High Power Communication Research Articles

Design and Verification of Thermal Control System of Communication Satellite

The multiple working modes, complex working conditions, frequent changes in external heat flux, and high power consumption of communication satellites all pose great difficulties to their thermal design. This paper mainly describes the design of a thermal control system for high-power communication satellites. Firstly, new efficient heat transfer technologies and thermal control materials for spacecraft are introduced. Secondly, the structure and internal heat source of the satellite are introduced. Thirdly, the external heat fluxes are analyzed, and the position of the heat dissipation surface and extreme conditions are confirmed. Then, a thermal control system is designed around the difficulties of thermal control. With heat pipes, the temperature uniformity of +Y deck, −Y deck, and +Z deck increased by 8 °C, 9.9 °C, and 34.2 °C, respectively. Furthermore, the maximum temperature of the power controller, secondary power supply, bidirectional frequency converter, and solid discharge decreased by 32.5 °C, 22.0 °C, 14.0 °C, and 164 °C, respectively. Finally, a thermal balance test is performed. The test results show that the temperatures of the solid-state power amplifier, on-board computer, power controller, secondary power supply, and bidirectional frequency converter meet the requirements of the thermal control indices. In addition, the temperature of thermal-sensitive components such as batteries and the storage tank also meets the requirements. The thermal design scheme is reasonable and feasible, and the thermal balance test verifies the correctness of the thermal design.

A High-Power and Broadband GaN SPDT MMIC Switch Using Gate-Optimized HEMTs

A high-power, broadband monolithic microwave integrated circuit (MMIC) single-pole double-throw (SPDT) switch is designed with gate-optimized high-electron-mobility transistors (HEMTs) using AlGaN/Gallium nitride (GaN) technology. The foot length of the gate is varied from 200 to 250 nm, and the head length is varied from 500 to 750 nm in the T-gate structure to optimize the radio frequency (RF) performance. The SPDT switch is designed in a series–shunt–shunt topology using gate topology as a design parameter. The switch has achieved an insertion loss better than 0.75 dB throughout the 3.5–13.5-GHz bandwidth. It can transmit 30-W output power at 0.1-dB compression point and handle 47.5-dBm input power at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\textrm{1\,dB}}$</tex-math> </inline-formula> . The isolation is above 25 dB, and the return loss is better than 11 dB. With its low insertion and high power-handling capacity in broadband, the SPDT switch shows state-of-the-art performance for high-power communication systems and radar applications.

Aesthetic experience models human learning.

Aesthetic experiences have the potential to promote learning and creativity by enhancing the ability to understand complexity and to integrate novel or disparate information. Offering a theoretical framework for understanding the cognitive benefits of aesthetic experiences, this paper argues they are the necessary outcome of human learning, in which natural objects or artworks are evaluated in a multi-dimensional preference space shaped by Bayesian prediction. In addition, it contends that the brain-states underlying aesthetic experiences harness configurations of the apex three transmodal neural systems-the default mode network, the central executive network, and the salience network-that may offer information-processing advantages by recruiting the brain's high-power communication hubs, thus enhancing potential for learning gain.

Wave solutions to the more general (2+1)-dimensional Boussinesq equation arising in ocean engineering

The novel wave profiles for the more general [Formula: see text]-dimensional Boussinesq equation are established in this paper. To get such outstanding results, we employ the potent Sardar sub-equation technique. The recognized explanations for several physical difficulties have been studied. These technological advancements have been proven to be helpful for the transmission of long-wave and high-power communications networks. The circumstances that gave rise to the emergence of these solutions are described in detail. The physical characteristics of the governing equation have been depicted in contour plots and three dimensions.

Structural Parameters Optimization of Corona Ring of Tethered Balloon-Type VLF Antenna

The antenna end of the tethered balloon-type high-power VLF communication system will be exposed to an extremely strong alternating electric field environment when it is in operation. Due to dielectric loss, an abnormal temperature rise may occur at the antenna end, which may lead to an antenna fracture in serious cases. It is an effective measure to install a corona ring at the end of the antenna to prevent such accidents. In this paper, the structural parameters of the corona ring, including ring radius, tube radius, and ring depth, are optimized based on intelligent optimization algorithm to significantly improve the electric field distribution and restrain the temperature rise to the maximum extent. The effectiveness of the optimization results is verified by simulation.

