High-Power Simultaneous Wireless Information and Power Transfer System Based on an Injection-Locked Magnetron Phased Array

We built a phased array system for high-power simultaneous wireless information and power transfer (SWIPT) using four 5.8-GHz injection-locked magnetrons. In the magnetron injection-locked state, the transmission efficiency was measured at different modulation rates. The fluctuation in the transmission efficiency was not more than 0.5%. We observed that dynamic beamforming does not affect communication quality. Using the magnetron phased array system, SWIPT experiments revealed that a frequency modulated (FM) signal that carries a video camera signal is transmitted and decoded during dynamic beamforming. In this SWIPT system, the main lobe transfers power, and information can be demodulated in front of the magnetron phased array from −90° to 90°. The maximum transmitted microwave power of the proposed system is 1637 W

Phase Synchronization Principle in 5.8 GHz Magnetron Phased Array

2023 24th International Vacuum Electronics Conference (IVEC), 25-28, April 2023, Chengdu, ChinaThis paper analyzes the influence parameters of the phase control of the magnetron in detail and proposes a method to realize the frequency locking and phase synchronization of the magnetron. The noise-inhibition of the magnetron has made great progress in previous research, and the power and phase can be simultaneously controlled. Based on this principle, the phases of multiple magnetrons are synchronized and successfully applied to phased arrays. A 2×2 5.8GHz magnetron phased array was constructed with a maximum output power of 1680W and the beam-forming experiment of the magnetron phased array was demonstrated for wireless power transfer

Satellite power system: Concept development and evaluation program. Volume 3: Power transmission and reception. Technical summary and assessment

Efforts in the DOE/NASA concept development and evaluation program are discussed for the solar power satellite power transmission and reception system. A technical summary is provided together with a summary of system assessment activities. System options and system definition drivers are described. Major system assessment activities were in support of the reference system definition, solid state system studies, critical technology supporting investigations, and various system and subsystem tradeoffs. These activities are described together with reference system updates and alternative concepts for each of the subsystem areas. Conclusions reached as a result of the numerous analytical and experimental evaluations are presented. Remaining issues for a possible follow-on program are identified

Performance Comparison of Phase Change Materials and Metal-Insulator Transition Materials for Direct Current and Radio Frequency Switching Applications

Advanced understanding of the physics makes phase change materials (PCM) and metal-insulator transition (MIT) materials great candidates for direct current (DC) and radio frequency (RF) switching applications. In the literature, germanium telluride (GeTe), a PCM, and vanadium dioxide (VO2), an MIT material have been widely investigated for DC and RF switching applications due to their remarkable contrast in their OFF/ON state resistivity values. In this review, innovations in design, fabrication, and characterization associated with these PCM and MIT material-based RF switches, have been highlighted and critically reviewed from the early stage to the most recent works. We initially report on the growth of PCM and MIT materials and then discuss their DC characteristics. Afterwards, novel design approaches and notable fabrication processes; utilized to improve switching performance; are discussed and reviewed. Finally, a brief vis-á-vis comparison of resistivity, insertion loss, isolation loss, power consumption, RF power handling capability, switching speed, and reliability is provided to compare their performance to radio frequency microelectromechanical systems (RF MEMS) switches; which helps to demonstrate the current state-of-the-art, as well as insight into their potential in future applications

Plasma Dynamics

Contains reports on six research projects.National Science Foundation (Grant ECS82-00646)National Science Foundation (Grant ECS82-13485)U.S. Air Force - Office of Scientific Research (Contract F33615-81-K-1426)U.S. Air Force - Office of Scientific Research (Contract F49620-83-C-0008)U.S. Air Force - Office of Scientific Research (Contract AFOSR-84-0026)U.S. Navy - Office of Naval Research (Contract N00014-83-K-2024)Sandia National Laboratory (Contract 31-5606)Sandia National Laboratory (Contract 48-5725)U.S. Department of Energy (Contract DE-ACO2-78ET-51013)National Science Foundation (Grant ECS82-13430

位相制御マグネトロンを用いた大電力マイクロ波無線電力伝送システム

京都大学0048新制・課程博士博士(工学)甲第22843号工博第4783号新制||工||1748(附属図書館)京都大学大学院工学研究科電気工学専攻(主査)教授 篠原 真毅, 教授 大村 善治, 准教授 後藤 康仁学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDFA

