Antenna Configuration Research Articles

A detailed insight of 2 × 2 high isolation wideband dual notched band MIMO antenna with evolution initiated by theory of characteristics mode

AbstractThis research investigates the MIMO antenna by using the Theory of Characteristics Mode (TCM) where 10 modes are subjected in designing. Also, 5 modes are the significant mode and 2 modes correspond to non-significant which defines the operating bandwidth and notched bands. The proposed 2 × 2 MIMO antenna configuration is designed for wideband applications with a size of 0.44 × 0.68 mm2. The two isolated 12-sided polygons radiating patches placed adjacent to each other share a common ground which is printed on an FR4 substrate. The measured impedance bandwidth covers bandwidth 3.11–11.98 GHz with two bands rejecting capability: Wireless Local Area Network (WLAN) and Downlink-Uplink Satellite (DUS) system. These two interfering bands are mitigated by etching a C-type slot on the radiating patch and an inverted U-type slot in the microstrip feed. The simulated and measured results are also compared in the far-field region (Normalized Radiation Efficiency (NRE), Peak Gain (PG), and 2-D/3-D radiation pattern). Proposed MIMO antenna also offers good diversity performance with ECC2×2 < 0.00001, DG2×2 > 9.999 dB, TARC2×2 < −15.0 dB, CCL2×2 < 0.001 b/s/Hz and MEG2×2 ≅ −3.0 dB.

Millimeter-Wave Broadband MIMO Antenna Using Metasurfaces for 5G Cellular Networks

Developing a millimeter-wave (mm-wave) antenna that enables wide bandwidth with its operating band covering the entire global 5G spectrum is highly desirable but very challenging for achieving both compact size and high-performance antenna. Herein, the mm-wave microstrip patch antenna (MPA) and its multiple-input multiple-output (MIMO) configuration based on the metasurfaces for 5G system applications are proposed and investigated by the simulation method. To improve performance and keep the low-profile and low-cost MPA antenna, square ring resonator (SQRR) metasurface and radiating patch are printed on a single dielectric layer. With the presence of the metasurfaces that acting as a secondary radiator, the performance of the designed antenna is significantly improved with a wide operating band in the range of 23.9-30.7 GHz, high peak gain of 9.4 dBic, and radiation efficiency of above 87%. Based on this design, four-port MIMO antenna configuration is performed for evaluating a MIMO system that realizes the advantage features such as compact size, wide bandwidth covering the entire global mm-wave 5G spectrum band of 24.25-29.5 GHz, and excellent diversity performance characterized by good isolation between the adjacent elements and low envelope correlation coefficient. Thus, the MIMO antenna design is a very promising candidate for 5G MIMO mm-wave applications, specifically in cellular systems.

Radio-Frequency Near-Field Sensor Design for Minuscule Internal Motion

We present the improved design of a radio-frequency (RF) near-field sensor for minuscule internal motion inside structures and small animals. The design tradeoffs of the antenna placement and transceiver configuration are explored experimentally by a structural setup of the fluid stirrer. The sensor performance is benchmarked in various antenna configurations and quadrature baseband sampling settings. An optimized antenna pair holder design is then applied to a continuous touchless recording for the respiration and heartbeat of nestling and adult tree swallows noninvasively. Furthermore, we also built a low-power portable all-in-one RF sensor printed circuit board (PCB) using the system parameters from previous experiments. A 40-min experiment on a conscious and free-to-move 13-day-old nestling tree swallow for respiration monitoring was successfully conducted.

Index modulation aided generalized space-time block coding: A unified MIMO framework

In this paper, Index Modulation (IM) aided Generalized Space-Time Block Coding (GSTBC) is proposed, which intrinsically exploits the benefits of IM concept, diversity gain and spatial multiplexing gain. Specifically, the information bits are partitioned into U groups, with each being modulated by IM symbols (i.e. Spatial Modulation (SM), Quadrature SM (QSM),etc). Next, the structure of GSTBC is invoked for each K IM symbol, and a total of μ = U/K GSTBC codes are transmitted via T time slots. A Block Expectation Propagation (B-EP) detector is designed for the proposed IM-GSTBC structure. Moreover, the theoretical Average Bit Error Probability (ABEP) is derived for our IM-GSTBC system, which is confirmed by the simulation results and helpful for performance evaluation. Simulation results show that our proposed IM-GSTBC system is capable of striking an efficient trade-off between spatial multiplexing gain, spatial diversity gain as well as implementation cost imposed for both small-scale and large-scale MIMO antenna configurations.

