Receiver Antenna Research Articles

3D Huygens Principle Based Microwave Imaging Through MammoWave Device: Validation Through Phantoms

This work focuses on developing a 3D microwave imaging (MWI) algorithm based on Huygens principle (HP). Specifically, a novel, fast MWI device (MammoWave) has been presented and exploited for its capabilities of extending image reconstruction from 2D to 3D. For this purpose, dedicated phantoms containing 3D structured inclusion have been prepared with mixtures having different dielectric properties. Phantom measurements have been performed at multiple planes along the z-axis by simultaneously changing the transmitter and receiver antenna height via the graphic user interface (GUI) integrated with MammoWave. We have recorded the complex S21 multi-quote data at multiple planes along the z-axis. The complex multidimensional raw data has been processed via an enhanced HP based image algorithm for 3D image reconstruction. This paper demonstrates the successful detection and 3D visualization of the inclusion with varying dimensions at multiple planes/cross-sections along the z-axis with a dimensional error lower than 7.5%. Moreover, the paper shows successful detection and 3D visualization of the inclusion in a skull-mimicking phantom having a cylindrically shaped inclusion, with the location of the detected inclusion in agreement with the experimental setup. Additionally, the localization of a 3D structured spherical inclusion has been shown in a more complex scenario using a 3-layer cylindrically shaped phantom, along with the corresponding 3D image reconstruction and visualization.

Outage Analysis of Coordinated NOMA Transmission for LEO Satellite Constellations

This work investigates the performance of a downlink non-orthogonal multiple access (NOMA) based coordinated low-earth orbit (LEO) satellite system. Two LEO satellites are assumed to coordinate their transmissions to serve three users simultaneously using NOMA protocol, where only one user lies in the intersection of the footprints of the two satellites. We investigate the reliability of the proposed architecture, which is expressed in terms of the outage probability (OP). We derive closed-form expressions of the users’ OPs taking into considerations different realistic losses effects on the link budget including receiver antenna gain, satellite antenna gain, antennas pointing errors, shadowing, small-scale fading, and large-scale free space path loss. The channels between satellites and the three users are assumed to follow shadowed-Rician (SR) fading. The mathematical analysis is verified by the extensive representative Monto-Carlo simulations. Finally, we demonstrate the impact of the system parameters on the considered system as well as the superiority of the NOMA scheme over conventional OMA system.

Data Transmission Over Linear Time-Varying Channels

Many traditional data transmission schemes over wireless communication channels heavily rely on the assumption that channel state information is available. However, for time-varying channels it is not possible to reliably decide the validity of the previously performed channel estimate. Therefore, message transmission methods taking the time-varying nature of the communication channel into account must perform both data transmission and channel estimation simultaneously. This paper proposes two data transmission schemes over linear time-varying wireless communication channels with a single transmit antenna. In the first case we consider a single antenna receiver and in the second scenario the receiver is equipped with an antenna array. Both schemes rely on sparsity assumptions.

Evaluation and Performance of Path Profile Characteristics in Communication System

This study presents the evaluation and performance of path profile characteristics in communication system, to determine the path profile characteristics such as margin fade (dB), receiver power (dBm), 2-ray propagation model (dB), free space propagation model (dB), LOSMAX (km) and critical distance (km). Data were obtained from Network ‘A’, using three different links within a geographical location in Edo State. Receiver power is mathematic model, the sensitivity of the receiver, which depends on the bandwidth (data rate) (dBm) of antennas were considered in this analysis. All the path profile characteristics were determined, it was observed, that increase in path length distance of microwave line of sight, will necessitate the increase in transmitter power in decibel. The Path length distance and margin fade of the three basic mobile propagation links were determined. It was observed that path length distance characteristic as such the length of distance, obstacle, reflection, diffraction from ground, water bodies and atmosphere resulted to the pattern of radio margin fade signal obtained in receiver antenna. The margin fade determined are 28.83 dB, 12.95 dB and 21.24 dB for the three different links considered from Network ‘A’ in Auchi, Nigeria.

