Abstract This paper presents a study on Active Frenquency Selective Surface (AFSS) for applications in modern wireless communication systems. Initially, an FSS with an element inspired by convoluted metallic lines printed on a dielectric substrate of FR-4 is proposed. The unit cell size is equal to 10.2 % of the wavelength in free space for the frequency of 1.53 GHz. An equivalent circuit model is proposed to better understand the operating principle of the FSS. Four Schottky diodes have been inserted in a symmetrical manner for switching, and three operating states are analyzed (all diodes in off state, all diodes directly polarized and therefore conducting, and two diodes conducting and two diodes off). The reconfiguration allows the frequency response to vary between frequencies from 0.8 GHz to 2.5 GHz. The FSS proved to be stable with respect to the angle of incidence of the plane wave on the circuit surface. The simulated numerical results for the designed prototype was obtained by ANSYS HFSS software. The prototype was built and the experimental characterization of the transmission coefficients, bandwidth and resonance frequency was performed. The values obtained in the experiment were compared and discussed with the simulation results, which showed good agreement. AFSS (AFSS systems Initially FR4 FR 4 FR- 102 10 2 10. 153 1 53 1.5 switching state off. . off) 08 0 8 0. 25 5 2. surface software coefficients performed agreement 15 1.

Abstract In this article, a comprehensive analysis of the approach known as Split-Step Wavelet Parabolic Equation (SSW-PE) in modeling radio wave propagation is presented. The SSW-PE introduces innovations, such as the application of narrow-angle and wideangle approaches, referred to as NAPE and WAPE, respectively. Furthermore, the SSW-PE demonstrates the incorporation of refractivity variations, modifications in terrain modeling for better representation, and considerations of surface boundary conditions. In addition to its innovative aspects, this study aims to provide a complete guide for effectively replicating the algorithm, thereby promoting the advancement of propagation studies using wavelets. The effectiveness and applicability of this approach are validated through comparative studies with well-established solutions, including the Discrete Mixed Fourier Transform (DMFT) version of the Split-Step Parabolic Equation (SSPE) method. Comparisons with measurements from real propagation cases are also conducted. Statistical analysis confirms the innovative potential of the SSW-PE algorithm, which also offers computational efficiency for rapid and consistent simulations. Thus, this article contributes to a comprehensive and innovative analysis, providing tangible resources for the research community interested in expanding this methodology. SplitStep Split Step SSWPE SSW PE (SSW-PE presented innovations narrowangle narrow angle approaches WAPE respectively Furthermore variations representation conditions aspects algorithm wavelets wellestablished well established solutions DMFT (DMFT SSPE (SSPE method conducted simulations Thus methodology

Article This paper develops an easy design analysis for a simple high selective T-shaped band-stop filter (BSF) loaded with a capacitance. It applies the developed design theory to obtain an appropriate capacitance value for tuning the cut-off frequency. This paper clearly explains the design mechanism for such a simple tunable BSF using ABCD matrices. Simulated filters loaded with capacitances (up to 1.1 pF) show a change in rejection frequencies from 2 GHz (un-tuned) down to 1.047 GHz with 50dB rejection and around 36% -3dB fractional bandwidth. It also shows the effect on pass frequencies which change from 1 GHz down to 111 MHz, while the separation between pass and stop frequency remains around 1 GHz. Measurements on fabricated prototypes match the simulation and theory for tunable frequencies closely. It also compares the performance of the filter with previously reported similar structures. Tshaped T shaped bandstop band (BSF cutoff cut off matrices up 11 1. pF untuned un tuned (un-tuned 1047 047 1.04 dB 36 3dB bandwidth MHz closely structures 104 04 1.0 3 10 0

