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In this paper, a low-cost compact decoupled bandwidth enhancement technique is proposed to address the high mutual coupling issue between wideband closely-spaced multiple-input and multiple-out (MIMO) patch antennas. The wideband decoupling property is realized by combining two decoupling circuits introduced by defected ground structure (DGS) and coplanar decoupling structure, respectively. An equivalent circuit is given to clarify the decoupling mechanism and provide physical insight. To validate the feasibility of the proposed design scheme, two prototypes of decoupled wideband patch arrays based on coplanar-fed and probe-fed schemes are simulated, fabricated, and measured in the 5.8 GHz ISM band, respectively. Experimental results show that for both of the two kinds of prototypes, the poor isolation can be improved from 10 dB to better than 20 dB within a wide-matched bandwidth of 10% under an extremely close edge-to-edge distance of $0.038 \lambda _{0}$ . In addition, systematic validation for radar sensing performance has been discussed by integrating the proposed antenna with the custom-designed radio frequency system. Moreover, the performance metrics of MIMO parameters and verification of extending to $1\times 4$ antenna arrays are also discussed for both two basic feeding schemes. Compared with the two-element patch arrays, multi-element patch arrays maintain decent performance for isolation enhancement and wideband isolation bandwidth larger than 10%, indicating the proposed decoupling technique is promising for large-scale wideband MIMO systems in integrated sensing and communication applications (ISAC).

To meet the requirement of autonomous driving development, high-quality point cloud generation of the environment has become the focus of 4D mmWave radar development. On the basis of mass producibility and physical verifiability, a design method for improving the quality and density of point cloud imagery is proposed in this paper, including antenna design, array design, and the dynamic detection method. The utilization of apertures is promoted through antenna design and sparse MIMO array optimization using the genetic algorithm (GA). The hybrid strategy for complex point clouds is adopted using the proposed dynamic CFAR algorithm, which enables dynamic adjustment of the threshold by discriminating and calculating different scanning regions. The effectiveness of the proposed method is verified by simulations and practical experiments. Aiming at system manufacture, analysis methods for the ambiguity function (AF) and shooting and bouncing rays (SBR) tracing are introduced, and an mmWave radar system is realized based on the proposed method, with its performance proven by practical experiments.

In this study, we present that the plasma sphere can focus and enhance the evanescent and transmitted waves. Electromagnetic waves propagating in a plasma sphere with a positive or negative permittivity, which leads to the enhancement of transmitted and evanescent waves, are analyzed. The intensity of the focused beam can be hundreds of times stronger than that of the incident wave. The enhancement effect is associated with plasma frequency, collision frequency, and incident wave frequency. The results illustrate that the electromagnetic wave can be focused, reflected, and oscillated by controlling the electromagnetic parameters of the plasma sphere. With a strong field enhancement available, it is possible to be used in microwave power amplifiers, plasma antennas, reflectors, etc.

In this article, the average power handling capability (APHC) of corrugated slow-wave transmission lines (SWTLs) is investigated. Firstly, the attenuation constants of conductor and dielectric are extracted by the multiline method. Secondly, the thermal resistance of corrugated SWTLs is analyzed based on the constant-angle model. To deal with the non-uniform corrugated structure of SWTLs, the concept of average heat-spreading width (AHSW) is introduced. Finally, the APHC of the corrugated SWTL is calculated using the attenuation constant and the thermal resistance. In addition, the APHC considering the temperature-dependent resistivity of metal conductor is also presented. For validation, the APHCs of SWTLs with different geometric parameters are evaluated. The results agree well with those obtained by the commercial software.

In the automatic placement of integrated circuits, the force directed relaxation (FDR) method [Goto, S. (1981). An efficient algorithm for the two-dimensional placement problem in electrical circuit layout. IEEE Trans. on Circuits and Systems, CAS-28(1), 12-18] is a good iterative optimization algorithm. In this article, an improved force directed relaxation (IFDR) method for standard cell placement is presented, which provides a more flexible and efficient cell location adjustment scheme and a more extensive searching scale for better iterative placement optimization than the FDR method. A new heuristic algorithm based on local optimization is combined with the IFDR method to improve the placement. Experiments on the Microelectronics Center of North Carolina (MCNC) standard cell benchmarks [http://www.cbl.ncsu.edu/pub/Benchmark_ dirs/Layout Synth92/] have been done, and the results show that total wire length is reduced up to 25% and by an average of 16% in comparison with that from the placement algorithm of TimberWolf7.0.

A hybrid method of generalized transition matrix (GTM) and physical optics (PO) with synthetic basis functions (SBF) is proposed to analyze electromagnetic systems on electrically large platforms. Based on domain decomposition method (DDM), the proposed approach is to divide the whole problem into a GTM region and a PO region. The GTM algorithm can simulate antennas and scatterers accurately, and the PO algorithm is applied to obtain current distribution on the electrically large platform. With the characteristics extraction technique using SBFs on the GTM models, the number of unknowns can be greatly reduced and the computational efficiency can be further improved. PO region is regarded as an environment background and the unknowns in the PO region need not to be directly solved. Numerical examples will be shown to demonstrate the feasibility of the hybrid method.