Experimental and computational investigation of heat transfer in a microwave-assisted flow system

Microwave technology is gaining popularity as a tool for chemical process intensification and an alternative to conventional heating. However, in flow systems non-uniform temperature profiles are commonly encountered and hence methods to characterise and improve them are required. In this work, we studied the effects of various operational parameters-microwave power, inlet flow rate, tube orientation and pressure-on the electric field and temperature profiles of water flowing in a PTFE tube (2.4 mm internal diameter), placed in a commercial single-mode microwave applicator. A finite element model was developed to estimate the longitudinal temperature profiles and the absorbed microwave power, while in situ temperature monitoring was performed by a fibre optic probe placed at multiple locations inside the tube. The water temperature inside the tube increased by increasing the microwave power input and temperature profiles stabilised beyond 20 W, while the percentage absorbed microwave power showed the inverse trend. When changing the tube orientation or decreasing the inlet flow rate, microwave absorption decreased significantly. When the pressure was increased to 2.3 bara, water temperature increased by ~ 20 o C. Results from this study provide valuable insights on achievable temperature profiles and energy efficiency of microwave-assisted flow synthesis systems.

Materials Optimization and GHz Spin Dynamics of Metallic Ferromagnetic Thin Film Heterostructures

Metallic ferromagnetic (FM) thin film heterostructures play an important role in emerging magnetoelectronic devices, which introduce the spin degree of freedom of electrons into conventional charge-based electronic devices. As the majority of magnetoelectronic devices operate in the GHz frequency range, it is critical to understand the high-frequency magnetization dynamics in these structures. In this thesis, we start with the static magnetic properties of FM thin films and their optimization via the field-sputtering process incorporating a specially designed in-situ electromagnet. We focus on the origins of anisotropy and hysteresis/coercivity in soft magnetic thin films, which are most relevant to magentic susceptibility and power dissipation in applications in the sub-GHz frequency regime, such as magnetic-core integrated inductors. Next we explore GHz magnetization dynamics in thin-film heterostructures, both in semi-infinite samples and confined geometries. All investigations are rooted in the Landau-Lifshitz-Gilbert (LLG) equation, the equation of motion for magnetization. The phenomenological Gilbert damping parameter in the LLG equation has been interpreted, since the 1970's, in terms of the electrical resistivity. We present the first interpretation of the size effect in Gilbert damping in single metallic FM films based on this electron theory of damping. The LLG equation is intrinsically nonlinear, which provides possibilities for rf signal processing. We analyze the frequency doubling effect at small-angle magnetization precession from the first-order expansion of the LLG equation, and demonstrate second harmonic generation from Ni81 Fe19 (Permalloy) thin film under ferromagnetic resonance (FMR), three orders of magnitude more efficient than in ferrites traditionally used in rf devices. Though the efficiency is less than in semiconductor devices, we provide field- and frequency-selectivity in the second harmonic generation. To address further the relationship between the rf excitation and the magnetization dynamics in systems with higher complexity, such as multilayered thin films consisting of nonmagnetic (NM) and FM layers, we employ the powerful time-resolved x-ray magnetic circular dichroism (TR-XMCD) spectroscopy. Soft x-rays have element-specific absorption, leading to layer-specific magnetization detection provided the FM layers have distinctive compositions. We discovered that in contrast to what has been routinely assumed, for layer thicknesses well below the skin depth of the EM wave, a significant phase difference exists between the rf magnetic fields Hrf in different FM layers separated by a Cu spacer layer. We propose an analysis based on the distribution of the EM waves in the film stack and substrate to interpret this striking observation. For confined geometries with lateral dimensions in the sub-micron regime, there has been a critical absence of experimental techniques which can image small-amplitude dynamics of these structures. We extend the TR-XMCD technique to scanning transmission x-ray microscopy (STXM), to observe directly the local magnetization dynamics in nanoscale FM thin-film elements, demonstrated at picosecond temporal, 40 nm spatial and less than 6° angular resolution. The experimental data are compared with our micromagnetic simulations based on the finite element analysis of the time-dependent LLG equation. We resolve standing spin wave modes in nanoscale Ni81 Fe19 thin film ellipses (1000 nm × 500 nm × 20 nm) with clear phase information to distinguish between degenerate eigenmodes with different symmetries for the first time. With the element-specific imaging capability of soft x-rays, spatial resolution up to 15 nm with improved optics, we see great potential for this technique to investigate functional devices with multiple FM layers, and provide insight into the studies of spin injection, manipulation and detection

