Because you're seeing different currents at the two stub terminals, you
must be modeling it with wires, which should reflect reality quite well.
Look carefully at the currents along the stub and you'll find they're
not equal and opposite on the two conductors. Such a radiating stub *is*
very different from a coil. That shouldn't be surprising. I have a high
level of confidence that if you built the antenna just like you modeled
it, you would find the results to closely agree with the model.

Roy Lewallen, W7EL

Cecil Moore wrote:
Wes Stewart wrote:

On Mon, 03 Nov 2003 09:26:05 -0600, Cecil Moore
wrote:

|Roy Lewallen wrote:
| If you could build an antenna from | straight conductors and
lumped inductors, the result would be very close | to EZNEC's
predictions.
|
|Hard to prove since lumped inductors are impossible in reality. Why
|does EZNEC show so much difference between lumped inductors and stub
|inductors?
I see no such difference in my model.


There shouldn't be a lot of difference. I have modeled two short dipoles,
one loaded with a lumped inductive reactance and one modeled with the
same reactance using an inductive stub. EZNEC reports the following:

Inductance lumped j335 10'stub

current in segment just before the coil .8374 amp .8384 amp

current in segment just after the coil .7971 amp .5642 amp

The relative difference just before the coil is quite small, 0.12%.

The relative difference just after the coil is quite large, 41.28%.

There just cannot be that amount of difference between a coil and a
stub.