Analysis of hard surfaces of cylindrical structures of arbitrarily shaped cross section using asymptotic boundary conditions

The surface equivalence principle is used to formulate the problem of infinitely long cylindrical structures of arbitrary cross section and loaded with metallic strips. The strips are tilted by an angle with respect to the cross section plane. Special cases are considered when the strips are directed along or transverse to the cylinder axis. The excitation is an oblique plane wave incident with arbitrary polarization. The asymptotic strip boundary condition (ASBC) is used to simplify the problem. The surface integral equations are solved using the method of moments. The numerical solution is verified with the series solutions of the circular cylinders loaded with helical strips. Several applications of hard surfaces are presented for structures loaded with tilted strips such as the struts loaded with tilted strips to reduce the equivalent blockage width of the struts and make it polarization independent.