S-parameters Research Articles

A wide-band circularly polarized antenna array using a sequential phase feed structure applied to 5G-band

In this article, a 2×2 broadband circularly polarized antenna array using the sequential rotation (SR) technique in the feed network is presented. This antenna covers the 5G-band of 3.5–3.6 GHz and 4.8–4.9 GHz. So, it can be used for 5G-band communication [1]. The performance of the antenna is obtained by simulation and experiment, as follows: the bandwidth of S11 parameter below -10 dB is 3.7 GHz (3.3–7 GHz), and AR bandwidth (AR < 3 dB) is 2.4 GHz (3.5–5.5 GHz and 5.8-6.2 GHz ), the maximum gain is about 10.2 dBi, and the gain is greater than 0 dBi in the range of 3.6–6.5 GHz.

5G Antipodal Reconfigurable Base Station Antenna for Modern automobile tracking applications

This paper presents antipodal dipole antenna which is also a base station antenna which is highly suitable for tracking an automobile especially cars/trucks. This antenna contains 4 planes, including the reflector plane, brick on which two poles are present. The Gain of the antenna is around 6.9 to 7.1 dB based on the width of the dipole of the antenna. The directivity remains the same in all width of the dipoles and the S11 parameters values changes as of the width of the dipole. Comparatively the antenna has a good gain and S11 values in frequency 6.5 GHz at the dipole width of 4mm. This antenna finds its way in medical fields to improve the communication inside the automotive vehicles. The proposed antenna is a reconfigurable antenna, which has good gain at multiple frequencies. The reconfigurable is made possible using Metamaterials. The Antipodal structure of the antenna is due to presence of multiple planar types in the antipodal structure of the antenna. Even if the frequency not properly received by the antenna, the reflector plane reflects the frequency towards the one plane at the back of the brick, so the gain is maintained at a desired level.

Power Transfer Analysis of an Asymmetric Wireless Transmission System Using the Scattering Parameters

The most widely adopted category of the mid-range wireless power transmission (WPT) systems is based on the magnetic resonance coupling (MRC), which is appropriate for a very wide range of applications. The primary concerns of the WPT/MRC system design are the power transfer capabilities. Using the scattering parameters based on power waves, the power transfer of an asymmetric WPT/MRC system with the series-series compensation structure is studied in this paper. This approach is very convenient since the scattering parameters can provide all the relevant characteristics of the WPT/MRC system related to power propagation. To maintain the power transfer capability of the WPT/MRC system at a high level, the scattering parameter S21 is used to determine the operating frequency of the power source. Nevertheless, this condition does not coincide with the maximum possible power transfer efficiency of the system. In this regard, the WPT/MRC system is thereafter configured with a matching circuit, whereas the scattering parameter S21′ S21’is used to calculate and then adjust the matching frequency of the system. This results in the maximum available power transfer efficiency and thereby increases the overall performance of the system. Theoretical investigations are followed by numerical simulation and experimental validation.

Design of microstrip coupled-line bandpass filter

This project contains basic information, design, 3D projection, simulation, and analysis of Microstrip Bandpass Filter. The filter was composed of the feed lines connected to the two ports with the parallel coupled lines between them. The separation between these elements is reduced to the minimum for the purpose of reducing the error. Ultimately, the microstrip bandpass filter was designed with a 400 MHz bandwidth. We end up with these result: at the 4.43 GHz, S11 parameter is -9.868 dB and S22 is -1.808 dB, while at the 4.83 GHz, S11 is -9.995 dB and S22 is -1.826 dB.

Simulation and comparison of single and differential ended CG-CS LNA for Cognitive Radio

In this paper, comparison of common gate-common source single ended and differential ended Low Noise Amplifier (LNA) for Cognitive Radio (CR) receiver is presented. LNA for CR receiver architectures operating over a frequency range of 50–900[Formula: see text]MHz is designed for narrow band applications. In this work, Noise figure (NF), Third-Order Intercept Point (IIP3), voltage gain and scattering parameters (SP) have been analyzed. The voltage gain is 10.16866[Formula: see text]dB for single ended and 29.21371[Formula: see text]dB for differential ended, NF is 1.012[Formula: see text]dB for single ended and 3.8[Formula: see text]dB for differential ended. Power gain (S21) obtained is 15.67481[Formula: see text]dB for single ended and 14.89[Formula: see text]dB for differential ended. Compression point is [Formula: see text][Formula: see text]dB for single ended and [Formula: see text][Formula: see text]dB for differential ended, Third-Order Intercept Point (IIP3) is 1.97705 for single ended and 5.01608[Formula: see text]dB for differential ended amplifier, respectively. The design has been implemented using CMOS technology with cadence virtuoso design environment/automation tools.

