Longitudinally slotted cylindrical shield with finite thickness and electrical conductance

The problem of determining E-waves in the presence of a metallic cylinder with a longitudinal sectorial slot in a wall of finite thickness is examined with allowance for the high conductivity of the structure. This problem is reduced to a set of linear algebraic equations with respect to the unknown amplitudes of the diffraction harmonics. Both thin and thick screens are considered, and the effective broadening of the slot is determined. The narrow-slot approximation is used to obtain explicit expressions for resonant-frequency shifts caused by field penetration into the screen and slot. Fluctuations of the frequency dependence of the level of the field passing through a slightly transparent open screen are observed.