Franklin Collinear Antenna 2 Levels Different Sides using Array Method 4 Stacking Units 360ᵒ with Integrated Reflector and Power Combiner for ADS-B S-Receiver Mode

In this study, an antenna system that could cover the 360ᵒ detection area using the microstrip method was created. The antenna design proposed uses the franklin collinear method with the addition of an array of arms to the left and right of the antenna and the addition of reflectors as a gain enhancer. The four antenna array units are combined using a power divider (combiner) as a unifying antenna. Antenna design with end fire radiation pattern cannot be used in receiving the ADS-B antenna system, because it works only in certain sectors with certain beamwidth, so it needs to be modified by adding an array of 4 units that make up 360◦ radiation of directional diagrams. The addition of the reflector is done by testing the optimum width. The most optimum width is obtained by the width of the side addition on the side of the antenna aperture cross section width of 80 mm. Based on the results of experiments that have been carried out for the design of receiver antennas for ADS-B applications that are required in the form of a radiation pattern in all directions using the reflector technique, the most appropriate gain increase is to use a phase difference for the antennas that are closest both left and right by 90o in ¼ λ conditions in the integration process using a 4 way power combiner. Response return loss at frequency 1.0752 GHz and 1.109 GHz is -15 dB, it means antenna has 33.8 MHz bandwidth with maximum response return loss at -23.22 dB and gain of 7.586 dBi, this antenna design is very suitable for use in the ADS-B application. Design and simulation at this antenna used CST software.

Statistical Beamforming Techniques for Power Domain NOMA System

Power-domain non-orthogonal multiple access (NOMA) assigns different power levels for near and far users in order to discriminate their signals by employing successive interference cancellation (SIC) at the near user. In this context, multiple-input-single-output NOMA (MISO-NOMA), where the base station (BS) is equipped with multiple antennas while each mobile user has a single antenna receiver, is shown to have a better overall performance by using the knowledge of instantaneous channel state information (CSI). However, this requires prior estimation of CSI using pilot transmission, which increases the transmission overhead. Moreover, its performance is severely degraded in the presence of CSI estimation errors. In this work, we provide statistical beamforming solutions for downlink power-domain NOMA that utilize only knowledge of statistical CSI, thus reducing the transmission overhead significantly. First, we derive the outage probabilities for both near and far users in the multi-user NOMA system without imposing strong assumptions, such as Gaussian or Chi-square distribution. This is done by employing the exact characterization of the ratio of indefinite quadratic form (IQF). Second, this work proposes two techniques to obtain the optimal solution for beam vectors which rely on the derived outage probabilities. Specifically, these two methods are based on (1) minimization of total beam power while constraining the outage probabilities to the QoS threshold, and (2) minimization of outage probabilities while constraining the total beam power. These proposed methods are non-convex function of beam vectors and, hence, are solved using numerical optimization via sequential quadratic programming (SQP). Since the proposed methods do not require pilot transmission for channel estimation, they inherit better spectral efficiency. Our results validate the theoretical findings and prove the supremacy of the proposed method.

Monostatic microwave ellipsometry for material characterization

We propose Microwave ellipsometry based on monostatic measurements in which the transmitter and receiver are located in the same location. The traditional ellipsometry technique is based on bi-static measurements in which the polarization state of the reflected wave from a sample is analyzed to estimate its electromagnetic properties. Initially, the ellipsometric methods had been applied in the optical spectrum since the wavelengths and the constituent atomic structure are comparable leading to the strong matter-wave interaction and polarization changes. Thanks to the recent advancements in metasurfaces, chiral sensing can now be potentially applied to characterize materials at the microwave frequencies in a compact laboratory environment. In this paper, we lay down the fundamentals of microwave monostatic elliposmetry method. We demonstrate the permittivity detection by a numerically simulated monostatic sensing set-up composed of L-shaped unit chiral unit cells etched on the dielectric sample and illuminated by a monochromatic linearly polarized electromagnetic source. We construct the Jones matrix to extract the polarization states from the reflection coefficients. The determination of the reflection coefficients is greatly simplified by using a cross-dipole antenna receiver which provides the ratio of the two corresponding orthogonal complex currents.

