There are about 116 AM broadcast stations in the U.S. using 50 kW transmitter power during the day. Some of them reduce power at night, however KFMB (760 kHz) San Diego operates with 5 kW non-directi
This is ~true only for a "far field" analysis (as defined by NEC software) for a vertical monopole -- which includes the propagation losses present in the radiated fields from that monopole, over an
You likely had an antenna with 1/2 wave of wire spooled up on a short fiberglass rod, which would never behave like a half-wave. You are exactly right. Unfortunately, this myth dies hard. Below is a
There is no magic about 120 radials, and long before 120 radials are reached the increase in field strength pretty much stops. According to the 1937 BL&E experiments and IRE paper, this depends on th
In 1937, Brown, Lewis and Epstein of RCA Labs published a benchmark experimental study of this in the Proceedings of the IRE - still covered by copyright. But clips from it have been available on lin
Just to note that NEC4 analyses of the fields of the elevation plane pattern from a monopole using a set of buried radial ground wires show essentially the same pattern shape at a distance of 0.1 km
As for the affect of trees on EM waves, below are the results of some simple measurements I posted earlier on another board. ___________________ Recording the relative readings on the dBµ and S/N dis
(C) How many elevated radials are "just enough"...? Depends on how many dB you want to throw away. If you can, do 12 to 16. 32 is the kill-the-loss, never-look-back number. ____________ The link belo
Developing this topic a little more, the link below shows a NEC4.2 model of a 1/4-wave, vertical monopole driven against a set of 4 x 1/4-wave horizontal wires used as an elevated counterpoise. The b
Guy Olinger posted: ...The very same NEC 4.2 with raised quarter wave radials over routine real life ground made of dirt will show field intensities in the ground. (etc etc) _______________ Sorry, bu
RE: Capability of NEC for Accurate Modeling of Groundwave Fields Close to a Monopole using Elevated Radials As an example... The FCC groundwave propagation chart for 1490 kHz (Graph 18-A) shows that
A certain Topband poster apparently originated and supports driving a 160m vertical monopole against an elevated, folded counterpoise ("FCP") in situations where dense and uniform buried radials are
Here are several data points on this subject. Recording the relative readings on the dBµ and S/N displays of a Tecsun PL-310 tuned to a 790 kHz directional station about 52 miles east of me, radiatin
Agreed. That a vertical monopole 5/8 wavelength and less in height, using a less than perfect ground plane has a certain takeoff angle above the horizon where radiated field is maximum is a very comm
The radiated field of a vertical monopole present on the surface of lossy earth decays at greater than a 1/R rate. But, for example, the field shown at a horizontal distance of 0.1 km in my surface w
Yes. I don't see how field values at a 100m (0.625 lambda) range and 9m (0.05625 lambda) altitude can tell us anything about the far-field behavior. Note that such radiation may be relatively close t
A frequency search for 700 kHz shows some high power night time licenses in AB and NB. I don't remember if those licenses existed before the downgrade the Clear Channel concept, which I think happene
Chapter 10 of RADIO ENGINEERS' HANDBOOK (1st Edition) by F. E. Terman has a good discussion of this beginning on page 674, but the page count on the subject is too much to link to here. Hope those in
Another source of this kind of information is the AM Pattern Book, published by the National Radio Club. They just published a new edition this year. The "Check it Out" link on the NRC website shows
Rick N6RK: The stumbling block with AutoEZ is that you have to have a copy of Microsoft Excel, and it has to be exactly that, not a clone like Open Office or Libre. ... Can anyone point me to an econ