ANTENNAS FOR 100 POUND DXPEDITIONS
14 FINAL COMMENTS TO VOLUME 1 This white paper discussed a small number of antennas and antenna configurations that can be created from simple materials or from popular commercial offerings. There is a great deal of lore and superstition surrounding antennas within the amateur radio circles. Some of these tales provide useful guidance; others are nonsensical. Sorting them out may not be easy but it is well worth one’s time to try. This white paper is a small step towards that goal. I owned the Force-12 Sigma-5 for several years. I sold it in the Spring of 2008 because it did not travel as well as I had hoped it might. I suspect the ham that bought it is putting it to good use in some semi-permanent installation. I note here that Force-12 (the company) has been purchased and the new owner seems keen to revamp the product line, increase quality, and streamline customer service. Force-12 antennas have a history of helping make DXpeditions successful. It is a company worth watching. I have purchased the TW Antennas TW2010 antenna system. This system has a very rugged carry bag that holds the antenna components, controller cable, 50 feet of coax, the controller box, and other small items. The X-base can ride on top of the bag, though it adds considerable weight. Though the analysis here shows the antenna to be slightly inferior in performance to the Sigma-5, it is much more rugged, breaks down smaller, packs easily, and has a much more polished look and feel. With a suitable wire ground system as described in this white paper, this could be a very good performer on a DXpedition—even over poor ground. I have deployed fishing pole vertical antennas with two or four elevated radials for band 80meters, 40-meters (which doubles as a nice 15-meter antenna), 20-meters, and 17-meters. These antennas consist of little more than a fishing pole, center insulator, and wires. Assembly at the DXpedition site is little more than unwinding the wires, taping the vertical section (and its Dacron rope leader) to the top of a fishing pole, standing the fishing pole up and lashing it to a fence post or small tree (or guying it), and stretching out the elevated radials. These antennas, especially the 80-meter and 40-meter versions, can be deployed off a second, third, or even fourth floor roof area to get the antenna well in the clear and the radials high off the ground. These antennas perform very well and weigh next to nothing. Though low-band antennas are out of the scope of this white paper, I will recommend this approach here. The Buddipole antenna systems perform very well as evidenced by this analysis. And, while the dipole configuration was disparaged in the initial discussions, that configuration can be very effective if deployed high above the ground. If, say, a 16 foot mast is extended above a roofline 30 feet high, then the antenna is now at 46 feet—a big difference from the 16 foot levels discussed here. As usual, anything written in a book or white paper like this must be used within the context of its discussion. Just because a Buddipole dipole will not perform well at 8 feet does not mean that a similarly configured system will not perform extremely well if somehow deployed in the clear at a much greater height. How much better? Anyone with access to EZNEC or other modeling programs can use the models supplied with this white paper to make that determination. Feel free to use, edit, and explore the model data presented here to learn more about these antenna systems in situations not explored here. 221