Miniature Microstrip Bandpass Filter Using Resonator-Embedded Dual-Mode Resonator Based on Source-Load Coupling

A novel miniature microstrip bandpass filter (BPF) using resonator-embedded dual-mode resonator is proposed. Two transmission zeros are created to improve the selectivity of the filter. Furthermore, source-load capacitive coupling is introduced to create a transmission zero above the passband. A 2.28 GHz BPF with 300 MHz bandwidth is designed and measured, the measured result agrees well with the simulation. The size of the filter is less than 0.21 ?? ?? 0.15 ??, where ?? is guided wavelength at the central frequency.