Quadrifilar Helix Antenna

Fresh from the shops of VE6AB, the QFH Antenna. I built the QFH to receive images from the NOAA 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 is required, constructed from RG58 coaxial cable.

 I am running tests at the moment on the QFH. I cut it for 137.500, although the dimensions can be changed for use on the Amateur Radio Satellites. It appears to have good ears.

My weather satellite equipment (mobile). The audio file from NOAA 18 was downloaded with my QFH antenna to the Hamtronics R139 Weather Fax Receiver, connected to my laptop. The image was then decoded, giving the final image (on the bottom right).

NOAA 18 [ ch 2-4, northbound 72 E ] at 2006-01-01 20:23 UTC