S11 Parameter Calculation of Frequency Selective Surface Based on Deep Learning

This paper proposes the FSS-CNN network model as a forward predictor, replacing the function of the Maxwell equation solver of commercial software. The predictor is different from the numerical optimization method, and the data-driven method based on machine learning (ML) can be expressed and generalize complex functions or data to discover unknown relationships between a large number of variables. In the frequency range of 2∼18GHz, the S11 parameter prediction of the corresponding metal pixel pattern can be easily realized by an accurate forward neural network model. The MSE reaches the level of less than 0.1 and the time consumption is less than 0.07s, which meets the requirements of fast, efficient and automatic calculation.

Elicitation of Scattering Parameters of Dual-halo Dual-dielectric Triple-material Surrounding Gate (DH-DD-TM-SG) MOSFET for Microwave Frequency Applications

This paper presents an analytical model for intrinsic short-circuit admittance (Y) parameters of DH-DD-TM-SG MOSFET. Y parameters have been modeled using different small-signal equivalent circuit parameter which is used to find the Scattering parameters. These Y parameters have further been employed for computing S-parameters. These parameters are further used to investigate the microwave performance parameters of the proposed device. The Unilateral Power Gain and the maximum oscillation frequency is determined to evaluatethe microwave performance. The proposed device shows a higher cut-off frequency (f_T) and maximum oscillation frequency as to TM-SG MOSFET. The proposed device exhibits a 4.2% improvement in U_T 2.81% in G_ms and 6.9% improvement in G_MTPG as compared to TMSG. The analytical result of DH-DD-TM-SG MOSFET is in accordance with the simulated results.

High quality and low loss surface acoustic wave SAW resonator based on chromium-doped AlN on sapphire

This paper aims to investigate the performances of surface acoustic wave (SAW) resonators based on chromium-doped aluminum nitride (AlCrN) piezoelectric thin film on c-cut sapphire substrate. The electromechanical properties of AlCrN (mass density, elastic, dielectric and piezoelectric constants) are obtained from density functional theory calculations for different Cr-doping concentrations. Piezoelectricity is enhanced for Al1 − xCrxN with different x concentrations. Using finite element analysis, the electroacoustic parameters such as phase velocity, electromechanical coupling factor K2 of surface acoustic modes are determined for different AlCrN thickness-to-wavelength ratios and different Cr-doping concentrations. Higher order SAW modes arise at Cr concentration x = 25%. The electrical admittance and scattering parameter S21 for the fundamental SAW modes are determined. High K2, low loss and high-quality factor are found after incorporating Cr dopant. The comparison of the obtained results with the available numerical and experimental data on AlN doped with Scandium Sc has shown a considerable improvement of SAW devices characteristics, confirming that AlCrN can be adopted as a new piezoelectric material for high performances SAW devices.

Wideband Inductorless True Time Delay Cell Based on CMOS Inverter for Timed Array Receivers

In this paper, an inverter-based true time delay (TTD) cell for timed array receivers is proposed. The proposed TTD cell is designed in TSMC 0.18 µm CMOS technology for multi-GHz operations. The delay cell is made from an all-pass filter by Pade approximation. The first-order all-pass filter is built by combining a constant gain stage and a low pass stage based on the approximation. The constant gain stage consists of two NMOS transistors. The low pass stage is created with an inverter cell, cascaded with a PMOS transistor. Active true time delay cells are used in delay lines (commonly in cascaded topology) to develop a timed array system. Because of that, size of the TTD cell is critical and is an important design factor. So in this paper, an inductorless inverter-based wideband TTD cell is proposed. The wideband input impedance matching is achieved without bulky inductors using the resistive feedback technique in the inverter cell. More than wideband input impedance matching, flat gain, and flat delay response for the TTD cell are obtained with this technique. With the inverter-based input and complementary output structure, the TTD cell is a self-biased circuit. So, additional bias circuit is not needed. The proposed TTD cell consumes 8.7 mW from a 1.8 V supply. The achieved wideband delay is 10.6pS. Only 3% delay deviation over the 1–5 GHz band is observed, and this shows the excellent quality of the provided delay. The insertion loss is − 3.9 dB and is tolerable for a TTD cell. The input and output wideband impedance matching is ensured, and the S11 and S22 parameters are lower than -14.7 dB and − 10.9 dB, respectively. At last, the proposed TTD cell shows good linear performance, and IIP3 is around + 11.7 dBm.