Si photonic crystal optical antenna serial array and frequency-modulated continuous-wave light detection and ranging action

Photonic crystal waveguide slow-light grating emits a free-space optical beam and steers it widely by changing the optical wavelength or waveguide refractive index. In the reverse process, returned light is coupled into the device again. We have proposed to use this optical transmission and reception antenna as a beam scanner for light detection and ranging (LiDAR). Ideally, a large-aperture antenna can narrow the transmission beam and enhance the reception efficiency. Actually, however, the transmission and reception performance is not scalable owing to waveguide loss even though the waveguide is simply lengthened. A serial array configuration in which the waveguide is divided into multiple antennas is effective for mitigating this problem. In this study, we fabricated such a device using Si photonics technology and obtained a small beam divergence of 0.02° at a telecom wavelength. Then, we observed the ranging operation by adding an optical setup of frequency-modulated continuous-wave (FMCW) LiDAR and confirmed that the divided antenna device improved the reception intensity by 12 dB. Moreover, we fabricated a FMCW LiDAR chip in which the serial array antennas were integrated in parallel with switch trees and Ge photodiodes and obtained point cloud images by two-dimensional beam scanning.

Imaging of Subwavelength Microstructures by Time Reversal and Neural Networks, From Synthetic to Laboratory-Controlled Data

Imaging of a subwavelength microstructure made of a periodic grid-like finite set of circular rods is carried out from transient scattered field data in different configurations of sources and receivers. The goal is to identify the position of possibly missing rods. Time reversal is confirmed as a cheap yet efficient first-order diagnostic method even in the demanding context of a subwavelength microstructure. Tools of deep learning, expected to be valid in general circumstances if data acquired in sufficient numbers, are in parallel developed to image the microstructure. To that effect, recurrent neural networks (RNN) and convolutional neural networks (CNN) are both used. Pros and cons of all approaches are illustrated by comprehensive simulations from synthetic data computed via a finite difference time domain method (FD-TD) software carefully tailored to the microstructure model and used also to make the networks learn the microstructures. The analysis is completed from examples of laboratory-controlled data acquired on a microstructure prototype set within a microwave anechoic chamber. These examples confirm the good promises of neural networks even with rather scarce data as exemplified in a forward scattering case—fixed source and receiver antennas face each other and the microstructure is rotated between them.

Digital Self-interference cancellation in the era of machine learning: A comprehensive review

In-band full-duplex (IBFD) transmission has been identified as a promising solution to improve spectral efficiency as compared to half-duplex (HD) systems. One of the major challenges of FD systems is to effectively manage the self-interference (SI) produced by the transmitter antenna to the local receiver antenna. In this survey paper, we first review and discuss the preliminaries related to SI cancellation (SIC). Furthermore, this survey presents the advancements to the date of digital SIC approaches and highlights the advantages and limitations of each approach. The survey also summarizes different hardware platforms used for SIC along with their key features. Additionally, we also survey and compare different FD techniques for their SIC performances. Finally, this paper identifies a variety of new research areas in the era of machine learning and deep learning for digital SIC.

Design of the New Wideband Vivaldi Feed for the HERA Radio-Telescope Phase II

This article presents the design of a new dual-polarized Vivaldi feed for the Hydrogen Epoch of Reionization Array (HERA) radio telescope. This wideband feed has been developed to replace the Phase I dipole feed and is used to illuminate a 14 m diameter dish. It aims to improve the science capabilities of HERA, by allowing it to characterize the redshifted 21 cm hydrogen signal from the Cosmic Dawn as well as from the Epoch of Reionization. This is achieved by increasing the bandwidth from 100–200 to 50–250 MHz, optimizing the time response of the antenna–receiver system and improving its sensitivity. This new Vivaldi feed is directly fed by a differential front-end module placed inside the circular cavity and connected to the back end via cables that pass in the middle of the tapered slot. We show that this particular configuration has minimal effects on the radiation pattern and the system response.

