[Antennas] Re: Hairpin monopoles

[Roy Koeppe]

Oh, oh, regarding,

"It's not a matter of what I think - it's a simple fact. The resistive
component of the antenna's input impedance (the radiation resistance) is
generally higher than a conventional, non-folded radiator."


This old hams' tale has persisted throughout the years and now rears its
head again? Radiation resistance and input impedance are two entirely
separate things. With a folded element the input impedance is simply
stepped up by transformer action alone, just as if you installed a
transformer at the feedpoint. Radiation resistance, on the other hand,
remains constant. Actually, most folded monopoles have a slightly LOWER
radiation resistance than their single conductor counterparts. This
obeys the law about "the thinner the conductor, the higher the radiation
resistance, for the same self-resonant element." Fat elements are
physically shorter than thinner ones for the same resonant frequency,
hence have a lower radiation resistance.

73,     Roy      K6XK/0