in the field.
On another occasion, I was all set up ready to do a POTA activation and discovered there was no sidetone audible when I operated my paddles. The problem was easily diagnosed; a wire had broken away from a connector in my go-box. This could have been another failed field operation, but I carry a Weller butane soldering iron in my truck and fixed the problem in short order. I have been breathing solder smoke since I was a pre-teen. As a young kid I couldn’t afford to buy a soldering iron so I improvised. I wrapped some “Eureka” (aka Constantan) resistance wire around the blade of a small screwdriver and hooked it up to my 12 volt model train controller. It melted solder very well and was used to build a transistor amplifier for my crystal set. Perhaps today I would have used a cigarette lighter to heat the screwdriver.
Tip: always carry a soldering iron, that can be powered in the field, in your vehicle when operating outdoors. Or a cigarette lighter. And don’t forget the solder too.
NOTAM*: Danger to “avian nation”
*NOTAM: Notice to Airmen
How get your antenna up in the trees? Sure, go and buy one of those nice arborist throw line kits, or a fancy air pressure launcher made from plumbing pipes. Or a slingshot and reel of fishing line. Or none of the above. I attended a Winter Field Day with my club a few years ago. One of the members brought his slingshot, fishing line and lead sinker along. He successfully shot the line up over a branch about 80 feet high. Then used it to pull up some paracord – but the fishing line snagged on a tree limb high above the ground. The antenna ended up only about 30 feet high and the fishing line wasn’t retrievable, becoming a danger to “avian nation”.
“Up, up and away in my beautiful balloon”
I use my fameless “Sand Grenades” – a plastic party balloon filled with 4 ounces of sand – and a length of Mason’s Twine which is a very cheap, very lightweight, immensely strong and slick type of cordage. I keep the sand grenades and twine in a Ziploc freezer bag which has a secondary use. If the zipper at the top of a Ziploc bag is folded back, the bag becomes self-supporting and serves as a Field Expedient “throw bag” to keep the “throw line” clean and free of dead leaves and other debris.
Knots So Useful
It is useful to know how to tie knots. There are numerous resources online that can help. I tie a Bowline at both ends of my throw line. Sand Grenades are attached using a Lark’s Head knot formed from the loop of the Bowline. When operating QRP an end insulator isn’t really necessary. I attach my antenna wire to the throw line by tying a simple overhand knot at the end of the wire. Another Lark’s Head knot at the other end of the throw line grips the wire securely by engaging with the overhand knot in the wire.
Tip: Learn to tie some basic knots; they will be very useful for ham radio in the field
Incidentally, Ziploc bags have another use. The zipper at the top of the bags creates a very effective air-tight seal. They can be used to create an air cushion to protect delicate equipment. For example, place a small CW key or microphone inside the bag then seal the bag trapping a pocket of air inside. The bag’s contents will then survive being bounced around inside a backpack.
A little known property of Ziploc freezer bags is they can also be used for cooking meals in the field. Place your post-activation lunch inside, seal, then boil in a pan of water to reheat your meal.
Tip: Ziploc bags have multiple uses; add them to your EDC (Every Day Carry) pack
Field experience taught me a special technique using my Field Expedient arborist kit. Field antennas don’t usually need to be very high. My 20m/40m EFHW (End-Fed Half Wave) only needs to be about 25 feet high. For 20m, the wire is about 31 feet long and erected as a sloper. If you invoke Pythagoras, the far end of the wire will be 22 feet higher than the feed end. The feed end is attached to my backpack about 2 feet above ground. For 40m, another 31 feet of wire is attached to the 20m wire and the antenna is erected as an inverted-V with the apex only about 24 feet high – not perfect, but field expedient.
For 20m, here is what I do: using only about 35 feet of throw line, I attach the far end of the antenna wire before throwing it up into the tree. The throw line becomes the support line for the antenna. The sand grenade becomes the weight that holds the antenna in place. That arrangement is fast and perfectly adequate for an antenna that is only going to be up for an hour or two. You don’t need to use “Sand Grenades”; improvise! Fill a Ziploc bag with soil and use it for a throw weight. Or take off one of your socks and fill it with some soil. Or use a small rock.
Tip: always carry Ziploc bags, or an old spare sock and lots of Mason’s Twine in your vehicle. A Swiss Army knife is very helpful too.
I have a small canvas EDC (Every Day Carry) bag full of “oh #@&*! I forgot to bring …” emergency supplies in my truck. It holds a spare coax, a long DC power cord with cigarette lighter plug at one end and Anderson Powerpoles at the other end, an emergency 20m dipole, spare wire, Mason’s Twine, tools and numerous other bits and pieces that I might need to rescue success from potential failure out in the field. For anything else I might need, ingenuity and nature will provide.
** Do you have any other tips you would like to share? Let me know in the comments. **
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Ham Radio Outside the Box 
You have some really cool ideas here. Thanks!
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