The Study of Cooling Mechanism Design for High-Power Communication Module with Experimental Verification

With the continued development of 5G mobile communications technology, the implementation of high-power communication systems has become a key indicator of developed nations. Communication modules are also trending toward wide bandwidth and high-capacity Multi-Input and Multi-Output systems. As the signal transmission speed and resolution continue with the increasing trend, the power used to operate these communications systems increase, causing extreme heat generation by transmit/receive modules (T/R module). In conditions where computation load increases in micro design systems, chips must operate in environments that are narrow, sealed, and have no convection, which can drastically increase the thermal load within a system. If no proper cooling system is utilized, the system fails or operates at impacted performance due to excessive temperatures. To solve the aforementioned problem, this study aimed to optimize the design of the cooling system in the T/R modules of communications systems by integrating heat pipes, cooling fans, cooling fins, and cooling chips within a limited space. We also proposed four types of cold plates based on the different directional clamp-in configuration methods of heat pipes within copper panels and utilized the finite element method to simulate and analyze the heat dissipation performance. The simulation results reveal that cold plates of types I and II can achieve a better heat dissipation performance. Finally, types I and II cold plates were selected for production and experimental verification. The results show that heat dissipation performances were similar to simulation results. The results also confirmed that type II cold plate has a better temperature uniformity and heat transfer efficiency. Thus, the cooling mechanism depicted in this study is viable in practical applications. The proposed mechanisms can also provide a reference for heat dissipation design patterns in different electronic module settings.

Towards building a culturally informed consent process in Central Asia

ABSTRACT Researchers working in Central Asia often report difficulty obtaining Western-style signed informed consent statements. The principles underlying informed consent were developed in cultures characterized by low-power distance and individualism, low context communication and a rules basis, whereas many Central Asian cultures emphasize high-power distance, collectivism, high-context communication and relationships. Yet, consent is an important principle. We interviewed scholars who grew up in Central Asia, but completed graduate work in the United States, Canada or the UK, to ask their recommendations for developing a culturally appropriate consent process. The common themes that arose include working within a network, building relationships of trust with potential participants and not utilizing legal-type documentation as a basis for consent.

Design Considerations of Sequential Switching Shunt Regulator for High-Power Applications

Sequential switching shunt regulators (S3Rs) are widely used in the satellites owing to their simple structure and high reliability. The high-power communication satellites require a power supply with a high bus voltage and large solar array section current. However, a large solar array capacitance and new time-division multiple access operations complicate the design of a lightweight and cost-effective power supply by increasing the difficulty in dissipation and thermal control. On the basis of passive current limitation, in this article, we propose a novel shunt regulator with only one output diode and a protection strategy to achieve high efficiency, appropriate shunt current limitation, and low turn-off delay. In addition, to reduce the dissipation of an S3R cell when feeding the solar array current to the main bus and to satisfy the single point failure-free requirement, an innovative self-retriggerable diode short-circuit fault detector circuit is proposed, which includes a protection switch for a safe thermal or electrical operation. Finally, simulation and experimental results are presented to validate the proposed shunt regulator and the corresponding control method or protection strategy.

Defected Ground Structure Printed Antenna with Triangular Slot

Double Layer Single Feed dual resonant frequency patch antenna is presented in this paper. After design the patch, we are etched triangular and rectangular slots at the top and bottom layer of the patch. After design the antenna structure, we got a remarkable result and the operating frequencies are used for the various applications of microwave Communication. Two triangular slots are designed at the top layer from the both sides of the patch with one rectangular slot from the bottom layer and also one h-type slot is introduced at the middle portion from the rest at bottom layer to obtain the desired resonant frequency. The different shapes of the patch used to improve the gain bandwidth performance of the antenna. We get two operating frequencies for this triangular shaped printed antenna. 1st frequency is applicable for microwave radiometry from aircraft to measure ocean wind speed and rain characteristics in hurricanes and the other is used to design BeO POWER CHIP RESISTOR which is applicable for Microwave and RF high power communication, microwave amplifiers and power dividers. This paper includes an extensive analysis of simulated results for this above mentioned microstrip printed patch antenna. All results are simulated and verified by the network analyzer. Due to the basic characteristics of proposed printed antenna, it is suitable for the applications in long distance radio telecommunication systems. It is also applicable for satellite communication and microwave relay systems.

An Overview of Data Telemetry in Inductively Powered Implantable Biomedical Devices

In modern implantable medical devices (IMDs), wireless data transmission between inside and outside of the body is essential to control IMD parameters and report the acquired data to the external part of the system. Unlike conventional far-field data communication, which is more suitable for free space, near-field data transfer techniques have been widely adopted for transcutaneous data links in IMDs. These data links should be designed for robustness against misalignments and interference, while maintaining high power efficiency, sufficient bandwidth, and communication range in either uplink (IMD to outside) and/or downlink (wearable external part to IMD). In this article, we review fundamental principles and practical considerations for designing short-range transcutaneous data telemetry, along with novel techniques presented in the literature, which are categorized in uplink/downlink, passive/active, single/multi-carrier, and carrier-less pulse-based data telemetry methods.

