[Elecraft] dipole antenna efficiency

[Geoffrey Mackenzie-Kennedy]

Shaun Oliver  <shaun.oliver at optusnet.com.au> wrote:

>I was thinking of using 18 mm electrical conduit. with 2 mm spacings for 
>each turn of the wire.

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The diameter is a bit on the small side for the low bands, but NM Helix 
antennas working as 'quarter wave' radiators on the low bands designed for 
mobile use, and whose diameter was similar, performed well when evaluated 
using a proper antenna range, better than a base loaded 8ft whip. The 
important consideration is that the antenna resonates within the range of 
frequencies used in the band for which the antenna is designed. I have not 
tried a single NM Helix with an external tuner for multiband operation nor 
tried to model one using EZNEC.

Good luck!

73,
Geoff
GM4ESD

PS  'Old scribe'  --- hmmmpf :-)