[MLB-WIRELESS] New world record for wifi link (125 Miles).

David Smith dwsmith at bigpond.net.au
Wed Aug 3 16:47:06 EST 2005


Horizontal polarisation has been shown to be better over long distances. 
    All the amateur weak-signal microwave ops use H-pol.

In discussions with Tony this morning, I did some calcs of what would be 
required for a legal linkup over the path from Mt Buffalo to Camels 
Hump.  Assuming that a preamp (e.g. Longreach 2.5dB NF) is in line, the 
Rx noise floor is about -98dBm in a 20MHz bandwidth.  Using a 22dBi dish 
and allowing for 2dB of feedline loss, there's a link there using legal 
power (+36dBm) - although the 5dB margin is not a lot.

It could almost be done with the large Hills gridpacks, although you'd 
be betting on the advertised gain matching actual - has anyone measured 
them?  Perhaps 1.5m solid dishes might be better.  Or a 1.8m mesh 
satellite dish which could possibly be assembled in-situ.

I've never been to either, but I'm not sure that either Camels Hump or 
the peak of Buffalo (The Hump?) are accessible directly by car.  If not, 
it means that all of this would need to be lugged up to the sites.

I have a 2.4GHz portable SSB setup that might be handy for setting up 
the link.  Mike Borthwick also has one (G'day Mike ;-))

Regards,
Dave
VK3HZ

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