Array Radiator Research Articles

A Pattern Correlation Decomposition Method for Analysis of ESPAR in Single-RF MIMO Systems

A systematic and general method for obtaining orthogonal far-field radiation patterns using any electronically steerable parasitic array radiator (ESPAR) embedded in a propagation environment with an arbitrary power angular spectrum (PAS) is described. The method is useful in designing single-RF multiple-input multiple-output (MIMO) systems where the orthogonal patterns can be utilized as a basis set for beamspace MIMO. The method utilizes the correlation matrix of the open-circuit radiation patterns and is termed the pattern correlation decomposition method (PCDM). PCDM is applicable to any antenna type (including realistic antennas with losses), array configuration, PAS and overcomes the limitations of previously proposed techniques. PCDM also provides closed-form solutions for the antenna currents to generate the orthogonal patterns. It also provides an estimate of the effective aerial degrees-of-freedom of the ESPAR. In addition, efficient optimization approaches to finding the optimal reactive loads that excite the required orthogonal radiation patterns are provided. Simulation examples using a 5-element and a 8-element planar inverted-F antenna array including material losses in various PAS are provided. These show that the proposed approach increases system capacity by up to 7 bits/s/Hz or equivalently reduces the required transmit power by up to 73% compared with previous approaches.

Metasurface-Based Beam Scanning Array With In-Band Co-Polarized Scattered Field Shaping

In this article, a novel array of radiation and scattering function-integrated metasurface antenna (RSIMA) elements is proposed, simulated, and measured for radiation beam scanning and two examples of in-band co-polarized (IBCP) scattered field shaping. The RSIMA consists of a slot-connected metasurface (SCMS) subarray of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times $ </tex-math></inline-formula> 3 unit cells and a substrate integrated slot waveguide (SISW). When illuminated by plane waves, each SCMS unit cell can independently obtain a wide range of reflection phases by tuning structural parameters. When excited by the coaxial port of SISW, the SCMS subarray will also act as a radiation carrier of RSIMA. Moreover, the layout change of SCMS subarray will not significantly affect the radiation performance of RSIMA. Based on the principle of phase compensation and the phase superposition method, the phase distribution for two examples of scattered field shaping can be designed. In simulations and experiments, the array of 12 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times12$ </tex-math></inline-formula> RSIMAs radiates an IBCP beam scanning over ±31.5° in the E-plane and shapes the IBCP scattered fields into a deflected vortex beam (DVB) and a deflected high-gain multi-beam (DHMB). It is worth mentioning that the SCMS layout change between two examples of scattered field shaping does not significantly affect the radiation performance of the RSIMA array.

Analysis and Design of Fourth Harmonic Boosting Technique for THz Signal Generation

In this paper, an analysis method is presented to mathematically characterize the harmonic current generated by the voltage at fundamental or harmonic frequency in the transistor of a high-frequency harmonic oscillator. Using this analysis method, the relationship between the second harmonic voltages and the fourth harmonic drain current in the transistor is investigated, and the requirement on the second harmonic voltages for fourth harmonic boosting is found. Moreover, an approach of modeling the voltage-current relationship in the transistor of a high-frequency harmonic oscillator at harmonic frequency as an equivalent linear relationship is proposed. This modeling method facilitates the design of the second harmonic embedding network around the transistor, thus helping to propose a harmonic oscillator topology in which the requirement on the second harmonic voltages for fourth harmonic boosting is fulfilled. Using the proposed fourth harmonic boosting technique, a 0.6-THz radiator array is designed in 40-nm bulk CMOS. In measurement, the 0.68-<inline-formula> <tex-math notation="LaTeX">$\text {mm}^{2}$ </tex-math></inline-formula> radiator array achieves a radiated power of 0 dBm and a DC-to-THz efficiency of 0.08&#x0025; at 586.7 GHz under a 0.9-V supply voltage.

