A Quad-Channel Diplexer Using Stub-Loaded Step Impedance Resonators

Area of Science:

• Electrical Engineering
• Electromagnetics
• Microwave Engineering

Background:

• Diplexers are crucial components in radio frequency (RF) systems for simultaneous signal processing at different frequencies.
• Existing diplexer designs often face challenges in achieving high selectivity and isolation across multiple passbands.
• Step impedance resonators offer a flexible approach to filter design, but integrating multiple bands efficiently remains an area of research.

Purpose of the Study:

• To design and validate a novel quad-channel diplexer capable of operating at four distinct frequencies.
• To enhance filter selectivity and isolation through innovative resonator coupling and feed network design.
• To demonstrate the practical feasibility of the proposed diplexer design through simulation and measurement.

Main Methods:

• Design of a quad-channel diplexer utilizing four stub-loaded step impedance resonators.
• Implementation of a common feeder T-joint to integrate the resonators.
• Application of a 0-degree feed at input/output for generating transmission zeros.
• Coupling of stepped impedance resonators with stub loads to form dual-band filters.

Main Results:

• Achieved four passbands centered at 2.6 GHz, 3.48 GHz, 4.8 GHz, and 6.3 GHz.
• Constructed two dual-band filters with good performance characteristics.
• Obtained good impedance matching when combining the dual-band filters.
• Demonstrated high isolation (|S23| > 20 dB) between the dual-band filters.
• Simulation results closely matched measured data, validating the design.

Conclusions:

• The proposed quad-channel diplexer design effectively integrates multiple frequency bands.
• The use of stub-loaded step impedance resonators and specific feed techniques leads to high selectivity and isolation.
• The validated design shows promise for applications requiring multi-channel RF signal processing.