Stochastisation of microwave oscillations in microstrip log-periodic antenna-generator with LF noise-like modulation.

Microwave solid-state oscillators of noise-like signals are of the great interest for wireless telecommunication systems, imaging systems and electronic warfare. In the paper, the possibility of power combining in the array of three independent noise-like oscillators is investigated. The noise-like oscillators are based on the microstrip log-periodic antennas which are integrated with field-effect transistors. As an active element, NE350184С field-effect transistor with 13.5 dB gain at 12 GHz is chosen. It was previously shown that single-frequency, multifrequency or noise-like generations are possible in the active antennas. The main factors that affect the generation type are the current in the drain-source circuit of the transistor and the distance between the antenna plane and reflecting screen. It is experimentally shown, that using of the noise-like oscillator arrays makes possible the spectrum and power combining, but the construction is not enough stable and reliable.

RF-Powered Low-Energy Sensor Nodes for Predictive Maintenance in Electromagnetically Harsh Industrial Environments

This work describes the design, implementation, and validation of a wireless sensor network for predictive maintenance and remote monitoring in metal-rich, electromagnetically harsh environments. Energy is provided wirelessly at 2.45 GHz employing a system of three co-located active antennas designed with a conformal shape such that it can power, on-demand, sensor nodes located in non-line-of-sight (NLOS) and difficult-to-reach positions. This allows for eliminating the periodic battery replacement of the customized sensor nodes, which are designed to be compact, low-power, and robust. A measurement campaign has been conducted in a real scenario, i.e., the engine compartment of a car, assuming the exploitation of the system in the automotive field. Our work demonstrates that a one radio-frequency (RF) source (illuminator) with a maximum effective isotropic radiated power (EIRP) of 27 dBm is capable of transferring the energy of 4.8 mJ required to fully charge the sensor node in less than 170 s, in the worst case of 112-cm distance between illuminator and node (NLOS). We also show how, in the worst case, the transferred power allows the node to operate every 60 s, where operation includes sampling accelerometer data for 1 s, extracting statistical information, transmitting a 20-byte payload, and receiving a 3-byte acknowledgment using the extremely robust Long Range (LoRa) communication technology. The energy requirement for an active cycle is between 1.45 and 1.65 mJ, while sleep mode current consumption is less than 150 nA, allowing for achieving the targeted battery-free operation with duty cycles as high as 1.7%.

Energy Efficiency Analysis of MIMO Wideband RF Front-End Receivers

Energy-efficiency is crucial for modern radio-frequency (RF) receivers dedicated to Internet of Things applications. Energy-efficiency enhancements could be achieved by lowering the power consumption of integrated circuits, using antenna diversity or even with an association of both strategies. This paper compares two wideband RF front-end architectures, based on conventional low-noise amplifiers (LNA) and low-noise transconductance amplifiers (LNTA) with N-path filters, operating with three transmission schemes: single antenna, antenna selection and singular value decomposition beamforming. Our results show that the energy-efficiency behavior varies depending on the required communication link conditions, distance between nodes and metrics from the front-end receivers. For short-range scenarios, LNA presents the best performance in terms of energy-efficiency mainly due to its very low power consumption. With the increasing of the communication distance, the very low noise figure provided by N-path LNTA-based architectures outperforms the power consumption issue, yielding higher energy-efficiency for all transmission schemes. In addition, the selected front-end architecture depends on the number of active antennas at the receiver. Hence, we can observe that low noise figure is more important with a few active antennas at the receiver, while low power consumption becomes more important when the number of active RF chains at the receiver increases.

Usage of multi-objective genetic and multi-objective differential evolution algorithms on energy and spectral efficiencies in massive MIMO systems

There is a significant increase in the use of wireless communication and it is expected that this increase will continue progressively. In the near future, cellular network technologies are expected to be capable of increasing the area throughput hundreds of times in order to cope with the increase in data traffic. Increasing spectral efficiency (SE) with massive multi-input multi-output (Massive MIMO) systems is one of the main methods used to meet these expectations. SE means the amount of information transmitted successfully with each complex sample. Increasing the transmission power and the number of active antennas while increasing the SE increases the amount of energy consumed to very high levels. The fact that high energy consumption is harmful to the environment and costly makes it important to increase energy efficiency (EE). Various studies are carried out with the aim of bringing optimum levels of the SE and EE parameters which has trade-off between each other. Multi-objective intelligent optimization techniques are applied on the trade-off for detecting optimum SE-EE values. In this paper, multi-objective genetic algorithm (MOGA) and multi-objective differential evolution algorithm (MODEA) are used to obtain optimum values of certain factors (amount of transmit power, number of active antennas and number of user equipments). At the last stage, the calculations made for all values of the mentioned factors and the optimization results (performed in a relatively short time compared to these calculations) are shown on the same graph.

