High Frequency Diffraction by Rectangular Hole in a Thick Conducting Screen - H Polarization Case

H-polarized plane wave diffraction by rectangular hole in a thick conducting screen has been analyzed by Kirchhoff approximation (KA). The diffraction fields from this hole can be considered as field radiations from equivalent magnetic currents assumed by closing the aperture. The internal fields in the hole region expressed by parallel plane waveguide modes are shown first, then these fields are again converted into the equivalent currents for the diffracted field from the lower hole aperture.