Higher-order mode coupling between H-plane T-junctions and cross-guide slot couplers in feed networks of waveguide slot arrays

The effect of higher-order mode coupling between an H-plane T-junction and closely spaced cross-guide slot couplers, as used in the feed networks of slotted waveguide arrays has been investigated. The effect has been found to be significant and a procedure is proposed to compensate for this effect as part of the design procedure of slotted waveguide arrays. The effect can be adjusted for by changing the lengths and angles of the coupling slots, using a pre-determined database of S-parameters computed with a full-wave analysis procedure.