A low-profile linearly polarized antenna based on artificial magnetic conductor (AMC) is proposed. Triangle cuttings and Π-shaped slots are introduced on a traditional double-sided printed rectangular dipole antenna to realize ultrawideband characteristic and miniaturization. A novel 6 × 6 AMC array is proposed for the purpose of reducing the profile of the dipole. The AMC unit consists of a circular patch with four groups of symmetrical edged slots. Experimental results for the proposed antenna exhibit a 40% impedance bandwidth (4.77–7.12 GHz), maximum gain of 9.9 dB, and a front-to-back ratio of approximately 25 dB. The total height is 6mm (0.12 λ ₀ at 6 GHz). Compared to the slotted dipole antenna with perfect electrical conductor, the profile is reduced from 0.19 λ ₀ to 0.12 λ ₀ . This antenna with the advantages of simple-fed structure, low cost, easy fabrication can be a good candidate for C band communications.

In this communication, a multilevel fast multipole algorithm (MLFMA)-based direct method is proposed for solving electromagnetic scattering problems that are formulated using the electric-field integral equation (EFIE) approach. The method is based on the multilevel compressed block decomposition (MLCBD) algorithm. Previously, the matrix filling procedure of the MLCBD is based on the matrix decomposition algorithm-singular value decomposition (MDA-SVD) method. Although the MDA-SVD is more efficient than direct filling, it requires a longer filling time for the far-field matrix than for the MLFMA. The problems are used to demonstrate that the matrix filling memory requirement of the MDA-SVD is also higher than that of the MLFMA. Hence, the MLFMA is utilized to reduce both the matrix filling time and memory of the MLCBD. Numerical results are presented to demonstrate the accuracy and efficiency of the proposed method.

In this paper, a method for extracting multimode S-parameters in guided wave structures is presented based on the finite-difference time-domain (FDTD) electromagnetic method in conjunction with the frequency domain singular value decomposition (FD-SVD) scheme. The present method can calculate the multimode S-parameters directly from the field distribution in the frequency domain. It is found that the proposed modal analysis and multimode S-parameters extraction agree excellently with the analytic value and other available simulation techniques. Also, the method for multimode S-parameter extraction is validated by various microstrip discontinuities.

In this communication, an adaptive grouping technique-based MLSSM-MLFMA scheme is proposed to analyze objects with local fine structures efficiently. The MLSSM-MLFMA algorithm utilizes multilevel fast multipole algorithm (MLFMA) to accelerate dealing with the boxes whose size is larger than 0.2 wavelength, and uses multilevel simply sparse method (MLSSM) to decompose the boxes whose size is less than 0.2 wavelength. Meanwhile, the adaptive grouping technique is applied to improve the performance of MLSSM-MLFMA algorithm. The conventional octree-based grouping scheme divides the target into boxes with the same size at each level. It leads to some boxes that contain a large number of discrete unknowns, while some boxes contain fewer unknowns to simulate the object with local fine structures. Therefore, the computational efficiency of MLSSM-MLFMA algorithm will be improved. By using the proposed grouping technique, the memory requirements and computational times are much less than that of conventional octree-based grouping scheme for analyzing the objects with local fine structures.

In this paper, a 4.2–7.2 GHz (52.6%) beam-steering microstrip antenna was proposed. The proposed antenna consists of three tapered slots and feeds. The three radiation directions of the antenna on the plane are independent of each other, and the three feeds correspond to the three radiation structures. Symmetry isolation trenches are introduced to improve isolation between different ports. Radiation pattern simulation and measurement show horizontal beam steering at the sampled frequencies of 4.2, 5, 6, and 7.2 GHz. The results shows that the overlapped beam of the three ports in the E-plane and H-plane can cover more than 200 degrees and 60 degrees, respectively. Apart from the capability of beam-steering, high isolation (more than 28 dB) of the proposed antenna in the operating band is obtained.