Scattering from a large planar slotted waveguide array antenna

The problem of scattering from a large planar slotted waveguide array anten na is investigated. The structural scattering and slot scattering are solve d independently through the application of the equivalence principle. The f ormer is calculated by a high-frequency method, such as the physical optics (PO) and the shooting and bouncing ray (SBR) method combined with edge dif fraction. The latter is solved using the method of moments (MoM) in conjunc tion with global sinusoidal basis functions and Galerkin's testing techniqu e. Special attention is paid to the evaluation of the admittance matrix ele ments, which involve the internal and external mutual coupling. Numerical r esults are presented to demonstrate the effects of a variety of factors on the radar cross section (RCS) of a slot array, and these include the number of basis functions in the MoM solution, the external mutual coupling betwe en the slots, the waveguide terminations, and the host object. Also given a re the RCS space distribution and the time responses of slot arrays to illu strate their unique scattering characteristics. The RCS of a complicated re al slot array is given finally to demonstrate the capability of the numeric al method as well as the distinct features of its RCS pattern.