Reg, G4FGQ wrote:
"According to textbooks, the field strength from 1 KW at 1 kilometre =
300 millivolts per metre."

Terman agrees with Reg`s signal strength produced by 1 KW radiated at a
distance of 1 kilometer of: 300 millivolts per meter.

There are some conditions. The transmitting antenna is vertical and
short compared with a 1/4-wavelength. It is nondirectional in a
horizontal plane. The height of both antennas is low enough so that the
space wave does not dominate propagation between them. Terman`s field
strength derives from the equation first given by Sommerfeld and
includes a factor aounting for ground losses.

Best regards, Richard Harrison, KB5WZI