[Great-River-DX] RE: triband antenna comparison

[Lew Gordon]

Hi Jay,

All of Mosely's antenna performance figures were done in the 
marketing department.  Mosely, HyGain, and Cushcraft are the main 
reasons that ARRL will not print commercial gain figures in their 
publications.   I recall at Dayton one year when I questioned one of 
the above engineers at their booth why they fabricate gain 
figures.  His response was, "If we didn't we wouldn't be competitive."

Well known antenna engineer/physicist Dick Bird, G4ZU/F6IDC actually 
measured the efficiency of the Mosely and HyGain tribanders about 20 
years ago using thermal technology. i.e.  By calculating the thermal 
mass of the loading coils/elements and measuring the temperature rise 
while powering the antenna with 1000 watts for a period of time, one 
can determine the power required to cause the temperature 
rise.  Subtract that from 1000 Watts and you have what's 
radiated.  His measurements indicated almost 2 dB loss per trap in 
the driven element on 20M.  Overall, the tribander had a actual free 
space forward gain of about 3 dB.  Of course the directivity is as 
advertised which misleads the user into thinking that is gain.  (Gain 
= directivity - losses)

BTW, every person I have talked to using the Steppir rave about its 
performance.  The ability to have an almost perfect match any where 
between 14 to 30 MHz eliminates the need for a tuner.  I have 
examined the antenna at Visalia and it is well constructed.  Besides 
you gain 17 and 12 meters.

73,

Lew Gordon, K4VX