Charging Mobile Devices in Indoor Environments

Wireless power transfer promises to revolutionize the way in which we use and power mobile devices. However, low transfer efficiencies prevent this technology from seeing wide scale real-world adoption. The aim of this work is to use quasioptics to develop a system composed of a dielectric lens fed by a phased array to reduce spillover losses, increasing the beam efficiency, while working on the antenna system’s Fresnel zone. The DC-RF electronics, digital beamforming and beam-steering by an FPGA, and radiating 4 × 4 microstrip patch phased array have been developed and experimented upon, while the lens has been designed and simulated. This paper details these preliminary results, where the phased array radiation pattern was measured, showing that the beam is being generated and steered as expected, prompting the lens construction for the complete system experimentation.

Spatial control over ultrasonic cleaning of mining equipment using a phased array technology

Purpose. To develop methods for spatial control over ultrasonic cleaning by using ultrasonic phased array of radiators. To simulate the cleaning process using the developed methods to prove their effectiveness. Methodology. Application of the ultrasonic array as a basic radiator for ultrasonic cleaning enables redistribution of intensity in the bath by increasing it in the most contaminated zones of the cleaned object. Geometric and physical laws provide analytically defined parameters of the beam. Findings. The authors determine basic parameters for the ultrasonic beam through considering input and output data of the 3-D fuzzy interval controller. The focus distance is calculated by means of the arrival time of the threshold signal considering distances between the sensor and the array. The azimuth is directed into the bath center and dependent on its height only. The zenithal angle is calculated as a ratio of intensities of the current arrays and the nearest adjacent ones towards the greatest one. By default, the beam is directed to the bath center for the phased array with the greatest intensity. The simulation reveals that the applied approach enables a 41.5% increase in intensity in the contamination zone, this improving energy efficiency of cleaning and reducing time required for ultrasonic treatment. Originality. The authors suggest new methods for forming control over ultrasonic cleaning, which enables considering spatial distribution of this process by optimizing energy losses. Practical value. The new approach to spatial control over ultrasonic cleaning enables redirecting intensity in the bath to the most contaminated zones, this allowing an increase in energy efficiency of large mining machines of complicated configuration.

Design optimization of linear arrays and time‐modulated antenna arrays using meta‐heuristics approach

AbstractThis article presents an approach to design a non‐uniformly excited linear array antenna (LAA) and an alternate solution to LAAs in the form of time‐modulated linear arrays (TMLA) for optimum far‐field radiation pattern synthesis. The performance analysis of both the antenna arrays is studied, and the advantages and limitations of the proposed design approaches are presented with numerical outcomes. The far‐field radiation pattern is optimized to reduce the interference by simultaneously lowering the sidelobe levels and increasing the directivities of LAAs and TMLAs. A recently proposed meta‐heuristics computation technique called whale optimization algorithm (WOA) is employed to get the optimal results. The current excitation amplitude and the inter‐element spacing of the 16‐element LAA are optimized with WOA to attain the desired results. However, due to the large dynamic range ratios (DRRs) of excitation weights, array feed network complexities are increased, which restricts the design of typical LAAs. TMLAs can be regarded as an alternative solution where the problem of large DRRs as well as the design complexities of LAAs are eliminated. The concept of ‘time’ is vital in time‐modulation as it plays the role of an added degree of freedom realized by periodically turning ON and OFF the radio‐frequency switches with an electronic control circuit to achieve an enhanced array radiation pattern. WOA is utilized to determine the optimal switch‐ON time periods for each array element and the optimal inter‐element spacing of a 16‐element TMLA. A set of numerical results validates the advantages of TMLAs over LAAs, and the limitations of TMLAs with respect to LAAs are also indicated. The performance of both the arrays is then compared with other published literature results to establish the superiority of the proposed approach.

