A few comments:
1.) Someone mentioned a 1WL feeder on 20. A feedline one WL
on 20 meters might be three 1/2 wl on 15, but that is a 180
degree flip in phase! 540 degrees is NOT the same as zero.
360 is the same as zero, 720 is the same as zero, and so on.
First antenna has no phase delay. Second has 360 (0) on 14
MHz, 540 (180) on 15, 720 (0) on 10.
Now an exercise. How long does the line have to be to
effectively hit zeros on 20, 15 and 10? Do we actually save
coax?
2.) When lines are not equal errors can add. If I misjudge a
line 10% that is 720 deg long, I'm in trouble. If I misjudge
initial length and change frequency, now I'm really in
trouble.
3.) If I have SWR added, unequal lines make things worse.
Phase can advance in one line and retard in another. The
only line that does not change phase with SWR is a lossless
line and exact multiples of 1/4 wl. Phase error peaks when a
line is an odd multiple of 1/8th wl.
4.) What does the 40m element do to phase?
73 Tom
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