Impedance bandwidth of a slotted waveguide array: Impact of waveguide length and element shape

The slotted waveguide array is a suitable as standalone antenna and subarray for large array antennas. Its design is complicated, in particular for understanding the impedance bandwidth. As a resonant array of resonant elements, the bandwidth is naturally small, but the role of the main parameters — the waveguide length, the number of slots, and the slot shapes — on the impedance bandwidth is not widely understood. This paper contributes a study which illuminates these roles. Analytic modelling of the slots and waveguide and their interaction is not yet sufficiently accurate to draw specific design conclusions. The complexity of configuration calls for a simulation approach. The results here give direct design information and can assist with formulating transmission line modelling. They show that the impedance bandwidth against the waveguide length for a given slot configuration follows a reasonable trend whereas the impact of the element shape is secondary, and is generally more complex for the larger bandwidths.