%0 Journal Article
%K thin films
%K Permittivity
%K Ferroelectric devices
%K Electric field effects
%K Barium titanate
%K Barium strontium titanate
%K Waveguide couplers
%K Bandwidth
%K Dielectric films
%K Gold
%K Microstrip devices
%K Voltage-controlled Lange couplers (VCLC)
%A G Subramanyam
%A F.A Miranda
%A F Van Keuls
%A R.R Romanofsky
%A C.L Canedy
%A S Aggarwal
%A T Venkatesan
%A Ramamoorthy Ramesh
%B IEEE Microwave and Guided Wave Letters
%D 2000
%G eng
%P 136-138
%R 10.1109/75.846924
%T Performance of a K-Band Voltage-Controlled Lange Coupler Using a Ferroelectric Tunable Microstrip Configuration
%V 10
%X We report for the first time on the performance of a Au/Ba0.6Sr0.4TiO3 (BSTO)/MgO two-layered microstrip voltage-controlled Lange coupler (VCLC) designed for Ku- and K-band frequencies at room temperature. Tight coupling of 3 dB or higher was obtained over a frequency range of 14–19 GHz. At K-band frequencies, the coupling was voltage-controllable using the nonlinear dc electric field dependence of the relative dielectric constant of BSTO (εrBSTo)- The coupling level was improved from —11.6 to —3.7 dB at 20 GHz with an applied dc electric field of 16 kV/cm. The introduction of the ferroelectric tuning layer enhances the bandwidth of the VCLC in comparison with a Lange coupler with no ferroelectric layer. This work demonstrates another advantageous application for ferroelectric thin films in passive microwave components. © 2000, IEEE. All rights reserved.