The origin and development of radar refers to a later pre-war period in comparison with radio communication. And, nevertheless, the armies of the countries of the fascist bloc, as well as England, the USA and the Soviet Union, by the beginning of World War II, were armed with radars for various purposes, which primarily provided air defense. Thus, the German air defense system used the Freya early warning radar (range up to 200 km) and Bolshoi Würzburg (range up to 80 km), as well as the Maly Würzburg antiaircraft gun aiming radar (range up to 40 km). Somewhat later, powerful stationary radars of the Wasserman type (with a range of up to 300 km) were put into operation. The availability of these funds made it possible by the end of 1941 to create a fairly slender air defense radar system, which consisted of two belts. The first (external), began at Ostend (110 km north-west of Brussels) and stretched to Kukshaven (100 km west of Hamburg). The second (internal) one went from the northeastern border of France along the German-Belgian border and ended at Schleswig-Holstein. With the introduction of the Mannheim-type anti-aircraft artillery fire control radar (range up to 70 km) in 1942, additional posts began to be established between these two belts. As a result, by the end of 1943, a continuous air defense radar field was formed.
During the course of the war, England built a network of stations along the southern coast, and then along the entire east coast. This is how the Chain Home line was born. However, German intelligence soon revealed not only the location, but also the main parameters of this network. In particular, it was found that the directional diagrams of the British radars in relation to the surface of the earth (sea) make up a certain angle, forming blind zones in the detection system. Using them, the fascist aviation carried out the approach to the coast of England at low altitudes. The British had to create an additional radar line to provide a low-altitude field.
Thanks to the created system, which worked in close cooperation with other types of reconnaissance, the British were able to timely detect enemy aircraft, raise fighter aircraft into the air and alert anti-aircraft artillery. At the same time, the need for continuous air patrols disappeared, as a result of which interceptor fighters were used with greater efficiency. The losses of Hitler's aviation increased sharply. So, only on September 15, 1940, the Germans lost 185 of the 500 aircraft that participated in the raid. This forced them to switch mainly to night raids.
At the same time, a search began for methods and means that make it difficult to detect aircraft in the air by enemy radar systems. The solution to this problem was found in the use by aviation of passive and active interference to radar equipment.
Passive jamming was first used by the crews of British bombers during the raid on Hamburg on the night of 23-24 July 1943. Metallized tapes (aluminum foil), called "Windou", packed in special cassettes (packs), were dropped from aircraft and "clogged" the screens of enemy stations. In total, about 2.5 million cassettes, 2 thousand tapes each, were used in the raid on Hamburg. As a result, instead of 790 bombers participating in the raid, German operators counted thousands of aircraft, unable to distinguish real targets from false ones, which disrupted the fire control of anti-aircraft batteries and the actions of their fighter aircraft. The effect of interference on anti-aircraft artillery radar has been especially successful. The overall effectiveness of German air defense after the start of the large-scale use of passive interference decreased by 75%. Losses of British bombers were reduced by 40%.
To distract and exhaust the air defense forces, aviation sometimes imitated false massed raids in distracting directions with passive interference. For example, on the night of August 18, 1943, during a raid on the Peenemünde missile center, the British undertook a diversion: several Mosquito aircraft, using passive jamming cassettes, imitated a massive raid on Berlin. As a result, a significant part of fighter aircraft from the airfields in Germany and Holland was raised towards the jamming aircraft. At this time, the aviation operating on Peenemünde met almost no opposition from enemy air defense systems.
The means of passive interference have been constantly improved. For example, anti-aircraft artillery shells stuffed with passive reflectors were used to jam aircraft radars. Suppression of ground and ship radars was carried out with the help of missiles equipped with "Windo". Sometimes, instead of cassettes with foil, planes towed special metal nets, which are decoys for operators of fire control and guidance stations of aviation. German aircraft first used passive jamming in August 1943, during raids on British targets and ships off the coast of Normandy.
The next step in the development of means of combating radar was the use of active interference by the belligerents, that is, special electromagnetic radiation suppressing the radar receivers.
Aircraft jammers such as "Carpet" were first used by the Anglo-American aviation in October 1943 during the raids on Bremen. By the end of the same year, on-board active jammers were installed on all heavy bombers B-17 and B-24 of the 8th and 15th American air armies operating in Western Europe. The British bomber aviation was equipped with such transmitters only by 10%. True, the British, in addition, had special jamming planes used for group cover of aircraft detachments. According to the foreign press, for one downed bomber before the use of radio interference, the German air defense spent an average of about 800 anti-aircraft shells, while under conditions of active and passive interference on the radar - up to 3000.
