A Skeleton Slot for 23cm.

14/5/07

I've wanted one of these for years but 'never got round to it'. Recently my small portable ATV RX & TX were working well enough to go out and try them. However, my Alford slot or 10 ele beam seemed massive by comparison so I really needed the skeleton slot. Another incentive was that I often wondered if its low wind resistance would make it a feasible antenna on a mag mount on the roof of a car.

Antenna on standoff
Antenna testing

The photo on the left shows the finished antenna mounted directly on my SWR meter. I used the conductor wire from old style mains power cable (2.5mm2). For the ¼-wave Pawsey stub balun I used 1.0mm2 wire, complete with sleeving, from lighting cable.

I was concerned that the SWR meter readings were being effected by the close proximity of the antenna (and me!). The situation was improved when I used a ½ metre length of semi-rigid coax with SMA connectors (photo on right) to give a little separation. This was also helpful when I came to use it with my ATV RX.

The test setup was in this position merely for taking photographs; I moved away from the wall during the tests.

Sources for useful & relevant information I used are:
24cm Walk-About Hat Aerial! by John Stokley, G8MNY - CQ-TV 159
A Compact Omnidirectional Antenna by Roy G8CKN of Antec - The United Kingdom Radio Society

Alford Slot Antenna articles by G3JVL in magazines, RSGB Microwave Handbook V3 etc.


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