Radiation Pattern Nulling in Phased Array Antennas Using Superior Discrete Fourier Transform and Dolph‐Tschebyscheff Based Synthesis Techniques

AbstractThis study proposes an improved method for sector nulling in the radiation pattern of rectangular phased array antennas using two different synthesis techniques; an orthogonal Discrete Fourier transform and a quasi‐orthogonal Dolph‐Tschebyscheff based technique. In traditional synthesis techniques, broad elemental beams serve as local field basis functions (FBFs) in an array. Instead, the proposed methods produce low sidelobe narrow beams as FBFs. A set of these FBFs can effectively constitute the array's radiation pattern in a confined angular region. By properly weighting these FBFs, sector pattern nulls in a designated angular range are synthesized without severely distorting the patterns outside this area. The FBFs' optimal weights can be efficiently calculated using a nonlinear minimum least squares error technique, which is later transformed into the array's elemental excitation coefficients. Along with faster convergence, this technique allows control over peak sidelobe level, null depth, and width, making it suitable for GPS anti‐jamming, 5G communications, and other applications requiring interference suppression.

Direction of Arrival Estimation Based on Received Signal Strength Using Two-Row Electronically Steerable Parasitic Array Radiator Antenna.

In this paper, we present a novel approach to direction-of-arrival (DoA) estimation using two-row electronically steerable parasitic array radiator (ESPAR) antenna which has 12 passive elements and allows for elevation and azimuth beam switching using a simple microcontroller, relying solely on received signal strength (RSS) values measured at the antenna output port. To this end, we thoroughly investigate all 18 available 3D antenna radiation patterns of the antenna measured in an anechoic chamber with respect to radiation coverage in the horizontal and vertical direction and propose a generalization of the power-pattern cross-correlation (PPCC) algorithm involving a high number of multiple calibration planes (MCP) as well as specific combinations of radiation pattern sets. Additionally, a new way of RSS-based DoA estimation accuracy assessment, which involves thorough testing conducted along the elevation direction when RF signals impinging on the antenna arrive from arbitrary θ angles, has been reported in this paper to verify the overall algorithm’s performance. The results obtained for different signal-to-noise ratio (SNR) levels indicate that two-row ESPAR antenna can produce, even for low SNR values, accurate DoA estimation in the horizontal plane without prior knowledge about the elevation direction of the unknown RF signals by using appropriate combinations of only 12 3D antenna radiation patterns.

A parametric array loudspeaker featuring a Langevin transducer, a circular aluminum plate, and composite polymer steps

A parametric array (PA) loudspeaker generates highly directional sound beams by exploiting the PA phenomenon. Before such loudspeakers were fabricated from stepped plate transducers, arrays of small ultrasonic radiators were employed. A stepped plate transducer generates broadband PA sound by exploiting the multi-resonance characteristics of its structure, even though it has only a single radiator. However, the design process is difficult because the plate must be thicker than the steps. In this study, we present a new method for fabrication of stepped plate PA loudspeakers (SPPALs); we employ a Langevin transducer, a circular aluminum plate, and composite polymer steps. The new stepped plate is fabricated by molding the composite steps on a flat plate. This is unlike the conventional stepped plate, in which both the plate and steps are made of the same metal. Using this method, although the radiation plate is thinner than the steps, such stepping is associated with minimal changes in the natural frequency and mode shape. Therefore, the SPPAL design process is simplified. We experimentally confirmed that the new stepped plate exhibited the desired bending mode. The SPPALs exhibited a maximum sound pressure of 61 dB at 2 m and a half-power beam width of < 5°; the sound was highly directional.

Development of antenna system for use in meteorological and climatic control complexes

The synthesis of a cylindrical antenna array for ground-based mobile weather monitoring complexes, based on quadrifilar radiators, is considered. The basic mathematical expressions for determining the electrodynamic characteristics of both the radiator from the antenna array and the AA itself are presented. Various phenomenological models of these radiators are considered. The approach to the synthesis of phenomenological models of the radiator and antenna array as a whole is described. The results of such synthesis are given, and the main characteristics and values of DG, CG, SWR, RP for the given type of radiator and AA in the corresponding frequency range are obtained. Techniques for using phenomenological models for operational synthesis of electrodynamic structures such as cylindrical AA and quadrifilar radiator are developed and described in detail. The possibility of applying this approach to the synthesis of this type of structures for radar weather monitoring systems is shown.

