Compact and Wide-Stopband Bandpass Filter Using Hybrid Shielded EMCSIW and CSRR Resonators with a Mixed...

Area of Science:

• Electromagnetics and Microwave Engineering
• Applied Physics
• Electrical Engineering

Background:

• Microwave filters are crucial components in modern wireless communication systems.
• Existing filter designs often face challenges with size reduction and performance optimization.
• Substrate-integrated waveguide (SIW) technology offers a planar solution for microwave circuits.

Purpose of the Study:

• To design and validate a novel, compact second-order bandpass filter (BPF).
• To explore the integration of complementary split ring resonator (CSRR) structures within shielded eighth-mode circular substrate-integrated waveguide (SD-EMCSIW) resonators.
• To achieve flexible control over transmission zeros and enhance upper-stopband performance.

Main Methods:

• A hybrid filter design combining SD-EMCSIW and CSRR resonators was conceptualized.
• Electromagnetic simulations were performed to analyze filter characteristics and operating mechanisms.
• The filter was fabricated and experimentally measured to validate simulation results.
• Metallic via-holes were incorporated to improve upper-stopband rejection.

Main Results:

• A second-order BPF prototype operating at 8.3 GHz with an 8.1% fractional bandwidth was realized.
• The filter exhibited two transmission zeros adjustable near the passband.
• Superior upper-stopband rejection of 15 dB was achieved at 2.85 times the center frequency.
• The fabricated filter achieved a compact size of 13.5 mm × 13.0 mm.

Conclusions:

• The proposed hybrid SD-EMCSIW and CSRR BPF design offers a promising solution for compact and high-performance filtering applications.
• The integration of CSRR structures and metallic via-holes effectively enhances filter characteristics.
• The design demonstrates flexibility in transmission zero placement and achieves excellent size reduction.