[Antennas] SWR Isn't Enough - Working in a high SWR setting

2002年4月29日 09:56:28 -0400

Ladder line is definitely not suited for use in conduit, buried or
otherwise. There is an RF field surrounding such a line that needs
protection from:
 Metal objects (running parallel to it for any appreciable length),
because such will alter the impedance and (probably) lower the
efficiency by introducing loss near current loops.
 Poor dielectrics (running parallel) because they will introduce
losses near voltage loops.
Different authorities recommend different amounts of separation of the
line from these influences, ranging from twice the line spacing to 5
times the line spacing. I tend to go along with the higher separation
limit.
I don't understand what you would be using matching stubs for. It is
obvious that you envision using a "tuner" (transmatch) because you wish
to use the ladder line to avoid the losses associated with high SWR.
Under that condition, no matching stubs are necessary.
Harvey/W4TG