Abstract This paper will propose an innovative compact, low-cost, low-profile inverted U-shaped patch antenna with a single and dual band-notched ultra-wideband (UWB) with split ring resonators (SRRs). To achieve our main goal based on the reduction of electromagnetic interference in narrowband communications (WLAN, WiMAX, and satellite), four-element rectangular split-ring resonators (SRRs) array are placed nearby the feedline to create notch band at approximately 5.15-5.35 and 5.725-5.85 GHz. The SRRs antenna's measured data indicate a directivity of 8.52 dBi, a gain of 7.18 dBi, a reflection coefficient of -27 dB, and an efficiency of 84.3%. The realized prototype, including the SRRs and CSRRs structures, were carried out using a PCB prototyping machine. Reflection coefficient measurement is obtained using a vector network analyzer (VNA) PNA-X from Agilent Technologies. The measured values of the proposed antenna, with 50 x 38 x 1.6 mm3 in total and constructed on a FR4 substrate with permittivity of ɛr = 4.3, loss tanδ = 0.0024 and substrate thickness of h = 1.6 mm, correlate well with the simulated values. The proposed antenna, compared with other published work, is a good candidate to operate in WLAN, X-band. compact lowcost, lowcost low cost, cost low-cost lowprofile profile Ushaped U shaped bandnotched notched ultrawideband ultra wideband UWB (UWB SRRs. . WLAN (WLAN WiMAX satellite, satellite , satellite) fourelement four element splitring (SRRs 5.155.35 515535 5.15 5.35 5 15 35 5.15-5.3 5.7255.85 5725585 5.725 5.85 725 85 5.725-5.8 GHz antennas s 852 8 52 8.5 dBi 718 7 18 7.1 27 -2 dB 843 84 3 84.3% prototype structures machine VNA (VNA PNAX PNA X Technologies 16 1 6 1. mm FR 43 4 4.3 00024 0 0024 0.002 work Xband. Xband band. X-band 155 5.155.3 51553 515 5.1 535 5.3 5.15-5. 7255 5.7255.8 572558 5725 5.72 585 5.8 72 5.725-5. 8. 71 7. 2 - 84.3 4. 0002 002 0.00 5.155. 5155 51 5. 53 5.15-5 5.7255. 57255 572 5.7 58 5.725-5 84. 000 00 0.0 5.155 5.15- 5.7255 57 5.725- 0.

Abstract A novel wideband high-selectivity substrate-integratedwaveguide (SIW) filtering antenna with controllable radiation nulls is proposed. This antenna is composed of a two-layered SIW resonator, two radiating slots on the top layer, and two coupling slots on the middle layer. A vertical SMA connector is located at the bottom and feeds two SIW cavities simultaneously. By adjusting the parameters of these slots, three radiation nulls will be achieved, and two radiation nulls can be easily controlled. For demonstration, one prototype of the filtering antenna is fabricated and measured. Measurement results show that the fractional bandwidth for |S11| < -10 dB is 8.9% (3.86-4.23 GHz), the gain is 6.08 dBi at center frequency 4.05 GHz, three radiation nulls are achieved at 3.7 GHz, 4.3 GHz, and 5.19 GHz, respectively. The out-of-band skirt selectivities of two sidebands are 150 and 332 dB/GHz, respectively. highselectivity high selectivity substrateintegratedwaveguide substrate integratedwaveguide (SIW proposed twolayered layered resonator layer simultaneously controlled demonstration measured S11 S |S11 10 -1 89 8 9 8.9 3.864.23 386423 3.86 4.23 3 86 4 23 (3.86-4.2 GHz , GHz) 608 6 08 6.0 405 05 4.0 37 7 3. 43 4. 519 5 19 5.1 respectively outofband out band 15 33 dBGHz dB/GHz S1 |S1 1 - 8. 864 3.864.2 38642 386 3.8 423 4.2 2 (3.86-4. 60 0 6. 40 51 5. |S 3.864. 3864 38 42 (3.86-4 3.864 (3.86- (3.86 (3.8 (3. (3 (

