NEC-LIST: Low angle radiation?

I found an unexpected result on a model I'm running. I could not find
a modeling error, so as a control, I modeled a 1/2 wl dipole at the
same height and ground conditions.

To my bewilderment, the unexpected result is still there.

Here is an NEC deck that illustrates what I'm seeing. It is a 1/2 wl
dipole for the 40m amateur radio band at about 1/4 wl high over a
radial cliff (30m radius and 15m high) with very poor ground
characteristics.

My radiation paterns are showing a significant low angle lobe. I
guess I should not complain about 6dbi gain with a takeoff angle of 18
degrees. The sharp angular shape of the lobe just looks suspicious to
me.

Have I made some hideous error, or is this pattern legitimate?

(P.S. I thought about sending a GIF of my elevation pattern, but I did
      not know what the list policies were concerning attachments. I
      can send a GIF to anyone that wants it.)

CM 40m 1/2 wave dipole at 1/4 wl high
CM on radial cliff, 30m radius, 15m high
CM very poor ground conditions
CE
GW 1 21 0 -33.25 33 0 33.25 33 0.0033695
GS 0 0 .30479
GE 1
GN 0 0 0 0 5.0 0.001 5 0.001 30 15
EX 0 1 11 0 1 0
LD 5 1 1 21 5.8001E7
FR 0 4 0 0 7 0.1
RP 3 1800 1 1000 -90 0 0.1 1
FR 0 4 0 0 7 0.1
RP 3 1 360 1000 70 0 1 1
EN

Thanks.
Received on Wed Feb 16 2000 - 05:28:04 EST