Microstrip phase inverter using interdigital strip lines and defected ground

A new wide-band microstrip phase inverter is reported in this paper. The interdigital striplines, defected ground and vias are used to obtain 180° phase shift. The structure is simple and can be realized with ordinary microwave integrated circuit(MIC) fabrication process. The lumped-element model of the phase shifter is devised to facilitate parameter optimization. The fabricated phase inverter has a bandwidth of 105.6% (2.065-6.682 GHz), with 1 dB insertion loss and a phase deviation less than 10°.