SIW Slotted Waveguide Array With Pillbox Transition for Mechanical Beam Scanning

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A dual-layer pillbox antenna is proposed for mechanical beam-scanning applications at millimeter-wave frequencies. It consists of three main subsystems (multislot quasi-optical transition, input part, and radiating part). The input and radiating parts are placed in two different layers, and the quasi-optical transition behaves as a 180 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ} ~E$</tex></formula> -plane coupler-type bent. The latter is made of an integrated parabolic reflector and several coupling slots etched in the metal layer located between the two substrates hosting the input and radiating parts. A physical optics analysis of the transition is proposed and compared to full-wave simulations. The radiating part is a planar slotted waveguide array. The input part is an <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex></formula> -plane integrated sectoral horn placed in the focal plane of the parabola and moved along a straight line to obtain the beam scanning. For the horn aligned with the parabola axis, the radiation patterns present half-power beamwidth equal to 6 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ} $</tex></formula> and 15 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ} $</tex></formula> in <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$E$</tex></formula> - and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex></formula> -plane, respectively. The scan range is <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm 35^{\circ} $</tex></formula> . This mechanical scanning approach represents an attractive solution for those applications where a continuous steering of the main beam is required.