[TowerTalk] Advances in Antennas [was Building Antennas]

[GM3SEK]

Dino Darling wrote:
> 
>> From the perspective of one who has come back into the VHF game 
>> after almost 40 years off the air:  Many VHF yagis of old turned 
>> out to have much less gain than people thought.
> I remember when I first got licensed, someone had found out that you 
> can get better gain and F/B by REMOVING one element from Cushcraft's 
> 11 element 2M beam and re-spacing the elements!

There were many VHF long yagi designs developed from the 1940s through 
the 60s and 70s, but all the amateur designs were based on range 
measurements with large margins of error. The famous NBS designs were 
based on accurate measurements, but even they couldn't escape the 
limitations of cut-and-try optimization. Such methods can easily lead 
into dead-ends... and we now know that's exactly what *did* happen.

Computer analysis shows that many of the so-called "classic" designs for 
VHF long yagis are actually quite poor performers. In terms of gain and 
pattern, they don't give good value for the boom length and number of 
elements. There are lots of modern yagi designs that are better in every 
way. For the same number of holes and saw-cuts, why not build a good one?

There are links to several families of modern designs in my 'VHF/UHF 
Long Yagi Workshop' pages at www.ifwtech.co.uk/g3sek



73 from
Ian GM3SEK