Antenna Power Research Articles

Development of TWA mock-up for TITAN

The challenge of tokamak auxiliary heating method ICRH is to couple large amount of power through the plasma boundary, where an evanescence layer has to be crossed, without exceeding the voltage standoff at the antenna. Travelling Wave Array antenna has been proposed for ICRH of future fusion reactor such as DEMO in view to decrease the antenna power density. However, so far the voltage standoff of a TWA antenna in the ICRH frequency range (30–60 MHz) has never been demonstrated. A TWA mock-up has been designed and will be tested in the CEA/IRFM testbed TITAN to assess its compatibility to RF high power operation. In this paper, the main characteristics of the TWA mock-up are reported in detail. In addition, some near-field RF analyses are presented, containing reflection characteristics, port voltage, electric field and k// spectrum. Meanwhile, the structural evaluation of the antenna during its lifting process is carried out to check with safety requirements. The assembly strategy of the whole structure is also explained elaborately to ensure the fluency and correct integration of the TWA mock-up. Finally, the RF assessment of antenna straps critical dimensions is briefly described.

Ka-band time-domain multiplexing front-end with minimum switch area utilization on 22 nm fully depleted silicon-on-insulator CMOS technology

AbstractA time-domain duplexing radio frequency (RF) front-end with integrated antenna switch, power amplifier (PA), and low noise amplifier (LNA) was developed aiming for fifth-generation communication (5G) applications covering 24–28 GHz frequency range. Antenna switch utilizes pre-existing LNA input matching network together embedded with grounded shunt transistor switch to provide sufficient isolation of receive side from PA. Respectively, high impedance of off-state PA is assumed to achieve acceptable receive performance. Resulting output power is 13.6 dBm with 15 dB of peak small-signal gain at 28 GHz. Maximum average channel power was 4.8 dBm with 100 MHz 64-QAM OFDM signal within 5G adjacent channel power ratio and error vector magnitude specifications. Receive (RX) front-end achieves 5 dB noise figure at 24 GHz and 7 dB of peak gain. Performances of amplifiers degraded only by 2 dB from switch integration. The front-end dissipates 183 and 4.6 mW of power in transmit and receive mode, respectively. The simplistic design method minimizes cost both in circuit area (only 0.19 mm2) and design time making this front-end an attractive alternative in massive phased array applications using 22 nm complementary metal oxide semiconductor (CMOS) fully depleted silicon on insulator process.

Ion cyclotron resonance heating fast and slow wave excitation and power deposition in edge plasmas with application to ITER

The antenna power coupling to the plasma centre and its possible deleterious coupling to the plasma edge are key parameters in an ion cyclotron resonance heating system. The influence on these parameters by the confluence between the slow and the fast magnetosonic waves is studied for the case of large machines. Until now, the modelling of the scrape off layer region has been calculated by ANTITER II, which contains only the fast wave description and where the confluence with the slow wave (S wave) is approximated by the Alfvén resonance. In the present study, a complete modelling of the slow and fast waves is made by ANTITER IV. The modelling by the two codes is compared and shows the important role of the Alfvén and the lower hybrid resonances for the excitation of large fields and associated power deposition at the edge of the plasma even far from the antenna location. The ANTITER IV modelling is thereafter applied to the case of the ITER antenna with a reference density profile and heating parameters. A comparative study is made for the edge power deposition and the excitation of large fields for different toroidal phasing cases of the antenna. This study also takes into account the tilting of the antenna array with respect to the total magnetic field in front of the antenna. If the Faraday screen is field-aligned, the excitation of the S wave occurs at the wave confluence; however, in the case of non-alignment the antenna directly excites the S wave. This effect is studied and quantified. All edge effects, even the direct excitation of S waves, can be strongly reduced by tailoring the current distribution in the straps of the antenna array. Resulting cases for the minimisation of edge power deposition in ITER and the reactor are studied.

