Archive for June, 2008

Active Whip Antenna

June 29, 2008

I’ve been playing a bit with this active LF/MF/HF whip antenna which I borrowed from work for an “operational evaluation”. I designed the high-impedance preamplifier that is mounted in the base of the antenna and the matching power supply, which uses a bias tee to supply power of the coaxial cable. That’s useful since there’s a 50m cable run from my shack to the antenna, which is mounted on the other side of the house to minimize interference from my transmit antennas.

I haven’t had much chance to evaluate it yet, but it seems to perform well for it’s size, and I don’t receive any interference or de-sensing from my own transmissions unless the receiver connected to the whip is tuned to (or near) a harmonic of the transmit frequency. Plus it looks good in black (although I’m not sure that my wife is thrilled by the “temporary” addition). I think I’ll use it to hunt around on 160m, where I don’t currently have an antenna.

In the longer term, it might be a nice receive antenna for a CW Skimmer setup. I’m opposed to the use of skimmer in single operator unassisted contest classes, but think it is an excellent tool for propagation study – have a look at the online skimmers at skimmer.dxwatch.com. Of course that’s if the company will let me keep it for a while, or forget that I have it!