The author has expanded the results in reference[1]

where the effect of transverse components in the magnetic field of slot was not taken into consideration to simplify the problems. Based on the modified inter-boundary conditions

relevent coupled wave equations have been obtained for the slot-coupled system. At cut-off resonance points

first-order approximate solutions are in agreement with the results as shown in ref. [1]. However

at the slot-resonance points

theoretical analysis and experiments have confirmed that strong coupling would occur in the slot-coupled system owing to slot-resonance. By the use of such phenomenum

it is possible to design microwave devices with very short lengths.