G8IFF/M0NHF/KC8NHF's ATX Walkabout Dipole





The kit, minus cable. The brown tubes are 19" long extensions that mount below the ATX loading coils. The extensions are lengths of insulating tube with plug and socket at either end and a conductor down the center. I used Tufnol tube (19mm OD, 12.7mm ID) and 3mm brass rod.
The dipole center. The input connector (bottom) center pin is connected to the center pin of the left hand connector. The right hand connectot is short circuited.
The antenna configured as a dipole. It could, of course, be mounted vertically.
The antenna configured as a "hortical", i.e. a vertical whip with tuned counterpoise.


I made the extensions for 2 reasons:
Configured as a dipole, the ATX whips appeared not to be long enough.
A loaded dipole is more efficient if the loading coil is closer to the top of the antenna.

I would suggest that, when adjusting an antenna to length, it may be better to adjust the length to resonance, i.e. make the antenna resistive with no reactive component, and use a tuner to get the impedance back to 50R as, for good performance, resonance is more important than a good match. Unfortunately this will require the the use of some sort of analyzer rather than just a SWR bridge.
Actually, the above is incorrect. Being resonant doesn't show any increase in radiation efficiency so adjust for best match.