Spectral Efficient Modem Design With OTFS Modulation for Vehicular-IoT System

A 5G network’s use-case in the Internet of Things (IoT) is a breakthrough, offering networks the ability to handle billions of connected devices with the proper blend of speed, latency, and cost. The IoT networks implemented in high-speed scenarios like intra and intervehicular communications in autonomous driving vehicles, high-speed vehicles, and trains will experience a Doppler effect. Orthogonal frequency-division multiplexing, the popular transmission technology for existing new-radio IoT (NR-IoT), is limited in providing reliable connections in high-speed vehicular scenarios. The performance of such system degrades with higher-order antenna configuration due to the lack of channel state information in highly mobile environments. The recently proposed orthogonal time-frequency space (OTFS) modulation is a strong contender that can handle high mobility but requires efficient transceiver design to be deployed in vehicular NR-IoT (V-IoT) systems. To conserve the resources and minimize the air time of the devices, we have proposed an embedded pilot design in the Delay–Doppler domain for the V-IoT systems. In the designed frame structure, the pilot’s position is optimized as per the vehicle speed to maximize the spectral efficiency of the system. The increase in spectral efficiency is at the cost of interference in the channel search region of the received Delay–Doppler domain OTFS signal. So a new joint estimator and the low-complex detector are proposed to handle the interference. The proposed efficient transceiver design with the spectral efficient pilot patterns allows us to conserve resources and remove complex encoder–decoders like the low-density parity check in NR-IoT.

Orientation Sensing With a Loop Resonator Based on Its Re-Radiation Pattern

This article presents an analytical model of the radiation pattern of a loop resonator, which is frequently used as chipless radio-frequency iDentification (RFID) tags. The radiation pattern of this resonator can be used in practice as a sensor to determine the orientation between the tag and the antenna. Contrary to already implemented chipless RFID angle sensors, the one introduced here allows to extract rotation of the tag or the antenna position in 3-D using a novel approach based on the resonator radiation pattern. An analytical model is developed to measure the tag orientation determining both the inclination and azimuthal angle of the tag in a spherical coordinates system for both monostatic and bistatic antenna configurations. Uncertainties are studied with Monte Carlo simulations. Simulations and measurements are performed to validate the orientation extraction and evaluate the performance of the proposed solution. We show that the accuracy of this totally passive and wireless sensor is always below 5° in the measurable range with a maximum error lower than 3° for the monostatic case.

Analysis of Facet-Loaded Rectangular DR-Rectenna Designs for Multisource RF Energy-Harvesting Applications

In this article, the characteristics of four spiral-facet structures are studied for RF energy-harvesting (RFEH) applications for increasing the harvesting power from the surrounding atmosphere. A rectangular dielectric resonance antenna (RDRA) is selected and placed above an FR4-epoxy substrate. Metallic rectangular spirals are then placed on the dielectric resonator (DR) surface to create resonances with insensitive polarization characteristics. The proposed spirals help provide wideband/multiband characteristics at 4.85, 5.0, 5.5, 5.8, and 6.25 GHz that covers 5G 4.9, WLAN 5.0, WLAN 5.5, Wi-Fi 5.8, and Wi-Fi 6E bands, respectively. The minimum gain achieved is 5 dBi in all possible configurations. A broadband rectifier circuit (4.67–7.0 GHz) with a staircase multistage transmission line matching network (MN) covering all resonant frequencies in various facet-loaded antenna configurations is proposed for RF-to-dc conversion purposes. The rectifier’s maximum power conversion efficiency (PCE) is achieved as 77.3% at a 13.5 dBm input power level, and the corresponding output voltage is 4.92 V.

A General 3-D Nonstationary GBSM for Underground Vehicular Channels

Reliable and efficient communications are indispensable for vehicles in underground environments. Underground wireless channels present a number of unique properties, such as guided propagation, rich scatterers, and near-field/far-field effect. In this article, a 3-D twin cluster geometry-based stochastic model (GBSM) is proposed to describe underground vehicular channel characteristics in both pillar and tunnel scenarios. The proposed model supports arbitrary trajectory mobility of vehicles and multiple antenna configurations at the transmitter (Tx) and the receiver (Rx). The cluster time evolution is modeled by different scatterer generation and updating methods to simulate the channel characteristics such as nonstationarity, near-field/far-field differences, and waveguide effects. Based on the proposed channel model, the statistical characteristics of the channel are derived and simulated, including the temporal autocorrelation function (ACF), spatial cross-correlation function (CCF), delay power spectrum density (PSD), Doppler PSD, and so on. Besides, underground channel measurements at 2.5/3.5 GHz are conducted in a garage scenario. Comparison results of channel measurements and simulations validate the accuracy and usefulness of the proposed GBSM.