Multifunctional Hyperelastic Structured Surface for Tunable and Switchable Transparency

We leverage the crucial hyperelastic properties of a multifunctional structured surface to optimize the reconfigurability of the electromagnetic transmission under large nonlinear mechanical deformations. This multiphysics, multifunctional, hyperelastic structured surface (HSS) offers two simultaneous intriguing functionalities; tunability and switchability. It is made of copper resonators and a Polydimethylsiloxane (PDMS) substrate, which is one of the most favorable deformable substrates due to its hyperelastic behavior. The proposed HSS is fabricated via an original cost-effective technique and the multiphysics functionalities are captured in both experimental tests and numerical simulations. Leveraging the hyperelastic behavior, we demonstrate up to 8% percent shift in the resonance frequency in the GHz range, for average applied mechanical strains of around 17%. The hyperelastic deformations can continuously increase/decrease the magnitude of the scattering parameter S21 in the frequency range of 10.9 GHz to 11.8 GHz by more than 40 dB, changing from being largely transparent to opaque and vice versa. The potential of hyperelastic behavior to account for the multifunctionality of the HSS is validated experimentally.

Electromagnetic shielding performance of copper and silver-plated hybrid yarn based multilayer fabrics in C &amp; X band frequency range

In the present study, a strategic designing of multilayer shield was planned to enhance the multiple reflection phenomenon to achieve maximum absorption properties in microwave frequency (C &amp; X band) range. Multi-layer EMR shields were developed using pure cotton fabric and conductive woven fabrics, incorporated with copper- based &amp; silver-plated hybrid yarn. First of all, single layer fabrics were produced in five variants, nomenclature as L1A (pure cotton) L1B, L1C (copper-based hybrid yarn), LS1B and LS1C (silver plated hybrid yarn). These five variants were used to prepare four sets of double &amp; triple layer fabric. In both double and triple layer composition, L1A fabric (pure cotton) was used as top layer followed by B and C series fabrics, containing copper and silver-plated hybrid yarn. The EMSE performance in C and X band frequency range of single layer, double layer and triple layers in terms of scattering parameters S11(reflectance) &amp; S21 (transmittance) in vertical and horizontal wave polarization was studied. It was found that number of layers, layer composition, orientation of metallic yarn, frequency and EM wave polarization have significant influence on overall electromagnetic shielding effectiveness.

Application of Broadband Microwave Near-Field Sensors for Glucose Monitoring in Biological Media

The paper presents results of numerical simulation and experimental testing of a microwave sensor for non-invasive glucose monitoring. The sensor represents a conical horn with a conical conductor inside expanding toward the horn aperture. Such a sensor has a significantly wider passband in comparison with sensors of other designs. It is essential that the sensor geometry provides formation of an extended near-field zone with high electric field strength near the sensor aperture. A clear relationship between the dielectric permittivity of the phantom biological tissue and the frequency dependence of the parameter S11 of the sensor is observed at frequencies in the range from 1.4 to 1.7 GHz. This circumstance can be used to develop a procedure for measuring the glucose level in blood that correlates with the parameter S11 of the sensor. From the viewpoint of monitoring of the glucose content in blood, the most convenient body sensor location is on the hands or feet, in particular, wrists.

