Ka-band loaded-line phase shifter design on flexible substrate

This paper describes a phase shifter design on flexible liquid crystal polymer substrate, in which a coplanar waveguide line is periodically loaded with tunable inter-digital capacitors. The metal layer of the capacitors is positioned beneath a tunable BST layer. This leads to capacitance variation when different DC biasing voltages are applied. The proposed phase shifter has been designed at K_a band and simulated using both full-wave EM solver and circuit simulator. This phase shifter shows an insertion loss of 1.4 dB and a phase shift of 55.7° at 32 GHz. Return losses at both ports are more than 20 dB, which indicates very good impedance matching.