Topband: Another DXpedition 160 Vertical Idea

[Doug Waller]

>>I've seen this warning many times, but when I actually
>>compared a half wave vertical with no radials to a quarter
>>wave vertical with radials, the difference was too close to
>>measure (ie less than 3 dB).

This comparison is dependent on the quality of the ground under and around the antennas.

Up to half of the far field signal strength is derived from the ground reflected wave.   If no ground radials are placed, the antenna's average
radiation height can be raised to reduce ground loss under the antenna, but the ground reflected wave is then reflected further out from the antenna's base, and is now totally dependent on the quality of that ground with no radials.

For 160m DX'peditions and small lot DX'ers, a short vertical with big topload and short, closely spaced radials a little longer than the vertical height, should be the best compromise between antenna gain and a practical  installation.  A cage of four vertical wires placed on a 12 foot circle, can eliminate most ground loss inside that circle, for both ground return currents and non-radiating magnetic near-field absorbtion.  This is the area where most loss takes place per the Intensity = Power / Distance squared formula, so a minimal radial field  for this configuration may perform as well as a single vertical with more radials.

73, Doug / NX4D