Peter Inscribed thus:

Hi all

I have just modelled both the Slim Jim antenna and J Pole antenna
using MMANA-GAL at the same frequency (145MHz) all other parameter
equal and was some what surprised that they appear exhibit the same
gain and radiation pattern. Based on an article I read in a English
magazine many years ago I have always believed the Slim Jim had a
slight edge over the J Pole. Wonder if others had a similar view and
if my modelling is correct are there any advantages with the Slim Jim
design?

The difference is negligible. They both suffer from unbalanced feed
currents and thus feeder radiation. There is or was a commercial
design that attempted to reduce that.

73's
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Best Regards:
Baron.