A COMPACT U-SHAPED DEFECTED GROUND STRUCTURE MICROSTRIP LOW-PASS FILTER WITH WIDEBAND REJECTION

摘要

A compact triple U-shaped slots etched on the microstrip ground are used to implement a novel low-pass filter. A rectangular open stub and a radius stub are used to produce transmission zeros and thus result in wide stopband. Good low-pass performance and wide stopband characteristics can be achieved by this new structure. One prototype is fabricated to demonstrate the validity of the design strategies. The simulated and measured results indicate that the insertion loss is less than 0.25 dB and the return loss is less than -16.7 dB in the whole passband. In addition, significant improvement on rejection band can be observed; the stopband bandwidth better than -25 dB is about 105% (from 2.6 to 8.4 GHz).