A New Compact Wideband Filter Based on a Coupled Stepped Impedance Resonator

Area of Science:

• Electrical Engineering
• Microwave Engineering
• Electromagnetics

Background:

• Modern communication and radar systems require compact and wideband filters.
• Existing filter designs often face limitations in size, bandwidth, and stopband performance.
• Stepped Impedance Resonators (SIR) offer potential for miniaturization and enhanced filtering characteristics.

Purpose of the Study:

• To introduce and validate a new compact wideband filter based on a short-circuit coupled stepped impedance resonator (SIR).
• To demonstrate the filter's flexibility in achieving tunable bandwidths for diverse applications.
• To verify the design's suitability for next-generation microwave circuits requiring size-compactness.

Main Methods:

• Analytical solution derived for the proposed SIR resonator to predict performance.
• Design and simulation of a compact two-coupled short-circuit SIR filter at 1.23 GHz using CST Microwave Studio.
• Fabrication of a four-resonator filter using Rogers RT/duroid 6010.2LM material and experimental validation.

Main Results:

• The SIR resonator enables compact size and a wide stopband response.
• Increasing the impedance ratio of the SIR extends the stopband and reduces overall length.
• The implemented filter achieved a 29.4% relative bandwidth centered at 1325 MHz with 1.3 dB insertion loss.

Conclusions:

• The proposed short-circuit coupled SIR filter design is validated through simulation and experimental results.
• The structure offers flexibility, achieving relative bandwidths from 5% to 50%.
• This component shows significant potential for next-generation microwave circuits demanding flexibility and compactness.