Showing posts with label alford slot. Show all posts
Showing posts with label alford slot. Show all posts

22 Apr 2013

23cms omni-directional horizontal antennas?

At the moment I'm still pondering the bands to try at my new QTH in a few months from now.  One possibility is 23cms, a band I have never used on TX.

One consideration at the new QTH is antenna (non) visibility and I am anxious to go for "neighbour acceptable" solutions on all bands. For 2m SSB/CW/data I am still minded to use a couple of stacked big-wheel antennas giving around 5dBd horizontal gain. Up above the apex of the roof, this should soon be lost being not that much bigger than a TV yagi. The partly vertical feeder to this will load up on the HF bands as a nice stealth antenna: I have used the coax to my 10m halo as a very effective HF antenna, even on 472kHz despite being only a few metres long.

But what about 23cms?  Maybe to just get on the band simply and with an unobtrusive antenna the Alford slot is worth a try? If I understand correctly, these give an omnidirectional horizontally polarized signal with around 10dBd gain. Placed at the top of the mast, maybe above the big-wheel and inside a PVC pipe as a radome, and fed with low loss coax (or with the transverter up near the antenna) this might be enough to work the locals during UKAC contests.  Alford slots are popular for 23cm beacons and ATV, so why not for local 23cm SSB/CW activity or for weak signal data modes?

Another possibility would be a big-wheel (or should it be tiny wheel?) on 23cms. This would be about 12cms across only!

The photo above was from an eBay item which sold for around £130 back in April. Is anyone aware of commercially available 23cms horizontal omni-directional antenna?