Miniaturized Band Pass Filter Design Using Half Mode Substrate Integrated Coaxial Resonators

Area of Science:

• Electromagnetics
• Microwave Engineering
• Filter Design

Background:

• Substrate Integrated Waveguide (SIW) technology offers planar integration for microwave circuits.
• Conventional SIW cavities can be bulky, limiting miniaturization in filter applications.
• Resonator design is crucial for achieving desired filter characteristics and size.

Purpose of the Study:

• To propose a novel Half-Mode Substrate Integrated Coaxial Resonator (HMSICR).
• To investigate the application of HMSICR in designing compact Bandpass Filters (BPFs).
• To demonstrate significant frequency and size reduction compared to conventional counterparts.

Main Methods:

• The HMSICR is developed by bisecting a Square Substrate Integrated Coaxial Resonator (SICR).
• Periodic thru-via arrays mimic sidewalls; a central patch is shorted via blind vias.
• A four-HMSICR BPF is fabricated and measured; resonators are vertically stacked for further miniaturization.

Main Results:

• The proposed HMSICR achieves a 70% resonance frequency reduction compared to conventional SIW cavities.
• A fabricated BPF using stacked HMSICRs demonstrates a record high size-reduction rate.
• The design enables substantial miniaturization of microwave filters.

Conclusions:

• The HMSICR is an effective resonator for developing highly miniaturized BPFs.
• The proposed structure offers a significant advantage in terms of size and frequency reduction.
• This work presents a new approach for compact filter design in microwave applications.