Design of tri-band ENZ SIW sensor for microwave testing of materials in 3G and 4G GSM bands

This paper presents a novel tri-band epsilon-near-zero (ENZ) substrate integrated waveguide (SIW) based microwave sensor for microwave material testing at global system for mobile communications (GSM) bands. The prototype RF sensor is designed, simulated, and tested for the microwave characterization of materials in 3G and 4G frequency bands. The proposed design provides a substantial reduction in the sensor size, and facilitates complex permittivity measurement at multiple frequencies with reasonable sensitivity as compared to the conventional SIW based sensors. The device is fabricated using multiple layers of FR4 substrate, and the RF signal is coupled using SMA connectors which is then tested for various reference samples. The measured data are found to be in good agreement with their reference values thus validating the proposed design methodology.