FallViewer: A Fine-Grained Indoor Fall Detection System With Ubiquitous Wi-Fi Devices

The safety of the elderly has attracted much attention nowadays. Among various daily activities, fall is one of the most dangerous events for the elderly, especially those who live alone. Most existing works on fall detection are based on wearable devices, which are inconvenient in using. Several solutions only use coarse-grained Wi-Fi signal information that contains many biases, and lack considerations on environmental changes. These situations motivate us to design a fine-grained and robust fall detection approach. In this article, we propose a fall detection system, called FallViewer, based on analyzing the channel state information (CSI) of Wi-Fi signals. To get fine-grained information, we propose phase and amplitude calibration methods for deviation correction. Then, an adjustment approach for antenna power is designed to eliminate the multipath interference. Furthermore, we apply a double sliding window to get a flexible threshold, which improves the robustness of FallViewer to various environments. Finally, FallViewer extracts features of the processed Wi-Fi signal and sends the features to a LibSVM for classification. Through experiments in different environments, FallViewer can detect fall events with an average accuracy of 95.8%, which indicates that FallViewer can work reliably and effectively.

RF wave propagation simulation for ICRF antenna in EAST

ABSTRACT The propagation performance of radiofrequency (RF) waves excited by ICRF antenna in plasma has a great influence on the coupling effect. In this paper, the propagation characteristics of fast wave (FW) and slow wave (SW) under tokamak experimental condition are calculated, and the influence of angular frequency w 0, antenna power spectrum k// and tokamak total magnetic field B 0 is illustrated based on the typical operating parameters in EAST. By applying perfect matched layer (PML) boundary processing method to simulate single-pass absorption and using finite element method (FEM) to solve Maxwell equations in frequency domain, the propagation and coupling simulation of RF waves in cold plasma for EAST ICRF antenna in B-window were carried out to obtain the polarization characteristics of fields and the relationship between the coupling impedance and the gap length from antenna to the FW cut-off layer. The analysis results in this paper provide useful reference and guidance for the study of propagation coupling of ICRF waves in EAST and other magnetic confined fusion devices.

Interaction between filaments and ICRF in the plasma edge

• Recent progresses in understanding of interaction between filaments and ICRF in the plasma edge are summarized. • RF induced convective cells can poloidally distort, stretch and break up filaments and influence the local plasma transport in the SOL. • The mutual influence of multiple filaments induces poloidally distributed and radially extended stripe structures in the wave fields and causes wave scattering. • Filaments redirect part of the RF power from the perpendicular direction to the parallel direction as a result of rectification of antenna power spectrum and mode conversion of fast wave to slow wave. Ion Cyclotron Range of Frequencies (ICRF) heating is a standard heating method for magnetic confinement fusion devices. ICRF waves can interact with filaments in the scrape-off layer (SOL) and induces a series of important phenomena. Understanding their interaction and the related physics is essential to the success of ICRF heating and plasma confinement. This paper is a review paper summarizing the recent progress in understanding of interaction between filaments and ICRF in the plasma edge and presents some key experimental and simulation results. In particular, the influence of RF convective cells on filament transport and the influence of filament on RF wave scattering, energy spectrum density, power redirection and wave mode conversion are discussed in detail. Most results shown in the paper make use of the published work, and some new results about mode conversion are also present.

Effects of RF bias frequency and power on the plasma parameters and ash rate in a remote plasma source

