[Elecraft] Portable Antennas

[Jim Brown]

Eric, K7TV wrote:

>The HFPACK yahoo group has conducted tests of shortened antennas which seem 
>to indicate that losses in loaded antennas are quite small when the total 
>antenna length is at least half the full length. They compared to reference 
>full-length antennas *at the same height*. As to bandwidth, the automatic 
>tuner in my KX1 easily takes care of that

I agree. I've used loaded dipoles for both 160M and 80M that are roughly 65% 
of full size and found them to work quite well. I've also modelled  both of 
these antennas using NEC, using measured values for the coils (both 
inductance and resistance). The models show that the efficiency of both 
antennas is only about 0.5 dB less than a full size half wave dipole, and an 
SWR bandwidth that is less than half that of a full sized half wave dipole. 
I can't measure the efficiency, but the SWR behaves like the NEC model. I've 
had both antennas in the air at multiple locations, and can run full legal 
power into both antennas over all of 160M and 80/75M. 

73,

Jim K9YC