Transmitter Antenna Research Articles

Performance Analysis of Reflective Intelligent Surface Assisted Bidirectional Full‐Duplex Communication Systems Over Nakagami‐m$$ m $$ Fading Channels

ABSTRACTIn this paper, a passive reflective intelligent surface (RIS) assisted bidirectional full‐duplex (FD) wireless system in a realistic Nakagami‐ fading with reflective elements and two source nodes is proposed. The source nodes are equipped with dual antennas for FD mode transmission and reception. The primary cause of degradation in the performance of the FD system is self‐interference, which can be reduced by increasing the number of reflective elements on the meta‐surface. Analytical expressions have been derived for the proposed RIS‐aided bidirectional FD wireless systems in terms of outage probability and bit error rate (BER). Numerical results show that doubling the number of reflecting elements considerably improves the outage performance of the proposed system in terms of signal‐to‐noise ratio (SNR) compared with RIS‐assisted half‐duplex (HD) mode. Additionally, different modulation schemes have been employed to evaluate the BER performance of the proposed system. The accuracy of analytical expressions is validated by matching Monte Carlo with analytical simulations.

The Application of Multiple Input Multiple Output (MIMO) Technology in Wireless Communications

Abstract: With the rapid advancement of wireless communication technology, enhancing data transmission rates, system capacity, and reliability has emerged as a key challenge. The paper investigates the application of Multiple Input Multiple Output (MIMO) antenna technology in wireless communication. By using multiple antennas for simultaneous signal transmission and reception, MIMO technology can effectively mitigate multipath effects and enhances channel capacity. And channel models of MIMO systems, capacity optimization strategies, and power allocation methods are also discussed. The results indicate that MIMO technology significantly improves transmission rates and signal quality in complex propagation environments. However, practical applications continue to face challenges such as channel estimation errors and antenna correlation. Therefore, the paper highlights the significance of MIMO technology in wireless communication systems and outlines potential directions for future research.

Transmit and Receive Antenna Port Selection for Channel Capacity Maximization in Fluid-MIMO Systems

Transmit and Receive Antenna Port Selection for Channel Capacity Maximization in Fluid-MIMO Systems

Integration of fixed-frequency and FM-CW (frequency-modulated continuous-wave) reflectometers for coincident turbulence measurements on LTX-β (Lithium Tokamak eXperiment-β).

The fixed-frequency and frequency-modulated continuous-wave (FM-CW) reflectometers on LTX-β (Lithium Tokamak eXperiment-β) have been configured to use the same transmission lines and antenna arrays for coincident views of the core and edge plasma. The fixed-frequency channels (13.1-20.5 and 20-40GHz, tunable between discharges) provide time-resolved measurements of density fluctuations, while the FM-CW channels (13.1-20.2 and 19.5-33.5GHz) measure the density profile and fluctuations, with high spatial resolution and a sampling rate determined by the frequency sweep interval (5 μs). Data from both reflectometers are synchronously acquired to simultaneously leverage the wide bandwidth and high spatial resolution of the respective systems. Experiments showed that mutual crosstalk interference is momentary and does not diminish the capability of either system. Spectral analysis indicated broad power spectra (several hundreds of kHz) and suggests that the signals from the FM-CW system are consistent with under-sampled fixed-frequency signals. Radial correlations were explored using data from the two reflectometers, as well as from the FM-CW system alone. The core channels showed high levels of agreement between these two comparisons, suggesting that the data from the reflectometers are interchangeable for statistical estimates. For the edge channels, comparisons using data from the FM-CW reflectometer alone showed significant decorrelation due to time lag caused by the finite frequency up-sweep duration. Alternatively, this effect is eliminated when cross-correlating data from the different reflectometers. These results highlight the advantages of operating the fixed-frequency and FM-CW reflectometers in this manner, where the combined system can overcome the limitations of each separate system.

Secrecy Analysis of Transmit Antenna Selection with Hybrid GSC/SC in AF-MIMO Relay Systems

Secrecy Analysis of Transmit Antenna Selection with Hybrid GSC/SC in AF-MIMO Relay Systems

Impact of hardware impairments and BS antenna tilt on 3D drone localization and tracking

Today, GPS-free drone localization is increasingly gaining attention in various applications, but it faces significant accuracy challenges in three-dimensional (3D) space due to various impairments. This study investigates the effects of carrier frequency offset (CFO), phase noise (PN), and down-tilted base station (BS) antennas on drone positioning and tracking. Additionally, we explore the impact of inter-site distance (ISD) and BS density on drone position estimation accuracy. In our methodology, we consider a flying drone equipped with a single transmission antenna and BSs configured with 4 × 4 antennas under specific impairments. We first analyze the effects of these impairments on the signal’s covariance matrix. Then, using the MUSIC algorithm, we estimate the azimuth and elevation angles, which serve as the basis for drone localization using the Least Squares (LS) method across all BSs. Finally, the estimated positions feed into an Extended Kalman Filter (EKF) for tracking. Our results present a sequential analysis of the impact of all impairments on the off-diagonal covariance matrix, on the Angle of Arrival (AOA) estimation and 3D drone localization. We use simulations to demonstrate how hardware impairments affect 3D drone localization accuracy under varying ISD and BS densities.

