By Ross Glover ZL1BGB
It’s always fun mucking around with lengths of tube and making antennas.
We used to have heavy drapes on three windows in our lounge, with net curtains. The ZLCAT loved grabbing onto the net curtains and shredding them, so we decided to do away with the drapes and nets. We went for vertical venetian blinds.
One day, I was looking at the curtain tracks out in the shed and the brain went into “construction mode”. Ah ha! Where’s that tape measure?
Oh loverly! A length of track 2 metres long. There’s the making of a J-pole.
From one end I measured down 1.460m and marked where the shorting bar would join onto the ¼ wave section made from another piece of curtain track.
That shorting bar was made from an “L” mounting bracket that held the track to the window frame. At the top of the ¼ wave section, a piece of Perspex was bridged between the ¼ wave section and main radiator.
Measured up 140mm from the shorting bar for the feed point.
Be sure and use a wire wheel on the electric drill to remove the powder coating at feed point and shorting bar.
There is 540mm below the shorting bar on which are fastened two of the “L” mounting brackets onto which are mounted another two “L” brackets. So you end up with wot looks like ½ a German swoss emblem.
I mounted the J-pole on the fence post, connected a ? length of coax with 5 turns 6 inches dia’ and 2x 12 inches of flying lead, one to the feed point and the other to a PL259.
Plugged into the handheld and was able to trigger all Auckland repeaters and 730 Warkworth, from my QTH in Pakuranga.
ZL1JW answered my test call on 730. We then went to simplex and carried on a QSO.
I’ve yet to use an MFJ Analyser to see wot frequency the J-Pole resonates on.