CYMBELINE MK 1 MORTAR LOCATING RADAR (RADAR, FIELD ARTILLERY NO 15)
The basic Cymbeline system (Radar, Field Artillery, No 15) Mortar Locating Radar is a mobile, lightweight single unit radar on a two wheel trailer with a turntable stand with four adjustable legs for leveling and is usually deployed together with Field Artillery. The Mk 1 was transportable and could be underslung on a helicopter for placement in areas inaccessible by road.
The Cymbeline could locate a firing mortar with an accuracy of 50 metres. Soviet 82 mm mortars could be located at up to 10 km and the larger 120mm mortars up to 20 km. Secondary roles were area and vehicle surveillance, helicopter and light aircraft control, meteor balloon tracking, rapid survey and was also used to observe and adjust artillery high angle fire as well as ground and airburst artillery fire.
The main elements were the antenna, the Foster scanner that was the main electronic unit and a two-stroke Wankel rotary generator (weighing 390 kg. This was strapped to a simple 590 kg trailer from where it was operated. Off the trailer the radar was 2.29 metres high with the antenna up, 1.07 metres with antenna folded, 1.7 metres wide and 1.5 metres long. The radar itself had a nominal 100 Kw peak average output and a nominal pulse repetition frequency of 4000 pulses/second. The radar was connected by cable to the operator’s console (‘Indicator Azimuth Unit’) and connected to this was the ‘Mortar Coordinate Indicator’ that displayed the located mortar’s position to the detachment commander.
The Foster scanner converted a narrow radar beam, about 40 mils diameter, into one 720 mils wide and 30 mils high. This beam had five pre-set operating positions determined by five different radar horns that directed the beam onto the antenna at slightly different angles. Two beam positions were used with a mortar bomb being recorded by the operator as it went through each beam. This gave two ranges and elevations, and the time interval. The operator marked his screen at each bomb position and changed the beam angle which also recorded time. He then placed electronic markers against his marks (which represented the bomb’s position in the horizontal plane) which the analogue computer used to calculate the mortar co-ordinates using the expected mortar altitude that has been previously set.
Setting-up the radar involved orientating it in a known azimuth (the basic mounting could cover an arc of 4 800 mils) and setting the datum beam elevation between -90 and 360 mils so that it was above the radar horizon. Other beam positions, 25, 40, 45, 65 and 90 mils were relative to this datum. The lowest beam position was used to alert the operator that a bomb was in flight and where to expect it on his screen; once alerted he tilted the beam into the first position and then into the next. The angles were pre-selected according to the local circumstances.
When deploying, the radar troop normally comprised a radar command post, the radar itself, listening posts (LPs) and a reconnaissance party. The task of the LP’s was to report mortars firing and the area they were in. Radars were only switched on in response to reports of hostile mortar fire thereby avoiding continuous transmission to minimise the risk of detection. Radars reported the hostile mortar locations to the radar command post, from where they were reported to the Brigade Artillery Intelligence Officer and Regimental Headquarters for rapid artillery counter-fire.
A maintenance section with radar technicians deployed with the radar command post and serviced radars as necessary. The troop commander was the Brigade Artillery Intelligence Officer and with the troop's artillery intelligence section was located at Brigade headquarters. South Africa deployed these radar's in South West Africa (Namibia) at Forward Bases close to the Cut-Line (Angolan/SWA Border) as well as at M’Pacha and Katima Mulilo in the Eastern Caprivi Strip.
Besides the United Kingdom, Cymbeline users included South Africa, Denmark, Egypt, Cameroon, Morocco, Finland, Iraq, Kuwait, Malawi, New Zealand, Nigeria, Norway, Oman, Saudi Arabia, Singapore and Switzerland. France acquired the radars that were captured in Iraq.