I've used screens when I needed a wide bandwidth ground system, but never under other conditions. Adding a screen or preferably, additional short radials at the base will assist in stabilizing the re
Excellent work, Cristi. A suggestion for this last part of the analysis. Rather than look at the vertical angle where the radiation peaks, look at the field strength at some chosen low angle, like 10
To Rich's point, I created a buried field in 4NEC2 using the radial geometry wizard and a vertical wire radiator 40m tall, all wires being of #12. The radial field consists of 64, 0.5 wavelength radi
The measured MW data looks compelling and agrees with the NEC surface wave analysis. Even accounting for frequency disparity between the BC band and 160m, low angle field strength remains robust. Ric
Mr. Fry supplies a monolithic, complete fill up to three degrees at some unspecified frequency over unspecified ground out 2.8 km. The difference between that and the NEC pattern generated for 1/4 wa
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
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
AM broadcast band antennas 5/8 & 1/2 wave tall are rarely used any more. I noticed a reduction of the tall AM towers starting about the 1960's. An optimized half-wave design (180-195 electrical degre
Most of the reasoning for this unexpected negative result was attributed to the minor high-angle lobe produced by the 5/8 wave coming back down and interfering with the main lower angle signal. As a
Bob, A non-issue. Many of us have been running 8877s with Ep of 4KV. For example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the specified limit of 4KV. Some owners have been converti
First, they would be fools or have idiots for engineers to have more than 120 radials. The only real reason they use 90 radials or so is it sometimes gets them out of expensive proof-of-performance m
Right, typically a couple hundred ohms. Modeling the base Z of a thick broadcast tower is very difficult with MoM software. Changes in thickness can result in large base Z changes. Just to be clear,
In the vehicle I often like to use an old (i.e. analogue and inexpensive) spectrum analyser like some of the portable Texscan CATV ones. As CATV companies have transitioned from NTSC to QAM channel l
Tha's a great topic and I'm sure Frank will add a lot of interesting information. About twenty years ago, I became interested in the 1921 transatlantic tests and slowly began collecting information.
This white paper, written by Clarence Beverage may be of interest to the discussion: http://www.commtechrf.com/documents/nab1995.pdf Paul, W9AC -- Original Message -- From: "ZR" <zr@jeremy.mv.com> To
Mike, I rarely recommend YouTube videos, but Belden has produced a 3' 37" second video promoting their ProSNS line of Snap-N-Seal F connectors. This list is tightly run, or I would otherwise post a l
The standard drop cable is a bonded foil with single braid, it has been that way since the late 1970's. The current best grade is "Brightwire" by CommScope. Any good cable will far exceed FCC specs w
Jim, The major semiconductor manufacturers (e.g., Fairchild) who once mass-produced JFETS in TO-92 style cases have now "obsoleted" most of them. This occurred approximately 2-3 years ago. When shock
"As an example though, EZNEC shows FS of a vertical as virtually zero at zero degrees. We know that isn't true." And as has been repeated a number of times between myself and Richard Fry, the right t
Ditto what Clay wrote about Barry's informative topband presentations at our local club meetings in Joliet, Illinois. During my junior high school years, I happened to live a short distance from the