The effects of the RF bias frequency (2–27.12 MHz) and power (0–50 W) on plasma parameters, i.e., effective electron temperatures, electron densities, and electron energy probability functions (EEPFs), were investigated in a remote plasma source. A small cylindrical Langmuir probe based on the Druyvesteyn method was used for the measurements. When the bias power was changed from 0 W to 10 W for each bias frequency, the electron density decreased and the effective electron temperature increased at a given antenna power. As the 2 MHz bias power increased to 50 W, the electron density increased remarkably, whereas the effective electron temperature decreased. Simultaneously, the EEPF evolved from a Druyvesteyn-like distribution to a nearly Maxwellian distribution. In contrast to 2 MHz, when increasing the bias power of 12.5 MHz or 27.12 MHz, there was no distinct change in the effective electron temperature by the bias power and the electron density increased slightly or barely changed. Moreover, the EEPFs retained a Druyvesteyn-like distribution during the bias power increase. These results reveal that the plasma parameters are more controllable at lower bias frequencies, and the analysis is presented in relation to the electron heating mechanism. Therewithal, the ash rate for a 2 MHz bias power was observed to be the highest among the three frequencies when the discharge was operated with pure oxygen.

Performance Analysis and Design of MIMO Power NOMA With Estimated Parameters Error Statistics Along With SIC and Hardware Imperfections

In this work, we propose to design and subsequently analyze the performance of a power non-orthogonal multiple access (power-NOMA) system, having multiple input multiple output (MIMO) antennas with the consideration of various imperfection statistics. Three key issues emerge, while NOMA is in place. The first one is the user order mismatch due to estimated channel, which impacts the NOMA performance. The second one is the imperfect successive interference cancellation (SIC) at the receiver, which impacts the interference cancellation at the NOMA receiver. The third issue is the imperfection arising due to hardware circuits, which include fixed-pointed digital logic, analog and radio frequency (RF) circuits. To some extent, these issues have been addressed in bits and pieces in the context of single antenna power NOMA design, however they have not been addressed all together in the context of MIMO power NOMA. There are several key contributory aspects in this work. Key part is the exploitation of these parameter estimation error statistics along with the imperfections in transceiver hardware chains and SIC at the receiver. We propose a MIMO NOMA based on the maximum sum-rate criterion. An analytical framework has been presented in this regard. Numerical results demonstrate that the consideration of these error statistics improves the overall sum-rate performance.

Joint Antenna Selection and Power Allocation for Secure Co-Time Co-Frequency Full-Duplex Massive MIMO Systems

In this paper, we design a co-time co-frequency full-duplex (CCFD) massive multiple-input multiple-output (MIMO) network to improve the utilization of time–frequency resources and physical layer security. Simultaneous information transmissions of the base station and the users are regarded as same-frequency interference against interception by eavesdroppers. To promote energy conservation and improve utilization of system resources, we propose a joint antenna selection and power allocation (JASPA) strategy for CCFD massive MIMO networks. Considering the trade-off between secrecy performance and system communications quality, we formulate optimization functions based on JASPA for two security concerns. We design a quantum-inspired backtracking search algorithm (QBSA) to obtain the optimal JASPA scheme. Simulation results show that the performance of the proposed QBSA is superior to previous intelligent algorithms in CCFD massive MIMO systems. The effectiveness of the proposed JASPA scheme is demonstrated under various communications scenarios, and can be considered a cornerstone for future research in wireless communications domain.

A Novel Mode-Stirred Reverberation Chamber Design for 5G Millimeter Wave Bands

A novel mode-stirred reverberation chamber (RC) is designed and analyzed for millimeter wave bands. The size of the proposed RC with dimensions of 0.9 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times0.9$ </tex-math></inline-formula> m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.1$ </tex-math></inline-formula> m is suitable for user equipment (UE) tests. Two Z-shaped mode-stirrers are applied to generate a uniform field. To fulfill the communication and test requirements for user equipment, reference, measurement and link antennas with a large bandwidth are utilized, which can support both the frequency range (FR) 1 and FR2 bands of the 5G spectrum. The lowest usable frequency (LUF) and mode density were first calculated and examined. Then, the power transfer function (PTF) from 2 GHz to 40 GHz was obtained to verify the path loss. Three measurement campaigns were carried out to verify the accuracy of the RC. Firstly, the transmission power of the passive antenna for a conductive test was compared with the RC over the air (OTA) total radiated power (TRP) for single-tone signals. Then, signals with bandwidths of 100 MHz and 400 MHz were applied. A maximum power difference of only 0.8 dB was found in the above two experiments. Furthermore, the TRP for the same commercial 5G UE in both RC and compact antenna test range (CATR) systems was measured and compared. To the best of the authors’ knowledge, this is the first work to provide TRP results for 5G millimeter wave bands in a RC. The test results show that the TRP values for the two systems are almost the same with a maximum deviation of 0.5 dB, while the time required to carry out tests using the RC is lower than that for the CATR system.

