Baluns : What They Do And How They Do lt

Posted date: April 09, 2015in: AntennaNo Comments

By Roy lV. Lewallen

I’ve always been a bit bothered by balunst since I was never sure what they are supposed to dot let alone hotv they might go about doing it.

The majority of articles deal with various ways o f building and testing baluns, or the advantages of one type over another, but almost never a word about when or why a balun is neeessaryr if at all. Like most amateurs, there have been few occasions when I have been able to tell if a balun has any effect on an antenna system, and when it has, the effect hasn’t always been good!

The turning point came when I was trying to measure the resonant frequency of a folded dipole through a one-vravelength coaxial line. The bridge null varied a great deal as I moved my hand around the coaxial cable, or if the line or bridge was moved. A hastily eonstructed balun installed at the center of the dipole eliminated the problem. But why?

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