Active jamming and corner reflectors were most successfully used in the complex against airborne radar bomb sights (reconnaissance radar and aimed bombing). For example, the Germans learned that during night raids on Berlin, bombers are using the Weissensee and Mügelsee lakes, located near the city, as radar-contrast landmarks. After numerous unsuccessful experiments, they managed to change the coastal shape of the lakes with the help of corner reflectors mounted on floating crosspieces. In addition, false targets were created, simulating real objects, at which the Allied aviation often carried out bombing. For example, during radar camouflage of the city of Kustrin, corner reflectors were placed in such a way that characteristic marks of two "identical" cities were observed on the screens of aircraft radars, the distance between which was 80 km.
The combat experience accumulated during the war by the air defense forces and the air force showed that in the conduct of electronic warfare, the greatest effect is achieved with the sudden, massive and complex use of means and methods of suppressing radar. A characteristic feature in this regard is the organization of electronic warfare during the landing of the Anglo-American assault force on the coast of Normandy in 1944. The influence on the radar system of the Germans was carried out by the forces and means of the air, naval, airborne and ground forces of the allies. They used about 700 aircraft, ship and ground (automobile) transmitters to create active jamming. A week before the landing of the expeditionary forces, most of the German radar stations exposed by all types of reconnaissance were subjected to intense bombardment. On the night before its start, a group of aircraft with jammers patrolled along the coast of England, suppressing German early warning radars. Immediately before the invasion, air and artillery strikes were launched at the radar posts, as a result of which over 50% of the radar station was destroyed. Simultaneously, hundreds of small ships and vessels in small groups headed for Calais and Boulogne, towing metallized balloons and floating corner reflectors. Ship guns and rockets fired metallized ribbons into the air. Passive reflectors were dropped over the ships in progress, and a group of bombers, under cover of interference, simulated a massive raid on Berlin. This was done in order to disorganize the operation of the surviving radar surveillance system and mislead the German command about the true landing site of the allied forces.
In the main direction of the landing, British bombers with jamming transmitters suppressed German radars and threw out smoke bombs to obstruct the enemy's visual observation. At the same time, air strikes were launched against large communication centers in the landing area, and sabotage groups destroyed many wire lines. On 262 ships and ships (from a landing barge to a cruiser, inclusive) and on 105 aircraft, jammers were installed, which practically paralyzed the work of German radars of all types.
When the Anglo-American forces were conducting active offensive operations, it became necessary to use radar to organize interaction between ground forces and aviation. The difficulty lay in the fact that radio, missiles, signal panels, tracer shells and other means by which interaction was carried out in the first period of the war, could ensure the coordinated actions of ground forces and aviation only under the condition of good visibility. The technical capabilities of aviation already at that time made it possible to use it at almost any time of the day or year, in any weather conditions, but only with the availability of appropriate navigation equipment.
The first attempts to partially use radar to ensure continuous interaction between ground forces and aircraft were made by the Americans during operations in North Africa. However, they managed to create a system of radar interaction only by the beginning of the invasion of the European continent.
Organizationally, such a system was based on the use of a group of stations that performed various functions, depending on their type. It consisted of one MEW early warning station (range up to 320 km), three or four TRS-3 short range detection stations (range up to 150 km) and several aircraft guidance stations for ground targets SCR-584 (range up to 160 km) … The MEW station, as an operational information center, was provided with telephone, telegraph and VHF radio communications with all radar and visual observation posts, as well as with the aviation headquarters, whose function was to make decisions on the current air situation and control air units. The SCR-584 station took the aircraft directly to the area of the object, which greatly simplified the search for the target. In addition, each radar of the system had a VHF radio station for communication with aircraft in the air.
A more difficult task than the use of radar to ensure interaction between ground forces and supporting aircraft was the use of radar equipment to detect ground targets and firing artillery (mortar) batteries of the enemy. The main difficulty lay in the very principle of operation of the radar - the reflection of the radiated electromagnetic energy from all objects encountered in the path of its propagation. And, nevertheless, the Americans managed to adapt the SCR-584 gun guidance stations to monitor the battlefield. They were included in the general artillery observation system and provided reconnaissance of ground moving targets in medium-rugged terrain to a depth of 15-20 km. Ground-based radar detection, for example, in corps artillery, accounted for about 10%, in divisional - 15-20% of the total number of reconnoitered targets.
Closed artillery and mortar positions using radar were first discovered during the battles on the bridgehead in the Anzio region (Italy) in 1943. The use of radar for these purposes turned out to be a more effective method than sound-metric and visual observation, especially in conditions of intense shelling and heavily rugged terrain. Marking the trajectory of the projectile (mine) from several directions on the radar indicators, it was possible to determine the enemy's firing positions with an accuracy of 5-25 m and organize a counter-battery fight. At first, the stations SCR-584 and ТРS-3 were used, and then a modified version of the latter - ТРQ-3.
The relatively successful use of radar by the Americans for conducting ground reconnaissance is primarily due to the fact that the Germans did not at all assume that the enemy was using these means for these purposes. Therefore, they did not take the necessary countermeasures, although they had experience in conducting electronic warfare in the air defense system, in the Air Force and the Navy.
