J-Pole Collinear for 2m

A makeshift, phasing-coil variant of a 2m J-Pole Collinear was recently homebrewed.

J-Pole Collinear for 2m - details

It was fabricated with a single length of 20SWG copper wire and taped to a bamboo pole for rigidity.

The coil section was 64 turns close-wound on a 10mm mandrel and then stretched to a length of 300mm.

SWR measured close to 1.5:1 across the 2m band.

Antenna performance exceeded that of a normal J-Pole at the same height.

A 16SWG rugged version, encased in a PVC pipe, is in the works.

Related post: PVC-encased Vertical Antennas for 2m
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Noise cancellation on 2m using 2 antennas

A while ago, static-type QRM was encountered right across the 2m band.

It proved to be a nuisance while receiving weak signals using either of the shack antennas - a 1/4λ Ground Plane at a height of 15m and a Slim Jim at a height of 10m, located 5m apart.

The noise was presumed to be of commercial origin as it was not present at nights and on weekends.

Then, on an impulse, both the antennas were connected to the rig through a BNC-T connector. Surprisingly, the QRM disappeared and the audio level went up considerably.

The offending noise had been phased out just like that!

The antenna feeder lengths were then changed one at a time. The QRM promptly returned, confirming that it was indeed phase cancellation at work.

SWR was 3:1 with both the antennas connected. Inspite of that, it was now possible to comfortably work through a distant repeater.
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