Richard Fry wrote:
A few years ago there was some discussion on r.r.a.a. about helically-
wound, normal-mode monopoles, and the rather common expectation that
they had higher gain than a linear monopole of the same physical
height (and with other things equal).

A recent NEC-2 analysis of this topic might be of interest:
http://i62.photobucket.com/albums/h8...r_Monopole.gif
.

I think the difference might be in gain, not directivity...
The IR losses in the conductors (and components) would be different in a
helically loaded monopole and a lumped network matching a short unloaded
monopole. One could probably construct examples for cases where either
one has lower loss.

There might also be a difference in the losses in the ground plane,
although, intuitively, I suspect they would be small. The current
distribution just isn't that different between the two cases


It would be interesting to run some cases where you use "wire" (1cm
diameter conductors on your helix are pretty big... I'd try something
like 1mm (18 AWG) or maybe 2mm (12 AWG)..

As I recall, NEC does figure out the losses accounting for skin effect,
etc., although it might not deal with the "proximity effect" from
adjacent turns.