Input Reflection Coefficient Research Articles

DESIGN AND SIMULATION OF S-BAND MICROWAVE AMPLIFIER FOR SATELLITE COMMUNICATIONS SYSTEM

This paper presents a novel design of S-band monolithic microwave integrated circuit (MMIC) amplifiers based on GaAs MESFET HFET-1102 transistors used in radiofrequency (RF) and microwave communications systems. Based on the Chebyshev gain response, an analytical method is used to design a two-stage lumped microwave amplifier. The matching networks constituted by lumped elements are transformed into T inductive networks, and the resulting amplifier is optimized using RF simulator software. In the following step, the lumped optimized amplifier is transformed into a distributed amplifier and implemented on Rogers TMM3 substrate largely used in microwave circuits. The final MMIC amplifier is stable in the frequency band (2-4 GHz), and excellent performances are obtained in terms of very high gain, reaching a peak of 35 dB, low input (S11) and output reflection (S22) coefficients, and very good output/input isolation (S12). For its RF characteristics, the proposed MMIC amplifier presented in this work is very suitable for space telecommunications in low earth orbit (LEO) satellites onboard receivers.

Design and fabrication of S-band power amplifier for wireless sensor networks

This paper discusses the process of designing and manufacturing a wideband power amplifier operating in the S-band. To amplify a low power and broadband radio frequency signals from 2.1 GHz to 2.5 GHz, the proposed power amplifier uses a diagram of a two-stages amplification with peak offset amplification frequency 2.3 GHz. The power amplifier is designed with a center frequency difference of 2.2 GHz and 2.4 GHz respectively to achieve a bandwidth of 400 MHz. The proposed power amplifier (PA) uses RF transistor SHF-0589 using gallium arsenide heterostructure field-effect transistor (GaAs HFET) technology for high gain and low power consumption. The complete amplifier achieves power gain 21.1 dB inband 2.1-2.5 GHz and achieve maximum power gain of 22.5 dB at the frequency of 2.4 GHz; the output power rise up to 33 dBm; input reflection coefficient (S11) reaches -19.2 dB and output reflection coefficient reaches -17.2 dB. The designed amplifier circuit can be used for wireless sensor networks operating at S-band.

Compact Wideband Tapered Slot Antenna Using Fan-Shaped and Stepped Structures for Chipless Radio-Frequency-Identification Sensor Tag Applications.

In this paper, two kinds of miniaturization methods for designing a compact wideband tapered slot antenna (TSA) using either fan-shaped structures only or fan-shaped and stepped structures were proposed. First, a miniaturization method appending the fan-shaped structures, such as quarter circular slots (QCSs), half circular slots (HCSs), and half circular patches (HCPs), to the sides of the ground conductor for the TSA was investigated. The effects of appending the QCSs, HCSs, and HCPs sequentially on the input reflection coefficient and gain characteristics of the TSA were compared. The compact wideband TSA using the first miniaturization method showed the simulated frequency band for a voltage standing wave ratio (VSWR) less than 2 of 2.530-13.379 GHz (136.4%) with gain in the band ranging 3.1-6.9 dBi. Impedance bandwidth was increased by 29.7% and antenna size was reduced by 39.1%, compared to the conventional TSA. Second, the fan-shaped structures combined with the stepped structures (SSs) were added to the sides of the ground conductor to further miniaturize the TSA. The fan-shaped structures based on the HCSs and HCPs were appended to the ground conductor with the QCSs and SSs. The compact wideband TSA using the second miniaturization method had the simulated frequency band for a VSWR less than 2 of 2.313-13.805 GHz (142.6%) with gain in the band ranging 3.0-8.1 dBi. Impedance bandwidth was increased by 37.8% and antenna size was reduced by 45.9%, compared to the conventional TSA. Therefore, the increase in impedance bandwidth and the size reduction effect of the compact wideband TSA using the second miniaturization method were better compared to those using the first method. In addition, sidelobe levels at high frequencies decreased while gain at high frequencies increased. A prototype of the compact wideband TSA using the second miniaturization method was fabricated on an RF-35 substrate to validate the simulation results. The measured frequency band for a VSWR less than 2 was 2.320-13.745 GHz (142.2%) with measured gain ranging 3.1-7.9 dBi.

