Corner effects on the mutual impedance between edge slots

An analysis for calculating the mutual impedance between two edge slots in a linear slotted waveguide array is presented. The analysis uses a 90° wedge Green´s function to account for the influence of the waveguide corners on the evaluation of the external mutual coupling. A novel asymptotic formula for the 90° wedge Green function´s is derived to expedite the numerical analysis for slots with large separation. Numerical results show that the phase of mutual impedance retards linearly with slot separation and the magnitude decays as the separation is increased. However, the mutual impedance of edge slots is larger and decays more slowly than that of longitudinal slots or other slots in a large ground plane. The distinguished characteristics can be attributed to the energy guiding effect of the waveguide corners, which is discovered and verified mathematically and numerically. Also shown in the numerical calculations are the incremental conductances of the individual slots in a linear edge slot array, which are compared, and found to be in good agreement, with the available experimental data