[VHFcontesting] Yagiphobia, Confusion and Infusion

[Jack W6NF]

On 9/17/2013 8:47 PM, John Geiger wrote:
> If you stack 4 of those elements, and it is omnidirectional, then the 
> gain has to come from somewhere. Where does it come from?  It would 
> probably compress the take off angle, but in terms of beamwidth gain 
> relative to a Yagi, it couldn't have any.
>
> It wouldn't allow you to null out noise coming from a specific 
> direction, which can be useful also.
>
> 73 John AF5CC
>
The gain of a yagis the result of "compression" of the vertical and 
horizontal planes of the antenna. The horizontal loop does the same in 
only the vertical plane. In the vertical plane additional gain does come 
from further narrowing of the E field and adds a bit more than 2.5db per 
doubling of the number of bays in the system.

M2, for example, specifies this for their 2-meter HO Loop:

> Gain, Typical @ 10 ft. ................ 4 dBd @ 10 deg

That gain would remain the same and the radiation angle should be 
decreased as the antenna height is increased, as is the case with a yagi.

As I indicated in another reply, I believe the predominant component of 
power line noise is vertically polarized, which gives the horizontal 
loop some immunity. I recognize that there is no front-to-back or 
front-to-side rejection to help minimize QRN but the loop stack at least 
allows one to have modest gain in all directions to enhance the 
probability of actually hearing someone otherwise inaudible in the nulls 
of even a smaller yagi.

73,

-- 
Jack, W6NF/VE4
Shelley, K7MKL/VE4