Design-simulation of light radiation of a novel fixed-bed photocatalytic system with LED arrays on the engineering-outlook

A novel radiation model was established for guiding the development of photochemical reactors to promote the simulation technology onto the fields of photochemical engineering. As the mainstreaming software, the comsol@5.5 with (User Define Function) UDF, described the physical phenomenon on the light distribution in the water with titanium dioxide nanotubes/Ti (TNTs/Ti) mesh layers. During the process, the light-emitting diode (LED) arrays radiation model on the external interface on the reactor constructed by CAD, was solved by means of UDF compiled. Afterwards, the results calculated in the comsol@5.5, acted the boundary conditions as bilateral incidents illumination of the reactor. Eventually, the research obtained the distribution results by solving the radiative transfer equation (RTE), presenting the numerical simulation computing results.

4-port UWB MIMO antenna with bluetooth-LTE-WiMax band-rejection and vias-MCP loaded reflector with improved performance

In this article, a 4-port MIMO antenna of dimension 0.46λ0 × 0.46λ0 × 0.01λ0 (λ0 is the lowest operating wavelength at 2.08 GHz) is proposed. It consists of array of fractal radiators sorted orthogonally with 0.05λ0 edge-to-edge separation and contorted feeds perform as impedance transformer. A centered π-shaped inverted-L notch asserts rejection at bluetooth-LTE-WiMax band. The MIMO configuration has common ground plane with no decoupling topology provides an inter-elemental port isolation > 15 dB. There are four vias-Metallic conducting probes (vias-MCP) connected to antenna ground and reflector. The conducting probes enroute the near-field currents from radiators and neutralize into the loaded reflector, with isolation improved > 20 dB and antenna performances are enhanced. The reflector has dimension 0.58λ0 × 0.58λ0 fixed at Hair = 0.07λ0 (≈ 10 mm). The antenna operates from (2.08–10.4) GHz with band rejection at (2.27–3.62) GHz, asserts improved gain characteristics (7–9.57) dBi at pass band and −4 dBi at notched band. This new technique of vias-MCP in the proposed multi-port configuration mitigates mutual interaction of surface wave coupling on radiators, reduces near-field condensed currents and couplate the surface waves into the loaded reflector to improvise impedance matching and gain characteristics for UWB wireless communication systems.

Irregular Subarray Design Strategy Based on Weighted L1 Norm Iterative Convex Optimization

Subarray technology is an effective tradeoff between the sensor array radiation performance and manufacturing cost control. This letter proposes an irregular subarray tiling strategy based on the weighted L1 norm iterative convex optimization (WL1X) method. We first establish a subarray partition model and solve the L0 norm constraint problem by weighted L1 norm iterative convex optimization and then the optimal solution is selected based on the radiation performance. Further, We adopt a good initial point for the local optimization to improve scheme acquisition and selection efficiency. The proposed method can quickly obtain a subarray partition structure with better performance. The effectiveness and potential of the proposed methods are verified by various numerical examples.

A 0.45-THz 2-D Scalable Radiator Array With 28.2-dBm EIRP Using an Elliptical Teflon Lens

