Scattering from a cylindrically conformal slotted-waveguide array antenna

Slotted-waveguide array antennas are widely used on modern airborne radar. However, conventional planar slotted-waveguide antennas have a significant contribution to the overall radar cross section (RCS) of the host vehicle. Reduction of the antenna's RCS is one of important aspects for the stealth technology. It is well known, the RCS of a flat plate is generally higher than that of a smooth curved surface. Therefore, it is possible to reduce the RCS by replacing a planar slot array with a curved slot array. Because of a large number of slots and the mutual coupling between slots and between slots and the waveguide, the analysis of the scattering from a slotted waveguide array is very difficult. As a result, only planar slot antennas have been considered in the past. Fan (see Ph.D. thesis, Tsinghua University, Beijing, China, 1995) presented the theory of analysis and design of cylindrically-conformal slotted-waveguide array antenna with a curved waveguide as the main guide and sectoral guides as the branch guides. We analyse its scattering properties, and to simplify the analysis, we neglect the coupling between the main guide and the branch guides.