Input Power Level Research Articles

ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ ЗАЩИТНОГО УСТРОЙСТВА

The protective device (limiter) at the receiver input is an important component, as it ensuresthe safety of the receiver operation in conditions of receiving powerful signals. The results of anexperimental study of a protective device in the 1-4 GHz band are presented. It is shown that theminimum bandwidth losses at a low power level do not exceed 0.63 dB, the maximum bandwidthlosses are 1.23 dB. At an input power of 25 dBm, the protective device operates in a non-linearmode, therefore it creates harmonics of the input frequency. The experimental amplitudefrequencyresponse (AFC) of the protective device, as well as amplitude characteristics at threefrequencies are presented. The experiment to remove the frequency response was carried out on avector analyzer of circuits. The experiment to remove the amplitude characteristics was carriedout using a standard signal generator and a spectrum analyzer at three frequencies: 1 GHz;2 GHz; 4 GHz. Structurally, the protective device is a polycor substrate on which all elementsexcept connectors are placed. The substrate is placed in a frame-type housing and closed with twosealed lids. Type III sockets according to GOST13317- 89 are used as connectors. A schematicdiagram and a brief description of the design are given. The following main parameters have beenachieved: losses do not exceed 1.23 dB in the operating frequency range from 1 to 4 GHz, theoutput signal power at a high input power level (f = 1 GHz; Rvh = 25 dBm) does not exceed12 dBm. The protective device is recommended to be used in the input circuits of communicationreceivers, navigation, radar and electronic warfare.

High‐efficiency broadband rectifier with compact size for wireless power transfer

AbstractIn this letter, an efficient broadband microwave rectifier with compact size for wireless power transfer is presented. It is proven that the proposed voltage doubler is easier to be matched than the series diode rectifier to achieve a wide bandwidth. In our analysis, the voltage doubler itself is already matched without the input matching network at the lower frequency band. For higher frequency band matching, a short section of microstrip line is connected to the input port of the voltage doubler. Thus, the proposed rectifier can operate over a broad bandwidth. To verify the design concept, a rectifier is fabricated, and the measurement results demonstrate that the power conversion efficiency is greater than 50% from 0.1 to 4.3 GHz at an 18 dBm input power level, and is higher than 70% within a wide bandwidth of 76.9%. In addition, when the input power is 18 dBm, the peak efficiency is 76.36% at 1.4 GHz. The results show that the proposed rectifier has the merits of compact size, broad bandwidth, and high efficiency.

An Ultrawideband High-Efficiency Rectifier Based on Harmonic Feedback Topology

With the rapid and extensive development of wireless communication and low power electronics, electromagnetic wireless power harvesting (WPH) draws more and more attention. As the core component for RF-to-DC power conversion, its characteristics determine the performance of the overall WPH system. To obtain as much dc energy as possible, ambient electromagnetic energy with various frequencies should be efficiently rectified. Therefore, it is important to widen the operating bandwidth of the rectifier. According to the theoretical analysis of the Schottky diode, it can be found that if the harmonic components generated by the diode can be fed back through a specific approach for rectifying, the bandwidth of the rectifier will be effectively improved. Therefore, a broadband rectifier has been proposed based on the previous principle. For validation, a wideband rectifier based on Schottky diode SMS7630 had been designed, fabricated and measured. When the input power level is 0 dBm, the conversion efficiency of the implemented rectifier is larger than 40% from 0.4 to 2.6 GHz within a relative bandwidth of 146.67%, exhibiting an ultrawide bandwidth compared with existing state-of-the-art configurations.

