2005 KØS, Kurt N. Sterba Strange Antenna Challenge

Chicken Wire Semi-Vertical

Red lines have been added to make the Chicken Wire more visible
 

Overview

    This antenna used three lengths of chicken wire. The vertical element (fed from the coax center conductor) was 24-feet long and about a foot or so in diameter. We used it last year in a couple antennas so it was a little "ratty" -- weeds hanging in it, and squashed flat at numerous points. We straightened it out as best we could and flew it. You'll note the vertical is really a "semi" vertical. We poorly estimated the height needed to get this antenna straight up. Oh well, maybe next year we'll get it truly vertical, heheheh!

    The ground plane was made of two 50-foot long rolls of 18-inch wide chicken wire. They crossed somewhat off-center of one another (laid out to conveniently fit between the various trees, bushes, and the station set up in the back year.

    Our balun was 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).

    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 CWSV

    Here is the log for the Chicken Wire Semi-Vertical, used on 28 May 2005. It is in Excel format (.XLS):

• k0s_2005_cwsv.xls

Connections

    This antenna was fed with 60-feet of RG-58 coax, through a home-brew 1:1 current balun, and then splitting out with #12 stranded wire to be clamped to the semi-vertical tube of chicken wire and the two 50-foot lengths of chicken wire (crossing over one another) that served as the ground plane.

Balun, and connections to the chicken wire vertical and ground plane
 

Using a dog bone insulator and hose clamp to secure the
shielding side of the coax to the chicken wire ground plane
 

    Above shows how we used a hose clamp and hose clamp to tightly press the #12 stranded wire against the chicken wire ground plane. We picked a spot close to where the 'vertical' element met the two crossing ground planes.

Semi-Vertical Feed Point	Ground Plane Chicken Wires
Feed Point and Ground Plane	Weed Infested Vertical

    Below are some measurements I took with my MFJ-269. It is very important to make certain your batteries are fresh! After the voltage drops below some value (unknown to me), yet still above the unit's display "Voltage OK" limit, the accuracy drops off tremediously! You have been forewarned! (I wish I had been, but during this special event was the first time I noticed this problem). One cure would be to build a little voltage regulator for the device, limiting and regulating the voltage are your selected value. This would come at the cost of (1) developing heat that would need to be dissipated, and (2) draining the batteries at a higher amperage rate. No free lunch, hi-hi!

    Hope to catch you on the air next year!

    -73- Erik n0ew