--- In [email protected], "chuckmf1135" <[EMAIL PROTECTED]> wrote: > > I received a 4 bay (folded j pole or dipole) it has 34" folded elements > and total boom length around 20'. I wangt to use this for amateur radio > use, however no one knows what freq their business was on. > I havent seen a setup like this before, two folded elements feed > w/coax - 50 ohm i guess to a tee then the two tees feed one tee which > feeds a single coax w/ N male connector, are the individual elements > 50 ohm? >
The characteristic impedance of a folded dipole is 300 ohms. 4 of them, fed in-phase, will present an impedance of 75 ohms at the feedpoint of the phasing harness, which will present an acceptable 1.5:1 SWR to a 50-ohm transmitter. As Nate mentioned, some manufacturers build the phasing harness with different impedances of coax to transform the antenna array's impedance to 50 ohms. As far as frequency goes, if you're saying that the length of an element, from the center of the top bend to the center of the bottom bend is 34 inches, it's definitely a high-band antenna. The larger the element tubing diameter, the broader the frequency range the antenna will cover, so you may get that to perform acceptably at 2 meters. See the construction article on the Repeater Builder website at www.repeater-builder.com/projects/exposeddipole.html - it's pretty much the antenna you have. George, KA3HSW / WQGJ413