Peak Cancellation Signal Generation Considering Variance in Signal Power among Transmitter Antennas in PAPR Reduction Method Using Null Space in MIMO Channel for MIMO-OFDM Signals

Peak Cancellation Signal Generation Considering Variance in Signal Power among Transmitter Antennas in PAPR Reduction Method Using Null Space in MIMO Channel for MIMO-OFDM Signals

Simulation Design of a Triple Antenna Combination for PET‐MRI Imaging Compatible With 3, 7, and 11.74 T MRI Scanner

ABSTRACTThe use of electromagnetism and the design of antennas in the field of medical imaging have played important roles in clinical practice. Specifically, magnetic resonance imaging (MRI) utilizes transmission and reception antennas, or coils, that are tuned to specific frequencies depending on the strength of the main magnet. Clinical scanners operating at 3 Teslas (T) function at a frequency of 127 MHz, while research scanners at 7 T operate at 300 MHz. An 11.74 T scanner for human imaging, which is currently under development, will operate at a frequency of 500 MHz. MRI allows for the high‐definition scanning of biological tissues, making it a valuable tool for enhancing images acquired with positron emission tomography (PET). PET is an imaging modality used to evaluate the metabolism of organs or cancers. With recent advancements in the development of portable PET systems that can be integrated into any MRI scanner, we propose the design based on electromagnetic simulations of a triple‐tuned array of dipole antennas to operate at 127, 300, and 500 MHz. This array can be attached to the PET inset and used in 3, 7, or 11.74 T scanners.

Satellite Onboard Transmitter Design With Spread Spectrum MIMO Antenna for 5G Wireless Networks

AbstractThe 5G new era implements standalone satellite communications that support wireless networking systems for future mobile communications by locating multiple satellites in low Earth orbit to provide global coverage of the entire Earth's surface. In this research, a newly found model of a satellite onboard transmitter using a uniform circular array multiple‐input multiple‐output antenna was designed to operate at a carrier frequency of 12 GHz and derived theoretical equations compared to the real‐time scenario. The integration of spread spectrum with multiple‐input multiple‐output antenna provides an advantage for higher capacity. It has a higher percentage of gain amplification on improving the transmission of electromagnetic power to meet the bandwidth requirement of center operating frequency, and this can transmit over a bandwidth of 1.28 GHz. The proposed satellite onboard transmitter model design aims to minimize the components, increase the speed of operations for higher bandwidth, and transmit large amounts of information to a large group of users. The transmitter can operate for the speed of 1.28 Gbps using pseudo‐random code, direct‐sequence spread spectrum, quadrature phase shift keying modulation, bandwidth separated in bands for 64 symbols using 128 Chebyshev‐type bandpass filter for transmission using 128‐element uniform circular array multiple‐input multiple‐output antenna. The satellite transmitter antenna produces a maximum gain of 14.526 dBi, and a maximum directivity of 17.986 dBi, and the efficiency at 12 GHz is 45.1% for the radiated power at 0.93 mW. This satellite transmitter will interconnect 5G wireless networks for the application of mobile communications complement terrestrial‐dependent networks.

Astrosense – a Printed Wearalbe Electrochemical Sensor for Monitoring Cortisol in Sweat during Human Spaceflight

The In Space Manufacturing of sensors and electronics can directly addresses the logistic challenge for long-duration human spaceflight missions by reducing mission logistics mass, increase reliability, mitigate risk, while also offering a high degree of customization and tailorability. This manufacturing approach relies on additive manufacturing technologies, due to its versatility, low power consumption, automation, fast manufacturing time with low waste generation, and ability to print a variety of materials. To ensure the health and safety of crew members, developing human health portable diagnostic tools that can be manufactured during long duration missions is necessary to ensure that the crew members are monitored in real time so that countermeasures can be deployed as soon as possible. Here we report the development of Astrosense (Figure 1), a wearable wireless and fully printed platform that integrates several sensors, including, electrochemical sensor for the detection of cortisol in sweat, temperature, CO2 and humidity sensors, as well as, the required hardware required to control each individual sensor.Astrosense consists of two sections, a reusable, and a disposable section. The reusable section contains the CO2,temperature, humidity sensor, the potentiostat that controls the cortisol sensor and the printed antennas for data transmission. The cortisol sensor, sweat harvest component and printed batteries will be located on the disposable section of Astrosense, so that they can be easily replaced once the sensor is either saturated, degraded or when the batteries need to be replaced. The disposable section will interfase with the reusable section of Astrosense through several medical grade adhesives and pogo pins. This allows for the easy replacement of the cortisol sensor as well as mounting and dismounting of the device on the human skin. Figure 1