Electromagnetic Wave Propagation From Low-Earth Orbit Satellite to Ground Station Considering Interpolated Atmospheric Environments

We propose a novel method to calculate the electromagnetic (EM) wave propagation from low-earth orbit satellite (LEO) to a ground station based on the physical optics (PO), ray tracing technique, and geometric optics (GO) considering interpolated atmospheric environments. Our method includes the reflector antenna analysis using PO, the interpolation of the meteorological data using PCHIP and Kriging interpolation, transmission analysis using ray tracing and geometrical optics. Tropospheric and stratospheric environments are modeled using meteorological data-air pressure and temperature, relative humidity, and rain rate-measured at 9 different radiosonde observatories in and around South Korea. Furthermore, we utilize Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) and Kriging-exponential methods for vertical and horizontal interpolations of the raw meteorological data, respectively. Hence, the interpolated atmospheric environments are amenable to the best use of ray tracing technique and GO. Subsequently, effective refractive indices of the stratified media can be extracted via millimeter-propagation-model93. The simplified Appleton-Hartree equation characterizes the ionospheric environment. Considering a sun-synchronous orbit satellite passing through South Korea, we calculate atmospheric attenuation, boresight error, received power, and compensation angle of satellite antenna for various conditions.

Design of microstrip patch antenna for Ka-band (26.5–40 GHz) applications

Abstract A simple microstrip patch antenna power fed with microstrip feeding for Ka band (26.5–40 GHz) application is proposed. This work is meaningful for next generation network applications at 29.87 GHz and 39.02 GHz. It is designed by using Rogers RT/Duroid 5880 (tm) substrate, with dielectric loss tangent 0.0009, relative permittivity 2.2 and height 0.79 mm. The simulation is done using Ansoft HFSS. The radiation performance such as S11, VSWR, Gain, Radiation Efficiency, Radiation Patterns and Surface Current Distributions are observed.

Low-Profile Spidron Fractal Dipole Antenna with a Ferrite-Loaded Artificial Magnetic Conductor for Manpack Applications

In this paper, a Spidron fractal dipole antenna with a ferrite-loaded artificial magnetic conductor (AMC) is presented. By applying ferrite composed of nickel–zinc with a high permeability value, a compact AMC that operates in the broadband frequency range within the high-frequency/very-high-frequency/ultra-high-frequency (HF/VHF/UHF) bands was designed. A Spidron fractal-shaped dipole antenna with a quasi-self-complementary structure was designed and combined with a miniaturized ferrite-loaded AMC. This allowed the designed AMC-integrated dipole antenna to operate in a wide frequency band, covering the HF/VHF/UHF bands, with low-profile characteristics. A prototype of the proposed Spidron fractal dipole antenna with the AMC was manufactured and measured and found to meet low VSWR (voltage standing wave radios) specifications of &lt;3.5 within the 20–500 MHz bandwidth range. The simulated and measured results are in good agreement. The size of the Spidron fractal dipole antenna with the AMC is 0.03×0.026×0.001λ3 relative to the wavelength of the lowest operating frequency. The received power of the Spidron fractal dipole antenna with the AMC was also measured when it was applied to relatively small applications, such as a manpack in this case.

