N0LX/P Using a Petlowany Coil as Ground Plane
3 July 2008
Using a 9" spiral coil as a complete ground system on 20 and 40 meters
Did it work? See report below.
Front yard setup using 14-foot graphite pole antenna and a Petlowany coil (resting on the plastic table) as a ground system
The PVC base details can be seen here
The setup includes my FT-817, a brand new Elecraft T1 autotuner, and the Petlowany ground coil.
The tuner had only been out of the box one hour. It did an amazing job finding a match on this unorthodox setup.
The windings are only 9 inches across!
The 9" coil is from a previous experiment
to duplicate Bill Petlowany's spiral-end antenna.
The banana plug was for the full antenna and not used here. I connected to the inside plug.
Looking up the 14-foot graphite pole
Note the Eclipse Mint tin used to house two banana jacks wired to a BNC jack.
Always pushing the envelope, I set up an
unusual portable operation this evening in my front yard. The antenna
was a 16.5-foot piece of 24-ga. wire wound around a Cabelas graphite
fishing pole and supported by a small PVC base. Instead of
radials for a ground, I tried a spiral coil from my earlier Petlowany
The amazing Elecraft T1 autotuner found a match on 20
meters. I worked Marty, KA7GKN in Arizona. Then, on 14.170 MHz, I
worked Theo, XE1YQQ, and Luis, XE1L, in Mexico City!. They both returned a 53
report. They were 58 and 56 respectively.
Then, I dared the T1 to find
a match on 40 meters. It took two tries, but it claimed a 1.0:1 match. Still
running 5 watts (but this time CW), I called CQ on 7.057 MHz and was
answered by Ed, KG4W, in VA and received a 559 w/QRN report from him. I
heard him at a 579. Not bad for a very compromised antenna and a
seriously compromised ground (Or is it?). It's hard to believe anything
nine inches square could possibly work as a ground on 40 meters, but it
Note: the first report I am aware of with someone using a Petlowany coil as a groundplane was in a World Radio report by William Caldwell, WA8ABE