The commercial radio installations I've seen never did that. There might be a dozen open wire lines running in parallel along tall poles for hundreds of yards or meters, but each open wire pair was five or ten times its spacing from the others.
Almost all of the RF field is between the two conductors of the open wire line. Maintaining reasonable spacing ensures it stays that way. I suspect the practice of twisting the lines originated with the use of 300-ohm "twinlead" for VHF television reception in the 1940's and 50's. Often such lead-in wires ran down the wall of a house or even alongside a metal rain gutter, sometimes almost touching the surface. They were normally twisted so each conductor had the same coupling to the wall, gutter, etc. I have no idea whether doing that provided any measurable benefit in practice. Certainly, any energy coupled to something else degraded the signal strength. In any case, if the lines must run very close to the earth, a wall or other structure, supporting them so each line is equidistant from the surface should have the same effect. Ron AC7AC -----Original Message----- For long horizontal lines near to the ground (<3ft, 1m, say) I've read that some folks rotate the line between supports, supposedly to maintain balance; what do you think about that? David G3UNA _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
