1/4 λ 1:1 balun
An easy to construct 1/4λ 1:1 balun for VHF/UHF antennas. The 1/4λ section acts as a coaxial sleeve.
Example:
For 144.2 MHz measure 0.52 m from the end (beginning) of the coax cable and remove approx 10 mm from the outer insulation without damaging the wire mesh. Next use a hose clamp or fabricate your own from a piece of copper or aluminium to clamp a wire or better a bit of wire mesh on to the cut out. This needs to be attached to ground. If the boom is grounded you can attach it straight to the boom. Weather proof and done.
For other frequencies you can use the below to calculate were to make the cut.
