[Antennas] " G5RV " TYPE ANTENNA / "CUSHCRAFT MA5V"ANTENNA QUESTIONS

[Pat W]

Right on George. You've managed to detail most of what
the G5RV is and isn't.  However, I discovered there is
another magical part of the antenna not discussed
before and that is the 1/2 wave of ladder line on 20m
becomes 1/4 wave line on 40m and causes an almost nice
transformation from high Z to low Z. I say almost
because my analysis shows that the 40m SWR is not
perfect as theory would describe.  However, it appears
that with proper tuning of element and feeder length, a
good compromise could be reached to provide low SWR on
40, 20, and 15 meters.  ALmost magical but not quite.

 My previous comments about coax length have nothing to
do with wierd impedance transformations on other bands,
 it is only the loss factor of coax fed against high
SWRs.
AN example of this is the G5RV on 10.1 mHz, the SWR in
is about 100:1 at the coax input, 66' of rg58 shows 9.9
dB loss! Even using low coax(9913), the loss is about
7.5 dB.  Clearly, coax is only meant for low SWR
situations. 
 I analyzed another version that instead of coax, uses
96' of ladder line with no coax and the loss never
exceeds 1 dB on any frequency and still exibits the
fairly good low SWR on 40/20/15 meters.

 Pat W0OPW 

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