[TowerTalk] Yagi gain vs rotary dipole.

[Jim Brown]

On Tue,11/25/2014 12:18 PM, Doug Turnbull wrote:
> Surely a dipole or Yagi has a certain maximum
> height beyond which not much is to be gained by going higher even for DX -
> QST did a study of the optimum height for a Yagi a number of years back.
> A wavelength above ground was generally best though of course by going
> higher lower angles were favoured and thus perhaps at times more distant DX.
> Beyond a certain height though I doubt there is that much gained unless one
> switches between antennas or stacks and this is well beyond the nature of
> the original question.

Earlier in this thread, I posted a link to a presentation at the 
Pacificon Antenna Forum about a study I did on exactly this topic, and a 
few others.

http://k9yc.com/VertOrHorizontal-Slides.pdf
>       I know boom length is important but are you saying that given a long
> enough boom that a three element mono-band Yagi would outperform a six
> element Monobander on a fifty foot boom.    The additional elements surely
> do add some forward gain - some.

The well known principle is that the gain of a Yagi is dependent both on 
boom length AND optimization of the design. A three element 20M Yagi on 
a 50 ft boom would NOT be an optimized design. :)

>    I know it may only be one to three dB and hard to recognize in the QSB.

One or two dB can be a lot if it gets you above the noise. I've worked a 
lot of DX by adding a couple of dB to my signal by carefully tuning the 
amp after a QSY.

73, Jim K9YC