A High-Power 3P3T Cross Antenna Switch with Low Harmonic Distortion and Enhanced Isolation Using T-Type Pull-Down Path for Cellular Mobile Devices

This paper presents a radio frequency (RF) triple pole triple throw 3P3T cross antenna switch for cellular mobile devices. The negative biasing scheme was applied to improve the power-handling capability and linearity of the switch by increasing the maximum tolerable voltage drop across the drain and source and reverse biasing the parasitic junction diodes. To avoid signal reflection through the antenna in off-state, all the antenna ports were equipped with 50-ohm termination to provide the pull-down path. Considering the simultaneous operation of antenna ports in different switch cases, the presented T-type pull-down path demonstrated improvement of isolation by over 15 dB. Using stacked switches, the 3P3T handled the input power level of over 35 dBm. The chip was manufactured in 65 nm complementary metal oxide semiconductor (CMOS) silicon on insulator (SOI) technology with a die size of 790 × 730 µm. The proposed structure achieved insertion loss, isolation, and voltage standing wave ratio (VSWR) of less than −0.9 dB, −40 dB, and 1.6, respectively, when the input signal was 3.8 GHz. The measured results prove the implemented switch shows the second and third harmonic distortion performances of less than −60 dBm when the input power level and frequency are 25 dBm and 3.8 GHz, respectively.

A 90° Twisted Quarter-Sectored Compact and Circularly Polarized DR-Rectenna for RF Energy Harvesting Applications

Radio frequency (RF) energy harvesting is the most adopted technique for replacing conventional batteries. However, the available RF energy in the surrounding atmosphere is low and unstable, so the antenna with high gain and polarization-insensitive characteristics is desired to collect a massive amount of power from the low-density environment. A 90° twisted quarter sectored circularly polarized and high gain dielectric resonator antenna (DRA) operating within the 5.8 GHz Wi-Fi band, is investigated first time of its kind in this letter. A circular-shaped aperture coupled feeding approach is investigated for energizing the proposed antenna. A metallic strip is placed on the right face of the optimized DRA for creating circular polarization characteristics. The optimized antenna (0.67 λ×0.67 λ×0.029 λ) offers a gain value of 7.02 dBc at 5.8 GHz frequency. A shunt-diode rectifier circuit is implemented for rectification purposes. The power conversion efficiency achieved at the operating frequency is 72.5% for an input power level of 5.75 dBm.

A new digital beam position and phase measurement implementation based on a field programmable gate array for the high intensity heavy-ion accelerator iLinac.

A new digital beam position and phase measurement (BPM) system was designed for the ion-Linac accelerator at the high intensity heavy ion accelerator facility. The fundamental and second harmonic signals are retrieved from the BPM electrodes to simultaneously calculate their respective beam positions and phases. All data acquisition and digital signal processing algorithm routines are performed in a field programmable gate array (FPGA). The position and phase information are obtained by using the in-phase and quadrature demodulation method. A practical and straightforward method is used to generate the second harmonic reference signal for processing the second harmonic beam signal. The reconfigurable filters are integrated into the FPGA to allow the measurement of short beam pulse length. The laboratory test results show that the achieved phase resolution is better than 0.2° and 0.03° when the input signal is -60 and -45 dBm, respectively. A position resolution better than 30 μm was achieved for an input power level of approximately -60 dBm, and it can reach 7 μm with the input power higher than -45 dBm. The entire execution time of the algorithm is accomplished within 3.4 µs, which provides a sufficient reaction time for the fast beam interlock signal to the machine protection system. The performance of this newly designed prototype BPM electronics was evaluated with the online proton beam.

Outside Front Cover: Plasma Process. Polym. 6/2022

Inside Front Cover: For a wide range of plasma processes, stable plasma ignition of remote plasma sources (RPSs) is essential to ensure the stability of the discharge, stable operating conditions, and high plasma density. An RPS operating at a gas pressure greater than 1 Torr relies on the reaction pathways leading to the high-level excited state to sustain the power balance and energy cascade at a high input power level. Further details can be found in the article by Cheongbin Cheon, Jung Hwan Yoon, Sanghyun Jo, Ho Jun Kim, and Hae June Lee (e2100251).

A Multifunctional Battery-Free Bluetooth Low Energy Wireless Sensor Node Remotely Powered by Electromagnetic Wireless Power Transfer in Far-Field.

