New UK distance record on 134 GHz

Southgate Amateur Radio News
January 17, 2016

Ian Lamb G8KQW and John Hazell G8ACE are very pleased to report a successful 134GHz CW contact which extended the existing UK 134GHz distance record to 35.6km on Saturday 16th January 2016.

This exceptional contact was made over a Line Of Sight (LOS) path from Chute Causeway (IO91FH20DP) near Andover to Cheesefoot Head (IO91JB00NV) near Winchester.

The existing 19.2km UK distance record on 134GHz was set by G8KQW and G8ACE on September 20th 2015.

Millimeter bands (24GHz and above) suffer losses due to oxygen and water vapour. Whilst there is nothing we can do to mitigate attenuation due to oxygen, the attenuation due to water vapour reduces in line with Dew Point Temperature (DPT) therefore operating on a very cold winter day would yield minimal water vapour attenuation.

The key enabler for success on this extended distance record contact was lower path loss due to less water vapour attenuation, DPT on 16th January 2016 was -1c whereas on 20th September 2015 it was 14.3c. The reduction in water vapour attenuation between the two tests was sufficient to overcome the ~9db increase in free space path loss attenuation over the 35.6km path.

Equipment used,

Transmitters: ~100 microwatts output Receivers: Sub-harmonic diode mixers with no RF amplification

Antennas: 0.3m dishes ~47dBi gain

All transmitters and receivers fitted with rifle sights for visual alignment

Ian & John