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This article presents a novel method for validating compass devices. To this end, the post-processing method was used, i.e., the previously recorded vessel’s heading from three compass devices was applied. A spectral analysis of the recorded heading in the frequency domain was conducted by applying the fast Fourier transform method. Based on a synthetic summary of the results of spectral analysis in the heading error frequency domain, the factors causing errors of low-frequency compass device indications, manifested by the vessel’s yawing due to the vessel steering errors on the pre-determined course and the external factors causing total drift of the vessel, were eliminated. To this end, the convolution functions in the form of the sum of input signals with an impulse response, i.e., the filter with a finite impulse response (FIR) and with an infinite impulse response (IIR), were used to compare the effectiveness of the methods estimating the vessel’s heading. The final stage of the research process in the methodology applied was the use of state- and time-discrete Markov processes whose task is to determine the matrices of the intensity of transitions between the states of individual compass systems.

An ultra-wideband band-stop plasmonic filter (UWB-BSF) in mid-infrared (MIR) range based on metal–insulator–metal (MIM) waveguide coupled with a hexagonal resonator is proposed in this work. Using RSoft CAD commercial software, the designed BSF is numerically and theoretically investigated by the 2D Finite-Difference Time-Domain method. To enhance the BSFs system in mid-infrared, obtaining ultra-wide bandgap width (UWB) with the maximum passband transmission at the left and right of the bandgap and a high value of the rectangular coefficient, we increase the number of hexagonal cavities. Hence, the number of hexagonal resonators controls the range of the filtered wavelength of the BSFs system. In the case of two hexagonal-shaped resonators, the Fano resonance appears on the left and right sides of the bandgap, forming a U-shaped transmission spectrum, which is very helpful for improving the performance of the band-stop filter. Furthermore, by changing the geometric parameters of the hexagonal cavities the filtered wavelength range is shifted toward the near-infrared (NIR) band. The center wavelength of the bandgap of the proposed nano-stop-band filter is adjustable by varying the geometric parameters of the structure. This device operates in the near-infrared (NIR) and mid-infrared (MIR) wavelength ranges. With a larger bandgap width and tunable performance, this proposed nanostructure provides an advantageous application for plasmonic integrated circuits and broadband transmissions.

In this paper, a ultra-wideband (UWB) bandpass filter with stopband characteristics is presented using a multi-mode resonator (MMR) technique. An MMR is formed by loading three dumbbell-shaped (Mickey and circular) shunt stubs placed in the center and two symmetrical locations from ports, respectively. Three circular and arrowhead defected ground structures on the ground plane are introduced to achieve UWB bandwidth with a better roll-off rate. The proposed filter exhibits stopband characteristics from 10.8 to 20 GHz with a 0.4 dB return loss. The group delay and roll-off rate of the designed filter are <0.30 ns in the passband and 16 dB/GHz at lower and higher cut-off frequencies, respectively. The dimension of the filter is 0.74λg × 0.67λg mm2 and was fabricated on a cost-effective substrate. All simulated results are verified through the experimental results.

This paper presents a novel single-layer dual band-rejection-filter based on Spoof Surface Plasmon Polaritons (SSPPs). The filter consists of an SSPP-based transmission line, as well as six coupled circular ring resonators (CCRRs) etched among ground planes of the center corrugated strip. These resonators are excited by electric-field of the SSPP structure. The added ground on both sides of the strip yields tighter electromagnetic fields and improves the filter performance at lower frequencies. By removing flaring ground in comparison to prevalent SSPP-based constructions, the total size of the filter is significantly decreased, and mode conversion efficiency at the transition from co-planar waveguide (CPW) to the SSPP line is increased. The proposed filter possesses tunable rejection bandwidth, wide stop bands, and a variety of different parameters to adjust the forbidden bands and the filter’s cut-off frequency. To demonstrate the filter tunability, the effect of different elements like number (n), width (WR), radius (RR) of CCRRs, and their distance to the SSPP line (yR) are surveyed. Two forbidden bands, located in the X and K bands, are 8.6–11.2 GHz and 20–21.8 GHz. As the proof-of-concept, the proposed filter was fabricated, and a good agreement between the simulation and experiment results was achieved.

A novel method for designing a compact low-pass filter (LPF) with a sharp cut-off and wide stop-band is presented. In this technique, a simple open-stub microstrip line is printed on top of a substrate and the desired performance is obtained by optimising the shape of the defected ground structure using the genetic algorithm. Details of the design procedure are presented and evaluated through designing two different LPFs. The first LPF is optimised for a 3.5 GHz cut-off frequency and a stop-band up to 10 GHz, whereas the second one is optimised for a 5 GHz cut-off frequency and the stop-band is extended to 16 GHz. Both filters are fabricated and good agreement between simulation and measurement result is obtained. The designed filters have a sharp transition along with a compact size of 25 × 20 × 0.787 mm3.