Harmonic Analysis in Gaseous Helium by Coherent Schrödinger-Maxwell Method

This paper concentrates on harmonic analysis in gaseous helium, including microscopic generation, selective filtration and macroscopic propagation. A coherent method is proposed, with time-dependent Schrodinger equation for harmonic generation and Maxwell's wave equation for harmonic propagation. By introducing the polarization source based on the microscopic single-atom response, the macroscopic nonlinear propagation can be efficiently solved by a set of linear equations at each harmonic frequency. Using the proposed method, we numerically investigate the propagation effects of selective harmonics in gaseous helium. Our results reveal that specific harmonics allow the synthesis of an isolated attosecond pulse, which presents a high beam quality and an excellent spatial profile with Gaussian-like distribution. Moreover, the generated pulse provides a promising potential on high power defense, quantum radar and communication.

Investigation on High Average Power Operations of Gyro-TWTs With Dielectric-Loaded Waveguide Circuits

Gyrotron traveling-wave tubes (gyro-TWTs) have been proved to be an attractive power source in many applications such as high-resolution radars, high-power communication systems, and electronic warfare systems. The main output indexes such as peak and average output power, interaction efficiency, and bandwidth are important for these devices. In addition, a great deal of reliability requirements such as nonstop stable operating time, operation lifetime, and environmental adaptability should be met. In this paper, detailed developing processes of gyro-TWTs in high average power operations are presented, including theoretical analyses, multiphysics simulations of key components, fabrication, and construction of the automatic hot test platform. Finally, the measured results of a Ka -band gyro-TWT for industrial applications are presented. The amplifier exhibits an excellent performance of 100-h nonstop stable operation, a 1-dB fraction bandwidth of 8%, an efficiency of more than 20%, and a peak power and an average power of more 150 and 10 kW, respectively.

Low-cost wireless power efficiency optimization of the NFC tag through switchable receiver antenna

Near-field communication (NFC) readers, ubiquitously embedded in smartphones and other infrastructures can wirelessly deliver mW-level power to NFC tags. Our previous work NFC-wireless identification and sensing platform (WISP) proves that the generated NFC signal from an NFC enabled phone can power a tag (NFC-WISP) with display and sensing capabilities in addition to identification. However, accurately aligning and placing the NFC tag's antenna to ensure the high power delivery efficiency and communication performance is very challenging for the users. In addition, the performance of the NFC tag is not only range and alignment sensitive but also is a function of its run-time load impedance. This makes the execution of power-hungry tasks on an NFC tag (like the NFC-WISP) very challenging. Therefore, we explore a low-cost tag antenna design to achieve higher power delivered to the load (PDL) by utilizing two different antenna configurations (2-coil/3-coil). The two types of antenna configurations can be used to dynamically adapt to the requirements of varied range, alignment and load impedance in real-time, therefore, we achieve continuous high PDL and reliable communication. With the proposed method, we can, for example, turn a semi-passive NFC-WISP into a passive display tag in which an embedded 2.7″ E-ink screen can be updated robustly by a tapped NFC reader (e.g. an NFC-enable cell-phone) over a 3 seconds and within 1.5cm range.

Indoor Channel Modelling for SISO and Massive SIMO in the 60 GHz mm-Wave Band

In this paper, an indoor two dimensional channel modeling scheme is proposed for fifth generation (5G) 60 GHz millimeter-wave (mm-wave) communication systems. mm-wave systems are one of the most important candidate technologies to be used in 5G communications because of their advantages such as wide bandwidth, high power communication allowance and small sized, massive numbered antenna arrays. Therefore, modeling of the characteristics of the millimeter-wave channel is substantial.Characterization and modeling studies of mm-wave channels were performed using ray tracing method for both single and massive numbered antennas. The results in terms of multipath delay spread and multipath power content are investigated and a useful simulation is created that will be used to test future hardware implementations.DOI: http://dx.doi.org/10.5755/j01.eie.23.4.18720

Passive intermodulation model and experimental verification of cascaded microwave devices

Passive intermodulation (PIM) is a complex problem in high-power microwave devices and satellite communications. In this paper, an effective calculation method is proposed for predicting PIM power levels of the cascaded microwave devices. First of all, the analytical formula of intermodulation voltage is derived based on the nonlinear I–V characteristics of microwave devices. Then, the mathematical model of point sources is constructed by the transmission line theory and extended to the cascaded microwave devices. The passive intermodulation products (PIMP) of the cascaded microwave devices are evaluated based on the point-source model. The relationship of PIM between a single microwave device and the cascaded system is revealed. Eventually, the corresponding experiments are designed to verify the accuracy of point-source model and the cascaded model to predict the third-order PIM power level, which address the problem of PIM prediction of the cascaded microwave devices.

