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
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