This article presents a novel coherent, scalable radiator array achieving the highest effective isotropic radiated power (EIRP) and highest dc-to-terahertz (THz) efficiency among silicon-based scalable THz sources beyond 400 GHz through co-design and optimization methods of the THz power generation and radiation. First, a 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 slot antenna array with silicon substrate loading is optimized for high radiation efficiency and good radiation pattern without silicon lens. A low-cost Teflon lens is introduced and effectively illuminated by the radiator achieving a highly directive beam. Second, a novel 2-D scalable coupled harmonic oscillator array is proposed as the excitation network to feed the antenna array. The oscillator is optimized for the second-harmonic generation to provide high output power and efficiency. The chip is fabricated in a 65-nm CMOS process, and the core area of the chip is 0.55 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The radiated power of −2.4 dBm and 8.8-dBm EIRP are achieved at 449.8 GHz with 373-mW dc power consumption and 0.16% dc-to-THz efficiency under 1.2-V supply voltage. By adding an elliptical Teflon lens, 28.2-dBm EIRP is measured at 452.3 GHz under 1.2-V supply voltage, and a maximum EIRP of 29.1 dBm is measured at 458.3 GHz with 1.4-V supply voltage. By changing the bias and supply voltages, a 4.6% frequency tuning range is achieved. At 452.3 GHz, the measured phase noise is −76.4 dBc/Hz at 1-MHz offset.

Design of Multi-band Compatible Trigeminal Monopole Array Antenna for Unmanned Aerial Vehicle

Compared with the performance index of UAV system antenna, a compatible trigeminal monopole array antenna is proposed. This antenna uses photosensitive resin as the substrate material, and can be made with UAV shell using 3D printing technology, realizing the integration of the antenna system and UAV. The antenna uses a trigeminal monopole antenna as the basic radiation unit, which is arranged in accordance with the Sierpinski fractal structure to form fractal radiation array. While enhancing the radiation through the array, it ensures that the antenna has a larger working bandwidth. In radiation performance test, the antenna is operating over a frequency spectrum of 1.038-11.916 GHz, and the minimum S11 is -37.92 dB. The proposed antenna has multi-band compatibility, better radiation performance, and greater performance redundancy.

A Wideband Antenna for mm-Wave Antenna-in-Package Application

Antenna-in-Package has been widely applied for millimeter-wave systems that integrate the MMIC chip and antenna into one package. For organic substrate Antenna-in-Package solutions, probe feeding and aperture-coupled feeding patches are generally used as radiation units. In this work, a patch antenna is proposed using coupled resonation; a wideband, high-gain and compact 3-D antenna package integration is realized. An equivalent circuit model is analysed for the coupled structure. &#x03BB;/4 coupled line is adopted for impedance matching, the whole antenna is designed on the same thick radiation patch substrate, with less organic substrate lamination layers. For millimeter-wave Antenna-in-Package structures, vias are generally used for vertical interconnections, which function well in the lower millimeter-wave frequency range. For operation frequency higher than 100GHz, design difficulties may be encountered for via interconnection, with performance degeneration on impedance matching and transmission loss. This work integrates a H-shaped slot instead of vias on an organic substrate, realizing a high frequency and wideband mm-wave transition. An interconnection structure is also adopted to convert a microstrip line to differential microstrip line in the feeding network. Antenna prototype with 2&#x00D7;4 radiation array is designed for verification purpose at 20GHz frequency range with simulated bandwidth of 23%. The prototype is fabricated with separate PCB boards assembled with screws, measured antenna gain is 12.7dBi-13.5dBi. The proposed structure provides a wideband and low-loss solution for potential higher frequency mm-wave Antenna-in-Package applications.

DESIGN OF 6G COMMUNICATION SYSTEM AT THZ FREQUENCY BANDS

Toward increasing the data rates further, Teraherk (THz) frequency bands (0.1 -10 THz) became the central aspect of sixth-generation (6G) networks that support massive connectivity, low-latency, highly secure communications, data rates [hundreds of gigabytes per second (Gbps)], and denser networks. THz transmission is a complementary wireless technology for high-speed wireless extension of the optical fibers for 6G. The availability of materials for antenna fabrication and feasibility in designing ultra-massive multi-input-multi-output (U-mMIMO) systems motivates one to explore its peak performance at THz frequency bands. In this paper, a multiuser U-mMIMO system was designed with hybrid beam-forming features and its performance was tested at 0.142 THz bands for different numbers of base station antennas and modulation orders. Each user had one or more number of independent data streams, and the total number of users considered in the multiuser U-mMIMO system were 4 and 8. The metrics we considered in evaluating the performance were error vector magnitude, antenna array radiation patterns, and equalized symbol constellations. The results of simulations strongly recommend exploring the THz frequency bands for building next-generation wireless systems that satisfy the needs of the near future.