Distributed resource allocation in ultra-dense networks via belief propagation

Ultra-dense networking is widely accepted as a promising enabling technology to realize high power and spectrum efficient communications in future 5G communication systems. Although joint resource allocation schemes promise huge performance improvement at the cost of cooperation among base stations, the large numbers of user equipment and base station make jointly optimizing the available resource very challenging and even prohibitive. How to decompose the resource allocation problem is a critical issue. In this paper, we exploit factor graphs to design a distributed resource allocation algorithm for ultra dense networks, which consists of power allocation, subcarrier allocation and cell association. The proposed factor graph based distributed algorithm can decompose the joint optimization problem of resource allocation into a series of low complexity subproblems with much lower dimensionality, and the original optimization problem can be efficiently solved via solving these subproblems iteratively. In addition, based on the proposed algorithm the amounts of exchanging information overhead between the resulting subprob-lems are also reduced. The proposed distributed algorithm can be understood as solving largely dimensional optimization problem in a soft manner, which is much preferred in practical scenarios. Finally,the performance of the proposed low complexity distributed algorithm is evaluated by several numerical results.

Robustness of spiking Deep Belief Networks to noise and reduced bit precision of neuro-inspired hardware platforms.

Increasingly large deep learning architectures, such as Deep Belief Networks (DBNs) are the focus of current machine learning research and achieve state-of-the-art results in different domains. However, both training and execution of large-scale Deep Networks require vast computing resources, leading to high power requirements and communication overheads. The on-going work on design and construction of spike-based hardware platforms offers an alternative for running deep neural networks with significantly lower power consumption, but has to overcome hardware limitations in terms of noise and limited weight precision, as well as noise inherent in the sensor signal. This article investigates how such hardware constraints impact the performance of spiking neural network implementations of DBNs. In particular, the influence of limited bit precision during execution and training, and the impact of silicon mismatch in the synaptic weight parameters of custom hybrid VLSI implementations is studied. Furthermore, the network performance of spiking DBNs is characterized with regard to noise in the spiking input signal. Our results demonstrate that spiking DBNs can tolerate very low levels of hardware bit precision down to almost two bits, and show that their performance can be improved by at least 30% through an adapted training mechanism that takes the bit precision of the target platform into account. Spiking DBNs thus present an important use-case for large-scale hybrid analog-digital or digital neuromorphic platforms such as SpiNNaker, which can execute large but precision-constrained deep networks in real time.

Investigation on thermo-mechanical responses in high power multi-finger AlGaN/GaN HEMTs

Both transient temperature and thermal stress responses in high power multi-finger AlGaN/GaN high electron mobility transistors (HEMTs), caused by their self-heating effects, are characterized in the present study. Instead of using commercial software, self-developed algorithm based on hybrid time-domain finite element method (TD-FEM) is applied for thermo-mechanical co-simulation of such 3-D structure. The temperature-dependent properties of most constitutive parameters of all materials involved, in particular for electrical conductivities, thermal conductivities, thermal expansion coefficients, and Young’s modulus, are described by several sets of nonlinear polynomial expressions. The algorithm accuracy is validated in detail, with good agreement achieved in comparison with the commercial software COMSOL. It is believed that this study will be useful for effectively evaluating the reliability and lifetime of AlGaN/GaN HEMTs and their monolithic microwave integrated circuits (MMIC) used in high power communication systems and radars.

Power Distance, Uncertainty Avoidance, and Technology: Analyzing Hofstede's Dimensions and Human Development Indicators

Correlations between Hofstede's dimensions of power distance and uncertainty avoidance and selected indicators of the Human Development Report (HDR) were analyzed. Three communication technology indicators—that is, cell phone subscription, Internet use, and the number of telephone mainlines—were predicted to measure the development of a nation. Results indicate a negative correlation between high power distance and communication technology in terms of the three technologies examined in this study. We found a negative correlation between power distance and human development. Negative correlations were also found between uncertainty avoidance and two cell phone subscription as well as internet use.

Optical Fiber for High-Power Optical Communication

We examined optical fibers suitable for avoiding such problems as the fiber fuse phenomenon and failures at bends with a high power input. We found that the threshold power for fiber fuse propagation in photonic crystal fiber (PCF) and hole-assisted fiber (HAF) can exceed 18 W, which is more than 10 times that in conventional single-mode fiber (SMF). We considered this high threshold power in PCF and HAF to be caused by a jet of high temperature fluid penetrating the air holes. We showed examples of two kinds of failures at bends in conventional SMF when the input power was 9 W. We also observed the generation of a fiber fuse under a condition that caused a bend-loss induced failure. We showed that one solution for the failures at bends is to use optical fibers with a low bending loss such as PCF and HAF. Therefore, we consider PCF and HAF to be attractive solutions to the problems of the fiber fuse phenomenon and failures at bends with a high power input.