First shear horizontal mode plate wave in LiNbO<inf>3</inf> showing 20 km/s phase velocity

Abstract

Currently, cognitive radio using a white space of digital TV (DTV) channels is receiving a lot of attention. One of the key devices of a cognitive radio handset is a tunable filter capable of adjusting frequency and bandwidth (BW) throughout DTV band. The authors developed ultra-wide band resonators in a DTV band and ultra-wideband filters fully covering all DTV channels using Oth shear horizontal mode plate wave (SHo) in a (0°, 120°, 0°) LiNb03 plate. However, they are fabricated on a self-suspended ultra-thin LiNb03 plate of only 0.5-0.6 11m in thickness, which is mechanically fragile and difficult to fabricate at high yield. A much higher phase velocity than that of SHo is required to make the plate practically thicker. The objective of this study is to explore a different mode of plate wave showing much higher phase velocity and wide BW. By FEM simulation, it is clarified that a first SH mode (SH1) plate wave propagating in two kinds of new proposed structures, which are different from suitable SHo mode structures for wide BW, has higher velocity than 20,000 m/s and wide BW of 24%.Keywords-DTV; plate wave; J-th shear horizontal mode high velocity, wide band, new structure '