ENSURING THE STABILITY OF A GNSS–STATION

Receiving antennas of GNSS–stations are placed on buildings, special pedestals, the foundations of which are often located in the zone of significant soil deformations under the influence of variations in hydrothermal factors. This can distort the obtained results of monitoring the earth's surface and call into question the reliability of their interpretation. Depending on the characteristic conditions of the device of the base station of the global navigation satellite system, on the design solutions and the functional purpose of the buildings that are the bases for the location, appropriate decisions are made on the location of the GNSS station.
 The system of operation of the elements of the equipment of the base station of the global navigation satellite system, the design features of the receiving antennas, their attachment to building structures have been investigated. The preferential conditions for choosing a place for the installation and operation of the receiving antenna of a GNSS–station are indicated, groups of places for installing receiving antennas on the supporting parts of the roofs of buildings are highlighted. The efficiency of using GNSS–stations as a set of methodological, technical and organizational principles of activity in the global positioning system is considered.
 The components of the system for examining the external structures of buildings and structures are highlighted: a subsystem of structural solutions for building objects, the organization of examination of external structures, external factors of hydrothermal origin, a subsystem of design solutions for the operation of a GNSS–station, a subsystem for organizing installation and connection. An assessment of the main characteristics of the design solutions for the operation of a GNSS–station was carried out, in particular, the selection of structural elements of buildings and structures for installing the station antennas, the determination and processing of the coordinates of points.

Performance evaluation of a typical low-cost multi-frequency multi-GNSS device for positioning and navigation in agriculture – Part 1: Static testing

This paper evaluates and compares the static performance of low-cost and legacy geodetic multi-frequency multi-GNSS positioning device (PD) in terms of the GNSS signal strength, RTK (Real-Time-Kinematic) availability and positioning accuracy, and time to first fix (RTK-TTFF/TTRF), which were measured for short and medium baselines (SBL and MBL) with different receiver resets and GNSS signal obstructions. The evaluation results indicated that the low-cost PDs, which were combined from a single u-blox ZED-F9P receiver and multiple low-cost GNSS antennas, performed at almost the same accuracy level of the legacy PDs and were superior in term of the RTK-TTFF/TTRF performance. The low-cost PDs could track satellites of four GNSS constellations with high signal strength of about 50dB-Hz resulting in almost full-time availability of RTK-fixed solution, and millimeter-level and centimeter-level accuracy of the horizontal positioning for the SBL and MBL, respectively. Furthermore, the low-cost PDs could acquire and reacquire RTK-fixed mode in less than 12 seconds and 4 second, respectively, and hold for any significant time in static applications.

Third-order Volterra MMSE receivers for enhanced single and multiple antenna interference cancellation

Data-like interference mitigation in wireless communications systems, and in mobile cellular networks in particular, has always been a challenging problem which is becoming even more so for 5G networks and beyond including the Internet of things (IoT), to support a massive number of low data rate devices for given spectral resources. A promising solution to this problem consists in using one dimensional signaling (i.e., real-valued modulations) jointly with widely linear (WL) processing at the receiver, which has the capability to process up to 2N−1 data-like interference from N antenna receivers, and to fulfill, for N=1, single antenna interference cancellation (SAIC) of a one-dimensional interference in particular. However, when the signal of interest (SOI) and observations are jointly non-Gaussian, which is the case for most of digital radiocommunications systems, WL receivers become sub-optimal and optimal receivers become non-linear. It is then of interest to propose new non-linear receivers to improve performance of WL receivers. In this context, the paper aims at introducing, for small-scale systems, third-order complex Volterra (CV) minimum mean square error (MMSE) receivers, for the reception of a digital linearly modulated SOI whose waveform is known, corrupted by potentially non-Gaussian and non-circular interference, omnipresent in practical situations. Properties, performance and adaptive implementation of these receivers in the presence of non-Gaussian and potentially non-circular interference up to the 6th-order are analyzed in this paper. In particular, some of these receivers are shown to enhance WL receiver performance for SAIC of one rectilinear interference such as binary phase-shift keying (BPSK) interference. Whereas some other receivers allow us to fulfill SAIC of 4th-order non-circular interference such as quadrature phase-shift keying (QPSK) interference, which is not possible using WL receivers. These new receivers open new perspectives for cancellation of non-Gaussian and potentially non-circular interference up to 6th-order in radiocommunication networks.

