INVESTIGATION ON RADIATING ELEMENTS FOR ELECTRONICALLY STEERED PHASED ARRAY ANTENNA FOR AIRBORNE SATCOM

Abstract

Demand for onboard communication on aircraft is increasing day by day. Long distance communication is required between pilot and air traffic control station. One of the primarily means for long distance communication is satellite communication. Due to its various advantages, they are used universally for voice, data and video links. For wide area coverage in military and civilian applications, geostationary satellite communication is widely used. SATCOM is also required for TV reception and broadband internet services. Linear orthogonal polarizations are used at transmit and receive frequency bands to utilize frequency reuse capability. For airborne mobile antenna applications, both antenna beam and polarization tracking should be met simultaneously. Reflector/lens antennas are generally used in such type of communication system [1]-[3]. Mechanically steered tracking antennas [4]-[5] generally have lower efficiency and higher side lobes which limit its use in some applications. One of the disadvantages of the above mentioned antennas is that they are bulky, having large volume and large RCS. For stealth applications, airborne qualifications of these types of antennas become very difficult. Further the parabolic reflector antenna uses dual axis positioning system and stabilization platform which requires periodic maintenance. Reliability has been one of the major issues with mechanical steering system. Owing to various advantages of Electronically Steered Antenna, it has become very important sub system of airborne SATCOM system for beyond the line of sight (BLOS) communication system. People are migrating to Electronically Steered Antenna for satellite communication system. It not only helps in speeding up the pointing mechanism but also reduces the maintenance cost of antenna system. Electronically Steered Antenna fully removes the above problem by making it automatic steered system. Besides providing solutions to above, they can also be made conformal to the host platform on which they are mounted. This reduces the resultant radar cross section of the airborne platform.