Discriminant value of automated leucocyte VCS parameters in the detection of tropical infections

IntroductionIn India, infectious diseases are a leading treatable cause of morbidity and mortality. Mangalore being endemic to many vector‐borne diseases, their incidence is known to show seasonal variations with sharp increase during monsoon. Leucocytes have substantial role in the immunological pathogenesis of infections.MethodsThe present series was a hospital‐based cross‐sectional study performed in a tertiary care hospital for a period of three months from June‐August wherein the cell population data of cases of malaria, dengue, leptospirosis, typhoid and rickettsial infections along with equal number of healthy controls were collected and analysed. Effectiveness of leucocyte‐related volume (V), conductivity (C) and scatter (S) parameters by Coulter®DXH800 haematology analyser in predicting these infections was appraised.ResultsA total of 324 cases comprising of malaria (50%), dengue (30.9%), leptospirosis (13.9%), typhoid (4.0%) and rickettsial infections (1.2%) were included. There was statistically significant differences (P < 0.05) in the mean values of complete blood count parameters—haemoglobin, total leucocyte count, red blood cell count, haematocrit, red cell distribution width, differential leucocyte count, platelet count and plateletcrit between cases and controls and also between specific infections. The mean volumes of neutrophil, monocyte and lymphocyte were considerably increased in malaria and dengue fever compared to leptospirosis, typhoid and rickettsial infections. VCS parameters were the least altered in typhoid fever, except for a strikingly high conductivity and scatter of eosinophils.ConclusionsHaematological analysis is a part of routine evaluation of any case of febrile illness. This study showed that there are specific alterations in VCS parameters in different types of infections such as malaria, dengue, leptospira, typhoid and rickettsia, the information and analysis of which comes without any additional cost.

A high gain, compact active disc-cone antenna based on non-foster matching circuit

The conventional passive matching technology of antenna is limited by the gain-bandwidth constraints. The antenna miniaturization can be only achieved in a very narrow frequency band with a low gain in the high frequency (HF) and very high frequency (VHF) bands. In order to realize the broadband matching and high gain design of the miniaturized disc-cone antenna, a non-Foster matching circuit, which consists of a negative impedance converter, a transformer and a current buffer, is proposed for impedance matching of the miniaturized disc-cone antenna. It is different from the conventional non-Foster matching circuit, which is merely composed of a negative impedance converter. Compared with the classical design, the size of the miniaturized antenna loaded with the proposed circuit is reduced by 60.9%. The S11 parameter of the antenna is less than −15 dB in the frequency range of 150–250 MHz, and the gain improvement of the non-Foster matching circuit to the miniaturized disc-cone antenna is more than 10 dB. Therefore, the matching circuit proposed in this research has better impedance matching performance and gain improvement compared to the conventional design. The results from the experiments validate the feasibility and effectiveness of the new design scheme.

Miniaturization of asymmetrical gaussian profiled corrugated horn

In this paper, miniaturization of the asymmetrical profiled corrugated horn with low sidelobes, low cross-polarization, and good beam symmetry is presented. The miniaturized corrugated horn is designed at 2.48 GHz and optimizes the result between the frequency sweeps of 2 GHz to 4 GHz. At design frequency, the result of the S11 Parameter is -30.2966 dB, and the S11 Parameter remains below -20 dB between 2 GHz to 4 GHz. The asymmetrical profiled corrugated horn comprises the Gaussian Profiled Corrugation part and the most widely used Variable Depth Slot Mode Converter. The purpose of the mode converter is to generate hybrid mode in the corrugated horn antenna. The length of the asymmetrical profiled corrugated horn antenna after applying the miniaturization technique is only 3.5λ long. The designed horn full-fill the number of S-Band applications such as Satellite communication, Radio astronomy, Weather Radar, Surface ship radar.

Porous Phantoms Mimicking Tissues-Investigation of Optical Parameters Stability Over Time.

Optical phantoms are used to validate optical measurement methods. The stability of their optical parameters over time allows them to be used and stored over long-term periods, while maintaining their optical parameters. The aim of the presented research was to investigate the stability of fabricated porous phantoms, which can be used as a lung phantom in optical system. Measurements were performed in multiple series with an interval of 6 months, recreating the same conditions and using the same measuring system consisting of an integrating sphere, a coherent light source with a wavelength of 635 nm and a detector. Scattering and absorption parameters were determined on the basis of the measured reflectance and transmittance. The tested samples were made of silicone and glycerol in various proportions.

