A waveguide problem involving a thick iris in the theory of electromagnetism (Q1432776)

The authors consider the problem of electromagnetic wave propagation in a rectangular waveguide, in which is present a thick iris, i.e., an obstacle in the form of a rectangular thick perfect conducting metal plate placed parallel to the longer side of the waveguide. It is formulated as a boundary-value problem whose solution is obtained in the form of trigonometric series. The relations involving series coefficients are transformed in two ways into integral equations which are then solved approximately. The graphs of the reflection coefficient vs. the parameters of the iris and the wave number are constructed. It is obtained that while for the thin iris the reflection coefficient increases with the wave number, this coefficient starts fluctuating when the thickness increases and assumes zero values for a discrete set of wave numbers.