Using Arduino GPS modules for navigation control and monitoring

The paper evaluates the possibilities of connecting and using publicly available Arduino GPS Gy-GPSV3 modules based on the Ublox NEO-M8N chip and GPS/GLONAS ATGM336H with the NMEA 0183 Protocol. Both modules are equipped with active antennas, are configured for GPS (USA), GLONASS (Russia) and Beidou (China) satellites and are close in terms of their declared technical characteristics. They perform their functions of tracking coordinates and calculating the primary parameters of the carrier’s movement quite satisfactorily, both in conditions of a favorable landscape, and in conditions of mountainous terrain and urban development. Relatively low power consumption (25-30 mA) and dimensions, easy connection allow them to be used in Autonomous monitoring systems. However, a stable accuracy of more than 10 m is achieved only if there is simultaneous communication with 10 satellites or more, and signal reception inside premises and other shielded objects is not provided. A real cold start lasts more than a minute. Setting the operating modes of the modules provides mainly only filtering of measurement errors in a given range of heights and speeds. Of these modules, GPS/GLONAS ATGM336H is in clear priority, since it is significantly ahead in accuracy, availability of command control, and cost (at the moment it is 3 times cheaper) at standard settings when using the same type of antenna, power supply, and dimensions. No significant impact of visible environment phenomena on the operation of GPS receivers used (communication with satellites) was recorded. At the same time, closely located or relatively powerful household radio frequency transmitters affect accuracy, reducing it by 2-3 times. Signal communication can be improved by using or adding a more powerful overall antenna, which in certain conditions will also allow you to capture satellites that are closer to the horizon. As a result, with such characteristics and capabilities, the considered GPS modules can be successfully used only for navigation purposes and for receiving accurate time signals (synchronization of measurements). Using them for the purpose of measuring physical quantities (for example, parameters of surface waves, level, flow velocity, etc.) with modern requirements for accuracy makes sense only for large-scale processes.

On the Performance of the Multiple Active Antenna Spatial Modulation with 3-Dimensional Constellation

In spatial modulation (SM), a single signal symbol is transmitted from a given physical antenna, where both the signal symbol and the antenna index carry information. SM with multiple active antennas (MA-SM) transmits several signal symbols from a combination of antennas at each channel use, thereby increasing the spectral efficiency. MA-SM is proposed in combination with a new 3-dimensional constellation, where signal symbols transmitted from a given antenna combination are rotated before transmission. In this paper, we derived an upper-bound on the error probability of the MA-SM as a function of the rotation angles. The search for the optimal rotation angles is modeled as a multi-objective optimization problem. We concluded based on both analytical and simulation results that the 3-dimensional constellation with the optimal angles achieved negligible improvement. Therefore, we do not recommend using the 3-dimensional constellation with the MA-SM system.

Design and qualification of Ku-band-radiating chains for receive active array antennas of flexible telecommunication satellites

Airbus Italia recently developed enhanced passive components as key elements for its telecommunication Ku-band antenna product lines, tailored to reconfigurable payloads. This paper describes the design and qualification of a dual linear polarization Ku-band-radiating chain, developed for the DRA receive (Rx) active antennas embarked on the Eutelsat Quantum satellite. The feed chain covers the entire Ku-band frequency range allocated for fixed satellite services providing receive functionality and embedding sharp rejection features over the adjacent transmit band. The proposed design provides high radiation efficiency (>90%) and polarization purity (XPD > 33 dB), together with low RF losses and flat group-delay variation over a 13% fractional bandwidth, keeping a compact size and reduced axial length. The unit has been optimized for high reproducibility in high volume productions, typical of large DRA applications, for which stringent mass and dimensional constraints, as well as excellent amplitude and phase tracking among similar units, are key features. Details of the feed chain design and an overview of RF and environmental qualification test results are presented.