In-Band SCS Reduction of Microstrip Phased Array Based on Impedance Matching Network
Peng-Fa Li, Shi‐Wei Qu, Shiwen Yang, Jun Hu
Abstract
A novel method to reduce in-band scattering cross section (SCS) of a phased array while maintaining high radiation performance is proposed in this article, by using a special impedance matching network. The optimum load impedance curves of a phased array element are theoretically analyzed according to the antenna scattering mechanism first, and they are approximated by an impedance matching network cascaded to the element afterward. Then, an E-plane <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times32$ </tex-math></inline-formula> linear microstrip array antenna operating in 8–10 GHz is designed to validate the proposed idea, and a parallel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RLC</i> circuit is adopted to match the optimum element impedance curves in the operating band, whose <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> values are determined by minimum mean square error criterion. Practically, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RLC</i> circuit is implemented simply by strip lines with open-circuited and short-circuited shunt stubs, as well as an impedance transformer. According to numerical and experimental studies, the proposed array antenna features an obvious in-band SCS reduction (SCSR) of typically above 6 dB compared to its conventional counterpart without the impedance matching network, while maintaining high radiation, aperture efficiencies, and reflection coefficient around −10 dB.