Some earlier posts have implied that monopoles installed at sites with poor earth conductivity don't produce much low angle radiation. Probably this is based on an observation of the NEC far-field pa
Hello Richard, What I understand from your simulation (above) is that the near and far field are functions to ground conductivity. The less ground conductivity, the less electrical field will be meas
Cristi YO3FFF wrote: That means, the radiation pattern will be affected too because the electromagnetic wave will be much curved to the ground, so the groundwave intensity will be direct proportional
I have linked to an image of a NEC 4 vertical profile analysis of the WLS-AM radiator. As most everyone here knows, WLS is a legendary 50KW AM station in Chicago. WLS uses a 190 degree radiator and i
For DX we are interested in elevation angles from 3-15 degrees. How much error is there in a NEC model of a monopole at these elevations? Dave WX7G Sent from my Verizon Wireless 4GLTE smartphone I ha
The link below shows the NEC4.2 fields for a seawater path on 1850 kHz. The calculated field at 1 km in the horizontal plane for 1 kW of applied power is 309 mV/m. The theoretical maximum field for t
For DX we are interested in elevation angles from 3-15 degrees. How much error is there in a NEC model of a monopole at these elevations? Dave WX7G The issue here is one of measurement distance and t
from [Tom W8JI]: The issue here is one of measurement distance and the assumed flat earth, and how much the ground wave contributes to low angle radiation. We obviously know radiation at zero degrees
from [Tom W8JI]: The issue here is one of measurement distance and the assumed flat earth, and how much the ground wave contributes to low angle radiation. We obviously know radiation at zero degrees
If I just take a simple program like EZNEC, and use a small sense antenna out in the distance, the results follow the trend you posted from the helicopter. ... AFAIK, we do not have measurements of a
Just to point out that we don't have measurements of arrival angles at the ionosphere proving the fields shown in a NEC far-field analysis, either. Yet people seem to accept a NEC far-field pattern a
Tom, As I recall, HFTA software has an ionospheric module that calculates the predictability of arrival angle as a function of frequency, time of day, season, etc. Learning that program has been on m
Hi Paul, I think the important "take away" in these discussions is that the far field pattern alone is not enough to show the real vertical profile from a vertical monopole. The significance of the i
Have the folks at Radio Arcala OH8X learned something about 160M antennas and propagation? How has the vert/4-SQ vs Yagi performed? 73, Gary NL7Y _______________________________________________ Topba
How has the vert/4-SQ vs Yagi performed? A dipole and a vertical are a better test, because a four square traditionally has more losses and different gain than a Yagi. It would be interesting to see
I have not personally seen work to validate signal strength and prove the mechanics of arrival at various altitudes at 50 km. Tons of speculation, extrapolation. NEC4 says that it doesn't continue. B
Tom, Did you --or anyone else you are aware of-- ever A-B test a ~120' tower against a ~300' tower on 160? 73, Mike www.w0btu.com _______________________________________________ Topband reflector - t
Did you --or anyone else you are aware of-- ever A-B test a ~120' tower against a ~300' tower on 160? I A-B or A-B-C tested several antennas, including a low dipole, the high dipole, an element from
I A-B or A-B-C tested several antennas, including a low dipole, the high dipole, an element from my four square, a ~318 foot insulated tower vertical, and I think my tall omni vertical was about 190
This depends totally on the accuracy of the NEC model, and the analysis that the NEC operator asks NEC to perform -- which depends on the background, skill and experience of said operator. A NEC far-