[TowerTalk] Horizontal loop antennas

[dan hearn]

Mike: I believe these are frequently called Halo antennas. They are
usually half wave dipoles or folded dipoles which are formed into a
circle shape with the ends not touching. The usual dipole has no signal
off the ends due to its figure 8 shaped pattern. Bending it into a
circular shape makes it omnidirectional. I am sure the resonant
frequency shifts from what it would be for the same length dipole in a
straight configuration. 
  This sounds like a great experimental project. I would make a dipole
which is a bit longer than 492/f, where f is in megahertz and the length
obtained from this formula will be in feet. I would bend it into a
circle and measure the resonant frequency by grid dipping or looking for
lowest swr. Trim length as required and , if the SWR is not as low as
you want, use any of the usual matching methods. I have seen dipole
versions that use a gamma match. 
  I believe I have seen an actual construction article on this type
antenna a number of years back in QST. Good luck with your project. 

73, Dan, N5AR

mike dunlap wrote:
> 
> Hello All!
> 
> Just hoping that someone might  be able to point me in the proper direction
> for some plans for some good horizontal loop antennas for 6mtr 2mtr and
> 70ct.   Iv'e seen some made out of copper tubing and it looks like it would
> be a great project(s)!
> I thank you all in advance for your help and suggestions!!!
> A very '73 from Mike
> K0NWA
> 
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