Simple 50MHz J-Pole Antenna

The principle of the Wireman-J-Pole:

The picture shows the currents in the antenna. At the both ends of the Lambda/2-section (L1) you have a high impedance (some KOhms) and a low current.

At the other side at the end of the Lambda/4-line (L2) is a maximum of the current (low impedance of about 20 Ohms). The two ends are connected together through the metal of the coax-socket (see next picture below).

At the points XX you can find a 50-Ohm-point for feeding with the coax-cable.

Because the quarterwave-line is symmetrical, you should feed with a lambda/4-choke for a SWR of 1,0 at 50,150 MHz.

The bandwidth for a SWR <1,5 is greater than 1 MHz. The gain and pattern are the same as with a normal vertical dipole, but feeding is much more easier.

For the elevation plot and gain look at the other vertical with a Collins-filter!