2005 KØS, Kurt N. Sterba Strange Antenna Challenge

Chicken Wire Dipole

Chicken Wire Dipole and Operating Station in my Backyard
 

Overview

    After we finished with the "semi" vertical on the first day, we transformed the chicken wire ground plane into a Chicken Wire Dipole. Each of the ground planes was a 50-foot length of 18-inch wide chicken wire. We rolled each of these into a tube, about 8-inches or so in diameter, and hauled this up into the trees in my backyard.

    The feed point was rather low, at approximately 8-feet height. Overall, the antenna sorta looked like a big flying "M" with the legs rather stretched out. Each end was supported in a tree on opposite ends of the yard about 2/3 rds of the way from the center feedpoint to the far ends. A rope was used on the east end to straighten out that leg somewhave, but the other end just dangled from the tree branch. The highest points were likely both somewhere around 20 feet above the earth.

    Based upon this height we can safely assume we were experiencing NVIS propagation.

    We used the balun as before. It was again located at the breakout point between the coax and the short #12 stranded copper wires that were pressure connected to the chicken wire (with the assistance of a couple hose clamps and plastic done bone insulators). This is exactly the same method used with the semi verticle.

    The balun itself was home made: a Reisert "Cross-Over" design, 1:1 current balun. The toroidal core was an Amidon T-200-3 which has a permeability factor of 35. There are 12 turns around the core, with a "cross over" at the midpoint (comprising turn number six). The core was wrapped with 36-inches of LMR-240 coax, which was then cut to length, and had a SO-239 soldered to the unbalanced end. The balanced end was left free. For the k0s Strange Antenna Challenge, a "Euro" style connector was used to connect the balanced end of the balun to the wire feeders attached to the strange antennas. This balun was used on all the antennas this year.

Log for C.W. Dipole

    Here is the log for the Chicken Wire Dipole, used on 29 May 2005. It is in Excel format (.XLS):

• k0s_2005_cwd.xls

Connections

    As with the strange antenna used the prvious day, this dipole was fed with 60-feet of RG-58 coax, through a home-brew 1:1 current balun, which split out with #12 stranded wire to be clamped to the two horizontal tubes of chicken wire (~ 8-in. dia.).

Chicken Wire Dipole
What do kites, chicken wire, and trees have in common?
 

    Hope to catch you on the air next year!

    -73- Erik n0ew