# How do dual band J poles work?

My understanding is a J pole is a $$\frac{1}{2} \lambda$$ dipole attached to a $$\frac{1}{4} \lambda$$ impedance matching element.

How does this dual band work? What acts as the impedance matching element and what is the radiating element? Does the smaller rod act as the impedance match for 2 m and the larger one for 440 MHz with the longest rod acting as the radiating element?

How is a feedline connected to this?

• For the dual-band version, the feedline connects to the 19 1/4" element using a threaded stud adapter thing that has an SO-239 on the bottom and a 3/8" threaded coupling nut on top. Lemme dig up a link for that. I've built a couple of these dual-band units and found the SWR curves very disappointing. – Tyler Stone Aug 26 at 23:15
• Feedline connection: americanradiosupply.com/… – Tyler Stone Aug 26 at 23:20
• Instead of what? – Tyler Stone Aug 26 at 23:26
• @TylerStone for 440 MHz, better to use N connectors. They are waterproof, too. – Mike Waters Aug 26 at 23:36
• @Mike I am in no way endorsing or recommending these 1930s-era SO-239/PL-259 connectors, but its what Arrow uses on their J-poles and my understanding is that is part of what was asked. – Tyler Stone Aug 26 at 23:44