Friday, April 2, 2010

Ultimate Backpacking Yagi

If you’ve read my blog, you know I got started in amateur radio because I was looking for a reliable emergency communications solution for the backcountry. I found it, but in 2009 while taking my Scouts on a 50-miler, I knew next to nothing about radio. I wasn’t all that successful with my transmission. Part of the issue was that I didn’t know enough about programming the radio nor about VHR radio to set things up correctly. I had all the wrong data – wrong offset, wrong tone for opening repeaters, etc. But there is more – I had equipment problems. And now I know several reasons why!

  • Yaesu VX-7R: vx7rbigmy first challenge (not problem—challenge) is that my Yaesu VX-7R is a 5-watt hand-held unit (in ham radio vernacular, it’s called an “HT” or handie-talkie). 5 watts isn’t all that much power, you know? A decent 5-watt HT with a good antenna will transmit about 30 miles line-of-sight. I was never much more than 30 miles from any repeater, but there were trees all over the place. Nice things about the Yaesu? On standby, this puppy can remain on for a good two days. It’s a tough little unit, and the LCD has just enough info to keep you going, without getting too cluttered. What are you going to do with an awesome 5-watt handheld? Since they don’t make many handhelds with a higher wattage, especially with all these features, I’m sure not going to throw it out!
  • Whip Antenna: I own a Diamond SRH-999 antenna. This is an awesome quad-band antenna which will transmit and receive on 50, 144, 220, and 445 (6m, 2m, 1.25m, and 70cm). The problem is that a whip antenna transmits in a big circle—the transmit power is spread out 360 degrees!srh999
  • No Gain: the other problem with a whip is that there’s essentially no gain. The radio pumps out 5 watts, and that’s what’s transmitted out of the antenna.

So is there an answer to this problem? I’ve got a great little radio. I have learned so much more about VHF radio, repeaters, and programming my radio that I have all the repeater settings correctly dialed in now. But how do I get around the transmission limitations of a 5-watt HT with a whip antenna? Simple: the two-meter Yagi.

Directional Antenna: the Yagi

Welcome to the world of amateur radio antennas! As I’ve studied about radio, I have learned that it’s pretty incredible what you can do with a low-power radio. As a matter of fact, there’s an entire dark art in ham radio called “QRP” or low-power radio. Most QRPers use 5-watt CW (continuous wave, or Morse code) radios. Some of them are as small as an Altoids tin (I’ll be building one of those – it’s my reward for earning General class). If you can transmit cross-county on a fraction of a watt, with a 9volt batter, you ought to be able to transmit 30, 50 or even 60 miles with a 5-watt HT! It all comes down to having the right antenna. And the right antenna will accomplish two things: first, it will focus all your power into a narrow beam; second, it will actually increase your transmission power.

The antenna that accomplishes this? Simple – the Yagi or beam antenna. Remember the old TV antennas? Those are Yagi antennas!

But I’m not looking for just any antenna. I’m looking for a Yagi I can take backpacking.

  • 2-meter backpacking Yagi: Now, I thought I had the perfect antenna when I found the 2-meter backpacking Yagi plans presented at my local club. This has it all! It’s light (PVC and aluminum rod), it’s small (stuffs down into the PVC) and it’s convenient. Unfortunately, it calls for some pretty advanced stuff—ever try to by Delrin rod? Great stuff, but it’s not necessarily sold at your local Ace Hardware. I never really got started on this antenna, simply because I don’t know where to by aluminum rod, Delrin rod, etc.
  • Simple 2-meter backpacking J-match Yagi: so imagine my excitement when I found plans for a 2-meter J-match Yagi antenna. Not only is it easier to build, it’s made out of parts you can buy easily (aluminum grounding rod, apparently available at Radio Shack, and a few alligator clips).
  • Ultimate 2-meter backpacking Yagi: I had my heart set on building the J-match yagi, until I found the ultimate 2-meter backpacking yagi (see pages 5-6). Not only is this puppy light, it’s ultra-light and it’s ultra-compact! Check out in this youtube video how easy it is to build!

So tomorrow I have a slowish day and I plan on buying the parts for the J-Match 2m Yagi and building it. I’m going to keep an eye out for an arrow or even a broken fishing pole out of which I can build the KD5IVP antenna though. THAT’s going to be the bomb for backcountry communications!


  1. Update: I contacted the ham who built the antenna featured in the YouTube video - I've been having a tough time finding that 'music wire'. He replied with a pointer to the very wire on Ace's web site - free shipping to my local store (which is almost closer than my mailbox)!

  2. These are neat and can also be used for AMSAT birds. I'm planning on building one or two of these as well as a DBJ-2 for stringing up in a tree while camping. Sometimes you need height rather than forward gain.