Some effects of dielectric loading on periodic slot arrays

The applications of arrays of rectangular slots have been severely limited since their resonant frequency (where unity transmission occurs) and bandwidth change with incident angle. By utilizing a modal analysis solution which includes the effects of dielectric slabs on both sides of the array, we show that these dielectric effects can, with proper design, reduce or eliminate the unwanted changes in resonant frequency and bandwidth. The presence of the dielectric slabs also cause other changes in the transmission curves. Two of these changes are the occurrence of the Wood\´s anomaly ("blind angle") null at a lower frequency, and additional narrow resonances in the transmission curves. These phenomena are explained by considering the behavior of the Floquet modal impedances in the presence of the dielectric layer.