Anin‐band full‐duplexantenna fordual‐bandapplication

AbstractA dual‐band, dual‐polarized in‐band full‐duplex antenna with good isolation performance is presented for wireless local area network (WLAN) applications. A neutralization line is connected between the grounds of the transmitter (Tx) and receiver (Rx) antennas to enhance the isolation. Further enhancement in isolation is achieved by using a 180° ring hybrid coupler between receiving antenna elements. Here the dual‐band monopole antennas are used as transmitting and receiving antenna elements. For better isolation, the receiving antenna elements are placed opposite to each other and fed through the differential ports of the 180° ring hybrid coupler. The proposed structure is fabricated, and the comparison of measured results and simulated results are studied. The simulated and measured impedance bandwidths (≤−10 dB) of the antenna cover the entire 2.4 GHz WLAN band (2.4–2.48 GHz), and for this band, the measured isolation is better than 40 dB. For the higher band, the measured isolation is more than 40 dB for 200 MHz (5.15–5.35 GHz) of bandwidth. The simulated radiation patterns of the antenna are well‐matched with the measured patterns at both the frequencies.

Sentinel-6A precise orbit determination using a combined GPS/Galileo receiver

The Sentinel-6 (or Jason-CS) altimetry mission provides a long-term extension of the Topex and Jason-1/2/3 missions for ocean surface topography monitoring. Analysis of altimeter data relies on highly-accurate knowledge of the orbital position and requires radial RMS orbit errors of less than 1.5 cm. For precise orbit determination (POD), the Sentinel-6A spacecraft is equipped with a dual-constellation GNSS receiver. We present the results of Sentinel-6A POD solutions for the first 6 months since launch and demonstrate a 1-cm consistency of ambiguity-fixed GPS-only and Galileo-only solutions with the dual-constellation product. A similar performance (1.3 cm 3D RMS) is achieved in the comparison of kinematic and reduced-dynamic orbits. While Galileo measurements exhibit 30–50% smaller RMS errors than those of GPS, the POD benefits most from the availability of an increased number of satellites in the combined dual-frequency solution. Considering obvious uncertainties in the pre-mission calibration of the GNSS receiver antenna, an independent inflight calibration of the phase centers for GPS and Galileo signal frequencies is required. As such, Galileo observations cannot provide independent scale information and the estimated orbital height is ultimately driven by the employed forces models and knowledge of the center-of-mass location within the spacecraft. Using satellite laser ranging (SLR) from selected high-performance stations, a better than 1 cm RMS consistency of SLR normal points with the GNSS-based orbits is obtained, which further improves to 6 mm RMS when adjusting site-specific corrections to station positions and ranging biases. For the radial orbit component, a bias of less than 1 mm is found from the SLR analysis relative to the mean height of 13 high-performance SLR stations. Overall, the reduced-dynamic orbit determination based on GPS and Galileo tracking is considered to readily meet the altimetry-related Sentinel-6 mission needs for RMS height errors of less than 1.5 cm.

Optimization of Spectral Efficiency in Massive MIMO Network for Different Deployment Scenarios

