ARLA/CLUSTER: Novo recorde australiano en 78 GHz / SSB

[João Costa > CT1FBF]

New microwave distance records set in Australia

Using both digital and SSB on 78 GHz or the 4-millimetre band in the
Super High Frequency allocation, Alan Devlin VK3XPD and David Smith
VK3HZ have been busy setting record distances.

To show how much further the latest contact is, the record on that
band VK3XPD to Russell Lemke VK3ZQB was about 32 kilometres in
December last year.

The new records on May 15, had VK3XPD Mt William in Western Victoria
and VK3HZ on Melbourne's Mt Dandenong Observatory, extending their
efforts over two days to notch up a path of 139.8 kilometres.

A warm, bright and sunny sky and high-ish humidity, not really ideal
for 78 GHz propagation, the record contact was first on digital
WSJT/JT65C with -10 to -12 reports, then SSB had a 4 by 1 report.

The microwave exponent Alan VK3XPD points out that it not only sets a
record SSB distance, but also the inaugural digital record on that
band. That distance of 139.8 kilometres has been officially confirmed.

The lack of accessible high spots makes it very hard to find
line-of-sight paths greater than 150 km, so Alan VK3XPD believes the
current world record of 252 kilometres is unlikely to be challenged by
Australians.

Alan VK3XPD and VK3HZ used 10 GHz as their liaison frequency to guide
their very sharp 78 GHz dish antennas measuring 300 millimetres, which
have a gain of about 45 dBi, feed with a mere 1 milliwatt.

VK3XPD has also worked David Minchin VK5KK on 47 GHz and 78 GHz, over
a distance of 10 kilometres. The 47 GHz contact is claimed to extend
the VK5 Record on that band.

Additionally, VK3XPD has claimed VK5 records on 78 GHz with Iain
Crawford VK5ZD of 114 kilometres, on both SSB and digital modes. The
three claims of VK5 distances are still to be officially verified.

Alan VK3XPD now at HamRadio in Friedrichshafen Germany, is expected to
further talk about his exploits at the GippsTech conference in
Churchill east of Melbourne on July 12-13.

Jim Linton VK3PC