Tuesday, September 25, 2007

Antennas for travel: bring your brain

I announced earlier this month that I was working on a white paper Antennas for 100 Pound DXpeditions. I am still working on this, and will continue working on it through the end of this year before I can claim that I have a complete draft. I had a very early (and sketchy) version of this up in the NE1RD Download Area for a few days to solicit comments, but I've since taken it down. I will put up a new (partial) version again after my return from St. Kitts.
This exercise is really a continuation of the research that I had been doing since the beginning of this adventure, and especially a continuation of a series of blog posts that I had done a year ago called Antennas for travel. In those posts I talked about fishing poles, Force-12 Sigma-5, Buddipole, Buddistick, and Superantennas MP-1. One thing I should emphasize is this: I rarely use an antenna right out of the box without thinking about what it is doing and how I can make it better. So, for example, when I say I used the Superantenna MP-1 on Hawaii, please note that I didn't use the stubby little 4 foot whip that came with it; I used the 12 foot MFJ whip. Also, I didn't just use the stubby little 8 inch rod packaged with the antenna; I added a 22 inch Buddipole arm (or two). Check out the photo below.

What's the difference? There is a great deal of difference! If you start with a 12 foot whip and add another two feet or even four feet in Buddipole arms, you have a full-sized, or nearly full-sized antenna for 20m. Compare that to an antenna that is only a 1/2 or even 1/3 the length of a full-sized radiator you would have if you simply used the parts that came in the box. There is a great deal of difference indeed!
The most important part of any antenna system is your brain. Bring it, you might need it. {grin} Take a look a what an antenna system offers out of the box, then ask yourself, "what can be done to make it better?" For antennas that use the standard 3/8 inch by 20 threads, the most obvious thing you can do to better the performance of the antenna is to add a long (12 foot) whip, and extend the area under the loading coil with items like a Buddipole arm or Hustler fiberglass pole. Full-sized antennas are better than shortened compromises. Doing everything you can to eliminate the need for a loading coil also helps. (Capacity hats are worth a whole post by themselves!)

Experiment. Part of the charter of the Amateur Radio Service is to extend the knowledge of this science and art. Those are high-sounding words, but you can help fulfill that charter by being a little adventurous with the antennas you use while traveling. You'll likely get better performance, make more contacts, and have more fun.


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