Abstract This paper presents a numerical study and the optimization of very short discrete multi-pump Raman amplifiers using Tellurite-based optical fibers. While most studies about discrete Raman amplifiers usually focus on cases where hundreds of meters of fiber are used, here we consider a multi-pumped Raman amplifier setup with extremely short dimensions, in which the length of the gain media was varied from 2.5 to 30 meters. The optimization process was developed over an broad amplification band from 1520 to 1600 nm, considering a maximum acceptable ripple of 3 dB, and using 2, 3 and 4 pumps with individual powers always below 2.5 W. The results show that it is possible to achieve net gains as high as 10 dB for gain media around 20 meters, and close to 15 dB for 30 meters. These high gains highlight the fact that Tellurite-based optical fibers can be used for the construction of very short and compact broadband amplifiers using just a few pump lasers with modest optical powers. multipump multi Telluritebased Tellurite based multipumped pumped dimensions 25 2 5 2. 152 160 nm W 1 16

Abstract Mobile radio channel and its effects on the radio link path place fundamental limitations on the performance of wireless communication systems. This paper sets out a new approach for wideband modeling of mobile radio channels to classify distinct environments. It applies the hidden Markov model technique to different data sets of the main temporal dispersion parameters of the mobile radio channel: average delay and delay spread. The applied technique has proven to design properly the transitions among those temporal dispersion parameters, mapping statistically the transitions from one point in space to another, and it has revealed to be a feasible option to classify and describe statistically the wideband radio channel in each propagation medium. systems environments spread another medium

Abstract This paper presents outcomes of a comprehensive investigation of the performance features of the compressed-vdipole antenna, recently introduced in the literature as being particularly suitable for unmanned surface boat applications. The moment-method solution to the rigorously formulated electric field integral equations for the problem, provided an approximation to the distribution of current on the antenna. A comparison of computational results due to this formulation with available measurement data demonstrated very good agreement between the two; to lend credence to the validity of the formulation. Profiles of the antenna’s input and radiation-zone characteristics (including input impedance, return loss, E-field patterns, and maximum directivity) presented in the paper describe how choice of apex angle, antenna electrical length, and degree of compression, influence the performance of the antenna. compressedvdipole compressed vdipole applications momentmethod moment method problem two antennas s radiationzone radiation zone including impedance loss Efield E patterns directivity angle length compression

Abstract The development of radio frequency circuits is currently guided mainly through two objectives, which are size reduction and performance improvement of devices. Within a reception or transmission channel, the division and/or combination of power are the most delicate stages due to their large dimensions and high insertion losses, particularly in the case of dividers/combiners based on planar technologies. In this context, this study proposes an analysis and design of a new broadband power divider and combiner using stepped impedance. The power divider/combiner developed is designed to cover a broad frequency spectrum ranging from 1 GHz to 4 GHz, including wireless applications such as Global Mobile Communications Systems (GSM), Industrial, Scientific and Medical (ISM), and Sub-6 GHz 5th Generation (5G) applications. The proposed circuit was analyzed using the stepped transmission line impedance method and designed by Advanced Design System (ADS) on an Epoxy-FR4 substrate with a dielectric constant of 4.4 and a thickness of 1.58 mm. The achieved results showed excellent characteristics in terms of transmission across the input and output terminals, mismatches at all three terminals, and isolation among output terminals. A prototype was built and the measured results showed good agreement with those obtained by simulation. objectives devices channel andor losses dividerscombiners dividers combiners technologies context dividercombiner GSM, GSM , (GSM) Industrial ISM, ISM (ISM) Sub6 Sub 6 Sub- th 5G G (5G ADS (ADS EpoxyFR4 EpoxyFR Epoxy FR4 FR Epoxy-FR 44 4. 158 58 1.5 mm terminals simulation (GSM (ISM 15 5 1.

