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G0MWT, GX0MWT, GB5HF, GB100MWT & GB100-2MT
CARS Meetings: April - June 2022 |
©Copyright CARS
April Meeting
Tue 5-Apr-2022, 7.30-9pm
Online by Zoom"Radar History - from 1895!"
Philip Benstead
Our April talk provided a fresh and fantastically well-illustrated perspective on the history of radar.
Our speaker Philip Benstead has been involved with the development & implementation of radar systems from 1964 through to 2020. His career started as a Marconi Apprentice in 1963-68, including a time with Marconi Radar at Great Baddow. His early work included NADGE, before moving to Plessey Radar on the Isle of Wight in 1976. His time there covered MESAR, 996 and Watchman radars. After attending a talk at Bletchley he realised that radar history has some earlier origins than Robert Watson Watt.
Philip outlined some early chronology:-
- 1895: Russian Alexander Popov observed ships passing his lighting detector caused signal returns
- 1904: Christian Hulsmeyer (a German inventor), developed a crude proximity detector intended for ships to avoid colliding in fog ( granted a patent in 1904). But this was abandoned in 1905
- 1921: The basic Magnetron was invented by American Albert Hall (The Germans preferred the Klystron)
- 1933/4: German Rudolph Kuhnold develops prototype equipment that later became Freya radar
- 1935: On 26th February Daventry experiment by Watson Watt and Arnold Wilkins detects a Heyford Bomber illuminated by the 49m wavelength from the BBC Daventry Transmitter (following fears of RF Death Rays!, but also other experiments in the UA and Russia)
- 1940: Cavity Magnetron - Randall and Boot at Birmingham University (productionised by GEC/Marconi)
Prior to Daventry, the UK effort had been on acoustic detectors including unwieldy huge concrete sound mirrors. After Daventry, radar development moved in 1935 to Bawdsey Manor on the Suffolk coast prior where it developed rapidly to the deployment of the Chain Home (AMES Type-1) radar network, such as the mast now at Baddow.
One early key contrast was that whilst the Chain Home radar systems for the Battle of Britain were on ~20-30MHz, the German Freya system was up at ~220MHz (which is why the Germans did not correctly identify CH).
Another key difference was that Chain Home was one element of an integrated reporting and control system that Dowding implemented for RAF Fighter Command. In contrast the Germans did not integrate their radars to anything like the same degree.
Later on Magnetrons and other developments enabled the move to convenient microwave frequencies so that smaller antennas could form accurate directional beams; or even ground imaging for night time (H2S was at 3GHz) - the latter by Bernard Lovell (who later went onto create the Jodrell Bank radio telescope).
Our thanks to Philip for a fascinating 100-slide tour of radar history.
May Meeting
Tue 3-May-2022, 7.45-9:30pm
Danbury Village Hall"Is Life too Short for QRP"
Steve Hartley G0FUW
Steve Hartley G0FUW, will be talking about QRP – operating with low power, the G-QRP Club and how he went from being a CBer to now being Chairman of the G-QRP Club, a Trustee of the RCF and leader of Bath Based Distance Learning – and a former RSGB Board member too!
In brief: Is life too short for QRP, and how did I get here?
Note our new meetings venue!
CARS meet on first Tuesdays at Danbury Village Hall CM3 4NQ and no longer use Oaklands Museum.Radio Surplus to recycle? Members are welcome to bring it along and place it on a spare table!
This will be a hybrid meeting with Zoom in use as well
Meeting ID: 872 1544 6400 Passcode: 055551
June Meeting
Tue 7-Jun-2022, 7.35-9:30pm
Danbury Village Hall"10 Different Radio Topics"
Jim Salmon 2E0RMI
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Jim Salmon 2E0RMI, will cover a wide variety of 10 radio topics, different to Amateur Radio
Note our new meetings venue!
CARS meet on first Tuesdays at Danbury Village Hall CM3 4NQ and no longer use Oaklands Museum.
This will be a hybrid meeting with Zoom in use as well
Details to due course...
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