Richard Harrison"
Richard Fry wrote:
"Radiator efficiency for Class A stations (other than in Alaska) must be
such as to produce a groundwave of at least 352 mV/m at 1 km for 1kW of
antenna input power. A 90-degree omni radiator cannot do that."

Most such antennas have long been in place. Surely they are
grandfathered until the station is modified.
________________

The minimum efficiency for Class A is 362mV/m as I posted, not 352mV/m as
you "quoted me" above.

As far as the 50kW / non-D / 24-hr operations are concerned, their
facilities have avoided the use of 90° radiators nearly from their start,
due to the commercial/competitive need to generate a very strong groundwave
while avoiding self interference to that groundwave at night from their own
high-angle radiation. The advantages of using greater fractional wavelength
radiators to accomplish this has long been known and confirmed by field
measurements.

RF