Hi Ignacy - There's little hope that a vertical antenna hundreds of miles from salt water can ever close the gap with an antenna built over a salt marsh or within about a wavelength of salt water.
The purpose of radials is reduce losses in the power transfer between a feedline and a vertical antenna. Their effectiveness is best measured by measuring the RF current at the base of the vertical. Highly effective radial systems produce significantly more RF current in the vertical than a sparse radial system. Radials cover a very small fraction of the very large reflection zone (Fresnel zone) that produces low angle radiation. A vertical over a salt marsh or within about a wavelength of salt water will produce 6 dB or more of gain at low angles compared to a vertical with poorly conducting soil in its reflection zone. Radials have no useful effect in improving low angle radiation, low angle radiation from vertical antennas is determined almost entirely by highly conductive soil or salt water in the large reflection zone. 73 Frank W3LPL ----- Original Message ----- From: "Ignacy Misztal" <[email protected]> To: "topband" <[email protected]> Sent: Monday, December 19, 2022 10:50:53 PM Subject: Topband: Radials, EZNEC and far field Do more radials on a 160m vertical bring more improvements than shown by simulation? Most simulations, e.g. by EZNEC, show that going above 32 radials on 160m brings minimal improvement, say 1 db to 2 max. Even for low angle signals. On the other hand, some really loud stations on 160m, that are 5-10 db above the crowd, use a massive amount of radials. This is for inland stations, far away from salt water. Is there any discrepancy between modeling by EZNEC and real life performance with the number of radials? Does adding radials beyond 32 help much for low angles? Any real story? I have a shunt-fed 100 ft tower with 36 100ft radials. It is vastly inferior to a 40 ft high inv L with 1 radial by salt water that hears DX loud 2 hrs before the sunset. I am wondering whether by expanding to 50 200ft radials would narrow the difference. Ignacy NO9E _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