Constructing and optimizing epoxy resin-based carbon Nanotube/Barium ferrite microwave absorbing coating system

High-performance microwave absorbing coatings are highly indispensable for protecting human health and enhancing military strength. A single- and double-layer wave-absorbing coating system that employs complex microwave absorbers composed of the helical carbon nanotubes/doped barium ferrite composite with epoxy resin as the matrix was developed. The concentration and thickness of the coating were optimized by the numerical simulation and the adaptive genetic algorithm. The developed helical carbon nanotubes/doped barium ferrite wave-absorbing composites have a porous reticular structure, with abundant microscopic cavities and an adequately conductive network. The coatings are characterized by a flat surface, good uniformity, and high density. The reflectivity measured by the arch method is similar to that obtained through the finite element simulation, where the absorption bands of all the developed coatings are distributed in the range of 10–18 GHz. The optimized wave-absorbing coating exhibits the most uniform scattering pattern, the largest radar cross section (RCS) reduction, the smallest input reflection coefficient, and the highest absorptivity. Thus, it exhibits the best comprehensive microwave-absorption performance with a minimum reflection loss of −17.22 dB at 16.66 GHz. In particular, the absorption bandwidth of the coating can reach 9.16 GHz, which is attributable to its multiple synergistic electromagnetic attenuation mechanisms and its excellent characteristics of interference-cancellation and impedance-matching characteristics. Generally, helical carbon nanotubes/doped barium ferrite wave-absorbing coatings are promising candidates for applications in Ku-band microwave absorption.

Dual-band ends-fed dipole-like driver for dual-band antenna arrays

The article addresses the problem of dual-band structure designs based on the quasi-Yagi arrangements. The reported dual-band dipole antenna comprises the out-of-phase power divider, whose outputs excite the corresponding dipole arms to produce appropriate surface current distribution on them. The topology of the antenna itself is designed the way to provide high matching (the realized input reflection coefficient is not exceed minus 25 dB) at both central working frequencies. The low-band dipole is meandered to fit the substrate size. In addition, both the dipoles are excited on their remote terminals, which allows the more efficiently use of the circuit body space. The low profile implementation contributes to meeting the high demands of today and future wireless communications. The fundamental properties of linear dipole antennas, such as the Yagi, of being relatively simple in design, pure linearly polarized, having almost omnidirectional patterns made them of the great interest among researches. In addition, the Yagi arrangement itself allows building on its base even more complex antenna structures, comprised a number of linear dipoles, maintained along one of orthogonal axis. When centrally fed, the classical single-band Yagi antenna suffers from narrow band characteristics, becoming a kind of challenge, which has successfully been addressed by a number of researches in the past. At the same time, on the base of Yagi and quasi-Yagi designs it is possible to combine a number of radiating elements, producing, therefore, multi-band or wideband characteristics. This approach is highly efficient when designing multipurpose devices with different transmitting rates. In this project the novel approach for dual-band dipole antennas design is presented. The driven elements are excited from their remote terminals, forming the quasi-Yagi arrangement with untraditional excitation. The balancing scheme is formed by an out-of-phase power divider, whose outputs are connected to the dipoles arms. The topology of the antenna itself is designed to provide high matching (input reflection coefficient does not exceed minus 25 dB) at both center operating frequencies. When integrating a dual band balancing unit with the radiating elements it is crucial to provide low interference for better radiation characteristics. Besides, the surface currents on the ground plane, should not affect those on the radiating elements for better matching.

