Tunable Phase Shifter Using Composite Right/Left-Handed Transmission Line With Mechanically Variable MIM Capacitors

In the multifrequency base-station antenna, the beam tilt angle becomes frequency-independent due to be accomplished by designing the feeding cable length of the conventional phase shifter. To suppress the interference to the adjacent area in the lower frequency band, the tunable phase shifter that can vary main bean directions in the multifrequency band is proposed in this letter. The different phase shifts can be realized by using the dispersion relation of a composite right/left-handed transmission line. The tunable function is realized by mechanically sliding the patches of the metal-insulator-metal capacitors.