Compact Dual-Mode Bandpass Filter with Wide Stopband Using Capacitance Loaded Square Meander Loop Resonator

A novel dual-mode bandpass filter with wide stopband using capacitance loaded square meander loop resonator is presented. The resonator can exhibit dispersion effect due to loaded capacitance, which can reduce the size of resonator and suppress harmonic. The disturbed degenerate-mode resonances are used to form the passband while two transmission zeroes are generated on each side of the passband so as to obtain high selectivity. The circuit area of bandpass filter is only 0.14λg × 0.14λg, where λg is the guided wavelength at the center frequency. The measured result reaches good agreement with simulated result.