Design of Compact Multi-Layered Quad-Band Bandpass Filter

This letter proposes a compact quad-band bandpass filter that is based on a multilayered technique. The filter is designed to have four passbands at 1.575, 2.4, 3.5, and 5.2 GHz for the global positioning system, worldwide interoperability for microwave access, and wireless local area network applications. The filter possesses a multilayered structure for inductively connecting the uniform impedance resonators on the top layer with the stepped impedance resonators and tapped input/output coupling structures on the bottom layer, thereby providing multipath propagation to enhance the filter performance and compact circuit size. The measured results are in favorable agreement with the full-wave simulation results.