View Single Post
Old 11-Dec-2011, 3:15 AM   #8
Join Date: May 2011
Location: Central Illinois U.S.
Posts: 72
helical antennas

I have to agree with be236 at least somewhat I found rabbit ears site confusing at first to.
Start by clicking on the listings tab
Thanks for the tip there Dave I didn't realize that was a link I thought it was just a drop down. But like be236 I gave up pretty easily even though I'd seen very informative pages from links, my curiosity took me elsewhere.
What about helical antennas:
I know a helical will get a gain boost of 3 Db if it's receiving a circular polarized signal (if both match direction of rotation wise).
And a helical is equally sensitive to vertical and horizontal polarized signals (and all angles in between)
But will a helical reject multipath or bounced or out of phase signals?

The equal sensitivity to all angles of linear polarization seems to suggest that it would be more prone to multipath when receiving from a linear polarized transmitter.
But what about when receiving from a circular polarized source?

found out bounced CP signals off large objects are reversed in direction and attenuated ~20 db

Would the 3 dB extra gain make up for the multipath interference.
And finally while only some stations use circular polarization what about using this to null out a stronger circular signal by using a left hand helix instead of the standard right hand the desired linear polarized signal would suffer a 3 dB loss but the circular signal (being right handed) would suffer a 20-25 dB loss?

Thoughts, comments, corrections?

Last edited by ghz24; 24-Dec-2011 at 5:28 AM. Reason: added
ghz24 is offline   Reply With Quote