Background: Spectrum efficiency is labelled to be the most discussed area of wireless communication. Today, wireless communication is one of the fastest developing fields due to which there is a tremendous increase in subscribers that leads to the demand for more spectrum. Though the growth in the spectrum is not possible but optimizing it is a good alternative. Methods: This paper provides a detailed study of different methods used for the optimization of spectrum efficiency in massive multiple inputs and outputs. The main goal of this paper is to findout how the spectrum could be used efficiently to meet user demands. It includes the technique of fixing specific parameters like coherent block length, number of reception antennas, pilots reuse factor, signal to noise ratio, and number of users to make more efficient use of the spectrum. This paper also explains the achievement of spectral efficiency under different deployment scenarios i.e., urban, suburban, and rural in ITU-R M.2135 standard. Results: As seen from the results, steep SEs are accomplished by making a schedule of many UE for mutual broadcast, while the SE per UE maybe 1-4 bit/s/Hz. These high-class demonstrations show that massive MIMO e.g an SNR of 0-5 dB with a limited pilot reuse factor of β= 3, and the fast techniques are applied for lessening the distortion noise and instrument damage. According to the simulations, it is found that massive MIMO with M = 100 can produce a 10×gain in SE in the IMT-Advanced requirements of 3 bit/s/Hz/cell. For the bigger sizes of antennas, M = 500 massive MIMO can even give 40×gain over IMT-Advanced. Conclusion: With the advancement of technology, the number of users is increasing tremendously, leading to a shortage of spectrum. Hence, the need of the hour is to make efficient use of the available spectrum while maintaining the Quality of service. Therefore, researchers have proposed specific methods that fulfill this need. The paper realizes the SE approach on different deployment scenarios like urban, suburban and rural in the ITU-R M.2135 standard and proves that under all the three scenarios, P-ZF remained unchanged. As seen from the results, steep SEs are accomplished by making a schedule of many UE for mutual broadcast, while the SE per UE maybe 1-4 bit/s/Hz. These high-class demonstrations show that massive MIMO likes an SNR of 0–5 dB with a limited pilot reuse factor of β= 3, and the fast techniques are applied for lessening the distortion noise from instrument damage. According to the simulations, it is seen that massive MIMO with M = 100 can produce a 10×gain in SE in the IMT-Advanced requirements of 3 bit/s/Hz/cell. For the bigger sizes of antennas, M = 500 massive MIMO can even give 40×gain over IMT-Advanced. The outcomes in this paper suggest the uncorrelated fading, although for decreasing inter-user interference, correlated fading is required, to raise large SE with less β. This study makes SE independent of topography. Furthermore, optimization of energy under different deployment scenarios, along with these simulations, can optimize the spectrum to a greater extent.

Numerous Factors Affecting Performance of NOMA for Massive Machine Type Communications in B5G Systems

Massive machine type communications (mMTC) are one of the critical requirements for beyond fifth generation (B5G) communication systems. Services for a huge number of user terminals should be provided simultaneously due to the explosive development of mMTC. It is proved that non-orthogonal multiple access (NOMA) is effective in satisfying such a requirement. In this paper we evaluate the impacts of numerous factors, such as channel encoding, channel decoding, repetition number, multi-user detector, and number of receiver antennas, on the performance of NOMA. It is surprised to find that some conclusions drawn from orthogonal multiple access system may do not hold anymore for NOMA systems. The factors which have significant impact on the performance of NOMA should be paid more attention to in the system design. The analysis and evaluation results shine more light on how to design an effect NOMA scheme by considering both transmitter and receiver to fulfill the requirements of mMTC for B5G systems.

Fast and Cost-Effective Three-Dimensional Microwave Imaging Using a Cylindrical Setup

In this paper, we propose a fast and low-cost cylindrical microwave imaging system based on the use of arrays of transmitter and receiver antennas and a customized low-cost data acquisition circuit using off-the-shelf components. The complex-valued scattered data captured with the proposed system is processed using near-field holographic image reconstruction. To enhance this technique, standardized minimum norm (SMN) approach is employed to solve the relevant systems of equations. The performance of the proposed imaging technique and the data acquisition system is demonstrated via simulations and experiments.

Joint spectrum sensing and DOA estimation with sub-Nyquist sampling

This paper addresses the problem of joint spectrum sensing and Direction-of-Arrival (DOA) estimation under array receiver based on modulated wideband converter (MWC) with sub-Nyquist sampling. To simplify the structure of MWC, we connect one identical branch of MWC on each antenna of array receiver, reducing the overhead of hardware resources. Two joint spectrum sensing and DOA estimation (JSS-DOA) algorithms, referred to as CP- and MUSIC-based algorithms, are proposed to improve the robustness of estimation. The proposed approaches utilize Fourier series coefficients of a periodic signal provided by MWC to determine the subband positions where sources are located, and combine the recovered subband spectrum information to obtain estimates of frequencies. This strategy ensures robust frequency estimation accuracy under certain conditions and contributes to a robust DOA estimation under high noise level. We further provide a theoretical analysis of the working conditions for proposed algorithms, based on which the rationale of parameter setting is also reported. Finally, the performance of proposed algorithms is assessed via simulation experiments concerning multiple unknown sources under our receiver with sub-Nyquist sampling.