Joint Transmit and Receive Antenna Selection in MIMO-NOMA-Based Uplink Satellite Networks

Joint Transmit and Receive Antenna Selection in MIMO-NOMA-Based Uplink Satellite Networks

Synthesis and characterizations of silver nanoparticles-based conductive ink for high-frequency electronics

This work presents the synthesis and performance evaluation of silver nanoparticles (Ag NPs)-based ink for high-frequency applications. Through varying concentrations, ratios of precursors, and reducing agents, three inks having different NP sizes are made and transformed into patterns. Structural, optical, and morphological studies of as-prepared NP-based inks were carried out using different characterization tools. Finally, for feasibility verification, synthesized ink for printed electronics, a prototype fabrication of a micro-strip transmission line and inline patch antenna was made. The simulation was performed by CST Microwave Studio to optimize the parameters of the prototype antenna and transmission line. The optical microscope revealed smooth morphology of the antenna. The return loss of the fabricated transmission line and antenna analyzed by the Vector Network analyzer showed that the silver ink-based prototypes have good efficiency and low loss. Overall, the results highlight the remarkable performance of NPs towards printed radio frequency-based electronics.

Optimizing hybrid beamforming in millimeter‐wave massive multiple‐input multiple‐output systems: A gradient projection approach

AbstractMillimeter waves (mmWave) present an enticing opportunity for wireless communication due to their substantial bandwidth. However, mitigating signal losses within this spectrum necessitates employing numerous antennas for transmission and reception. In practical scenarios, dedicating individual RF chains to each antenna is often unfeasible. In response to this limitation, our research investigates a hybrid beamforming approach, seeking to optimize spectral efficiency through an alternating optimization (AO) technique. Our goal is to develop an algorithm that can be easily integrated into diverse hybrid beamforming configurations. On the other hand the pursuit of optimizing spectral efficiency while adhering to the constraints imposed by phase shifters results in a non‐convex problem. To confront this challenge, we employ a gradient descent framework combined with projection methods. We introduce the gradient prediction method (GPM), which leads to a closed‐form solution for projection. Simulations underscore that this hybrid beamforming structure can achieve the performance of a fully digital beamforming method when the number of RF chains is twice the total number of data streams, regardless of the number of antennas involved. Furthermore, we will conduct a comparative performance analysis of our proposed algorithm against other established benchmark algorithms to ascertain its superiority.

Beamforming of Transmit Antennas Using Grey Wolf Optimization and L2-Norm for Performance Enhancement of Beyond 5G Communications

Beamforming of Transmit Antennas Using Grey Wolf Optimization and L2-Norm for Performance Enhancement of Beyond 5G Communications

Transmit beampattern design for FDA-MIMO radar using complex manifold optimization

Frequency diverse array multiple-input multiple-output (FDA-MIMO) radar can produce time-stationary range-angle dependent beampattern. The problem with these beampatterns is the repeating lobes in the angle-range domain. Different methods are proposed to obtain better beampattern in terms of grating lobe and sidelobe suppression by using frequency offsets. However, these methods mostly choose the frequency offsets using an analytic expression and do not offer a control on the resulting range beampattern. In this paper, a new method for transmit beampattern design in range is presented. This method transfers the design problem into a tangential space and solves the problem using complex manifolds through an optimization procedure. The proposed approach considers amplitude tapering in the transmitter antenna elements and the practical instrumented range of the radar. Range beampattern constraints can be defined conveniently leading to an effective design process. Several simulations are done to show that the proposed method can significantly improve the beamwidth and sidelobe level in range patterns.

Efficient and Reliable Wireless Power Transfer Stent Rectenna System for Abdominal Aortic Aneurysm Surveillance

AbstractThis study presents an innovative wirelessly powered stent rectenna system for endovascular aneurysm repair (EVAR), targeting abdominal aortic aneurysm (AAA) treatment. The system includes an on‐body flexible transmitter (Tx) antenna and an in‐body rectifier‐integrated stent receiver (Rx) antenna, operating in the industrial, scientific, and medical (ISM) band of 868 MHz. The Rx stent antenna, made from a biocompatible nylon‐coated metallic wire, ensures mechanical stretchability, biocompatibility, and precise current distribution. The flexible Tx antenna is designed for wearable use. A miniaturized rectifier on flexible polyimide, coated with biocompatible polydimethylsiloxane, converts received power into DC energy. The EVAR stent system's performance is validated through measurements using a saline‐filled American Society for Testing and Materials (ASTM) phantom. Magnetic resonance imaging (MRI) compatibility studies using Sim4Life simulations assess potential heating and image artifacts, confirming the proposed stent's MRI suitability. Wireless power transfer experiments demonstrate reliable power delivery to the Rx in various real‐world scenarios, achieving a power transfer efficiency of 3.6% at 18 cm inside the phantom. The flexible rectifier shows a peak efficiency of 87% at 15 dBm input power. The proposed system's exceptional performance and efficiency highlight its potential for effectively wirelessly powering advanced AAA stents.

