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ZB-298
Tactical pulsed doppler radar - this page is a stub

ZB-298 was a mobile tactical ground-based static pulsed doppler radar, developed by Marconi-Elliot Avionic Systems Ltd. in Borehamwood (UK) around 1965. The device was intended for use by reconnaissance units and delivered a acoustic and visual output. It was used until the mid-1990s.
 
The unit operates in the 3 cm (10 GHz) X-band, and consists of a control unit that is connected to a rectangular antenna that is mounted on a tripod. Both the rotation and elevation angle of the tripod can be altered from the control unit.

The radar was typically used by infantry recon­naissance units and had an operational range from 50 metres to 10 km. From the acoustic output, based on the doppler-shift caused by a moving object, a well-trained operator could recognise people, animals, vehicles and tanks, and even give an indication of their volume.
  
ZB-298 in use. Photograph obtained from [2].

The visual output was used to determine the distance and size of the object. Through a lens on the control unit, the operator could see two faint red lines. The first line was caused by the radar's pulse and represented the station's position. The second red line was caused by the reflection and was written by means of a laser and a rotating mirror. The distance could be read from a scale.

The size of the object was determined by first rotating the antenna to the left until the object was lost. Next the antenna was rotated to the right until the object was lost. The difference in angle was used with the measured distance to calculate the size of the object. For this reason, a circle was divided into 1000 units (rather than 360 degrees) which makes the calculations easier. As an example: an object with an opening angle of 3 units, at a distance of 1 km, is 3 metres wide.

The ZB-298 was developed around 1965 and was used that same year by the British Armed Forces in Borneo, although this was not admitted until seven years later in 1972 [1]. The radar was introduced with the rest of the British Army in 1971, where it was known as Radar GS No. 14. It played in important (secret) role in the fight agains the IRA in Northern Ireland. It was later also introduced with some of the NATO partners, like Denmark and The Netherlands. By the mid-1980s the ZB-298 had become dangerous and obsolete but was kept in use until the mid-1990s.
 
ZB-298 in use
The system was portable but heavy, and could be carried by two people. When used in the field the antenna was mounted on a tripod that was marked in thousands (rather than degrees). When used on a vehicle, it was usually mounted on top of the vehicle by means of an electrically movable head. In the Netherlands, the ZB-298 was installed on the YP-408 RDR infantry vehicle and later also on the YPR-765 PR-RDR track-based reconnaissance vehicle, as shown below.

Dutch YPR-765 PR-RDR reconnaissance vehicle with ZB-298 radar. Photograph copyright Dutch MoD [3].

 
Detection
Pulsed radar systems, like the ZB-298, have a high-power Klystron that transmits a rather strong radio signal. This signal can easily be picked up by an eavesdropper or by an enemy recon­naissance unit with suitable equipment. This makes such radar systems potentially dangerous.
 
In the mid-1980s, it gruadually became known to Western intelligence that the signal from a static pulsed-doppler radar system could be detected and used to determine its location.

In the early 1970s, the Czechoslovak company Tesla had already developed a small portable radar locator, known as the MPR-4, which could detect, identify and locate any radar in the 1 - 10 GHz range. The MRP-4 could be carried on the chest and produced an acoustic feedback to the operator through a small in-ear speaker. It also had a meter that produced a visual indication.
  
Czechoslovak MRP-4 radar locator. Click for more information.

Althoug the MRP-4 was initially developed for the Czechoslovak Army, it was later successfully sold to most other countries of the Warsaw Pact and to the Soviet Union (USSR), where functional duplicates were made as well. The MRP-4 was deployed with every reconnaissance unit of the Czechoslovak Army and also with the Special Forces of the Hungarian Army. As a result, the ZB-298 became a dangerous device that was gradually phased out. Nevertheless it took until the mid-1990s, way past the end of the Cold War, before the units were oficially declared obsolete.

 More about the MRP-4 radar locator
 
References
  1. New Scientist, Technology review
    24 August 1972 p. 386.

  2. DAF YP408, Image of ZB-298 doppler radar in use
    Website. Retrieved July 2016.

  3. NIMH, Image of YPR-765 PR-RDR with battle field reconnaissance radar
    Ministerie van Defensie (Dutch MoD). 1982-1987. Retrieved July 2016.

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Crypto Museum. Created: Thursday 28 July 2016. Last changed: Friday, 10 February 2017 - 09:43 CET.
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