Robust Effective‐Medium Characteristics of Bianisotropic Reflective Metasurfaces based on Field‐Circuit Combined Analysis

AbstractAs a bridge linking propagating waves and surface waves, reflective metasurfaces (with metal cladding at the bottom) play a significant role in the field of beam steering. The feasibility and flexibility to control electromagnetic waves by reflective metasurfaces depend on the recognition of their physical properties by researchers. As for bianisotropic reflective metasurfaces, however, the effective‐medium characteristics cannot be appropriately described by conventional methods, which entail both transmission and reflection coefficients. Here, a robust method based on simplex S‐parameters is proposed to retrieve constitutive effective parameters (CEPs) for bianisotropic reflective metasurfaces. By illuminating the transverse electric‐polarization plane waves on a split‐ring unit cell normally and obliquely, the CEPs can be calculated with only S11 parameters. To demonstrate the effectiveness of the retrieval results, an analysis of small incident angles is employed to examine the consistency of both the x‐ and y‐directions effective impedance and determine the accurate range of the incident angles. Moreover, the sensitivity of the retrieval results to S‐parameters is also sufficiently discussed. This method is beneficial for the applications of one‐side complex materials, e.g., dual‐function reflective metasurfaces, multichannel reflectors, excitation of spoof space plasmon polaritons, and ground‐penetrating‐radar applications.

Fabrication of exchange coupled hard/soft magnetic nanocomposites: Correlation between composition, magnetic, optical and microwave properties

This paper studied the exchange coupling performance beside structural and microwave properties of SrFe12O19 (SFO) and x(CoTm0.01Tb0.01Fe1.98O4) (CoTmTb) (x ≤ 3.0) hard/soft ferrites nanocomposites (NCs). The structure and morphology of NCs were investigated by XRD, SEM, TEM and HR-TEM. Diffuse reflectance spectroscopic (DRS) measurements were applied on hexagonal ferrite, on spinel ferrite nanoparticles and on hard/soft NCs to specify the optical properties. Estimated Eg data are in a range between 1.32 and 1.79 eV. The magnetic properties were also inspected via measurements of magnetization (M) against magnetic field (H) at 300 K (RT) and 10 K (LT). The measurements performed at RT along with the plots of dM/dH versus H indicated that the NCs display good magnetic properties (exchange coupling behavior). The magnetic parameters such as (Ms, Mr, and Hc) show an enhancement in their values with an increasing the soft content at RT. Similarly, the maximum energy product (BH)max rises and reaches its max value for SFO/3(CoTmTb) NCs. Microwave properties of the SFO/x(CoTmTb) NCs were measured in the frequency range 33–50 GHz. From measured S11 and S21 parameters the main electrodynamic characteristics – permittivity and permeability (real and imaginary parts) were computed.

Low-Cost Metamaterial Loaded Microstrip Antenna for Defense Applications

We have designed a Metamaterial unit-cell for 9 GHz frequency. Periodic structure was used at 4.25 × 4.25 mm with a thickness of 0.35 mm and giving us the 99.99% of absorbance at 9 GHz in simulated results. We have implemented a rectangular microstrip antenna and loaded it with Metamaterial unit-cells which provided improved results. There were results available for reflection coefficient (s11 parameter) at 9 GHz and also helping for the reduction of the Radar Cross Section of an antenna, which reduced more than 20 dB and not affected its directivity and gain.

Field Uniformity Assessment of a Reverberation Chamber for a Large-Scale Animal Study

An exposure system was designed and implemented for the purpose of joint large-scale animal experiments conducted in Korea and Japan using a reverberation chamber (RC) in both countries. Prior to the start of the animal experiments, the parameters S21, electric field (E-field) uniformity, and Q factor were evaluated to confirm the performance of the developed chambers. The E-field uniformity, which is the most important performance factor of an RC, was evaluated at 900 MHz on 150 measurement values taken at 150 points in a loaded chamber with 80 live rats and in an empty chamber. The conditions of the loaded chamber with the rats are almost the same as the actual experimental environment and in which the rats, watering systems, animal bedding, cages, and cage racks were included. Two mean body weights of 330 and 470 g for the 80 rats were considered. The E-field uniformity was within the mean ± 1.0 dB and mean ± 2.3 dB under the empty and the rat-loaded conditions, respectively.