1st September 2002

New 76GHz distance record of 79.6km for G3PYB, G8BKE & G8ACE

From near Ventnor IOW (G3PYB) to Highclere SW of Newbury Berks. (G8BKE & G8ACE)

 

Dishes left to right. G8BKE Rx dish, Tx dish, G8ACE Rx dish, Tx dish.

G8BKE listening to G3PYB/P on 75976.2 MHz.

The view to the south from Highclere.

Dishes viewed from the rear are in reverse order

 

On the 1st of September 2002 successful two way contacts were made on 75976.2¹ MHz between G3PYB/P located near Ventnor, Isle of Wight and G8BKE/P and G8ACE/P located near Highclere to the west of the A34 and south west of Newbury, Berks. The distance 79.6km. Contact between G3PYB and G8ACE was on NBFM² and between G3PYB and G8BKE on NBFM² and CW (G8BKE)³. The success in making this contact, thought to be a new UK distance record for this amateur band was we think due to favourable humidity conditions prevailing on the day. Attempts during 2001 were by and large prevented by the Foot & Mouth restrictions. During earlier 2002 attempts the weather conditions were either unfavourable due to rain or excessive humidity often above 80-90%. G3PYB measured the humidity as low as 39% during these tests. The BBC web weather information gave humidity values for locations along the path of 58% for Ventnor and Newport IOW, 43% for Southampton and 35% for Andover and Newbury for 1400 GMT.  All significantly lower values than we had experienced in recent tests. The attenuation at these frequencies is significantly affected by water vapour. Earlier experiences show that in choosing a suitable test path a K value of 1 is much more likely to lead to successful exchange of signals rather than K=1.33 Additionally at least 20 metres of clearance has been found necessary between any intervening high ground and the LOS path to avoid penetration of the fresnel zone by trees and buildings when examining possible path profiles. These constraints mean that few long paths from accessible sites in the South of England will meet the concluded criteria for successful long distance communication at the limited transmit power levels we can obtain.

 

 

Listen to G8ACE relayed back on 2m FM for recording.         

 

Listen to G3PYB    

 

Visit the history of notable QSO milestones on 76GHz

 

View the G8ACE transverter workings

 

 

G8BKE concentrates on sending that all important signal report to G3PYB

 

Notes.

1.      UK preferred frequency for narrow band operation.  75976 - 75978 MHz.

2.      G3PYB and G8ACE use Impatt diode transmitters producing a few mW of  76GHz power.

3.      G8BKE uses a beam lead diode multiplier transmitter producing a little less power than the Impatt devices.

4.      Receivers are based on the DB6NT design using anti-parallel beam lead mixer diodes.