Electromagnetic-thermal co-simulation of large antenna arrays is performed, by using a supercomputing-based parallel domain decomposition method (DDM). In this paper, frequency-domain electromagnetic and thermal fields are solved self-consistently, and then coupled via Joule heat and temperature-dependent material properties. The developed co-simulation solver is firstly validated with the commercial software COMSOL Multiphysics. Then, the parallel performance of our in-house developed code, is examined in terms of scalability and efficiency. Finally, the temperature distributions over large-scale antenna arrays are obtained by our proposed solver in a highly efficient manner.

In this article, a large-scale electromagnetic-thermal-mechanical co-simulation solver is implemented, to simulate complex radio frequency components by using a high performance computing framework. The proposed solver integrates the frequency-domain electric field simulation, with time-domain thermal and thermal-induced stress simulations, via a multiphysics coupling iterative process. In order to speed up the cosimulation, a Krylov subspace method with a domain decomposition method (DDM) preconditioner is used. First, the developed multiphysics solver is verified with the commercial software COMSOL Multiphysics. Then, the parallel performance of our cosimulation solver, with different ghost mesh thicknesses, is tested on a supercomputer. Finally, some multiphysics results of filters and a real-world system-in-package (SiP) are obtained with our proposed solver.

As a newly discovered evolutionary algorithm, the particle swarm optimization algorithm has been widely used in the synthesis of array antennas, while it is seldom used in the synthesis of nonuniform array antennas. Two different nonuniform array antennas are optimized by binary particle swarm optimization and real particle swarm optimization in this article, which depicts the application of particle swarm optimization in the synthesis of nonuniform array antennas. Lower peak side-lobe level with uniform excitation can be obtained using this method. Meanwhile, the method of minimizing variable-searching space that can improve the efficiency of algorithm is used in particle swarm optimization. Compared with the standard genetic algorithm and the modified real genetic algorithm, particle swarm optimization shows high performance in the synthesis of nonuniform array antennas. To demonstrate the universality of the algorithm, a nonuniform circular array and a sparse linear array with a directional element are synthesized as well.

A parallel multiphysics simulation solver is developed to solve electromagnetic-thermal-mechanical coupling for some challenging large-scale antenna arrays. To achieve high scalability of supercomputer architectures, we reconstruct the preconditioned BiCGSTAB method and the non-overlapping domain decomposition method, so that the most resource-intensive matrix factorization steps can be performed in parallel independently within subdomains. The electromagnetic and thermal fields are solved separately, while coupled through the dissipated power and the temperature-dependent material parameters; after thermal steady state is reached, the mechanical simulation is stimulated subject to the temperature rise. The accuracy of electromagnetic-thermal coupling and thermal stress solution are first validated, and then the strong/weak parallel scalability experiments of the developed multiphysics solver are performed on supercomputer. Finally, an extremely challenging antenna array is simulated using the proposed solver, where to our best knowledge we bring the scale of multiphysics simulations excited by frequency-domain electromagnetic fields to the order of billion unknowns for the first time.

In this article, the influences of outgassing and flashover on the performance of a novel multipacting cathode are numerically investigated by using particle in cell-Monte Carlo collision (PIC-MCC) method, including the conditions of weak, medium, and strong outgassing. The numerical results demonstrate that under the condition of weak outgassing (0.1 Torr), multipacting is hardly influenced by gas ionization. Multipacting dominates the entire physical process. Due to the further improved output current by additional electrons generated from ionization, the weak outgassing can help cathode performance enhancement. Under the condition of medium outgassing (1 Torr), gas ionization first boosts multipacting developing and then tends to suppress multipacting process. During the initial stage, multipacting dominates the entire physical process. When multipacting tends to saturate, gas ionization will dominate the whole physical process. The rapidly increased output current will finally decrease gap voltage and induce the diode breakdown. Under the condition of strong outgassing (1 atm), multipacting is suppressed by gas ionization from beginning to end. Gas ionization dominates the whole physical process all the time. The strong effect of ionization collision will finally induce streamer discharge and diode breakdown.