A bandwidth enhancement technique for microstrip fed slot arrays

A theoretical model that shows that the concept of double-tuned waveguide coupled slots is a feasible approach for increasing bandwidth is developed. A full-wave integral equation technique has been developed which allows the analysis of not only thick slots. but also slots which are coupled through a section of waveguide. The latter case also provides a mechanism for improved performance. By adjusting the slots on the ends of the waveguide section to different lengths. one can essentially 'stagger tune' each slot to a different frequency, increasing the overall bandwidth. Within the limited range of parameter variation used, apparent bandwidth increases in the order of at least 50% have been seen. To illustrate the behavior of the structure, a 0.60 in*0.60 in cavity fed by a stripline with a ground spacing of .125 in at 9.7 GHz is studied.<>