I have recently mounted a 6-meter long Yagi. The driven element is a
(non-folded) dipole whose impedance is brought up to 200 ohm by significantly
shortening it (so introducing a high series capacitive reactance) and using a
(rather small) hairpin to resonate the residual reactance. The system is fed by
a 4-to-1 balun (200-to-50 ohm) made of a half-wavelength cable. The SWR at
resonance is almost perfect, but the SWR response vs. frequency is very sharp,
this meaning that the system has a high Q. I am wondering whether such a 200-ohm
feed technique could cause non negligible losses caused by the higher current
circulating in the hairpin (due to its low reactance as well as to the high
voltage on the high-impedance feed point, that is 200 ohm + reactance of the
shortened driven element). 73 Tony I0JX