This paper presents a multifunctional battery-free wireless sensing node (SN) designed to monitor physical parameters (e.g., temperature, humidity and resistivity) of reinforced concrete. The SN, which is intended to be embedded into a concrete cavity, is autonomous and can be wirelessly powered thanks to the wireless power transmission technique. Once enough energy is stored in a capacitor, the active components (sensor and transceiver) are supplied with the harvested power. The data from the sensor are then wirelessly transmitted via the Bluetooth Low Energy (BLE) technology in broadcasting mode to a device configured as an observer. The feature of energy harvesting (EH) is achieved thanks to an RF-to-DC converter (a rectifier) optimized for a low power input level. It is based on a voltage doubler topology with SMS7630-005LF Schottky diode optimized at −15 dBm input power and a load of 10 kΩ. The harvested DC power is then managed and boosted by a power management unit (PMU). The proposed system has the advantage of presenting two different power management units (PMUs) and two rectifiers working in different European Industrial, Scientific and Medical (ISM) frequency bands (868 MHz and 2.45 GHz) depending on the available power density. The PMU interfaces a storage capacitor to store the harvested power and then power the active components of the sensing node. The low power digital sensor HD2080 is selected to provide accurate humidity and temperature measurements. Resistivity measurement (not reported in this paper) can also be achieved through a current injection on the concrete probes. For wireless communications, the QN9080 system-on-chip (SoC) was chosen as a BLE transceiver thanks to its attractive features: a small package size and extremely low power consumption. For low power consumption, the SN is configured in broadcasting mode. The measured power consumption of the SN in a deep-sleep mode is 946 µJ for four advertising events (spaced at 250 ms maximum) after the functioning of sensors. It also includes voltage offset cancelling functionality for resistivity measurement. Far-field measurement operated in an anechoic chamber with the most efficient PMU (AEM30940) gives a first charging time of 48 s (with an empty capacitor) and recharge duration of 27 s for a complete measurement and data transmission cycle.

Numerical analogy of bioheat transfer and microwave cancer therapy for liver tissue

AbstractA numerical study of microwave cancer therapy for cylindrical‐shaped liver tissue with an elliptical‐shaped liver tumor has been carried out by this study. The time‐dependent electromagnetic wave and the bio‐heat transfer equations have been used as the governing equations and solved with appropriate boundary conditions using Galerkin's weighted residual scheme built‐in finite element method‐based COMSOL Multiphysics software. The coaxial applicator as well as the effects of different microwave input power levels (from 5 to 25 W), frequencies (from 0.7 to 5 GHz), and treatment time (from 0 to 1000 s) on hepatocellular carcinoma have been examined by this simulation and displayed graphically in terms of the microwave power dissipation, isothermal lines inside liver tissue, time‐dependent profiles of temperature at different locations inside the tumor, specific absorption rate (SAR), and surface average transient temperature distribution of tumor tissue. The results demonstrate that microwave input antenna power and frequency have significant impacts on the temperature distribution and SAR values of liver tissue. When the microwave input power, as well as frequency, is increased, SAR and tissue temperature values also increase but the high temperature is harmful to healthy tissue. It is observed from the performed analysis that the mean temperature of the tumor cell is about 56.86°C at a time of 180 s using 10 W microwave input power and 2.45 GHz frequency.

Broadband RCN-based RF-rectifier with a large range of power for harvesting ambient wireless energy

In this paper, a broadband RF-rectifier with a wide scale of RF input power levels, using FR-4 substrate, is proposed. A wideband resistance compression network (RCN) is applied to achieve the unique RF-rectifier design approach. The method improves the matching performance of the circuit over a broader range of the available input RF signals and frequency. The RF-rectifier circuit is configured in two sections. The two sections are configured using a modified L-section matching network (MN) through a series impedance transformer (ITx). A wideband RCN integrates the two RF-rectifier segments to a 50 Ω transmission line (TL). The design provides a wider span of accessible RF power from −15 to 15 dBm via a 2 kΩ load terminal. The proposed RF-rectifier achieved a simulated and measured fractional percentage bandwidth (FBW) of 38.5% and 38% from 1.780 to 2.620 GHz and 1.780 to 2.610 GHz, respectively. The maximum measured RF-to-DC PCE and output DC voltage (Vdc) realized by the proposed RF harvester are 75.5% and 3.2 V, respectively. The design also reached a high PCE of 88.25% and 15.10%, respectively, from the quad-tone signals at 10 and −20 dBm RF input power. The proposed RF-rectifier’s ambient evaluation produces a Vdc of 0.322 V and also activated a low-power bq25504-674 evaluation module (EVM) at 0.682 V.

