From Dave G3YMC
<The loop design programs RJELOOP1 and RJELOOP2, written
<by Reg / G4FGQ, both include induced ground loss when they
<compute the total loss resistance.
Thanks for the information on these programs. I have simulated my loop
with them and the results are astounding:
Using RJELOOP1 with a square loop (not strictly true, mine is very dog
legged), and 4mm dia wire gives:
RF loss resistance 0.347 ohm
Ground loss resistance 0.247 ohm
Total loss resistance 0.6 ohms
This agrees almost exactly with the measured results on my loop (0.66
ohms)! However the calculated bandwidth of 1.3kHz is far too high - I have
to retune if I QSY more than 100Hz! Note that these programs assume loop
or transformer coupling rather than my capacitive matching network -
perhaps this accounts for the discrepancy.
My loop wire is actually 2 wires of 2mm dia in parallel. I have taken the
diameter as 4mm to account for the fact that the skin resistance will be
lower than for a single conductor.
Thanks also for the replies on a formula for skin resistance, in particular
to Alan G3NYK. His formula agrees well with the approximation I had, and
now with G4FGQs program.
73s Dave G3YMC
[email protected]
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