Diffraction by two narrow slits in one of two parallel intinite conducting plates on which transverse electromagnetic wave is incident is analyzed extending the concept of the equivalent magnetic current induced in a narrow slit in an intinite conducting plate. Equivalent magnetic currents in two slits are calculated asymptotically in terms of series in wavelength, width of a slit, distance between two slits and distance between two plates. Reflection effect by the other plate and mutual coupling effect between two slits are shown graphically comparing the currents in two slits with the current in a slit.
The method presented here is so general that equivalent magnetic currents in any number of nonperiodic slits will be calculated using it systematically.
