Field Expedient Off-Center-Fed Dipole
You need a wire antenna up right now- not simply to transmit, but to efficiently receive information. In the event of a longer-term grid down situation or a breakdown in civil order, having an inexpensive antenna that’s fairly simple to replicate is going to be incredibly valuable and is the cornerstone of why I teach antenna theory and have students build simple improvised antennas in the RTO Course.
But that said, what I’m going to cover is a very specific type of antenna that good on 80-6M, or 3.5-54 mHz. An Off-Center-Fed dipole, sometimes called a Windom, a Carolina Windom, and most famously the Buckmaster, is a popular antenna type with hams because of its utility on many bands. I don’t personally favor them for everyday use because they do not offer as much gain as a standard resonant dipole- meaning you’re getting no additional benefit from using one aside from the fact that its efficient on several bands. I prefer a multi-band fan dipole, with specific wire cut for each band I use, but that takes a lot of material and is vulnerable to environmental damage over time.
The OCF is quick, efficient and doesn’t use much material. So building a few of them is pretty inexpensive and getting them hoisted and on the air is very simple.
What you’ll need:
- 4:1 Balun
- 50 ft 14 AWG wire
- 100ft 14 AWG wire
- Heat shrink tubing
- Ring Terminals
- Wire cutter and stripper
The conventional way to build this antenna says to make one leg 88ft and the other 44. Making things quick and dirty, because its field expedient (meaning not perfect but works), I round up to 90ft and 45ft. Cut 10ft off the 100ft spool, cut 5ft off the 50ft spool. Quick and dirty.
Next, slide on a piece of the shrink tubing and crimp your ring terminals. I pull off the plastic because it’ll get in the way. Slide the tubing over the crimp and melt it in place. The tubing secures the crimp, insulates it from the elements, and provides additional strength under strain.
Fasten the wire to the studs on your balun. Your antenna is ready for prime time, just get it hoisted to 30ft. Now all you need is a 50ft run of RG-8X from a CB shop and you’re good to go. For expediency’s sake, leave the wire on the spools. You can use the spools as insulators in a pinch, or carry a couple of electric fence insulators like we’ve used in class.
And with that, I just saved you the $250 a Buckmaster antenna costs. Keep the change, pay it forward.
NCS
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[…] it is, up-to-date receiving electronics and power efficiency when running off-grid. Coupled with a hasty wire dipole you’re good to […]
What brand of balun is shown in the pics? Just curious.
Its a compact 4:1 I found on eBay. Its the same as any other, just a little smaller.
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