Optimized phasing conditions to avoid edge mode excitation by ICRH antennas

An ion cyclotron resonance heating (ICRH) antenna system must launch radio frequency (RF) power with a wavenumber spectrum which maximizes the coupling to the plasma. It should also ensure good absorption while minimizing the wave interaction with the plasma edge. Such interactions lead to impurity release, whose effect has been measured far from the antenna location (Klepper et al. 2013; Wukitch et al. 2017; Perkins et al. 2019) and can involve the entire scrape-off layer. In the normal heating scenario, for which the frequency of the waves launched by the antenna is larger than the ion cyclotron frequency of the majority ions $\omega &gt; \omega _{\textrm {ci},\textrm {maj}}$ , release of impurities due to ICRH can be affected by minimizing the low $|k_{\parallel }| &lt; k_0$ power spectrum components of the antenna. Impurity release can be the result of low central absorption of the waves or power transfer from the fast to the slow wave due to the presence of a confluence in the plasma edge. In ASDEX Upgrade (AUG), a reduction of heavy impurity release by ICRH in the plasma was qualitatively well correlated to the parallel electric field and RF currents flowing around the antenna (Bobkov et al. 2017). In this article, we first show a correlation between the reduction in impurity release by ICRH in AUG and the rejection of the low $|k_{\parallel }| &lt; k_0$ region of the antenna power spectrum. We show that the same correlation holds for results obtained in the Alcator C-Mod tokamak. Finally, using this idea, we reproduce ICRH induced impurity release behaviour in a not yet published experiments of JET, and make predictions for ITER and DEMO.

Energy-Efficient Massive MIMO With Decentralized Precoder Design

This paper presents an energy-efficient downlink precoding scheme in a multi-cell Massive MIMO system. We approach the precoder design problem to maximize the system energy efficiency by jointly considering power control, interference management, antenna switching and user throughput in a cluster of base stations. This is computationally difficult as it requires solving a sparsity-inducing non-convex optimization problem, which is NP-hard. To alleviate the solution complexity, first a stochastic smooth approximation of zero-norm is applied in the antenna power management to enable fast, gradient-based algorithms. For efficient convergence, we develop a novel optimization algorithm combining augmented multiplier (AM) and quadratic programming (QP), and show how this scheme permits decentralized implementation by offloading parts of the computation to the individual base stations to reduce communication overhead. We provide theoretical proof that the proposed algorithm converges both locally and globally under realistic assumptions. Numerical results confirm that our method achieves higher energy efficiency with a superior convergence rate compared to different types of existing methods, and illustrate the relationship between energy efficiency performance and system design parameters.

Photoconductive Meta‐Antenna Enabling Terahertz Amplitude Spectrum Manipulation

In recent years, as a promising new method, integrating nanostructures to improve the power of photoconductive antennas has received widespread attention. However, there are few reports on the application of artificial electromagnetic structures to regulate the spectral features of photoconductive antennas. Herein, it is demonstrated that by integrating split‐ring resonator (SRR)‐like metallic structures onto the coplanar lines of the photoconductive antenna transmitter, one can significantly manipulate the spectral feature of the generated terahertz (THz) radiation. The guided THz wave along the coplanar lines is scattered by the SRRs to the far field and interferes with the THz pulse radiated from the photoconductive antenna gap, leading to enhancement of the photoconductive antenna's energy and modulation in the spectrum. Further studies have shown that the strength, frequency, and band‐pass/band‐stop characteristics of the modulation can be altered by changing the geometry and placement of the SRRs. Water vapor absorption is also discussed to exemplify the benefit of this novel meta‐antenna over the ordinary photoconductive antenna in sensing scenario. The photoconductive antenna proposed here takes the lead in using artificial structures to manipulate the spectral domain behavior of photoconductive antennas, which is of great significance for THz spectroscopy, imaging, and sensing.

