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From: K5CNF@antennex.con
Date: 28 Dec 2001
Time: 12:04:38
Remote Name: 64.219.21.136
At the lower frequency bands, below 30MHz the car body capacitivly couples to the ground it is on when in motion or parked. If you are parked, then the addition of radials may or may not help, depending on the band of operation. I have noticed several S units increase on 40 meters when I added a ground rod and connected it to the car body. No radials, just a ground rod clipped to the body at a ground point, namely the battery negative lead. On VHF/UHF the car body acts like the ground and radials are not needed. I think you will agree that radials are rather hard to manage when you are driving. Some people, in the past, put a large sheet of aluminum under their car to increase the capacitive coupling to ground. It did work, but was not a practical idea for mechanical reasons. My military experience showed me that a tracked vehicle, such as an armored personnel carrier, had great coupling to ground, both due to the tracks, which were insulated, on the ground and also the flat bottom of the APC being about 6 inches above ground. On 20 meters AM, (this was a LONG time ago) and a 16 ft.whip I had a splendid signal with a 100 watt Collins T-195 transmitter. Being parked in a very wet part of a swamp did help, but is not very practial for a normal car.