The 241-250 GHz bands are the highest frequencies globally allocated to amateur radio. Whilst powers and noise figures are challenging, experimentation is rising, helped by progress in lower bands such as 134 GHz and stable frequency sources. The high antenna gains available from small dish sizes facilitate portable operation, provided they are accurately aligned to accomodate the small beam angles.
G8CUB 241 GHz Transceiver - click for higher-res
The video below is of the first UK QSO that took place on 19-Feb-2016 15:00z on the 241GHz (1.2mm) band between Roger G8CUB/P and Chris G0FDZ/P in locator square JO01EP, Essex. The distance was 30 metres and the CW signals were 559 and 589. With signal to spare both ways an attempt was made to increase the distance to over 50m but with deteriorating weather likely, a decision was taken to limit to 30m as antenna alignment was taking a very long time to achieve
Roger G8CUB was transmitting on 241.01 GHz, Chris was on a nominal 241.02 although it was 1.3 MHz low at 241.0187 GHz. Both used separate Tx & Rx. All Txs (and Chris's LO) were derived from Elcom synths. Roger was using 16.0385 as LO (x15) into a Tektronix mixer. Chris used a 1mm diameter hole in the block on Rx with cut-off around 175GHz, whilst Roger used a piece of WR-03 - 173GHz cut-off.
John Hazell G8ACE is another millimetre wave enthusiast and has been making great progress on and distances. To reach 241.02 GHz, John uses a 2.678GHz source x5 x3 and a final x6 mixer.
Video: Further tests by John G8ACE over 400m distance - June 2016
Brian Justin WA1ZMS et al lead activity in the USA - click here for more
Similar distances to the UK - See here from 2001
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