Open Wire Feed Phase Question

[WA2SQQ]

Had a discussion with a friend of mine who is feeding a 160m dipole with open wire feed. He mentioned that he has a relay connected that he uses to reverse the two wires. I never heard of this - is there any chance that it's going to make a difference?

How about if this were used on a full wave loop?

[AB2EZ]

If there is only 1 feedline (i.e. not multiple antennas being fed simultaneously with separate feedlines), and if the currents in the feedline wires, at the feed point, are balanced (equal in amplitude and 180 degrees out of phase) ... then reversing the wires at the feed point will make no difference. I.e. Reversing the wires is equivalent to waiting one half of the time it takes for the RF to complete one cycle.

If you had two antennas, simultaneously fed by separate  feedlines, then reversing the wires in one of the feedlines, at its corresponding feed point, would cause a change in the radiation pattern... and possibly a significant change in the impedance looking into each of the two feedlines.

If you have unbalanced current (i.e. common mode current) flowing in all or any portion of the feedline, then the feedline itself would radiate... and reversing the wires at the point where the dipole connects to the feedline could result in a significant change in the radiation pattern of the feedline + dipole combination.

Stu