In the Soviet armed forces, the means of radar and electronic warfare were used by the air defense forces, aviation and the navy. The ground forces used mainly radio reconnaissance and jamming equipment. The first radar for detecting air targets in the observation, warning and communications troops was the RUS-1 ("Rhubarb") station, which was put into service in September 1939 and first used during the Soviet-Finnish war. By the beginning of the Great Patriotic War, 45 RUS-1 kits were manufactured, which subsequently operated in the air defense system of the Transcaucasus and the Far East. During the war with the Finns on the Karelian Isthmus, the early warning radar RUS-2 ("Redoubt"), which was adopted by the air defense forces in July 1940, underwent a combat test.
It should be noted that the RUS-2 station had high technical characteristics for that time, but tactically it did not fully meet the requirements of the troops: it had a two-antenna system, bulky and complex rotation drives. Therefore, the troops received only an experimental batch, counting on the fact that the single-antenna version of this station, called RUS-2s ("Pegmatite"), passed field tests and was to be launched into series.
In the development of domestic radar, the creation of RUS-2 type stations in comparison with the RUS-1 was a significant step forward, which radically influenced the effectiveness of air defense. Receiving data on the air situation (range, azimuth, flight speed, group or single target) from several stations, the command of the air defense zone (area) was able to assess the enemy and make optimal use of the means of destruction.
By the end of 1942, two prototypes of gun aiming stations called SON-2 and SON-2a were created, and in 1943 their mass production began. SON-2 stations played a very positive role in the combat operations of anti-aircraft artillery. Thus, according to reports from the 1st, 3rd, 4th and 14th corps, the 80th and 90th air defense divisions, when firing using these stations, 8 times less shells were used for each downed enemy aircraft than without the stations. In terms of the simplicity of the device and reliability in operation, the cost of production and transportation conditions, as well as in terms of the time of folding and deployment, the domestic radars were superior to the German, British and American ones created in the late 30s and early 40s.
The formation of radio engineering units began with the creation of the first radar unit near Leningrad in the fall of 1939. In May 1940, the 28th radio regiment was formed in Baku, in March-April 1941 - the 72nd radio battalion near Leningrad and the 337th radio battalion near Moscow. Radar technology was successfully used not only in the air defense of Moscow and Leningrad, but also in the defense of Murmansk, Arkhangelsk, Sevastopol, Odessa, Novorossiysk and other cities. In 1942-1943. So-called "high-altitude" attachments (VPM-1, -2, -3) were made to the RUS stations to determine the altitude of targets, as well as devices for identifying air targets using the "friend or foe" system, which made it possible to use them for guidance fighter aircraft against enemy aircraft. In 1943 alone, according to the radar, the number of fighter aircraft guided by air defense forces covering frontline targets increased from 17% to 46%.
A great achievement of Soviet radar was the creation of aircraft stations of the "Gneiss" series for the detection and interception of air targets. In 1943, these stations were equipped with aircraft of the first division of heavy night interceptors in the history of World War II. The Gneiss-2m radar was also successfully used on torpedo aircraft of the Baltic Fleet. In parallel with the creation of aircraft intercept stations, the development of radar sights was carried out. As a result, radars for interception and aiming were created (there were only intercept radars abroad) for air targets, as well as a radar bomb sight, which made it possible to carry out accurate bombing of ground targets, in any conditions, day and night.
When striking enemy targets, our bomber aircraft also used passive radio interference to suppress its early warning radar for air targets, target designation, and aim anti-aircraft artillery and fighter aircraft at the aircraft. As a result of the massive use of radar by the enemy in anti-aircraft artillery and on night fighters, the losses of our bombers have increased. This made it necessary to organize countermeasures to the enemy's radar system. When approaching the radar detection zone, our aircraft moved to low altitudes, using the "dips" in the radiation patterns of the enemy radar. In the target area, they gained a given altitude, changed direction and flight speed. Such a maneuver, as practice has shown, led to a violation of the calculated data of the fire control devices of anti-aircraft batteries and the disruption of attacks by enemy fighters. With the approach to the radar zone, the crews of the bombers threw out metallized ribbons, which created passive interference with the enemy's radar. In each air regiment, 2-3 aircraft were allocated to create interference, which flew above and in front of the strike groups. As a result, the ejected ribbons, lowering, hid the latter from radar detection.
The continuous development of means and methods of radar and electronic warfare during the Second World War had a significant impact on the methods of combat operations and the effectiveness of the air defense forces, air force, navy and ground forces of the parties. In the course of the war, the scale of the use of ground, ship and aircraft radar equipment and means of jamming was constantly growing, the tactics of their combat use was developed and improved. These processes were characterized by a double-edged struggle of the parties, which abroad in the post-war period began to be called "radio war", "war on the air", "radar war" and "electronic war".
