Jeff Fischer, WB4TT, recently decided to add a 520 foot horizontal loop to his antenna
farm. Jeff wanted this to be a homebrew antenna and not an off the shelf antenna. He made
his own 1:1 balun rated at a kilowatt out of 12 gauge magnet wire over which he applied a 3M
coating for extra insulation.
With the help of neighbor, Gil Thompson , KM4OZH, he created antenna mount points for the trees from hardware store hardware. These mount points are designed to flex with the trees to avoid snapping the antenna wire through metal fatigue. The mounts consists of an 8 inch eye bolt in the tree connected to two pulleys. The pulley connected to the eye bolt is connected to Dacron rope that is a loop to the ground to aid adjustment. This first pulley is connected to a second pulley that the antenna wire rides through. Jeff constructed the second pulley of plastics so there is no metal near the antenna wired. Above , there is a picture of the mount point assembly. In the future, Jeff and Gill will add counter-weights to allow for tree movement and ice and snow load. Gil did the tree work and there is a picture of that below.
Jeff used an antenna calculator to initially cut the horizontal antenna wire to 520 feet. He
used 12 gauge solid copper covered by insulation. Once up, the swr measurements indicated
that the wire was too long. This is likely because of the insulation causing a velocity factor
which was not used by the antenna calculator. They then cut the length back to 505 feet. The
antenna is up 50 feet while 62 feet would be ideal for 160 Meters as a quarter
wavelength. Jeff now gets a swr of 1.5 and is getting no unwanted rf in the garage. A previous
wire antenna had triggered the automatic garage door opener at high power until some toroid
and power line adjustments were made.
The antenna is fed with rg 213 coax and is still a work in progress. The antenna has
performed well on 160 meters and Jeff is looking forward to the ARRL 160 meter contest in