[TowerTalk] Crossfield Antenna

[Tom Rauch]

> Cable radiation, anyone?
>
> I've yet to see a review of a CFA/EH that demonstrated the
reviewer
> understood that possibility, took serious precautions
against it, and
> then measured it. Lacking all that, the feedline current
could be
> radiating as much as the antenna under test... or more.

Actually Ted Hart, who claims to be the inventor of the EH
antenna, gave a stern warning to never use common mode
chokes on the feedline of EH antennas because it stops the
system from working. What Hart actually said was:

"If you use RF beads, since the coax shield is not a
magnetic shield, the beads affect both the inner and outer
conductors. Therefore, most of the transmitter power will be
converted to heat. Not good."

He also said:

"RF on the Coax
Due to the large radiation at the EH Antenna, there will be
some RF coupling to the coax. Whether this is a problem is
dependent on the radio you use. Some are subject to RF
coupling into the audio system, which causes severe
distortion while transmitting. On some field day setups with
100 watt transmitters we have had so much RF on the radio
you can get an RF burn. Below we have suggested ways to
eliminate the RF coupling problem."

73 Tom