Radars are among the most important means for monitoring mobile targets in the fighting actions theatre, but they have different monitoring range and precision. Several types of radars have been developed and updated during the last decade, acquiring added efficiency. The vast majority of military strategists agree that array radar antennas are the most important among radar systems, highly dependable in modern wars long-range detection and monitoring operations.
German admiral Carl Dwenter termed them “the greatest weapon and most decisive in wars after the atomic bomb”.
The Americans consider them as the main element in the missile shield system.
The array antennas could be useful in taking over the horizon (OTH) pictures.
What are the array radar antennas?
What is their role in the fighting actions theatre?
A cursory historical glance shows that the first beginning of radars date back to the year 1886 when German scientist Henrich Hurtz successfully proved the presence of radio waves. He discovered that they are similar to light waves and are reflected on solid objects.
Research in this field was pursued by the British and Scottish scientists Maechel Faraday and James Maxwell respectively. In 1904, German scientist Christian Holtmer invented the first device for the detection of radio waves transmitted by ships. A quantum leap in the development of radio waves detection devices was made as a result of research and tests conducted by Italian scientist Geoglimo Marcouni as of 1922. It was possible to use high-frequency radio waves to monitor bodies hundreds of kilometers away.
At the American navy research laboratories the scientists Tailor and Wyoming sought to develop radar that operates on continuous 5 meter-long radio waves transmission. The pulsed radar was invented in 1925.
However, the year 1930 marked the beginning of the international race for the development of the radar, spearheaded by the U.S., the former Soviet Union, Germany, England and France. In 1935, the U.S. succeeded in inventing a pulsed radar with a 38.3 megahertz frequency, while in 1939 Germany invented the early warning radar. Joined by many countries of the world, the race is still continuing.
The most important types of radars used for military purposes include:
The bistatic is comprised of two basic units: one for transmission and the other for reception. The first unit is located far from the second and is used for guiding semi active guidance missiles.
The mill metric radar ;with a frequency range of 30 to 300 gigahertz, corresponding to a wave length sphere of 1 to 10mm, lower than the electro-visual waves sphere and higher than the mirror waves.
The pulsed Doppler radar is characterized by frequency change of radar waves due to relative movement between the radar and the target. It is mainly used to distinguish between mobile and immobile targets.
The over the horizon (OTH) detection radar use sky waves with a monitoring range of 3000 to 4000 km.
The 3D radar is capable of determining and measuring the target’s height, horizontal angle and direct distance from the radar.
Array radar antennas:
The antennas are the basic and decisive components in waves’ transmission and reception in radar systems. They are divided into two main types:
Parabolic antennas: these are parabolic semi-conductor reflectors and their focus contains a radioactive source.
Array antennas: a collection of radioactive elements distributed along one line or in equal parallel lines. They are completely suitable to long wave radars.
With regard to radiation model scanning potentials, they are divided into the following:
Electronic scanning: it uses microwave radars and equipment capable of altering phase angle between contrasting radiation elements received inside the radar system, allowing scanning in height angle and the radar antenna’s direction angle. This type of array antennas is reliable in managing patriot missile system, Mig 31 planes, French Rafael planes and PNP planes. And due to the great technological advances, shifting from silicon to Gallium Arcinanid in the manufacture of radars and high-frequency generators, the electronic scanning arrays have achieved greats advances in the last few years. They have become more efficient in fulfilling their assignments.
Mechanical scanning: in this type the signals accumulate in the required direction, vertical at the antenna level with the potential of obtaining a radiation model at a tilt angle of up to 60 degrees on the vertical level of the antenna. This allows the transmission and reception of electro-magnetic waves.
The mechanical scanning arrays are capable of controlling the radiation model’s shape and the size of the antennas side lobes, achieving high-precision results. This is in addition to the possibility of determining the signal’s phase and capacity in each radiation element of the array. This in turn ensures the collection of specific data about the target being monitored. This type of radar arrays is widely used to monitor surface and aerial targets.
Presently, there are important programs and projects for further developing and upgrading the efficiency of radar array. These include the joint French, German and British project to satisfy ever-growing demands to repel post-2010 modern aerial assault means. This is in addition to the American program aimed at creating a new generation of air-borne active radar arrays that operate on wave frequencies in the microwave sphere and are expected to be installed in F22 and FSX planes.
Military importance of antenna arrays:
Modern armies are relying increasingly on radar antenna arrays which the German admiral Carl Dwenter termed “the greatest weapon and the most decisive in wars after the atomic bomb.” The scope of its assignments has been widened and the Americans consider them the main element in the missile shield system. They are capable of monitoring the scope of land-based X-frequencies and sending early warning against international ballistic missiles and monitoring their course. Moreover, they are capable of locating the enemy’s strategic and military targets, such as military planes hangers, submarines, ships, military boats, aircraft carriers, tanks, artillery, vehicles and even personnel locations and movements. They also have the ability to automatically guide various missiles towards enemy targets achieving high-precision hits. They use electromagnetic waves to brighten the target, enabling the radar-guided missiles to pick up waves reflected from the target and swiftly attack it.
The antenna arrays of specific size are able to achieve their mission with high precision, particularly as regards determining the height as part of a 3D radar system. However the tactical size (medium) antennas are the most important in monitoring and follow-up operation as well as brightening enemy targets for quick automatic assault. Meanwhile, giant antenna arrays are capable of over the horizon (OTH) detection following up space ships and monitoring satellite activities.
To keep abreast of advances in military planes’ camouflage systems and high speeds of more than twice the speed of sound, laser-operated radar antenna arrays have been developed with the ability to detect and follow-up high-speed targets and automatically engage them. They could be satellite-borne, and in such case they can cover a massive area of more than 12 million square kilometers, monitoring minute military and climate details.
According to electronic communications experts, the laser-operated radar antenna arrays are reliable with regard to picking up enemy radar waves, determining their defense locations and the gatherings of their advanced weapons. They can also evaluate the enemy’s technological energy as well as its monitoring and distortion abilities. This is in addition to monitoring aviation traffic in both the military and civil domains. Add to this the potential to tap the enemy’s telecommunications to analyze its codes and uncover its important secrets.
By: Hosni Abdul Hafiz