Architecting CubeSat constellations for messaging service, Part I

In today’s modern and globalized world, connectivity is a key factor for businesses, production facilities, sensor networks, and ordinary people. However, there are still populated areas which are not covered by ground-based telecommunications infrastructure. This is where telecommunication satellite constellations come in, as they can provide coverage to remote and uninhabited regions and fill existing connectivity gaps to ensure data transfer.LoRa is one of the technologies designed for data transmissions over long distances with low power consumption. Alongside with other technologies of the Low-Power Wide Area Network family, it is widely used for Internet of Things applications. LoRa chirp spread spectrum modulation is robust against the Doppler frequency shifts encountered in low earth orbits, and it has already been used in IoT satellite communications. Due to the low transmitted signal power, the achieved data rate is not high, making it a suitable technology for telecommunications payloads on CubeSat platforms for messaging services. As compared to existing traditional communication satellite systems, CubeSat constellations are low-cost and may offer an affordable connectivity service to developing regions.This study is divided in two parts. In Part I the demand model is built based on the population distribution not covered by cell towers. The LoRa link performance is analyzed, considering the impact of LoRa channel parameters variation, such as spreading factor and channel bandwidth, while satellite orbital height, transmission antenna beamwidth, and transmitter peak power have a direct impact on the payload mass. Among thousands of possible configurations, 73 feasible payload designs have been downselected. In Part II of the study, the satellite mass and the total system cost are estimated based on the payload parameters obtained. Messages transmission simulation via a constellation is conducted in order to identify optimal constellation architectures for messaging service, as well as the main drivers of the system economic profitability.The presented analysis results provide a deeper understanding of LoRa connectivity advantages and limitations together with the performance drivers, which will support the optimization of future LoRa-based satellite communication systems and other IoT satellite constellations.

Literature Review on Simulation and Measuring Techniques for Transmission Lines and Antennas

Literature Review on Simulation and Measuring Techniques for Transmission Lines and Antennas

Improving physical layer security in distributed multiple‐input multiple‐output dual‐function radar‐communication systems

AbstractA distributed multiple‐input multiple‐output (MIMO) dual‐function radar‐communication (D‐MIMO DFRC) system is composed of multiple distributed dual‐function transmitters, multiple radar receivers and multiple communication receivers, which is capable of performing communication and radar tasks simultaneously. In a DFRC system, the goal is on optimising both the sum ‐rate in communication receivers and detection/localisation performance in radar receivers. The secrecy rate is maximised in D‐MIMO DFRC systems by decreasing the eavesdropper data rate as much as possible with a two‐step antenna selection method while maintaining optimal radar performance. In the first step of the proposed method, all transmitter antennas have been classified into groups based on their distance from each other, and each group is called a cluster. Then, a cluster of distributed transmitter antennas is selected based on path fading effects. In the second step of this method, the antenna selection algorithm is performed in the pre‐selected cluster based on channel capacity information utilising QR decomposition. The results show that this antenna selection method, along with low computational complexity and high performance, leads to the maximisation of the secrecy rate. In DFRC systems, it is desirable to minimise the total transmit power while satisfying system requirements to provide low probability of interception (LPI). Finally, after antenna selection, a power allocation strategy is also applied on the selected antennas to optimise the total transmit power and to maximise throughput in communication radar receivers simultaneously, and as a result it leads to provide LPI.

Design and Optimization of a Mid-Field Wireless Power Transfer System for Enhanced Energy Transfer Efficiency

Mid-field wireless power transfer (WPT) offers a compelling solution for delivering power to miniature implantable medical devices deep within the human body. Despite its potential, the current power delivery levels remain constrained, and the design of a compact source structure to focus the transmitter field on such implants presents significant challenges. In this paper, a novel miniaturized transmitter antenna operating at 1.71 GHz is proposed. Leveraging the antenna proximity-coupled feeding technique, we achieve optimal current distribution for efficient power transfer. Additionally, a receiver integrated within the human body is proposed, comprising a slotted ground and a meandering slotted radiating element. This receiver is excited via a coaxial feedline with a truncated ground. Our findings demonstrate wireless power transfer of −23 dB (0.501%) at a distance of 30 mm between the transmitter and receiver, alongside a peak gain of −20 dB with an impedance bandwidth of 39.61%. These results highlight promising advancements in enhancing energy transfer efficiency for deep-implant applications.