Pattern Synthesis in Butler-Matrix-Fed Cylindrical Antenna Array for Monopulse NR-IFF Radar Application

This paper presents the design and procedure of pattern synthesis in a cylindrical antenna array with electronic scan capability suitable for Non-Rotating Identification Friend or Foe (NR-IFF) radar system. To this purpose, 64 printed dipole antennas are placed around a cylindrical ground plane, out of which 16 elements in a 90-degree active sector are united to form the sum and difference radiation patterns required for monopulse technique. The electronic scan can be achieved through commutation of the active sector by a suitable feed network based on the Butler matrix, some variable phase shifters and SP4T switches. MATLAB and HFSS are linked together and particle swarm optimization algorithm is used to synthesize the desired radiation pattern in the active sector. This method is capable of taking into account the mutual coupling effect between the array elements and compensate for it during the design procedure.