Time reversal (TR) is a technique used to focus electromagnetic energy at a precise location by injecting timereversed signals recorded from an initial pulse. In conventional cavities, TR is constrained by the diffraction limit, reducing the efficiency of refocalization and requiring intrusive measurements. This paper proposes using spoof surface plasmon polaritons (SSPPs) on a corrugated surface instead of electromagnetic waves in a homogeneous volume. Simulations demonstrate that SSPPs reduce the focal spot size and limit the need for intrusive measurements. The results highlight the potential of SSPPs for precise energy delivery in electromagnetic systems, with applications such as plasma ignition.
This letter presents a miniaturized antenna designed for dual-camera wireless capsule endoscopy (WCE) systems, operating within the constrained internal space of the capsule. To address the increased spatial limitations imposed by the dual camera configuration which aims to eliminate blind spots in gastrointestinal inspection, this design employs a parasitic integration strategy. By loading antenna elements onto both sides of the circuit and connecting boards within a five-layer substrate structure, the proposed antenna achieves circular polarization and high gain without occupying additional volume. The meandered topology effectively increases the electrical length to achieve resonance at the target frequency. Measurement results demonstrate a good peak gain and specific absorption rate (SAR) compliance with IEEE safety standards. This work provides a promising solution for high-performance WCE systems.
This letter presents a compact dual-band high-gain T-shaped dielectric resonator (DR) antenna (DRA) operating in the Ku-band. The proposed design employs a T-shaped DR to simultaneously excite two higher-order modes, HEM₁₁₅ and HEM₁₁₇. A quasi-Fabry-Perot (quasi-FP) cavity formed between the T-shaped DR and the ground plane enhances the lower-band gain, while another cavity formed between the T-shaped DR and an intermediate copper reflector improves the higher-band gain. Measurement results demonstrate dual-band operation at 13.11–13.86 GHz (5.56%) and 15.72–17.01 GHz (7.88%), with peak gains of 13.9 dBi and 13.16 dBi, respectively, and a gain difference (ΔGain) of 0.74 dB. The proposed antenna provides a compact single-element solution with balanced high gain for Ku-band applications.
An Anderson-accelerated finite element domain decomposition method (AA-FEM-DDM) is proposed for electromagnetic simulations to improve the convergence robustness of the conventional Gauss-Seidel (GS) iterative solver for FEM-DDM. In the proposed method, one complete GS sweep is formulated as a fixed-point mapping, and Anderson acceleration is applied to the outer DDM iteration by using historical residuals and mapped iterates. The original subdomain FEM formulation remains unchanged. Numerical examples of filter structures show that the proposed AA-FEM-DDM agrees well with direct FEM results in terms of S-parameters. Compared with the conventional FEM-DDM(GS), the proposed method substantially reduces the number of outer iterations and remains convergent for cases where the GS iteration fails to reach the prescribed tolerance. For the tested large-scale model with a dense mesh, the proposed AA FEM-DDM reduces the total simulation time from 39,272.1 s to 8107.9 s.
This letter proposes a novel method for frequency selective rasorbers (FSRs) that could achieve multi-band transmission performance within a wide low reflection band. In the proposed design, independent chokes resonators (ICRs) and multi-slot resonators (MSRs) are developed and employed. The transmissive ICRs and the absorptive crossed-dipole elements are placed on opposite sides of the lossy-layer substrate, thereby avoiding spatial competition between them and leaving more space for additional resonators. MSRs are integrated on the lossless layer, whose pass- and stop-bands are matched to that on the lossy array, and therefore, the desired multi-band transmission and absorption responses are achieved. Due to the proposed symmetrical and miniaturized structure, stable performance could be obtained under variations in incidence angle and polarization, achieving four passbands around 4, 5.1, 6.2, and 7.8 GHz under all-polarized incidence, while maintaining a low reflection band spanning from 2.4 to 8.8 GHz. Finally, a prototype is fabricated, and the measured results are in good agreement with the circuit-calculated and software-simulated ones.