A triple band rectenna for RF energy harvesting in smart city applications

ABSTRACT Radio Frequency Energy Harvesting is found to be the best alternative to conventional batteries for providing endless power to the sensor networks connected to perform various applications in the smart city. The electromagnetic energy density in the ambient environment is very low and not uniform, which demands a high gain multi-band rectenna system operating at mostly available energy bands and a suitable rectifier circuit that offers large PCE performance. This paper introduces a triple-band monopole rectenna with enhanced performance for smart city applications. A defective ground structure (DGS) has been investigated for a significant increase in gain with an increasing number of resonant frequencies. The proposed antenna operates over a band of frequencies that lies within 1.25–3 GHz, which covers 1.8/2.1/2.45 GHz frequencies. The antenna offers the gain values of 4.16/6.54/10.2 dB at 1.8/2.1/2.45 GHz frequencies, respectively. A single diode series-connected rectifier has been opted to efficiently operate over a wide range of input power levels from −10 dBm to 5 dBm and offers a minimum conversion efficiency of 60% within the operating bands at 0 dBm input power. The rectenna system is experimentally measured and the measured output voltage at 2.45 GHz frequency is 1.123 V.

Optical Emission Spectra Characterization of Plasma Discharge During the Processing of Milk and Evaluation of its Quality Attributes

This study characterized the optical spectra of continuous low-pressure plasma system and evaluated its effect on milk processing. Plasma was characterized at different input power levels (24.8, 58.9, and 117.6 W which corresponds to the input voltage of 1, 1.5, and 2 kV) with a 1-cm electrode distance. Based on the characterization, the input power level 117.6 W was selected to produce maximum reactive species. The system was operated at 117.6 W to decontaminate milk flowing inside the quartz tube using three different milk flow rates 3, 6, and 9 mL/min (accounting for 5-, 2.5-, and 1-min plasma exposure time). The maximum reduction in total microbial count obtained after treatment was 1.2 log CFU/mL at an exposure time of 5 min (3-mL/min milk flow rate). Significant changes were observed in the physicochemical properties of milk after treatment. However, the only adverse effects observed were the viscosity and color of milk at 5- and 2.5-min treatment, which might be because of the use of unhomogenized milk. The continuous plasma system operated at 117.6 W reduced the microbial load in milk; further optimization of the process parameters is necessary for the complete elimination of microbial load and to increase the shelf life.

The microwave properties of tin sulfide thin films prepared by RF magnetron sputtering techniques

In this paper we present the microwave properties of tin sulfide (SnS) thin films with the thickness of just 10 nm, grown by RF magnetron sputtering techniques on a 4 inch silicon dioxide/high-resistivity silicon wafer. In this respect, interdigitated capacitors in coplanar waveguide technology were fabricated directly on the SnS film to be used as both phase shifters and detectors, depending on the ferroelectric or semiconductor behaviour of the SnS material. The ferroelectricity of the semiconducting thin layer manifests itself in a strong dependence of the electrical permittivity on the applied DC bias voltage, which induces a phase shift of 30 degrees mm−1 at 1 GHz and of 8 degrees mm−1 at 10 GHz, whereas the transmission losses are less than 2 dB in the frequency range 2–20 GHz. We have also investigated the microwave detection properties of SnS, obtaining at 1 GHz a voltage responsivity of about 30 mV mW−1 in the unbiased case and with an input power level of only 16 μW.