The periodic structure based on an array of multiple conducting strips per unit cell on a chiral slab is investigated in this letter. Instead of a single strip, a unit cell is constructed by equal and unequal lengths of double or triple strips. In this case, the array is periodic, as opposed to the traditional individual elements. The co-polarised reflectance, co-polarised transmittance and cross-polarised transmittance of new types of frequency selective surfaces (FSS) comprised of perfectly conducting double or triple strips on a chiral slab are analysed theoretically for a plane wave at normal incidence. The analysis is based on the modal expansions and moment methods together with the Floquet theorem. The unknown current coefficients induced on the conducting elements are computed by using the subdomain overlapping piecewise sinusoidal basis functions. By using two or three conducting strips per unit cell, FSS can be operated in different frequency bands. The double and triple strips per unit cell on chiral slab produce double and triple resonances, respectively. The structure can be used in band-stop filter, multiband antenna applications and subreflector systems as well as the polarisation rotator. The computed result of free-standing strip FSS is compatible with the measured and calculated results in literature.

This work presents a novel compact size and sensitive band-stop filter, whose notch frequency is 5.5 GHz, and it is suggested to estimate the concentration of blood glucose non-invasively. The filter is made on FR-4, with the size of the entire structure being 15 mm × 25 mm × 1.6 mm. A human finger-phantom model, comprising layers of skin, fat, blood, and bone, is built in an EM simulation environment (HFSS) to assess the sensing performance of the human finger-phantom. The glucose content in the blood layer is kept at a range of 0 to 500 mg/dL, with the ratio of the resonant frequency shift being assessed by placing the finger phantom on the proposed filter structure. The sensing principle is based on the fact that the resonant frequency of the microwave sensor changes with changes in glucose concentration in the tissue, and this is due to the changes in the dielectric properties of the tissue. The shifts obtained in the study are used for the evaluation of glucose concentration in blood as a non-invasive technique. This work explores five microstrip band-stop filters noted as Designs I, II, III, IV, and V. In these filters, better results of minimum and maximum frequency shifts of 0.1 and 1.4 MHz in Design I and 0.1 and 2 MHz in Design IV are observed. The simulated results of Design IV are verified with measured results. Good matching is also noted at the lower frequencies. The filters are compact, cost-effective, and give better sensitivity performance. Hence, the proposed design can be used for glucose monitoring in blood samples involving a non-invasive method.

A frequency selective surface for spatial filtering in the standardized Ultra-Wide Band (UWB) frequency range is proposed. A very large stop-band of 1.75–15.44 GHz has been obtained, with good polarization insensitivity and an angular stability of more than 60∘ and more than 50∘ in TE and TM incidence, respectively. Circuit models have been devised. The structure has been assessed by electromagnetic simulation and implemented on an FR4 substrate of 1.6 mm thickness, with an edge of the square-shaped unit cell of 15 mm. Tests in an anechoic chamber demonstrated good matching between simulation and experimental results and proper operation of the device.

A compact high-power broadband absorptive filter is designed by cascading a slotted waveguide harmonic pad with a wide stop-band reflective filter. Absorption is achieved by coupling a surface current standing wave to absorptive external auxiliary waveguides through a cascade of transversal broadwall slots in rectangular waveguide.

This study introduces a motion-sickness-reducing control strategy aimed at enhancing ride comfort in Electric Autonomous Vehicles (EAVs). For lateral control, the forward look-ahead distance was adaptively adjusted based on the Motion Sickness Dose Value (MSDV) analysis from ISO 2631-1, effectively mitigating lateral acceleration and its motion-sickness-related frequency components, leading to a reduced MSDV. For longitudinal control, Linear Quadratic Regulator (LQR) optimal control was applied to minimize acceleration, complemented by a band-stop filter specifically designed to attenuate motion-sickness-inducing frequencies in the acceleration input. The bandwidth of the band-stop filter used in this study was designed based on the motion-sickness frequency weighting specified in ISO 2631-1. The simulation results of the proposed control indicate a significant reduction in MSDV, decreasing from 16.3 to 10.46, achieving up to a 35.8% improvement compared to comparative control methods. While the average lateral position error was slightly higher than that of the comparative controller, the vehicle consistently maintained lane adherence throughout path-following tasks. These findings underscore the potential of the proposed method to simultaneously mitigate motion sickness and achieve a robust path-following performance in autonomous vehicles.