Evaluation of the thermo-acoustic instability frequency and growth rate via input reflection coefficient measurement for central heating equipment

Experimental measurement methods and theoretical evaluations based on low-order modeling approaches for both the growth rate and frequency at the onset of thermo-acoustic combustion instability are proposed, and their performance is evaluated. The developed techniques are demonstrated through a systematic measurement of the linear growth rate and frequency of evolving oscillations in the laboratory setup and also applied for the thermo-acoustic qualification of an industrial domestic boiler and a heat cell unit (combination of a burner with a heat-exchanger). Generic measurements have been done for a burner deck with premixed surface-stabilized Bunsen-type flames. The industrial domestic boiler and the heat cell unit are equipped with burners of a similar type but differ by their perforation pattern. They have been tested at different conditions and the experimental and theoretical results are compared. Two modeling strategies are tested: 1- in Laplace domain, with estimating a rational function in the complex domain to fit the measured frequency response, 2- exclusively in frequency domain, without estimating a rational function. Both methods include measurement of the frequency response of two reflection coefficients from i) the upstream part of the system, Rup, and ii) burner with flame completed by the downstream part of the appliance, Rin. Within the first approach, a procedure for an analytic continuation of the measured frequency response to the complex domain is applied and complex eigenfrequencies are calculated by solving the corresponding dispersion equation. An alternative approach was proposed by Kopitz and Polifke and allows estimating both the frequency of oscillation and the growth rate from the analysis of the polar plot of the system's characteristic equation in the frequency domain. The comparison shows that the unstable frequencies can be predicted accurately by both tested modeling strategies. This conclusion holds also for the tested industrial applications. The prediction of the instability growth rates is closer to the measured one when the modeling method in the complex domain is used. However, the frequency domain analysis provides less accurate, but still reasonable estimates of the growth rates and frequencies. Moreover, a good overview of thermo-acoustic performance of each industrial boiler/burner at different conditions is obtained via Rin measurements.

A compact dual-band frequency reconfigurable antenna with pin diode integration for smartwatch application

ABSTRACT In this article, a novel frequency reconfigurable antenna for Wi-Fi and WiMAX applications is proposed. The antenna uses PIN diodes for frequency reconfigurability, allowing it to seamlessly switch between two distinct frequency bands centred around the resonant frequencies of 4.1 GHz in the ON state and 5.2 GHz in the OFF state. The input reflection coefficient obtained from the designed antenna is below −10 dB. The measured and simulated gain of the antenna is 4 dBi and 2.65 dBi at resonating frequencies 4.1 GHz and 5.2 GHz the measured and simulated gain is 3.2 dBi and 2.93 dBi, respectively. The radiation pattern exhibits the same for both states. Optimization of the antenna’s dimensional parameters is done with the help of CST simulation software and the electrical parameter such as input reflection coefficient is measured using a Vector Network Analyzer to validate the prototype. The proposed antenna is fabricated on FR-4 substrate material with a thickness of 1.6 mm and a relative permittivity of 4.4. The proposed antenna’s size is 30 × 30 × 1.6 mm3 which is compact and suitable for smartwatch applications. The proposed antenna is compact and remains a good candidate for integration with the smartwatch.

Design of a low power LNA circuit with noise canceling approach in 90 nm CMOS process

In this manuscript, a low noise amplifier (LNA) circuit with low power consumption of 5.3 mW for 3–12 GHz ultra-wideband (UWB) is designed in 90 nm standard CMOS process. A noise-canceling (NC) approach consisting of both common-gate (CG) and common-source (CS) as input stage, followed by the gm-boosted current-reused stage to enhance the gain performance, is used in the proposed design. After noise-canceling, the achieved noise-figure (NF) is ranging from 2.28 to 3.55 dB for 3.1–10.6 GHz and a maximum of 4.0 dB at 12 GHz. Input-reflection coefficient (S11) of < −12.57 dB is achieved from this CG-CS input-matching stage. With the use of parallel-series LC matching with series-peaking-inductor followed by the gm-boosting stage improves the gain-bandwidth and delivers a flat power-gain (S21) of 18.33 ± 0.76 dB over 3–12 GHz. The CG configuration at the input side provides a high reverse-isolation (S12) of less than −78.23 dB and common-drain configuration with NMOS load at the output side ensures less than −11.79 dB output-reflection coefficient (S22) over the proposed frequency range. The proposed LNA is operated with 0.7 V Vdd and the achieved intercept points for input (IIP3) and output (OIP3) are −11.1 dBm and +6.2 dBm, respectively.

