[AMRadio] l00p antenna


Geoff w5omr at w5omr.shacknet.nu
Sun Jan 9 13:39:12 EST 2005


fkamp at comcast.net wrote:

> I have used a 40 meter right angle delta loop for several years now. 
> The feed line is coax attached about 30 percent up from one of the lower
> apexes of the triangle.  This is supposed to be the optimum feed for
> vertical polarization.  

Right.  I've heard/read that, as well.  For example, if the loop 
antenna were square and fed in the middle, then it would have 
vertical characteristics/tendancies.  But, I'm not looking to be 
vertical.  Heck, I have enough troubles with the neighbors, now ;-)

> I have also fed it with open wire line at the center of the lower wire
> section and used it as an all band antenna with tuner.  I understand
> this setup favors horizontal polarization.

For the same reason that feed the center of a vertical element 
causes the antenna to be vertical.

> The antenna works well in both configurations with the vertical setup
> being more effective when trying to work DX.  However, both
> configurations work better than the inverted vee that I used before I
> installed the loop.

By lowering the angle of radiation.  The signal squirts out 
towards the horizons, first, before it starts to 'skip', causing 
greater distances, as opposed to bouncing straight off of the 
ionosphere directly overhead and back down to the ground.

This would work wonderfully for me, working say Skowhegan, Maine, 
on a regular basis, vs. working Dallas, Tx (I live in San 
Antonio, TX) but if I could do BOTH, then that would be something 
I would be most interested in.

> My suggestion would be to set it up so that it can be used in both
> configurations.  I would think that shorting across the feed lines at
> one or the other feed points would allow the loop to be used in either
> configuration.  However, I have not tried this and am not sure how the
> unused feedline would effect the antenna since it is still connected to
> the loop.

I would think that anything hanging off of the radiating elements 
would also become a radiating element.

I'll just have to try it both ways, and see which works best for 
me, I suppose.

Thanks for the input, Frank.

73 = Best Regards,
-Geoff/W5OMR




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