Sunday, July 24, 2011

No ground antenna for backpackers, balconies or plastic car bodies

A common problem with backpacker or balcony antennas is finding a good counterpoise. Also cars and caravans with a plasic body are a problem. Althow nothing beats a set of resonant radials, the shown solution offers a 1/4 wave stub that wil create an artificial counterpoise. The mobile antenna mount must be isolated from any metal by a epoxy or plastic sheet and a normal T-Connector is used at the antenna feedpoint.  Be shure to shortcut the end of the stub. The length of the stub in meters equals  1/4 Lambda x 0.66 (this is the velocity factor of 50 Ohm RG-58 ) or can be calculated by deviding 50 by the frequency .So  if  you need a stub for  14 MHz the outcome is 3.57 m. but this length is not critical. The setup can be easily mounted on top of a rucksack. On a balcony the stub can be layd on the floor.
Disclaimer:I'm not responsable for any damage due to improper reproduction of my projects.