An Ultra-wideband Low-power Low-noise Amplifier Linearized by Adjusted Derivative Superposition and Feedback Techniques

Ultra-wideband (UWB) applications require low-power and low-noise amplifiers (LNAs) that can operate over a wide frequency range. However, conventional LNAs often suffer from poor linearity and high-power consumption. This research work proposes a novel LNA design that uses the adjusted derivative superposition (DS) technique and feedback to improve the linearity and reduce the power consumption of UWB LNAs. The DS technique enhances the third-order intermodulation (IM3) cancellation by adjusting the bias currents of the transistors, whereas the feedback improves the stability and input matching of the LNA. The LNA is implemented using a degenerated common source topology in a 180 nm standard CMOS technology. The simulation results show that the LNA achieves a power gain of 10–12.2 dB, an input third-order intercept point (IIP3) of about 12 dBm, and a noise figure of less than 2.5 dB over the UWB frequency band of 3.1–10.6 GHz. The input reflection coefficient is less than -10 dB, and the power consumption is 11.6 mW with a 1.5 V power supply. The designed LNA offers a novel and innovative solution for UWB applications that significantly improve the performance and efficiency of UWB LNAs whereas reducing the cost and complexity of implementation.

Analytic solution for pulse wave propagation in flexible tubes with application to a patient-specific arterial tree

In this paper, we present an analytic solution for pulse wave propagation in a flexible arterial model with tapering, physiological boundary conditions and variable wall properties (wall elasticity and thickness). The change of wall properties follows a profile that is proportional to $r^\alpha$ , where $r$ represents the lumen radius and $\alpha$ is a material coefficient. The cross-sectionally averaged velocity and pressure are obtained by solving a hyperbolic system derived from the mass and momentum conservations, and they are expressed in Bessel functions of order $(4-\alpha )/(3-\alpha )$ and $1/(3-\alpha )$ , respectively. The solution is successfully validated by comparing it with numerical results from three-dimensional (3-D) fluid–structure interaction simulations. Subsequently, the solution is employed to study pulse wave propagation in an arterial model, revealing that the wall properties and the physiological outlet boundary conditions, such as the resistor–capacitor–resistor (RCR) model, play a crucial role in characterizing the input impedance and reflection coefficient. At low-frequency range, the input impedance is found to be insensitive to the wall properties and is primarily determined by the RCR parameters. At high-frequency range, the input impedance oscillates around the local characteristic impedance, and the oscillation amplitude varies non-monotonically with $\alpha$ . Expressions for the input impedance at both low-frequency and high-frequency limits are presented. This analytic solution is also successfully applied to model flow inside a patient-specific arterial tree, with the maximum relative errors in pressure and flow rate never exceeding $1.6\,\%$ and $9.0\,\%$ when compared with results from 3-D numerical simulations.

Design and optimization of variable gain LNA for IoT applications using meta-heuristics search algorithms

In this paper, Variable Gain LNA (VG-LNA) parameters are optimized using the Particle Swarm Optimization (PSO), Firefly Algorithm (FA), and Genetic Algorithm (GA). A comparison of the three optimization techniques has been done and FA is depicting better results over GA and PSO. VG-LNA is composed of a Complementary Common Gate (CCG) and Variable Gain Amplifier (VGA). Gm-boost topology helps in increasing the gain while the current reuse technique provides less power consumption. Optimization algorithms simulated on MATLAB and the result shows minimum Noise Fig. (NF) is 2.62 dB, maximum gain is 17.8 dB, S11 i.e. input reflection coefficient is −13.5 dB and S22 i.e. output reflection coefficient is −14.7 dB at 50 Ω impedance matching while Figure of Merit1 (FoM1) is 36.14 dB using FA. The FA optimized parameters when simulated on Cadence Virtuoso software using GPDK 45 nm CMOS technology for the frequency range of 26–32 GHz then results show a minimum NF of 2.6 dB at 30.9 GHz, maximum gain of 16.9 dB at 30.5 GHz, S11 is −17.7 dB at 30.5 GHz, S22 is −21.2 dB at 29 GHz and FoM1 of 34.19 dB. The layout of the realized circuit has an area of 231.695 μm*164.48 μm i.e. 0.03811mm2.