Abstract This paper attempts to investigate the design of a modified Y-shaped demultiplexer based on photonic crystal. The designed structure is used to select four telecommunication wavelengths. In our design, four resonant cavities (RC)are utilized. A square lattice of silicon (Si) rods immersed in air matrix is used as a fundamental structure. Thus, our study is to investigate the effect of various design parameters on the output frequency. To simulate the performance of the proposed device, the Finite Difference Time Domain (FDTD) approach is used. The obtained results show that the average power transmission, quality factor, channel spacing, crosstalk, and full width at half maximum, are 99.925 %, 4638.785, 19.6 nm, from -40,119 to -24,316 dB, and 0.325nm, respectively. Additionally, the proposed demultiplexer is very compact with a total footprint of 269µm2, which is very suitable to be utilized in compact photonic integrated circuits (PIC). Yshaped Y shaped crystal wavelengths RCare RC Si (Si Thus frequency device FDTD (FDTD transmission factor spacing crosstalk maximum 99925 99 925 99.92 % 4638785 4638 785 4638.785 196 19 6 19. nm 40,119 40119 40 119 -40,11 24,316 24316 24 316 -24,31 dB 0325nm 0 325nm 0.325nm respectively Additionally 269µm2 µm PIC. PIC . (PIC) 9992 9 92 99.9 463878 463 78 4638.78 1 40,11 4011 4 11 -40,1 24,31 2431 2 31 -24,3 269µm (PIC 999 99. 46387 46 7 4638.7 40,1 401 -40, 24,3 243 3 -24, 4638. 40, -40 24, -24 -4 -2 -

Abstract In this paper, the application of AI and machine learning (ML) to the study of wireless propagation channels is investigated in two parts: first, an artificial neural network model is used to improve path loss prediction, and then, a pattern recognition model using multilayer perceptron (MLP) networks is used to identify and remove impulsive noise in power delay profiles (PDP). These studies were conducted based on field measurements in the 2400 MHz band in a public square with vegetation. The results are analyzed and compared with ordinary least squares (OLS) nonlinear regression results and results from similar studies. The Root Mean Square Error (RMSE) values between the experimental results of mean path loss and those provided by each propagation model are presented. The adjustment performed by OLS nonlinear regression and ANN significantly reduced the RMSE. The best results are those presented by artificial neural networks, with RMSE of 0.39 when using four neurons in the hidden layer of the ANN. The ANN used to identify and remove impulsive noise in power delay profiles (PDP) through pattern recognition proved to be more efficient than the CFAR technique. ANN technique found a larger number of valid multipaths compared to the CFAR technique. paper ML (ML parts first prediction then MLP (MLP PDP. PDP . 240 vegetation (OLS (RMSE 039 0 39 0.3 (PDP 24 03 3 0. 2

Abstract This paper proposes a methodology for developing antipodal Vivaldi antennas using RSIW (Ridge Substrate Integrated Waveguide) technology for a specific cut-off frequency. The technique employs metallic-vias and metalized cylindrical posts of reduced sizes inserted in the dielectric substrate. The simulations were performed using the ANSYS® Electronics Desktop software. The antenna RSIW is designed for a resonant frequency of 4 GHz and was fabricated on FR4 (ɛr=4.4 and tanδ=0.02). The structure is compared to an antipodal Vivaldi antenna (AVA) fed by a SIW. The structure proposed had an increase in bandwidth of 4.09 GHz and an increase in gain of 1.41 dBi. Ridge Waveguide cutoff cut off metallicvias metallic vias substrate ANSYS software FR ɛr=4.4 ɛr44 ɛr (ɛr=4. tanδ=0.02. tanδ002 tanδ tanδ=0.02 . 0 02 tanδ=0.02) AVA (AVA SIW 409 09 4.0 141 1 41 1.4 dBi ɛr=4. ɛr4 (ɛr=4 tanδ00 tanδ=0.0 40 4. 14 1. ɛr=4 (ɛr= tanδ0 tanδ=0. ɛr= (ɛr tanδ=0 tanδ=