Extracting mud invasion information using borehole radar — A numerical study

In hydrocarbon drilling, mud filtrate penetrates permeable formations and alters the pore fluid characteristics in the immediate vicinity of the borehole. Typically, the prevailing in situ pore fluids are displaced by the invading mud filtrate, which leads to gradually changing distributions of the fluid and electrical properties. Understanding this invasion process is crucial for the interpretation of logging data and associated reservoir evaluations. Conventional logging methods tend to be inadequate for this purpose as their resolution is too low. We find that invasion depth can be determined from borehole radar data using an optimized antenna configuration and time-lapse measurements. A series of parametric sensitivity analyses provide information about the effects of variations of the rock and fluid properties on the identification and extraction of borehole radar signals reflected from the invasion front. Our results suggest that by embedding the radar antennas in cavities filled with an absorbing dielectric material, it is possible to minimize the interference arising from the metal components of the logging tool. In the simulated reservoir scenario, a time-lapse measurement mode with a time interval of at least 6 h can reliably extract the radar signals reflected from the invasion front, and the proposed borehole radar has a lateral detection range from 0.15 to 1 m. A comprehensive range of parametric sensitivity analyses indicates that the signals reflected from the invasion front are principally influenced by oil viscosity, porosity, and mud and formation water salinity, as well as by molecular diffusion coefficient and cementation exponent. These properties and parameters should be carefully explored and assessed when applying borehole radar to evaluate mud invasion information in a reservoir environment.

A Shorted Stub Loaded UWB Flexible Antenna for Small IoT Devices.

In this manuscript, a compact in size yet geometrically simple Ultra-Wideband (UWB) antenna is demonstrated. The flexible-by-nature substrate ROGERS 5880, having a thickness of 0.254 mm, is utilized to design the proposed work. The antenna configuration is an excerpt of a traditional rectangular monopole antenna resonating at 5 GHz. Initially, a pair of triangular slots are employed to extend the impedance bandwidth of the antenna. In addition, a semi-circular-shaped, short-ended stub is connected at the upper edges of the patch to further increase the operational bandwidth. After optimization, the proposed antenna offers UWB ranging from 2.73-9.68 GHz, covering almost the entire spectrum allocated globally for UWB applications. Further, the antenna offers a compact size of 15 × 20 mm2 that can easily be integrated into small, flexible electronics. The flexibility analysis is done by bending the antenna on both the x and y axes. The antenna offers performance stability in terms of return loss, radiation pattern, and gain for both conformal and non-conformal conditions. Furthermore, the strong comparison between simulated and measured results for both rigid and bent cases of the antenna, along with the performance comparison with the state-of-the-art, makes it a potential candidate for present and future compact-sized flexible devices.

Wideband Dual-Polarized Octagonal Cavity-Backed Antenna with Low Cross-Polarization and High Aperture Efficiency

Simultaneously enhancing multiple antenna performance parameters is a demanding task, especially with a challenging set of design goals. In this paper, by carefully deriving a compatible set of enhancement techniques, we propose a compact/lightweight/low-cost high-performance L-band octagonal cavity-backed hybrid antenna with multiple attractive features: dual-polarization, wide impedance bandwidth, low cross-polarization, high gain, and high aperture efficiency. The ground cavity is octagonal, which allows the antenna to have a small footprint, and, more importantly, low cross-polarization and high aperture efficiencies when compared to a commonly-used square design. The hybrid design relies on the resonance merging of two radiating elements, i.e., radiating feedlines and a conductive open prism, to form a wide impedance bandwidth. To permit polarization diversity and low cross-polarization, it is differentially and orthogonally fed. Herein, a series of parametric simulation studies on antenna configurations provide information on how to improve the impedance bandwidth and cross-polarization performance. To verify the simulation studies, an antenna prototype was fabricated and tested. Excellent agreement between the simulated and measured results was reached.

