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A dual‐polarized wide‐beam (DPWB) antenna is optimized by a hybrid topology optimization (HTO) method, which combines the scalar isotropic material with penalization and the level set method. The HTO method has high optimization freedom degree, strong topology‐searching ability and fast convergence speed. The initial model of the antenna is designed as a dual‐feeding square microstrip patch antenna with short‐circuit metal walls around the patch. By optimizing the metal patch on the upper side of the model, the DPWB antenna is obtained. The DPWB antenna is symmetric with respect to both ports. When fed to either port, the half‐power beamwidth of the DPWB antenna can reach 166° (−82° ~ 84°) in the E‐plane and 124° (−62° ~ 62°) in the H‐plane. The performance is verified by both simulation and measurement. The DPWB antenna is further applied to a linear phased array, reaching an E‐plane scanning angle range of 160° (−80° ~ 80°) and an H‐plane scanning angle range of 122° (−61° ~ 61°), with the gain fluctuation less than 3 dB and the sidelobe level less than −10.1 dB. [ABSTRACT FROM AUTHOR]

A periodic wideband pixel absorber is designed by genetic algorithm (GA) combined with a fast circuit simulation method, namely, the internal multi‐port method (IMPM). In order to achieve a wideband absorption effect, the pixel connections of the absorber are optimized by GA into three states, that is, metal connection (no loss), disconnection, and lossy connection states. In the optimization, the performance of the pixel absorber is evaluated quickly by the IMPM, rather than by the time‐consuming full wave simulation. To validate the optimization performance, the optimized wideband absorber is simulated, fabricated and measured. The simulation and measurement results show that the absorber can achieve an 85% (5.5‐13.6 GHz) bandwidth with the absorptivity higher than 90%. Besides, the absorber is insensitive to the polarization and incidence angle of the waves. [ABSTRACT FROM AUTHOR]

A hybrid topology optimization method that combines the scalar isotropic material with penalization and the level set method is utilized to achieve the miniaturization of patch antennas while maintaining good radiation and polarization characteristics. In order to achieve this goal, the Heaviside projection filter is applied to obtain topologies that are more complex. Both the radiation power and the reflection coefficient of the antenna are utilized as sub‐objectives. Besides, by setting the radiation patch to be symmetrical, not only the numbers of optimization variables and optimization sub‐objectives are reduced, but also the cross‐polarization level is suppressed effectively, so that the optimization is accelerated. The optimized patch antenna achieves good performance in patch size, impedance matching, radiation pattern, gain, and polarization characteristics. Compared with the reference patch antenna, the patch size of the optimized antenna is reduced by 63%, while the maximum realized gain and efficiency remain basically unchanged, achieving more than 5.9 dBi and 90%, respectively. Due to its very small size patch, the antenna is particularly suitable for compact multi‐antenna and antenna array applications. [ABSTRACT FROM AUTHOR]

A hybrid topology optimization (HTO) method is utilized to optimize the isolation structure of a multiple-input multiple-output (MIMO) antenna. The HTO method, in which the scalar isotropic material with penalization (SIMP) and the level set method (LSM) are integrated, is based on the gradient optimization method with fast convergence speed. It combines the advantages of strong topology-searching ability of SIMP and smooth structure boundary of LSM. The proposed HTO method is adopted to optimize the isolation structure for good impedance matching, high isolation and high polarization purity of the MIMO antenna simultaneously. By setting the optimization structure as a symmetric one, the number of optimization variables is reduced by half. The optimization is validated by the full-wave simulation and the measurement. At the expected frequency of 5.8 GHz, the measured mutual coupling between the MIMO antenna elements with a center-to-center distance of $0.25\lambda _{0}$ is reduced by more than 24 dB, and the cross-polarization ratio reaches more than 27 dB. Furthermore, the reason for the isolation improvement is analyzed as well. [ABSTRACT FROM AUTHOR]

Abstract: As a model derived from a two-layer fluid system which describes the atmospheric and oceanic phenomena, a coupled variable-coefficient modified Korteweg–de Vries system is concerned in this paper. With the help of symbolic computation, its integrability in the Painlevé sense is investigated. Furthermore, Hirota’s bilinear method is employed to construct the bilinear forms through the dependent variable transformations, and soliton-like solutions and complexitons are derived. Finally, effects of variable coefficients are discussed graphically, and it is concluded that the variable coefficients control the propagation trajectories of solitons and complexitons. [ABSTRACT FROM AUTHOR]