Improved Design of Low Sidelobe Substrate Integrated Waveguide Longitudinal Slot Array

Abstract

A single-layer substrate integrated waveguide slot array is presented for use in low sidelobe applications. A compact three-level power divider is developed to provide the required phase distribution and enhanced co-phase bandwidth. Then, the Elliott’s design procedure is employed taking accurately into account both the external coupling and the high-order mode internal coupling. The measured radiation pattern and the frequency response are in very good agreement with design specifications and with simulated results provided by CST Microwave Studio. The measured sidelobe level at the center frequency is below <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 32.3 dB in the E-plane and below <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex> </formula> 33.8 dB in the H-plane for a design goal of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 35 dB.