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In this paper, mechanic–electric–circuit coupling algorithm based on the finite‐difference time‐domain (FDTD) method is proposed to analyze a one‐order microwave bulk acoustic wave (BAW) filter. FDTD method is used to solve the coupled mechanic–electric–circuit system equations to obtain the voltage and current at port position of the BAW filter in the time domain. Then S parameters of the BAW filter in the frequency domain are calculated using the Fourier transform. In our work, a one‐order BAW filter consists of two film bulk acoustic resonators (FBARs) by means of series and parallel. These two FBARs in the BAW filter are coupled together through an equivalent electrical connection. Similarly, multiphysical mechanic–electric–circuit analysis of the BAW filter is implemented in the commercial software COMSOL, which is realized by the time‐domain finite element method. The accuracy of the proposed method is verified by comparison with simulation results in COMSOL. In addition, the computational time and memory of the proposed method have obvious advantages over those of COMSOL. [ABSTRACT FROM AUTHOR]

This paper designs a mesa‐structured monolithic microwave integrated circuit (MMIC) limiter working in C‐band. The quasi‐vertical Si‐based PIN diodes are heterogeneously integrated on the SiC substrate with high thermal conductivity, such that the parasitic parameters are greatly reduced and the power capacity is enhanced. According to the measured results, a maximum insertion loss of 1.1 dB and a minimum return loss of 17.69 dB for both input and output terminals are realized to cover the 5–6 GHz frequency range. The flat leakage of 23 dBm is achieved for a 150 W continuous wave and 370 W pulse input signal level. We believe the proposed MMIC limiter provides an effective tool that can be used in the transmit‐receive modules working in C‐band. [ABSTRACT FROM AUTHOR]

In this paper, the multi-carrier microwave breakdown in air-SF6 mixtures is analyzed with the spectral-element time-domain method. In this process, a three-dimensional multi-physics model coupling Maxwell's equations with electron fluid equations is established. The tail-erosion and frequency shift phenomenon caused by multi-carrier microwave breakdown in different proportions of air-SF6 mixtures can be observed. Numerical results demonstrate that multi-carriers will make the wireless communication system sensitive to microwave breakdown. On the other hand, the different proportions of air-SF6 mixtures can obviously improve the breakdown threshold to inhibit the multi-carrier microwave breakdown, which is favorable to the propagation of multi-carrier microwaves in air. Meanwhile, increasing the pressure can suppress the frequency shift phenomenon, and the proportion of different SF6 in the mixed gas has little effect on the frequency shift of the transmitted wave. Our research provides theoretical guidance for comprehensively exploring the characteristics and physical mechanism of multi-carrier microwave breakdown in air-SF6 mixtures and is helpful for protection of microwave devices and plasma application. [ABSTRACT FROM AUTHOR]

In this paper, an efficient discontinuous Galerkin time-domain (DGTD) method is proposed to solve Maxwell's equations for nonlinear Kerr or Raman media. Based on our previous work, an arbitrary high-order derivatives DGTD method with a local time-stepping scheme is introduced for simulating dynamic optical responses in nonlinear dispersive media such that the nonlinear effects do not impose constraints on the stability conditions for linear subdomains. Therefore, the scheme enables the simulations in the nonlinear and linear media regions with independent time-stepping increments, which greatly improves the efficiency of the time-domain analysis. Moreover, by applying an iteration solution scheme, the proposed method preserves the intrinsic local features, which is favorable for the realization of highly parallelized algorithms. Numerical examples demonstrate the accuracy and the efficiency of our proposed method. We believe the proposed method provides an effective tool for numerical analysis of nonlinear optical phenomena.