Quadrifilar Helix Antenna
I built the QFH some time ago, to receive images from the NOAA Weather Satellites while mobile, although you may use this same antenna on your home for receiving weather fax from weather satellites orbiting the earth.
The QFH consist of two loops, one smaller than the other. The loops were constructed from 1/4 inch soft copper tube, and joined at the corners with 90 degree elbows.
The helix is wound anticlockwise as seen from the top to provide the proper polarization as used on the satellites.
The connections at the top are made with the braid of the RG58 coax, connected to one side of the long loop, and bridged across to the one side of the short loop through the perf board.
The center conductor of the RG58 coax is connected to the other side of the long loop, and bridged across to the other side of the short loop through the perf board.
The cap keeps the connections waterproof. The mast is made from 1.250 inch white pvc tubing. A 4 turn balun as seen at the top of the antenna is required, constructed from RG58 coaxial cable.