Compact microstrip triplexer based on twist-modified asymmetric split-ring resonators

On the basis of strong mixed couplings of two adjacent modified asymmetric split-ring resonators (SRRs), a compact microstrip filter unit is designed and its triplexer application is experimentally demonstrated by properly arranging the layout of three different sized filter units. The cross size of the proposed triplexer is only 20 x 16 mm. Both experimental and numerical results are obtained, which agree quite well with each other. The results show that such triplexer exhibits three quite close channels (2.15/2.95/3.80 GHz) and the isolations for all the three output ports are < 20 dB. The proposed triplexer can be flexibly integrated in the miniaturised multi-frequency/model radio frequency/microwave circuits.