Machine Learning Algorithms for Flow Pattern Classification in Pulsating Heat Pipes

Owing to their simple construction, cost effectiveness, and high thermal efficiency, pulsating heat pipes (PHPs) are growing in popularity as cooling devices for electronic equipment. While PHPs can be very resilient as passive cooling systems, their operation relies on the establishment and persistence of slug/plug flow as the dominant flow regime. It is, therefore, paramount to predict the flow regime accurately as a function of various operating parameters and design geometry. Flow pattern maps that capture flow regimes as a function of nondimensional numbers (e.g., Froude, Weber, and Bond numbers) have been proposed in the literature. However, the prediction of flow patterns based on deterministic models is a challenging task that relies on the ability of explaining the very complex underlying phenomena or the ability to measure parameters, such as the bubble acceleration, which are very difficult to know beforehand. In contrast, machine learning algorithms require limited a priori knowledge of the system and offer an alternative approach for classifying flow regimes. In this work, experimental data collected for two working fluids (ethanol and FC-72) in a PHP at different gravity and power input levels, were used to train three different classification algorithms (namely K-nearest neighbors, random forest, and multilayer perceptron). The data were previously labeled via visual classification using the experimental results. A comparison of the resulting classification accuracy was carried out via confusion matrices and calculation of accuracy scores. The algorithm presenting the highest classification performance was selected for the development of a flow pattern map, which accurately indicated the flow pattern transition boundaries between slug/plug and annular flows. Results indicate that, once experimental data are available, the proposed machine learning approach could help in reducing the uncertainty in the classification of flow patterns and improve the predictions of the flow regimes.

Optical injection locking based local oscillator regeneration for continuous variable quantum key distribution.

We develop an optical injection locking (OIL) based local oscillator (LO) regeneration for continuous variable quantum key distribution (CVQKD) by sending a weak polarization multiplexed pilot carrier from the transmitter. The OIL at the receiver has superior performance in terms of minimum input power and noise level at offset frequencies to the erbium-doped fiber amplifier (EDFA)-based scheme. The weak pilot carrier is recovered both in power and phase via the OIL while incurring little excess noise to the CVQKD system. The phase-locked LO enables heterodyne detection of a Gaussian modulated quantum signal with a simple data-aided phase recovery without pilot tone. The obtained parameters are compatible with a raw key rate of 0.83 Mbit/s in the asymptotic regime over a 22-km fiber transmission. The technique is expected to be used in more phase-sensitive quantum optical applications.

A High-Efficiency and Reconfigurable Rectenna Array for Dynamic Output DC Power Control

In this paper, an output power reconfigurable rectenna array is proposed for the first time to harvest RF energy. The proposed rectenna array can be used to capture abundant RF energy with high conversion efficiency in a wide range of input power levels and load impedance at 1.88, 2.35, 3.5, and 4.9 GHz simultaneously. The output DC power of the proposed rectenna array can be changed exponentially by altering the on-off state of the switches located between the antenna and the rectifier. The measured result shows that the output power is linearly related to the number of opened switches. Therefore, the proposed rectenna array can be flexibly applied to battery-free or low-power-requiring devices according to their different power needs.

Experimental Study of AM and PM Noise in Cascaded Amplifiers

An experimental study of amplitude modulation (AM) and phase modulation (PM) noise spectra in cascaded amplifiers was carried out as a function of the number of amplification stages and the input power. Flicker and white noise contributions were determined, as well as effective noise figure (NF) from AM and PM noise spectra from small-signal to large-signal regimes. Simultaneous measurements of AM and PM noise were performed, and associated correlation was measured as a function of the offset frequency from the carrier. Measurements exhibited, in general, quite low AM–PM correlation levels both in the flicker and white noise parts of the spectrum. In some particular amplifier configurations, however, measurements showed some peaks in the correlation at some specific input power levels in the transition zone, from a quasi-linear to strong compression. The results show that the effective noise figure decreases with the number of stages for a given carrier output power level.

Fast and Accurate Approach to RF-DC Conversion Efficiency Estimation for Multi-Tone Signals.