Engineering planar antenna using geometry arrangements for wireless communications and satellite applications

A triple-band microstrip patch antenna designed for the IEEE 802.16e WiMAX, IEEE 802.11a WLAN, C-band downlink communications, and Ku-band radar recent applications is suggested in this article. The planned antenna operates at 2.45, 6, and 14 GHz resonant frequencies. The antenna fulfilled triple-band physical characteristics covering industrial, scientific, and medical (ISM) bands between (2.1–2.8) GHz; (5.6–6.5) GHz for wireless local area network (WLAN) or ultra-wideband (UWB) services; and 12.7–16 GHz for future two-way 5G:6G either broadcasting or mobile satellite communications. To achieve better return loss performance, parametric studies are carried out using Microwave Studio (CST MWS). The proposed antenna is designed on the FR4 as a hosting medium of total size 46 × 38 × 1.6 mm3, combined with a planar transmission line (T.L.) feed and defected ground structure (DGS). The simulated antenna’s input reflection coefficient (S11) results and the far-field measurements show good agreement. The fabricated prototype achieves peak gain values of 2.8, 3.8, and 4.7 dBi, respectively, and bidirectional radiation characteristics. A comparative study with other recent publications is implemented to validate the consistency of the design.

Wideband signal combining circuit based on multichannel different‐/same‐frequency power combiner

AbstractA wideband signal combining circuit with continuous bandwidth based on multichannel different‐/same‐frequency power combiner is presented. Two‐way signals with the same frequency can be combined to a higher power signal. Two‐way signals with different frequencies can be combined into a broadband signal. A stepped impedance resonator (SIR) is used as a multimode resonator. The wider bandwidth is got by SIR. And the selectivity of the two filtering channels is improved by the introduction of SIR stubs, which generate four transmission zeros on both sides of the passbands. The high 3‐dB point of the low‐frequency channel overlaps with the low 3‐dB point of the high‐frequency channel. Therefore, the output passband is continuous. The measured frequency ranges of two channels are 1.34–2.21 GHz/2.21‐2.87 GHz, respectively, and from 1.46 to 2.74 GHz, the input reflection coefficient is such that the return loss is higher than 15.5 dB. The insertion loss of the two channels is 0.71/1.18 dB, and the measured isolation is higher than 15.4 dB. The measured bandwidth of the combining signal is 1.5 GHz (1.34–2.84 GHz).

Synthesis of a Multiband Microstrip Patch Antenna for 5G Wireless Communications

This paper presents a multiband microstrip patch antenna for future 5G Millimeter Wave (mm-wave) wireless technologies. The synthesized antenna is designed to be based on the genetic algorithm (GA) optimization tool in the high frequency simulation software (HFSS). The optimized dimensions of the engineered antenna are 24 × 24 × 0.203 mm3, comprising of a ground plane. The antenna design simulated results have been implemented via (HFSS) and microwave studio (CST) tools. The proposed antenna structure is engineered using Rogers RT-Duroid 4003 substrate as a dielectric medium. The Conformist rectangular and circular patches are modified to get multiband operation in the mm-wave band 25–32 besides 40–60 GHz frequency ranges. The input reflection coefficient (S11\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathrm{S}}_{11}$$\\end{document}) simulation results were compared with the measurements to check the validity of the design. The fabricated antenna radiation efficiency and gain values are also measured over the desired bandwidths. The measured gain and radiation efficiency values reached up to 9.75 dBi, 0.85%, and 10.75 dBi, 0.84%, for both bandwidths, respectively.

