As someone who is relatively inexperienced with the hobby, I am amazed
at the confusion and mysticism surrounding the "G5RV" antenna. It
appears to be nothing but a dipole, with a length of "balanced line" to
transform the impedance to a better match for coax at certain
frequencies.
A little consideration reveals that this antenna should suffer from
unwanted return currents unless a balun is used (like any coax-fed
dipole), and substantial loss in the coax at certain frequencies. So
why is this antenna better than two pieces of reasonably long wire
driven with balanced line and a tuner? What am I missing?
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Well done! You are correct about the G5RV in every respect.
As a multi-band HF antenna it is just another dipole without any magical
properties.
With the coax (Zo unspecified) its loss is greater than other dipoles.
Its balanced feedline impedance Zo is not specified. This important
performance parameter can be anything you like and the antenna will still
remain a G5RV.
It has an approximate impedance match at only one frequency, 14.15 MHz. You
will be very lucky to find a resonance in any other band.
The impedance match to coax at 14.15 MHz is not at the desirable 50 but 75
ohms.
It has a cloverleaf radiation pattern only in the 20m band, sometimes
praised as desirable if you work from South America into both Europe and the
USA as G5RV often did.
As with other balanced line fed dipoles a current or choke balun is best
when converting impedance from a balanced line to a tuner plus 50-ohm
transmitter.
But the biggest joke of all is the half-size G5RV. Mr R L Varney must be
turning over in his grave.
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Reg, G4FGQ
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