NEC-LIST:Groundwave gain compared to skywave gain

Good day all.

Hopefully these are simple questions.

The report by J Litva et al. [1] contains a diagram (Fig 32 p. 72) of
the measured vertical radiation pattern for a pair of Beverages using
an aircraft, and a balloon. What interests me is that this diagram
and others suggest that the groundwave gain for vertically polarised
antennas may pretty well be the same, or at worst about 3 dB less than
the far field peak gain, where the peak gain is at lowish take-off
angles. Is this a reasonable assumption to make? For example, in
[2] the predicted skywave gain for a quarter wave dipole with 120
ground radials is given as 0 dBi at 2 MHz. What is the corresponding
groundwave gain? Should I use 0 dBi as a worst case, or 3 dB less?

 I am dealing with a case involving the risk of inadvertent ignition
of fuel vapour at a planned filling station close to an existing radio
communications site. Possible antennas include vertical monopoles
with reflectors, Beverages and vertical half rhombics.

Also, does anyone have gain figures from about 2 - 30 MHz for a 600 m
long Beverage, spaced about 3 m above the ground? Many years ago I
started rewriting and compiling a program to do the necessary
calculations, but was unable to complete the task.

Best regards,
Duncan Baker.

[1] J Litva et al., "Beverage Antennas for HF Communications,
Direction Finding and Over-the-Horizon Radars," CRC Report No. 1282,
Department of Communications, Ottawa, August 1976.

[2] JL Thomas and ED DuCharme, "HF Antenna Handbook," CRC Report 1255,
Department of Communications, Ottawa, April, 1974.

--
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Prof. Duncan C. Baker (Pr. Eng., FIEEE, FSAIEE, Sci. Nat.)
Dept. of Electrical Electronic and Computer Eng.,
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