Walter Maxwell wrote:
"To anyone who believes the W5QJR EH conceptis valid."

OK. I read the first page: "Welcome to the Wonderful World of EH
Antennas". It said nothing of why I should be interested. Why convert an
existing broadcast antenna to EH?

FCC has a publication, "Rules of Good Engineering Practice for Standard
Broadcast Stations" which includes Mv/m at 1 mile on a radial over
perfect earth from a vertical antenna of various heights. It shows about
195 mV/m for a 1/4-wave grounded vertical.

This can be adjusted for any power or diistance from the sender:

E = Eo sq rt P/d

Eo = 195 mV/m for the 1/4-wave antenna at 1 mile

P = the actual radiated power

d = distance from antenna in miles

The mV/m at a mile assumes a perfect ground and a perfect antenna ground
system. FCC says 120 radials equally spaced and 1/2-wavelength long are
its standard. Efficiency typically exceeds 95%.

If the vertical radiator is higher (longer) than !/8-wavelength, the 150
mV/m at 1 mile, required minimum efficiency, can still be met with 120
radials on the earth that are only 1/4-wavelength long. The reduction in
efficiency is small.

Nobody has perfect ground unless he is at sea. For imperfect ground, the
FCC publishes "Ground Wave Propagation Curves" for various soil
conductivities.

In the FCC millivolt per meter numbers for vertical antennas of various
heights, the field strength only increases 5% in going from very short
to a full 1/4-wave height. This requires the near perfect ground. A
3/8-wave radiator only has a 15% advantage over a very short radiator.

If the radiator is a thin wire, bandwidth may be only + or - 1% of the
wire`s resonant frequency. Broadcast stations use towers of substantial
cross section as antennas. These provide several percent of bandwidth
and allow full audio range in the medium wave band.

A short antenna has low radiation resistance and high capacitive
reactance. This requires tuning out the large capacitive reactance
(small capacitance) with an equally large inductive reactance (large
reactor), and matching the very low drivepoint resistance of an
end-driven vertical to the higher impedance sending circuit. Resistance
involved in neutralizing reactance and matching the antenna to the
source is likely to be lossy for the too-short antenna. Walter has
already pointed this out.

Why would the EH antenna have interest?

Best regards, Richard Harrison, KB5WZI