Quad-band Compact MIMO Antennas for 5G Mobile Communications

Three types of quad-band millimetric-wave two-port MIMO antenna systems are proposed for the forthcoming generations of mobile handsets. A novel printed antenna is introduced to be the single element of the proposed MIMO antennas. It is shown that the proposed MIMO antennas are capable of producing both spatial and polarization diversities that enhance the performance of mobile communications. Two configurations of co-polarized two-port MIMO antennas are proposed to provide spatial diversity, whereas a cross-polarized two-port MIMO antenna is proposed to produce polarization diversity. It is shown that all the proposed MIMO antennas can operate efficiently over the four frequency bands centered at 28, 43, 52, and 57 GHz. Prototypes are fabricated for the proposed MIMO antennas for the sake of experimental evaluation. The measurements agree with the simulation results showing high performance of the proposed types of MIMO antennas including the impedance matching, radiation patterns, envelop correlation coefficient, and diversity gain. Both the experimental and simulation results show that the achieved bandwidths, at the four operational frequency bands, are 0.6, 0.6, 1.8, and 1.5 GHz, respectively. Also, the radiation efficiencies calculated at the four operational frequencies are 86.5%, 87.5%, 89.2%, and 90.0%, respectively. The dimensions and the results concerning the performance of the proposed MIMO antennas are compared to other designs for MIMO antennas available in some recently published work.

On the Application of Orthogonality Sampling Method for Object Detection in Microwave Imaging

We consider a further development of the orthogonality sampling method (OSM) for a fast localization of small object in microwave imaging (MI). In contrast to the scenarios considered in traditional approaches, if the location of the transmitter and the receiver is the same, it is very hard to measure the scattering parameter data or to distinguish the weak scattered signal from the relatively high antenna reflection. Here, we set the unknown measurement data as a constant and design an indicator function for the OSM. To demonstrate the applicability of the OSM and its dependence on the constant, we show that the designed indicator function can be represented in terms of an infinite series of the Bessel functions of integer order, antenna configuration, and applied constant. To improve the imaging performance for a proper identification of the object, we design a new indicator function of the OSM with multiple sources, rigorously explore its mathematical structure, and discover some properties including the improvement and uniqueness. Simulation results with synthetic and real data are exhibited to support the theoretical results and to illustrate the pros and cons of the designed OSM.

T-SLOT RECONFIGURABLE MICRO-STRIP PATCH ANTENNA WITH CAPACITIVE LOADING TECHNIQUE FOR WIMAX AND S-BAND APPLICATION

A lightweight, reconfigurable frequency T-slot S-band antenna (2.01 GHz) and WiMAX (3.5 GHz) implementations are suggested in this document. The T-slot is inserted into the center of the square micro-strip patch antenna. In the T-slot antenna, a 10 pF capacitor is used with the help of the capacitor frequency and a configurable antenna is obtained. This design has an advantage of size reduction up to 70.50% for the resonant frequency compared to a conventional square patch antenna. HFSS software is used for design and simulation of the proposed antenna.

New Self-Isolated Wideband MIMO Antenna System for 5G mm-Wave Applications Using Slot Characteristics

This paper proposes a simple novel technique for self-isolating a MIMO antenna for mm-wave applications. MIMO antenna elements with inter-element separation of 0.2 mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.023\lambda $ </tex-math></inline-formula> at 35 GHz) and measured high isolation (>50 dB) are presented. By observing the concentration of surface waves on the radiating patch, several rigorously optimized slots of different shapes, positions, and dimensions are etched on the patch to enhance the inter-element isolation and increase the bandwidth within 28-37.5 GHz. The circuit models of the reference and proposed antennas have been presented. The coupling is measured by the level of the differences in the output voltage in both antennas. The novel mm-wave antenna exhibits high impedance bandwidth (>29%), high isolation (>50 dB), high efficiency (>90%), and low envelope correlation coefficient (< 0.005). Two configurations of MIMO antenna (i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 2$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 4$ </tex-math></inline-formula> ) are fabricated and measured to validate the simulation outcomes. The single reference antenna has dimensions of 10x12 mm 2 while the 1x2 array has dimensions of 19x12 mm 2. The presented design is the first to exhibit such wideband isolation improvement without any external decoupling structure at the mm-wave frequency range, to the best of the authors’ knowledge.