The paper presents a computationally efficient and accurate numerical approach to evaluating RF–DC power conversion efficiency (PCE) for energy harvesting circuits in the case of multi-tone power-carrying signal with periodic envelopes. This type of signal has recently received considerable attention in the literature. It has been shown that their use may result in a higher PCE than the conventional sine wave signal for low to medium input power levels. This reason motivated the authors to develop a fast and accurate two-frequency harmonic balance method (2F-HB), as fast PCE calculation might appreciably expedite the converter circuit optimization process. In order to demonstrate the computational efficiency of the 2F-HB, a comparative study is performed. The results of this study show that the 2F-HB significantly outperforms such extensively used methods as the transient analysis (TA), the harmonic balance method (HB), and the multidimensional harmonic balance method (MHB). The method also outperforms the commercially available non-linear circuit simulator Keysight ADS employing both HB and MHB. Furthermore, the proposed method can be readily integrated into commonly used commercially available non-linear circuit simulation software, including the Keysight ADS, Ansys HFSS, just to name a few—minor modifications are required. In addition, to increase the correctness and reliability of the proposed method, the influence of PCB is considered by calculating Y parameters of its 3D model. The widely employed voltage doubler-based RF–DC converter for energy harvesting and wireless power transfer (WPT) in sub-GHz diapason is chosen to validate the proposed method experimentally. This RF–DC converter is chosen for its simplicity and capability to provide sufficiently high PCE. The measurements of the PCE for a voltage doubler prototype employing different multi-tone waveform signals were performed in laboratory conditions. Various combinations of the matching circuit element values were considered to find the optimal one in both—theoretical model and experimental prototype. The measured PCE is in very good agreement with the PCE calculated numerically, which attests to the validity of the proposed approach. The proposed PCE estimation method is not limited to one selected RF–DC conversion circuit and can also be applied to other circuits and frequency bands. The comparison of the PCE obtained by means of the proposed approach and the measured one shows very good agreement between them. The PCE estimation error reaches as low as 0.37%, and the maximal estimation error is 32.65%.

A 5.8 GHz RF Receiver Front-End with 77.6 dB Dynamic Range AGC for a DSRC Transceiver

This paper presents a 5.8 GHz highly sensitive, high-dynamic-range RF receiver front-end with Automatic-Gain Control (AGC) and a high image-rejection for a Dedicated Short-Range Communication (DSRC) application. It is formed by a transceiver common matching, a single to differential Low-Noise Amplifier (LNA), an active mixer with an Image Rejection Filter, and an AGC unit. The proposed AGC unit is composed of a power-detector over the intermediate-frequency signals of the downconverter mixer. The power detector produces a wide dynamic range response signal, which eases the controllability of the AGC unit. In addition, external components are minimized, and area occupation is optimized. The proposed RF-FE is fabricated and measured in a 130-nm RF CMOS process. Experimental results show an overall dynamic range of 77.6 dB while a high sensitivity performance to an input power level of −85 dBm is measured. An overall gain of 26.4 dB for the RF-FE is obtained. The input referred P1dB is measured to be around −28.3 dBm. The 2-stage RC poly-phase filter that is applied to reject the image signal results in a maximum image rejection ratio of 39 dB.

Far-Field Wireless Power Harvesting: Nonlinear Modeling, Rectenna Design, and Emerging Applications

Continuous advances in ultralow-power electronics are a fundamental driving force of developing far-field wireless power harvesting techniques, which generally harnesses low/ambient energy in free space or dedicated wireless power from a power base station. This article reviews recent developments and technology trends in far-field (radiative) wireless power harvesting, including modeling of rectification process inside nonlinear devices, insights into rectenna system design, and demonstrations of emerging applications. The rectification process inside nonlinear devices will be explored, upon which a device selection guideline is provided to help quickly identify suitable devices. Then, the optimization of rectenna design is discussed to realize efficiency enhancement at a limited input power level. Since far-field wireless power harvesting has become a critical enabling technology for battery-free Internet of Things, a series of promising applications is demonstrated in this article to highlight the challenges and opportunities in the field.