Mode matching analysis of biplanar slot arrays

A modal matching analysis of biplanar slot arrays imbedded in dielectric layers is presented. Calculated and measured results show that, with proper design, the dielectric matching layers can be adjusted to produce a biplanar slot array with a wide low-loss passband. Further, the bandwidth will be much less dependent on the incidence angle than in similar arrays without dielectric matching layers. One interesting feature of the investigation was the appearance of an unexpected passband null due to the dielectric filler material which occurs at a lower frequency than any possible Wood´s anomaly. This null was first predicted theoretically and later confirmed by measurements. By modifying the spacing between the slots this null can be removed from the passband.