Recovering the Elusive Spectral Width From Spaceborne Doppler Profiling Radar Measurements: The “ExpliSyT” Approach

This article presents a novel method to retrieve spectral widths from measurements of spaceborne Doppler profiling radars operating in low-Earth orbit. The proposed “ExpliSyT” approach, is based on a formulation of the Doppler broadening in terms of the distributions of reflectivity and velocity in the footprint. This formulation makes it possible to estimate the broadening and remove it from the spectral-width measurement. Two implementations of the ExpliSyT correction are described: 1) a numerical implementation that uses Wiener’s deconvolution, and 2) an analytical implementation based on Taylor expansions of the radar observations. The ExpliSyT corrections enable retrievals of higher-order Doppler information such as posterior power spectra. Results are shown for simulations of the radar of EarthCARE (Earth Cloud Aerosol Radiation Explorer developed by the European and Japanese space agencies) and a Displaced Phase Center Antenna (DPCA) configuration, for which the ExpliSyT corrections perform significantly better. A novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">canonical Doppler resampling diagram</i> is introduced to explain the correlation between non-uniform beamfilling (NUBF) and spectral broadening. This tool shows that 1) the NUBF of reflectivity modulates the spacecraft-induced spectral broadening, and 2) the NUBF of velocity can either broaden or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">shrink</i> the Doppler spectrum. This spectral shrinkage, although important, is not typically thought of when dealing with spaceborne Doppler radars. The ability to estimate spectral widths accurately from space paves the way for future microphysical and dynamical characterizations of hydrometeors in shear or turbulence.

A low profile dual band dual C - shaped monopole antenna for Wi-Fi, WiMAX and WLAN applications

This article presents a low-profile dual-band, dual C-shaped monopole antenna designed for Wi-Fi, WiMAX, and WLAN applications. The simulated results demonstrate that the proposed antenna achieves a 10 dB return loss and an impedance bandwidth ranging from 2.3–3.0/2.5 GHz and 4.1–6.0/5.1 GHz. The antenna configuration consists of two Cshaped branches, one inverted to the other, along with a ground plane. This design enables the antenna to generate two resonant frequencies while maintaining good radiation patterns and gain characteristics. Simulations were conducted on an FR-4 Epoxy substrate, resulting in a compact, low-profile size of 38×26×0.8 mm3. The obtained impedance bandwidth is 28% for the 2.5 GHz frequency range and 37.25% for the 5.1 GHz frequency range. Additionally, the simulated gain is reported as 3.5 dBi for 2.5 GHz and 3.0 dBi for 5.1 GHz. The proposed antenna offers a compact size, dual-band operation, wide impedance bandwidths, and reasonable gain levels, making it well-suited for Wi-Fi, WiMAX, and WLAN applications. Its design ensures efficient performance, allowing reliable wireless communication in the desired frequency bands. With its small form factor, the antenna can be easily integrated into various devices while maintaining excellent radiation patterns and achieving the desired impedance matching. Overall, the proposed antenna presents a promising solution for dual-band applications in the wireless communication industry.

Analysis of Antenna Locations (Roof, Fender, and Bumper) at 28 GHz in a Suburban Environment for V2I using SISO and MIMO Antenna Configurations

Analysis of Antenna Locations (Roof, Fender, and Bumper) at 28 GHz in a Suburban Environment for V2I using SISO and MIMO Antenna Configurations

A Novel Design for Dual-Band Wearable Textile Eighth-Mode SIW Antennas

A novel wearable textile dual-band antenna configuration based on a substrate integrated waveguide (SIW) cavity is presented. The miniaturization of the antenna is achieved by exploiting the magnetic field symmetry of a square SIW cavity, reducing its size to 1/8 of the full square cavity with an eighth-mode SIW configuration. This solution is applied to the design of a wearable dual-band antenna for Long Range (LoRa) applications. The antenna operating frequency covers both the UHF LoRa bands, the European (863-870 MHz) and the North American (902-928 MHz). The proposed design provides a low-cost and compact antenna, which is easy to fabricate and ensures a very good isolation and robustness with respect to the human body proximity. The commercial software CST Studio Suite has been used for the antenna design and simulations. A prototype has been fabricated and the measured results are in good agreement with numerical simulations.

Acoustic source localization based on acoustic leaky-wave antenna with heterogeneous structure.

In this study, an acoustic leaky-wave antenna (LWA) with heterogeneous structure is proposed and the functions of the spatial directional radiation and acoustic source localization are achieved via utilizing the presented antenna configuration. In the radiating mode, the designed antenna possesses peculiar frequency-scanning characteristics, which enable it to determine the directional radiation of sound waves with diverse incident frequencies. Considering the receiving mode, the antenna emerges with explicit directional frequency characteristics, which ensure its function of spatial acoustic source localization. Additionally, compared with the traditional acoustic LWA, the proposed antenna structure exhibits sharper directivity and has potential applications in high-precision acoustic source localization.