I have listened to much discussion about elevated and buried radials as an owner of a vertical antenna system with radials above poor soil. Al Christman, K3LC continued his investigation in an article written in the March/April 2005 issue of the National Contest Journal; A Study of Elevated-Radial Systems for Vertical Antennas - Part Two. It was reprinted by the American Radio Relay League in the book -- More Vertical Antenna Classics (2006).
His experimental design included all three low bands (40, 80, and 160 meters); three different types of soil; uniformly spaced radials around antenna base; and number of radials varied from 20 to 120 with incremental increases of twenty (2005).
Additionally, Christman modeled his experiment using EZNEC Pro software, version 4.0, with double precision NEC-4 calculating engine based on 0.25 wavelength vertical antennas and a large number of #12 AWG 0.25 wavelength buried radials.
Radials were modeled at a final depth of three inches.
Christman (2005) results suggested a significant difference in vertical antenna performance between that of buried versus elevated in relationship to soil quality, number of radials, and height. Subsequently, one achieved maximum efficiency that is highest gain and lowest take-off angle when soil is rated very good with a large number of buried radials on 40m, according to the article.
However, one's return on efficiency begins diminishing when approaching a count of 60 topping out at 80 buried radials, as the author noted small improvements (2005).
Additionally, given the poor quality of our soil where my vertical antenna system is located, Christman (2005) suggested an elevated vertical with base height of 12 feet or greater resonating on 40m outperformed that of a ground mounted vertical with numerous radials. I recommend reviewing Figure 3 on page 72 in More Vertical Antenna Classics (2006) published by the American Radio Relay League for greater detail.
Lastly, when examining performance on the Top Band (160m) Christman (2005) suggested a buried radial system significantly outperformed that of an elevated system. The performance difference over poor soil further suggested a buried system of no less than thirty five in contrast the data suggested an elevated system over very good soil for the Top Band, according his article.
Christman's study suggests a correlation between soil quality, height, and number of radials in relationship to antenna effiency (2005). Potentially, with the exception of 160m, efficiency improved when elevating the base of the antenna above poor soil whereas the complete opposite is true of very good soil. Additionally, his data noted diminishing effiency or neglible improvements beyond 60 to 80 buried radials, at the 40m wavelength.
73 from the shackadelic near the beach.
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