Abstract This paper focused on the design and practical implementation of a compact arrowhead slot Super Wide Band (SWB) antenna on a semi-flexible substrate for a wide range of applications. A tapered feed circular monopole antenna with an arrowhead-shaped slot structure is designed on RT/Duroid substrate with a compact physical dimension of 22 × 28 × 0.508 mm3. The impedance bandwidth of the proposed antenna is 95.93 GHz (3.1-99.17 GHz) with a peak gain of 6.91 dBi. The proposed antenna has a fractional bandwidth of 187% with a high Bandwidth Dimension Ratio (BDR) of 3049 which makes the proposed antenna suitable for a wide range of applications. The proposed antenna compactness is theoretically verified with the help of the fundamental dimension limit theorem. For wearable IoT applications compactness, conformal and bending capabilities of materials are essential and hence the proposed antenna is also tested under different bending conditions and achieved a minor effect on the antenna performance. Further in order to observe the signal correlation, the time domain analysis using similar antennas in face-to-face and side-to-side scenarios has been also analyzed. The simulated results of the proposed antenna exhibit good agreement with the experimental results of the prototype model antenna. SWB (SWB semiflexible semi flexible arrowheadshaped shaped RTDuroid RT Duroid 2 0508 0 508 0.50 mm3 mm 9593 95 93 95.9 3.199.17 319917 3.1 99.17 3 1 99 17 (3.1-99.1 691 6 91 6.9 dBi 187 BDR (BDR 304 theorem performance correlation facetoface face sidetoside side analyzed 050 50 0.5 959 9 95. 199 3.199.1 31991 31 3. 9917 99.1 (3.1-99. 69 6. 18 30 05 5 0. 19 3.199. 3199 991 99. (3.1-99 3.199 319 (3.1-9 3.19 (3.1- (3.1 (3. (3 (

Abstract This paper presents a novel nature-inspired tri-band frequency selective surface (FSS) characterized by closely spaced bands, angular stability, and polarization independence. The FSS element adopts a segmented Fibonacci spiral geometry. While a single-segmented Fibonacci spiral does not inherently possess polarization independence, the proposed proof of concept achieves this by cascading the same design geometry rotated by 90° between them. Resonant frequencies of 1.63 GHz, 2.46 GHz, and 3.43 GHz are achieved, with minimal separation ratios of 1.5 from the second to the first frequency and 1.4 from the third to the second. Additionally, angular stability is confirmed up to 45°. Simulation of the FSS is conducted using HFSS software, and the simulated results are rigorously validated against experimental data, demonstrating excellent agreement. natureinspired nature inspired triband tri band (FSS bands independence singlesegmented single 90 them 163 1 63 1.6 246 2 46 2.4 343 3 43 3.4 achieved 15 5 1. 14 4 Additionally 45 45° software data agreement 9 16 6 24 2. 34 3.

Abstract The equivalent wave impedance circuit model (ECM-WI) is presented for the analysis of frequency selective surfaces (FSS). The development of the analytical model is based on homogenization theory, as well as analogies between wave theory and transmission line theory. The coplanar strip model and the concept of wave impedance are used to scale the Marcuvitz model for periodic strip gratings of conductive strips, as well as to consider the influence of the presence of a lossy dielectric substrate on the frequency response of the FSS. In particular, the model is applied to the analysis of square loop FSSs and considering the normal incidence. The results obtained are presented by comparing full-wave simulations for the two proposed models, obtaining average deviations in absolute values (%) of 2.11 and 0.38 for resonance frequency and 3.45 and 5.49 for bandwidth. The prototype manufactured in FR-4 obtained a deviation of 2.56% for resonance frequency and 2.79% for bandwidth. ECMWI ECM WI (ECM-WI FSS . (FSS) strips particular incidence fullwave full models % (% 211 2 11 2.1 038 0 38 0.3 345 3 45 3.4 549 5 49 5.4 bandwidth FR4 FR 4 FR- 256 56 2.56 279 79 2.79 (FSS ( 21 1 2. 03 0. 34 3. 54 5. 25 2.5 27 7 2.7