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This study presents the design and optimization of a terahertz (THz) microstrip patch antenna enhanced with photonic bandgap (PBG) structures. The antenna is implemented on a Polytetrafluoroethylene (PTFE) substrate with Single-Wall Carbon Nanotube (SWCNT) conductors, leveraging the substrate’s low loss tangent and stable permittivity together with the high conductivity of SWCNTs to improve radiation performance. Key physical parameters, including air gap side, lattice constant, and substrate thickness, were varied using CST simulations to generate a comprehensive dataset. Four machines learning models Linear Regression, K-Nearest Neighbors, Decision Trees, and Neural Networks were trained, with the neural network achieving the best predictive accuracy (R² > 0.94) and very low errors across bandwidth (± 0.05 GHz), gain (± 0.1 dBi), efficiency (< 0.5%), and return loss (0.4 dB). Optimization through a genetic algorithm identified the optimal geometry (Y = 60 μm, D = 80 μm, h = 85 μm), yielding 36.8 GHz bandwidth, 9.4 dBi gain, 93.7% efficiency, and − 26.1 dB return loss. Specific Absorption Rate (SAR) analysis confirmed safety compliance, with a maximum value of 1.4 W/kg under FCC limits. By integrating electromagnetic simulation, machine learning, and evolutionary optimization, the proposed approach provides a faster and more accurate design methodology. Owing to its compactness, efficiency, and material flexibility, the antenna shows strong potential for non-invasive medical imaging, biosensing, and wearable health-monitoring in the THz domain.

In this work, the control and amplification of microwaves in a T-shaped circular waveguide in the S-band using a plasma switch are simulated using Computer Simulation Technology (CST) software and the Finite-Difference Time-Domain (FDTD) method. We present an innovative configuration that integrates a plasma switch into a T-shaped circular waveguide, enabling real-time control of plasma parameters to enhance microwave reflection and amplification. We determine the ratio of RF frequency to argon plasma frequency in the collisional regime and investigate the interaction, resonance, and complete reflection of electromagnetic waves. The variations in wave amplitude at three ports (input, side, and output arms) after interaction with the plasma switch at different plasma densities are analyzed and compared. Additionally, we discuss the temporal evolution of the electric field within the waveguide at the moment of complete reflection. By optimizing physical parameters, the proposed configuration demonstrates effective control, reflection, and amplification of high-power waves at high repetition rates.

Nanostructures can induce light multireflection, enabling strong light absorption and efficient photocarrier generation. In this work, silicon nanostructures, including nanocylinders, nanotips, and nanoholes, were proposed as all-optical broadband THz modulators. The modulation properties of these modulators were simulated and compared with finite element method calculations. It is interesting to note that the light reflectance values from all nanostructure were greatly suppressed, showing values of 26.22%, 21.04%, and 0.63% for nanocylinder, nanohole, and nanotip structures, respectively, at 2 THz. The calculated results show that under 808 nm illumination light, the best modulation performance is achieved in the nanotip modulator, which displays a modulation depth of 91.63% with a pumping power of 60 mW/mm2 at 2 THz. However, under shorter illumination wavelengths, such as 532 nm, the modulation performance for all modulators deteriorates and the best performance is found with the nanohole-based modulator rather than the nanotip-based one. To further clarify the effects of the nanostructure and wavelength on the THz modulation, a graded index layer model was established and the simulation results were explained. This work may provide a further theoretical guide for the design of optically tunable broadband THz modulators.

This study employs CST simulations to analyze the electromagnetic response and cable coupling characteristics of electric vertical takeoff and landing (eVTOL) aircraft under lightning conditions. Based on the SAE ARP5414B standard, lightning zoning was carried out, and three typical strike scenarios—the nose, wing, and vertical tail—were established. Referring to representative lightning current waveforms in SAE ARP5412B, Component A was selected as the primary excitation source. On this basis, the L9(33) orthogonal design method was applied to evaluate the influence of cable structure, length, and routing method on the induced current. The results show that nose attachment produces the strongest coupling to the airframe. Shielded cables effectively reduce the induced current in the conductor core by diverting most of the coupled current through the shielding layer, while unshielded single-core cables demonstrate the weakest resistance to interference. The induced current increases with cable length, and Z-shaped wall-mounted routing produces stronger coupling than straight or suspended routing. This research provides a systematic approach for evaluating indirect lightning effects in eVTOL and offers engineering guidance for electromagnetic protection and cable design.

