A recent online discussion contained an analysis of the radiation efficiency of a vertical monopole over real ground.

The poster dismissed the values calculated by 4NEC2 and proposed his own formula \(RadiationEfficiency=\frac{35.6}{\mathbb{R}Z_f}\) where 35.6 is the radiation resistance Rr of a quarter wave monopole over a perfectly conducting earth (PCE).

The reasoning seems to depend on Rr being independent of the ground type, but that is quite flawed.

## NEC insight

Let us look at an example of a quarter wave monopole with 120 shallow buried radials, average ground, at 3.8MHz.

Above is the model geometry. Continue reading NEC – vertical monopole radiation resistance study