A Wide-Band Bandpass Filter Using the Properties of Microstrip Open-Loop Resonator with Spurious Response Suppression

In his paper, a wide-band bandpass filter using the properties of microstrip open-loop resonator with spurious response suppression is proposed to develop the square loop wide-band bandpass filter with tuning stubs. The filter is based on square loop resonator consists of four identical branches with attached to inner and outer corner of the square loop. The introduction of two tuning stubs connecting opposite to the ports widens the passband and sharpens the stopbands. A prototype filter is designed at 2.45 GHz with 36% fractional bandwidth and 0.38 dB insertion loss. It is very useful for applications in the wireless communication systems.