Engineering Design of a Wideband and High-Gain Inline Slot-Array Waveguide Antenna Using Low-Cost Metallized Polymer Technique

In this article, a high-performance slot-array waveguide antenna with a low-cost metalized polymer technique for W-band applications is proposed. Choke groove structures are induced to enhance the gain, suppress the sidelobe level (SLL), and improve the isolation between two adjacent channels. A step structure and a chamfer structure are introduced in the horizontal-to-vertical waveguide transition to improve the antenna’s impedance matching. Based on these technologies, an eight-channel MIMO array antenna for an automotive radar sensor operated at 77 GHz is designed and fabricated. The proposed design adopts metal etching on the first layer for high precision requirements and the metalized plastic injection molded technique instead of the conventional computer numerical control (CNC) milling technique for cost reduction. Measured results show that wide impedance bandwidth (S<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$11\lt -15$ </tex-math></inline-formula> dB) is approximately 11.5% (74–83 GHz) with a high gain of 15 dB and low SLL of −22 dB.