I wonder what you consider narrow bandwidth. 500 KHz seems to be about par
for a decent 6 m beam.


This antenna shows an SWR of 1.7 at 150 kHz below the resonant frequency, where
the SWR is just 1, so I consider it narrow. Another antenna I have, also using
an hairpin match but at 50 ohm instead of 200 ohm, is by far broader. On both
antennas I have about 100 feet of low-loss 1/4" Andrew hardline, so the SWR is
only slightly influenced by cable loss.

Talking with the manfacturer, he told me that he preferred rasing the antenna
impedance up to 200 ohm, instead than to 50 ohm, because a 4:1 cable balun can
me more easily realized than a 1:1 balun. But doing so the feed system Q factor
increases quite a lot, causing a significant bandwidth reduction. Moreover ohmic
losses increase, due to the higher circulating currents (for a given RF power),
but I am not able to predict whether such extra losses are significant or can be
disregarded for all practical purposes.

73

Tony I0JX