Optimized Nonlinear Substrate Integrated Waveguide for Pulse Compression

Abstract

The time compression and associated frequency broadening of electromagnetic pulses has numerous applications in communication and radar systems. In this work, a new type of pulse compression device based on nonlinear ferroelectric materials in a substrate integrated waveguide (SIW) is proposed and simulated, with low temperature co-fired ceramic (LTCC) fabrication compatibility considered. The ferroelectric material Barium Strontium Titanate commonly used with tunable microwave components, is placed in vertical slabs within the SIW and driven with an input pulse into the nonlinear polarization region. The nonlinearity causes field amplitude dependent propagation velocity, resulting in a tendency for energy to 'pile-up' or compress in time. The fields within the SIW are simulated with a Finite Difference Time Domain (FDTD) method, and a Genetic Algorithm (GA) finds the optimal material configuration that maximizes pulse compression. Pulse compression of 58% is shown by simulation to be possible with the proposed design.