Multi-Layered Dual-Band Bandpass Filter Using Stub-Loaded Stepped-Impedance and Uniform-Impedance Resonators

The design of multi-layered dual-band bandpass filter using stub-loaded stepped-impedance and uniform-impedance resonators is proposed. The filter is designed to have dual-passband at 2.4, and 5.2 GHz for Wireless Local Area Network (WLAN). The multi-layered filter consists of the stub-loaded stepped-impedance resonator (SL-SIR) on the top layer and the stub-loaded uniform-impedance resonator (SL-UIR) on the bottom layer, that can provide the multi-path propagation to enhance the filter performance and compact circuit size. The proposed SL-SIR and SL-UIR play important roles for controlling the transmission zeros at each first and second passband edges. The measured results are in good agreement with the full-wave electromagnetic simulation results.