This paper presents the design of low sidelobe single-layer slotted waveguide arrays. The Taylor distribution with -25 dB sidelobe level is synthesized in two orthogonal directions in the aperture. The multiple-way power divider consisting of a cascade of novel π-junctions is introduced; each π-junction, two-way power divider, is so designed as to accept unequal power dividing by adopting an offset window. The smooth Taylor distribution is realized at the output of the multiple-way power divider, which was originally developed only for uniform distribution. A model antenna for Taylor distribution is tested at 76 GHz. The measured sidelobe level is below -24 dB in both E- and H-plane. The highest gain is 34.5 dBi with 50% efficiency which is only 15% lower than that for uniform aperture illumination.

The authors propose a novel waveguide two-way power divider, named as τ-junction, in a feed waveguide of a single-layer slotted waveguide array antenna. This junction occupies only a small space and is placed in the middle of a cascade of several power dividers. It suppresses the long line effect and widens the bandwidth of the feed waveguide. The junction has two inductive walls; one is for suppressing the reflection and the other is for controlling the ratio of divided power to the two output ports. Analysis using Galerkin's method of moments is verified by experiments of a 4 GHz-band model. We install the junctions in a 12 GHz-band single-layer slotted waveguide array. The gain reduction at the band-edge is suppressed.