Beam Steering Phased Array Antenna With Fully Printed Phase Shifters Based on Low-Temperature Sintered BST-Composite Thick Films

Abstract

This letter presents a novel approach to fully-printed phase shifters for electronically steering the beam of a phased array antenna at S-Band. The phased array consists of four microstrip patch antenna elements and phase shifters, as well as a four-to-one feeding network. As key components in the circuit, the phase shifters are provided with a microstrip loaded-line topology, equipping fully-printed metal-insulator-metal (MIM) varactors with low-temperature sintered BST composite thick films between the top and bottom silver electrodes. Furthermore, a simple biasing concept is implemented for controlling the phase shifter. The fully-printed, low-cost phase shifters achieved a phase shift of 274 <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 a FoM of 37.3 <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> /dB at 3 GHz. The length of the phase shifters was <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$0.2\lambda$</tex></formula> , where their phase shift versus length resulted in a 14.4 <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> /mm measurement, outperforming all previously reported phase shifters based on fully-printed low-temperature sintered BST thick film. The beam-scanning range of the four-antenna element array was <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\pm}30^{\circ}$</tex> </formula> .