HI Eric,
>From your response to the TA-33 feed question, you may be able to help me
with a question I have regarding antenna currents within a non-ideal coax
transmision line.....
Consider this common situation:
An HF transmitter supplying 100 watts to 10 ft of 50 ohm hardline coax,
terminated into a Bird, 50 ohm, shielded dummy load.
Power formulas (I squared R, and P= I x E) say that there would be 1.41
amps of RF flowing up the outside of the center conductor, and on the
inside of the hardline
shield...currents exactly matched.....and, neglecting the
negligable loss, constant anywhere on the 10 ft of hardline. Voltage a
tad over 70 volts. No currents on the outside of the shield...no way to
"Get Out" from inside the coax.
NOW, my own dilemma, and question....
Suppose a PL 259 TEE fitting is inserted partway up the coax. That is, a
barrel to accept the PL 259s in line, to the dummy load, and an
unterminated Male fitting sticking out the side. The side male pin
protrudes just a slight amount out of the coupling threaded ring, and the
fitting is just left open, exposed.
Can RF current flow, (leak) from the inside of the shield, now to the
outside of the shield, through the Tee fitting, and back down or up the
coax, and be radiated?
If so, is the remaining RF current headed to the dummy load on the
center conductor and matching current on the inside of the solid shield
still matched (equal and opposite polarity)? Is the RF current diminished
by the amount of current, leaked to the outside of the coax?
Answers to these questions can help me
understand some other situations, like RF current flow routes and
magnitudes on the
insides of Chassis' of HF amplifiers, towards the output connector if open
frame relays, only switching hot RF center conductors, are used as antenna
switches.....
73, DX de Pat, AA6EG/N6IJ
"The Contest Station from the Government"
Marina Amateur Radio Contest Station; N6IJ
599 DX Drive
Marina CA 93933
aa6eg@tmx.com
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