“QFH?” means “Do you have a quadrifilar helicoidal?”
As of this morning I am “QFH” and ready to receive NOAA weather satellites – in fact, I already have with the antenna indoors and propped against a wall. The resulting image is nothing to write home about but I have no doubt that once placed outside in the clear, the images will be fine.
This whole thing started with the Funcube Dongle Pro+ that I received a few weeks ago. Surfing the web to see what others were doing with this thumb-sized marvel sparked my interest in using it (for now) for this purpose.
I have absolutely no experience building VHF antennas but the online calculator made it into a simple project that cost a total of $6. That’s for the PVC and two wooden dowels that form the antenna’s skeleton. Most people use 1/4″ copper tubimg of even old RG-8 for the actual elements but, being a cheapskate, I just used 12g wire that used to be a dipole.
Following the dimensions given in the calculator led to a finished product that has a 2:1 SWR from 126-144 MHz. The NOAA sats are on ~137 MHz. Not that I’ll be transmitting but I wanted the antenna to be resonant in its required range.
Prior to building the antenna I tested the ability of the FCD+ to receive them using my 80m dipole. At times during a satellite’s pass, the signal was very strong; a few seconds later, no copy at all. This is because the satellites tumble as they pass overhead thus requiring an antenna with right-hand circular polarization like the QFH.
Work schedule (and satellite schedule) permitting, I’ll have decent images in a few days. There are quite a number of these satellites in orbit but only three are currently functioning.