Multiband bandpass filter with asymmetric dual‐band response based on metacell

AbstractThe impressive growth in present‐day wireless communication systems demands compact, low‐power, cost‐effective, planar multiband microwave devices to increase the speed of communication and reduce hardware requirements, which subsequently reduce the power requirement of the system. Accordingly, this article aims to design a multiband microstrip bandpass filter with asymmetric dual‐band response based on metacell. The proposed filter is designed for wide and narrow dual‐band responses with fractional bandwidths of 72% and 2.6%, respectively. For the first time in this article, a new application of metacell in the design of dual‐band filters is discussed. A folded asymmetric step‐impedance resonator and a novel metacell structure—Dual loop split ring resonators are used to obtain wideband and dual‐band responses, respectively. The proposed work discusses the design methodology, and analysis of metacell structure based on a quasistatic model and compares simulation results with experimental results. The proposed dual‐band filter presents an insertion loss (S21) of less than 1 dB and input reflection coefficient (S11) greater than 10 dB in both passbands centered at 3.3 and 5.7 GHz. The designed filter is suitable for wireless communication applications—Wireless Access in the Vehicular Environment.

Multifunctional THz Graphene Antenna with 360∘ Continuous ϕ-Steering and θ-Control of Beam.

A novel graphene antenna composed of a graphene dipole and four auxiliary graphene sheets oriented at 90∘ to each other is proposed and analyzed. The sheets play the role of reflectors. A detailed group-theoretical analysis of symmetry properties of the discussed antennas has been completed. Through electric field control of the chemical potentials of the graphene elements, the antenna can provide a quasi-omnidirectional diagram, a one- or two-directional beam regime, dynamic control of the beam width and, due to the vertical orientation of the dipole with respect to the base substrate, a 360∘ beam steering in the azimuth plane. An additional graphene layer on the base permits control of the radiation pattern in the θ-direction. Radiation patterns in different working states of the antenna are considered using symmetry arguments. We discuss the antenna parameters such as input reflection coefficient, total efficiency, front-to-back ratio, and gain. An equivalent circuit of the antenna is suggested. The proposed antenna operates at frequencies between 1.75 THz and 2.03 THz. Depending on the active regime defined by the chemical potentials set on the antenna graphene elements, the maximum gain varies from 0.86 to 1.63.

Ultrawideband Dual Circularly Polarized Waveguide Array Antenna for K- and Ka-Bands Satellite Communications

In the letter, a wideband dual circularly polarized (CP) waveguide antenna array is designed for K and Ka dual-band satellite communications. A multi-stage square waveguide structure is exploited into the radiating part to facilitate the excitation of a dual polarization response. A ridge waveguide polarizer is integrated to form the left-hand circular polarization (LHCP) and the right-hand circular polarization (RHCP). For a better arrangement of the feeding network, a transition structure with E-plane waveguides to double-ridge waveguides reduces the cross-sectional area of the feeding network. An 8 x 8 array antenna prototype was designed, fabricated and measured for demonstration purposes. The axial ratio (AR) and impedance bandwidth of the array antenna are more than 45%, according to simulation and measurement results. Input reflection coefficient and isolation lower than -15 dB for the dual CP from 19 to 30 GHz, the total antenna efficiency for the entire operating band exceeded 72%. For both polarizations, the peak gain ranges between 24.6 and 28.8 dBi from 19 to 30 GHz.

A compact printed hybrid‐mode antenna for dual‐band dual‐sense circular polarisation

