Topband: Quarter wave Vs Eigth Wave

[Pete Smith]

At 06:10 PM 4/16/03 -0400, George & Marijke Guerin wrote:
>In the latest edition of Low Band DXing by ON4UN it shows that a few long
>radials are not effective.  There is a table showing for 30 radials, only
>1/8 (0.125 wl) wavelength is enough, with 60 radials, about 3/16 or 0.19 wl
>is effective and with about 120 radials 1/4 wavelength is needed.
>The point is don't put down a few long radials.  More shorter radials are
>better unless you are committed to more than 60 radials, although you don't
>necessarily put them down all in the same week or month.
>More, shorter is better to avoid the near field ground losses of too few
>radials, and why some of the DXpedition antennas come with 30 or 40 radials
>each 70 feet long vs 16 radials 130 feet long


Also, in his recent series in NCJ, W4RNL went extensively into this using 
NEC-4, which can accurately model buried radials.  I remember being 
surprised by his results; while radials could help, and certain radial 
configurations offered the most return for effort, in the final analysis 
his modeling seemed to show that inherently good ground characteristics 
offered more benefit than the most extensive radial system.  To take an 
extreme example, a 1/4 wave vertical  overfour radials just under the 
surface of very good ground produced 2.10 dBi @ 17 degrees; 128 radials 
over good ground yielded 1.03 dBi at 23 degrees.  See NCJ Vol 29 No. 5, 
9/10-2001.


73, Pete N4ZR
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