Factors affecting the bit error rate performance of the indoor radio propagation channel for 2.3-2.5 GHz frequency band

The use of wireless in buildings based on microwave radio technology has recently become a viable alternative to the traditional wired transmission media. Because of the portable nature of radio transceivers, the need for extensive cabling of buildings with either twisted pair, coaxial, or optical fibre cable is eliminated. This is particularly desirable where high user mobility occurs and existing wiring is not in place, or buildings are heritage in nature and extensive cabling is seen as intrusive. Economic analysis bas also shown that significant labour cost savings can result by using a radio system or a hybrid mix of cable and radio for personal communication. The use of wireless systems within buildings introduces a new physical radio wave propagation medium, namely the indoor radio propagation channel. This physical medium has significantly different characteristics to some of the other forms of radio channels where elevated antennas, longer propagation path distances, and often minimally obstructed paths between transmit and receive antenna are common. Radio waves transmitted over the indoor channel at microwave frequencies behave much like light rays, they are blocked, scattered, and reflected by objects in the environment. As a direct result of this several phenomena unique to this form of physical medium become apparent, and they must be accounted for in the design and modelling of the indoor radio propagation channel transmission performance. In this thesis we analyse and characterise the indoor radio channel as a physical medium for data transmission. The research focuses on the influence of the radio physics aspects of an indoor microwave channel on the data transmission quality. We identify the associated statistical error performance for both time varying and temporally stationary indoor channels. Together with the theoretical analysis of the channel, a series of propagation measurements within buildings are completed to permit empirical validation of the theoretical predictions of how the indoor microwave channel should perform. The measurements are performed in the frequency range 2.3-2.5 GHz, which includes the 2.4-2.4835 GHz band allocated by spectrum management authorities for industrial scientific and medical radio use, (ISM band). As a direct result of our measurements, statistics related to channel noise, fading, and impulse response for the indoor microwave channel are obtained. The relationship between data transmission error statistics and the aforementioned phenomena is quantified and statistically analysed for the indoor radio channel and phase shift keyed (PSK) modulation. The results obtained from this research provide input data for the development of a simulation model of an indoor wireless mobile channel. Our measurements identify microwave ovens as a channel noise source of sufficient magnitude to corrupt data transmission in the ISM band, and an in depth analysis of the effect of noise emissions from operational microwave ovens on PSK modulation is presented in this thesis. As a result of this analysis, the estimated data error rates are calculated. Channel fading measurements provide results that will be used as the input data for the design of antennas for use on the indoor microwave channel. We also show that a data rate of eight megabits/second is possible over the typical indoor radio channel, with no requirement for adaptive delay equalisation to counter multipath signal delay spread

Frequency and phase locking of a CW magnetron:with a digital phase locked loop using pushing characteristics

The main body of work presented in this thesis is precise frequency and phase control of a 1.2 kW CW cooker magnetron (National 2M137) locked to a 10 MHz reference injected with a very small RF signal (of the order of -40 dBc) creating a suitable RF source for particle accelerators and other sophisticated applications. We will go on to discuss the characterization of the magnetron with differing heater powers and load conditions when operated with a low cost switched mode power supply. We similarly identify three different regimes of the magnetron operation with respect to the heater power: firstly low noise operation for small heater powers (up to 15W), secondly unstable operation for mid-range heater powers (15W to 30W) and thirdly high noise operation at high heater powers (30W to 54W). We then introduce a novel method to lock the magnetron output frequency to the 10 MHz reference using a digital frequency synthesizer IC (Analog Devices ADF4113) in a negative feedback loop, with this method we exploit the use of the pushing mechanism where the ADF41113 controls the power supply output to vary the magnetron’s anode current, keeping its natural frequency locked to the reference. We next investigate the injection locking of the frequency locked magnetron with small injection levels (-29 dBc to -43 dBc) under differing operating conditions and observe a phase jitter performance of the order of+/-13 o for very small heater power and -29 dBc injection level. We then fast switch/ramp the injection phase and establish the maximum rate of change of the magnetron output phase. This rate was found to be 4p/us for -29 dBc injection level and 44W heater power. We finally discuss the implementation of a fast DSP based feedback control on the injection phase to improve the magnetron phase jitter performance to below 1o r.m.s