Compensation for Asymmetrical Slot Fields in the Design of SIW Slot Arrays

For high-frequency applications, slot arrays are often implemented in Substrate Integrated Waveguide (SIW). In addition to retaining the high performance attributes of metallic slotted waveguide antennas, the manufacturing process for SIW slot arrays is simple and cost-effective. Although the viability of slot arrays in SIW has been widely reported, high-precision design of arrays to stringent specifications is limited. For shaped-beam or low side-lobe patterns, strict control over element excitation of each slot is vital. Conventional design principles fall short in this regard, largely due to failure of the simplified equivalent circuit for slots that does not account for the asymmetry in the slot field distribution. In this paper, we present an improved design technique that accommodates asymmetry in slot fields and incorporates the full T-network equivalent circuit for each slot.