FLASH radiotherapy requires real-time, non-invasive beam monitoring systems capable of operating under ultra-high dose rate (UHDR) conditions without perturbing the therapeutic beam. In this work, we characterized the extraction system of Supersonic Gas Curtain-based Ionization Profile Monitor (SGC-IPM) for its capabilities as a transverse beam profile and position monitor for FLASH protons. The monitor utilizes a tilted gas curtain intersected by the incident beam, leading to the generation of ions that are extracted through a tailored electrostatic field, and detected using a two stage microchannel plate (MCP) coupled to a phosphor screen and CMOS camera. CST Studio Suite was employed to conduct electrostatic and particle tracking simulations evaluating the ability of the extraction system to measure both beam profile and position. The ion interface, at the interaction region of proton beam and gas curtain, was modeled with realistic proton beam parameters and uniform gas curtain density distributions. The ion trajectory was tracked to evaluate the performance across multiple beam sizes. The simulations suggest that the extraction system can reconstruct transverse beam profiles for different proton beam sizes. Simulations also supported the system’s capability as a beam position monitor within the boundary defined by the beam size, the dimensions of the extraction system, and the height of the gas curtain. Some simulation results were benchmarked against experimental data of 28 MeV proton beam with 70 nA average beam current. This study will further help to optimize the design of the extraction system to facilitate the integration of SGC-IPM in medical accelerators.

The differential transmission line has been widely used in the field of high-speed signals with its unique transmission characteristics, and it will be affected by many factors during the transmission process. In this paper, the differential transmission line is taken as the research object, and a three-dimensional electromagnetic simulation software CST is used to study its signal integrity performance parameters including characteristic impedance, loss, and crosstalk. It is found through simulation that increasing the spacing between differential pairs will reduce the crosstalk. The smaller the differential pair length, the greater the value of the insertion loss. This will improve the quality of signal transmission.

The shielding efficiency of coaxial cable is characterized by its anti-interference ability in electromagnetic environment. The testing methods include three-axis method, GTEM chamber method, line injection method, power absorption clamp method, reverberation chamber method and so on. In practical application, it is found that the shielding performance of the cable under high altitude electromagnetic pulse (HEMP) does not accord with the shielding efficiency measured by the cable. While a typical multi-layer shielded cable is selected as the test object, a test method is designed and tested under electromagnetic simulator, and then the test results are verified and extended by CST simulation. Finally, the reason of this phenomenon is analysed theoretically, which has important reference significance for the prediction and testing of shielding efficiency of cable in HEMP environment.

Materials that absorb electromagnetic waves over an ultra-wide frequency band have great potential for military and civilian applications. In this study, a square-frustum-type metamaterial structure was designed and prepared using CI/silica gel composites and flake-shaped FeNi/silica gel composites as the filling substrate. The structural parameters of the square frustum were simulated and optimized using CST Studio Suite. The results show that the optimal performance was achieved when the base consisted of 50 vol.% CI/silica gel composites and 25 vol.% FeNi/silica gel composites with a cross-pattern distribution, the square frustum consisted of 50 vol.% CI/silica gel composites, and the total thickness, base thickness, base-edge length, and top-edge lengths were 5, 1.8, 2.5, and 1.5 mm, respectively. This arrangement can effectively absorb frequencies between 1.8 and 40 GHz, realizing ultra-broadband absorption. The excellent absorption performance of the absorber is attributed to multiple quarter-wavelength resonances and edge diffraction effects.

High-Intensity Radiated Fields (HIRFs) can cause severe interference to airborne GNSS equipment. This paper builds a CST model based on the real structure and evaluates shielding effectiveness (SE) with respect to frequency, material, polarization, angle of incidence, and aperture; anechoic-chamber tests combined with the DO-160G compliance method (Section 20, Class G) are then conducted, and this integrated scheme: (1) validates the simulation’s effectiveness and confirms the HIRF coupling risk; (2) reveals the GNSS failure mechanism—C/N0 decrease → DOP increase → loss of lock. Subsequently, an equation-based mechanism framework (cavity modes, slot/aperture coupling, waveguide-below-cutoff, thickness attenuation) is proposed, together with an effective-dimension correction, by which a single-point calibration can predict the remaining resonances. Accordingly, mechanism-aligned design strategies are provided (aperture control and honeycomb windows, geometric detuning and local absorbers, high-permeability inserts, multi-polarization and multi-directional protection), achieving predictable, verifiable, and quantifiable improvements in SE.