AbstractA compact printed hybrid‐mode antenna for dual‐band dual‐sense circular polarisation (CP) has been proposed. To achieve dual‐band dual‐sense CP, a hybrid mode produced by an L‐shaped element and a loop element is used. In the lower frequency band, the left‐handed CP is radiated by a vertical electric field from the L‐shaped element and a horizontal electric field from the loop element. In the higher frequency band, the right‐handed CP is radiated by a horizontal electric field from the L‐shaped element and a vertical electric field from the loop element. Both the L‐shaped and the loop elements produce resonances in the lower and higher frequency bands. The operational principle for dual‐band dual‐sense CP is clarified using the simulated orthogonal components of the electric fields and the simulated electric current distributions. Parametric studies are discussed in the design procedure. The simulated and measured input reflection coefficient, axial ratio, absolute gain, and radiation pattern are presented. The measured bandwidths of −10dB‐input reflection coefficient with a 3dB‐axial ratio are 2.37–2.55 GHz (7.32%) in the lower frequency band and 3.38–3.70 GHz (9.04%) in the higher frequency band. The antenna size is 0.0741λ2.452 and 0.151λ3.52 (λ f is a wavelength at f GHz).

A novel approach to the design of multi section ultra-wideband Jaumann absorber

A novel ultra-wideband Jaumann absorber design and analytical procedure that greatly enhance the absorption bandwidth and absorptivity level using few dielectric layers are described. The absorptivity bandwidth of the proposed structure is much better than the traditional absorbers. In Jaumann absorbers, determining resistivity of resistive sheets is a complex task and optimization techniques are generally utilized for the solution. The new contribution given in this paper is that the reflected waves from each boundary inside the dielectric layers are eliminated. Therefore, input reflection coefficient is obtained analytically using Binomial expansion without any approximation. Then a binomial matching procedure is applied to obtain the ultra-wideband absorption. Absorption enhancement is achieved by quarter wavelength dielectric slabs, resistive sheets with critical resistivities and a metallic ground plane backed final dielectric layer with high permittivity. Proposed structure is designed for normal illumination. Parallel and perpendicular polarizations are also studied for oblique incidences. Absorptivity and reflectivity variations are presented versus frequency in 0–40 GHz band for the 20 GHz design frequency for several structures. It is shown that choosing three layers backed with a final layer (εrb=20) structure gives absorptivity greater than 90% in a 6.8–33.2 GHz band region with a fractional bandwidth of 132%. CST Microwave Studio and AWR programs are used to prove the correctness of the proposed method. Great consistency is observed and demonstrated in the numerical results section.

Quad path, CG-CS resistive feedback LNA architecture for 25–35 GHz band

In this paper, a Quad Path Noise Cancellation (QPNC) Low Noise Amplifier (LNA)presented for 5G sub-band 25-35GHz using GPDK 45 nm Complementary Metal Oxide Semiconductor (CMOS) technology; which is composed of Common Source (CS) & Common Gate (CG) stages with resistive feedback and current reuse at the output. QPNC is used to cancel the noise of common gate transistors, which leads to reduce the noise fig. (NF). Resistive feedback is used to tradeoff between the input matching, gain, and NF i.e. overall refining the Figure of Merit (FoM) of the circuit. Mathematical analysis of impedance matching, gain, noise transfer function, and NF have been done using the small signal model of QPNC-LNA. Simulation has been done on Cadence Virtuoso software using GPDK 45 nm CMOS technology. Pre layout simulation result shows the minimum value of gain is 13.38 dB at 30.9GHz while the maximum value is 14.12 dB at 25.87GHz and flat over the entire frequency range. S11 i.e. input reflection coefficient is ranging from −16.16 dB at 25.21GHz to −11.52 dB at 35GHz for 50 Ω input impedance matching. NF value ranges from 2.69 dB at 25.69GHz to 3.77 dB at 35GHz. The IIP3 value for the proposed QPNC-LNA is 5.3 dB. For the four corners SS, SF, FS, and FF, process corner simulation has been performed. Post-layout simulation results depict the maximum value of gain is 12.71 dB at 25.75GHz. NF value is varying from 2.88 dB to 4.02 dB while the input reflection coefficient is ranging from −10.12 dB to −14.13 dB for 10GHz bandwidth. The circuit consumes 17.53 mW power at 1.2 V under a DC current of 14.61 mA, FoM1 is 8.36 dB and FoM2 of the proposed LNA is 49.35 dB. The layout of the proposed LNA is having an area of 0.03026mm2.