A MULTI-BAND MEANDERED SLOTTED-GROUNDPLANE RESONATOR AND ITS APPLICATION OF LOW-PASS FILTER

A slotted-ground-plane meandered-slot resonator with multi-resonance characteristics and a compact lowpass filter (LPF) by using the resonator are demonstrated in this paper. The meandered slot provides a wideband resonator with low insertion loss and very sharp cutoff frequency response. Unlike conventional design of cascading bandstop slotted-ground-plane resonators in the literature, the introduced LPF is presented, which consists of a modified-meander slot in the ground plane, a spurred C-like slot, and a uniform microstrip transmission line with constant characteristics impedance. Two rectangular-head slots, giving an increase in the inductance, are added at the two terminals of the meandered slot for purpose of frequency reduction. An arm aperture is embedded to form another resonant path so that an additional transmission zero could be generated. In order to increase rejection capability, the slot width of one section of the meandered-slot resonator is widened. Meanwhile, a C-like slot with a spur slit is also etched inside the meandered slot to improve rejection performance. The measured insertion loss at a passband is below 0.7 dB, and the rejection band over 20 dB is from 2.9 to 12.0 GHz.