A Microwave Differential Dielectric Sensor Based on Mode Splitting of Coupled Resonators

Area of Science:

• Electrical Engineering
• Applied Physics
• Microwave Engineering

Background:

• The avoided mode crossing phenomenon offers unique opportunities for designing sensitive microwave devices.
• Split-ring resonators (SRRs) are versatile planar resonators suitable for microwave applications.
• Differential sensing requires precise control over resonator coupling and frequency response.

Purpose of the Study:

• To explore the viability of avoided mode crossing for microwave differential sensor design.
• To implement and validate a differential sensor based on coupled split-ring resonators.
• To demonstrate the sensor's capability in characterizing materials based on their dielectric properties.

Main Methods:

• Theoretical investigation of avoided mode crossing using coupled resonator techniques.
• Design and simulation of a two-coupled-SRR system using 3D full-wave numerical methods.
• Experimental fabrication and testing of a microstrip-based microwave differential sensor.

Main Results:

• Demonstrated control over coupling strength by adjusting the distance between SRR splits, leading to increased frequency splits.
• Successfully utilized the coupled SRR system as a differential microwave sensor by modulating coupling with materials under test.
• Experimental validation confirmed the sensor's ability to differentiate materials with distinct dielectric constants (2.33 and 9.2).

Conclusions:

• Avoided mode crossing in coupled SRRs is a viable principle for novel microwave differential sensors.
• The proposed sensor design offers a sensitive and tunable platform for material characterization.
• This work paves the way for advanced microwave sensing applications leveraging coupled resonator physics.