OH2NLT 2m J-Stick antenna experiment 27.07.2004
One day I started to wonder how J-pole antenna really works. J-pole is end feed dipole. Sounds simple but there are lot more to understand how antenna feeding is done. After searching material about J-pole antennas I found this excellent articlehttp://snow.prohosting.com/w0rcy/Jpole/jpole.html after reading this and few other articles I decided to make few practical experiments with 2m J-pole.
Test antenna was constructed from 22mm copper tube what is available from local hardware stores. Test antenna was put together with soldering tin and gas torch by using ready corners and T-pieces. 135mm tube spacing for 22mm tube was calculated to give about 300R impedance. Rests of the dimensions are from iterative learning process.
Several feeding balun constructions were also tested. Tube balun bade from dual braid coaxial cable yield to simplest construction with good results. Test antenna SWR could be tuned to 1.0. Test antenna gives also excellent results compared to commercial 5/8 antenna at same position.
Construction and dimensions of test antenna
Picture of test antenna
50R double braid coax used for balun
Balun & feed point construction