Below is a link to a paper showing the effects of frequency and Earth conductivity on the propagation of groundwaves in the AM broadcast band.
The study confirms the physical reality that for long propagation paths and some sets of conditions, an AM broadcast station radiating 1 kW can produce...
For consideration / comment...
Radiation launched by vertical monopoles of 5/8-wavelength and less in height always is maximum in the horizontal plane -- regardless of earth conductivity and the number/length of buried radials they use.
This point is illustrated in the NEC4 analysis...
thread247-93327
The following statement was posted on 6 Oct 2004 in the referenced thread: "In FM and TV broadcast transmit antennas, the cavity-backed radiator has about the lowest (true) c-pol axial ratio, as installed."
In support of that statement, the attached gif shows the measured...
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Possibly of interest to some readers of this Forum, here is part of a post I wrote for an antenna newsgroup for amateur radio operators ...
Ground-mounted verticals up to 5/8-wave high used by ham operators have the same elevation pattern shapes as those used by broadcast stations. The peak...
Does anyone know of a source for a 32-bit Windows program to calculate MW broadcast groundwave field strength when frequency, power, radiator "efficiency," and ground conductivity are known? Hopefully one where conductivities could have several values along the length of a radial. Plotting the...