Theoretical and experimental investigations on optimization of the received power of a monopole antenna

Antenna is an essential component of telecommunication devices. Recently, the antenna has been used as a receiver in the rectenna solar cells as well as a vital component of cellular mobile telecommunications. The power of the received signal may depend on the physical shape of the monopole receiving antenna. The optimization of antenna’s geometry is essential to improve the antenna performance as a receiver. It is widely accepted that the physical length of the monopole antenna; with one fourth of the incident wavelength; possesses an optimal efficiency. In the current study, a power equation based on a recently modified electromagnetic (EM) wave theory has been derived. The proposed formula has been used to calculate the optimum length of the monopole antenna to optimize the received power by the antenna. The angle between the direction of the antenna’s plane corresponding to the direction of the propagation of the EM wave has been considered. some experimental investigations have been considered to confirm our theoretical investigations. In our experiment, the output voltage has been considered as a good indication of the harvested energy of the monopole antenna.

Power Control Optimization for Large-Scale Multi-Antenna Systems

Large-scale multi-antenna systems can effectively improve data transmission reliability and throughput for smart grid. However, the massive number of antennas and radio frequency (RF) chains also result in high complexity and energy cost. In this paper, we develop a new performance benchmark named energy economic efficiency for measuring the time-average throughput per energy cost. Then, we investigate how to maximize long-term energy economic efficiency via the joint optimization of communication and energy resource allocation. The formulated joint optimization problem is NP-hard because it not only involves long-term nonlinear optimization objective and constraints, but also involves both integer and continuous optimization variables. Next, we propose an online joint antenna selection and power control algorithm by combining nonlinear fractional programming, Lyapunov optimization, and bisection method. The proposed algorithm can achieve bounded performance deviation from the optimum performance without requiring the prior knowledge of future channel state information (CSI), energy arrival, and electricity price. Finally, a comprehensive theoretical analysis is provided, and the proposed algorithm is verified through simulations under various system configurations.

Radio frequency susceptibility test of Beidou airborne receiver

The radio frequency susceptibility testing method of RTCA/DO-160G section 20 has been widely utilized to verify the reliability of airborne equipments in civil aviation. However, there are only a few of theory analysis and practical test of Beidou airborne equipment based on the procedure of radio frequency susceptibility test originated from RTCA/DO-160G, the research of radio frequency susceptibility test stemmed from RTCA/DO-160G is aiming at provide theoretical reference and practical bases for civil Beidou airborne receiver. Firstly, a theoretical model of calibration for conducted susceptibility and radiated susceptibility is derived and validated its effectiveness, the derived theoretical model indicate that choosing a suitable injection probe that meets the requirements of standard is much more important than the choose of a high power amplifier, a method for estimating the input power of antenna is also obtained under far field zone. Secondly, an equivalence model based on the susceptibility probability is formulated between the anechoic chamber and reverberation chamber method of radiated susceptibility test, the theory and experimental results show that the model can predict the difference between these two test methods well. Finally, a susceptibility evaluation model is constructed in terms of the needed test signal. The practical minimum radiated susceptibility threshold for continuous wave and pulse modulated signal are 5 V/m and 40 V/m, which indicates the receiver shows a better endurance to pulse interference than continuous wave.

Hybrid PSO-HSA and PSO-GA algorithm for 3D path planning in autonomous UAVs

Unmanned aerial vehicles (UAVs) are a quintessential example of automation in the field of avionics. UAVs provide a platform for performing a wide variety of tasks, but in each case the concept of path planning plays an integral role. It helps to generate a pathway free of obstacles, having minimum length leading to lesser fuel consumption, lesser traversal time and helps in steering the aircraft and its corresponding antenna power signature safely around the hostile antenna to avoid detection. To optimize path planning to incorporate all the above-mentioned constraints, this paper presents two new hybrid algorithms particle swarm optimization (PSO) with harmony search algorithm and PSO with genetic algorithm. The hybrid algorithms perform both an exploratory and exploitative search, unlike the existing algorithms which are biased, towards either an exploitative search or an exploratory search. Furthermore, the hybrid algorithms are compared to the existing optimization algorithms and in all cases the hybrid algorithms give a minimum of 7% better result against PSO with up to a 40% better result against Invasive Weed optimization algorithm for a fixed computational time, suggesting better real-time applications.