Radiation analysis of conformal phased array antennas on distorted structures

The paper describes the development of computational models for the calculation of radiation characteristics of a phased array antenna, which is located on a steady deformed structure. The objective is to predict accurately the radiation pattern of a conformal phased array antenna and to assess the distortion of the radiation pattern due to deformation of the structure. The developed computational model is based on the high-frequency approximated methods: physical optics and incremental theory of diffraction. The model takes into account imperfections of antenna elements. For the validation of the computational model a conformal antenna is considered that consists of an array of microstrip patch antenna elements, which are mounted on plates of a dihedral aluminium structure. Results of the computational model are compared with data of measurements on the NLR Antenna Test Range. From the comparison it is concluded that the computational modelling provides satisfactory accurate results. The computational model is applied to assess the distortion of the radiation pattern of a C-band phased array antenna, flush-mounted on the skin of a reconnaissance pod under a fighter aircraft. The deformation of the skin of the reconnaissance pod is related to typical vibration due to an external aerodynamic gust load.