© WB5CXC 2011
Twin Lead J - Poles
This page illustrates how to build Twin-lead J-Poles (VHF / UHF).  You can make them as roll-up J-Pole antennas.  These are made from 300 ohm twin lead (old style TV lead-in wire).  Make several to carry in your Go-Kit, in your car, etc.  Making these J - Poles makes a good project for your radio club or ARES Group.
Strip the bottom 1/2” insulation of each side of the twin lead.  Solder the leads together.  Measure up from the bottom to the first dimension and strip off insulation from both sides of the twin lead, this is where the coax will attach.  Measure the next dimension, on the right side cut a 1/4” gap into the wire (cut the wire in two on the right side).  This is the quarter wavelength piece.  Measure the final length, this will be the half wavelength piece, cut the twin lead.  Connect the coax on the bottom section, the center conductor of the coax will go on the long side (left) and connect the outside (braid) on the short (right) side.  It is now time to check th SWR.  If it is no less than 2:1 you will need to adjust the position of the coax by moving it up or down.  You should only move it ~ 1/16 to 1/8” at a time.  Remember to check it a the portion of the band you will be using.
18
½
´
39
½
´
1
.
25
"
Co ax   S h ield
T ermin ated on  
sh ort  sid e of     
J
-
Pole
~
1
¼
´
450
oh m
Ladde r  
Li n e
2
M  J
-
P ole
4 50  
o hm   L a dd er  
L i n e
Mat ch i n g Details
Co ax   C en t e r  
T ermin ated on  
l o n g si de of  J
-
Pole