8134Re: [loopantennas] Re: Loop reflector
- Jan 5, 2011Andy;
I'm glad you spoke up.
Here is a link to an Eznec model of an 80m horizontal loop. I've never heard anyone claim a loop had the same pattern as a dipole until now.
At typical heights, this loop has a circular pattern and vertical radiation is straight up. At greater, 1/2 wavelength, heights the pattern will show a bit of a bulge opposite the feedpoint and a lower angle. Of course the pattern changes for the harmonics but never the same as a dipole. It's a great multiband antenna and very common.
----- Original Message -----
Sent: Wednesday, January 05, 2011 6:23 PM
Subject: Re: [loopantennas] Re: Loop reflector
> ... Think of a 1 wavelength
> horizontal loop as two half wave dipoles spaced 1/4 wavelength apart- it is
> obvious this is not omni and will have classic construction and destruction
> azimuth pattern.
OK ... but now think of it as four shortened (quarter wave) dipoles in a square.
Now it's not so obvious that it might have classic dipole radiation
Thinking that a loop is like two dipoles in parallel, is a real stretch.
And in fact a good 1 wavelength loop radiates nothing like a dipole!
Bend a circular loop into a square or triangle, and it's not quite so
omni anymore; but it's still close enough for government work.
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