Numerical study on coupling of microwave pulses into different shaped cavities through slots

Linear coupling processes of microwave pulses into rectangular and cylindrical cavities with narrow rectangular slots are investigated by finite-difference time-domain (FDTD) method. Phenomena of field enhancement, cavity modulation, and pulse width stretch are observed, especially the spectrum separation effect. When the electrical field of microwave pulses is parallel to slot short-side, the distribution of coupling microwave electrical fields inside the two cavities are calculated. The coupling electrical field in the plane, which is perpendicular to slot short-side, decreases rapidly near the inner wall of the cavity. In addition, in the cross-sections of the cavities, coupling electrical fields oscillate in a quasi-periodic manner, and the field amplitude is relatively uniform for the