Design and Feasibility Verification of 6G Wireless Communication Systems with State of the Art Technologies

Frequencies above 100 GHz are the promising frequency bands for 6G wireless communication systems because of the abundant unexplored and unused spectrum. The increasing global demand for ultra-high spectral efficiencies, data rates, speeds and bandwidths in next-generation wireless networks motivates the exploration of peak capabilities of massive MIMO (Multi–Input–Multi–Output) wireless access technology at THz bands (0.1–10 THz). The smaller wavelengths (order of microns) of these frequencies give an advantage of making high gain antennas with smaller physical dimensions and allows massive spatial multiplexing. This paper presents the design of ultra-massive MIMO (ultra-mMIMO) hybrid beamforming system for multi users and its feasibility to function at THz frequency bands. The functionality of the proposed system is verified at higher order modulation schemes to achieve higher spectral efficiencies using performance metrics that includes error vector magnitude, symbol constellations, and antenna array radiation beams. The performance results suggest to use a particular mMIMO antenna configuration based on number of independent data streams per user and strongly recommended to use higher number of data streams per user in order to achieve higher throughputs that satisfy the needs of 6G wireless systems. Also the performance of the proposed system at 0.14 THz is compared with mmWave systems that operate at 28 GHz and 73 GHz bands to justify the feasibility of the proposed work.

Relay-Aided Wireless Sensor Network Discovery Algorithm for Dense Industrial IoT Utilizing ESPAR Antennas

Industrial Internet-of-Things (IIoT) applications require reliable and efficient wireless communication. Assuming dense wireless sensor networks (WSNs) operating in a harsh environment, a concept of a time-division multiple access (TDMA)-based WSN enriched with electronically steerable parasitic array radiator (ESPAR) antennas is proposed and examined in this work. The utilized antenna provides one omnidirectional and 12 directional radiation patterns that can be electronically switched by the sensor node. We introduce a relay discovery algorithm, which selects those sensor nodes with an ESPAR antenna capable to act as relay. The selection of the relay nodes is based on a certain link quality threshold that algorithm uses as input. The outcome is a reduction in the number of layers or hops with a guaranteed Quality of Service (QoS). To emphasize the physical aspect of the wireless propagation, we introduce the measured antenna radiation patterns and consider two different path-loss propagation models representing blockage-free and blockage-prone industrial environments. A number of network simulations were performed and signal-to-noise ratio (SNR) as a link quality measure was examined with respect to the network density and different measured radiation pattern settings. The main outcomes show a tradeoff between SNR per link and the percentage of nodes that can serve as relays. As a result, we propose network design guidelines that take under consideration the QoS range with respect to SNR together with an optimal number of antenna radiation patterns that should be selected as a tradeoff between latency, energy consumption, and reliability in a network.

A Compact Active Ka-Band Filtenna for CubeSats

This letter describes the design of a right-hand circularly polarized planar filtenna (filter + antenna) that can reconfigure its operation between two center frequencies in the Ka-band. The filtenna structure is composed of a four-element array radiator and a reconfigurable bandpass filter, occupying an area of 31 × 14 mm. The circularly polarized array elements are fed by a sequential power divider for an enhanced polarization purity. The filter is based on a ring resonator loaded with a variable open stub. The length of the stub extends through a p-i-n diode switch, resulting in a change of the loaded reactance into the ring, and consequently tuning the filter's operating center frequency from 30.3 to 29 GHz. The proposed low-loss filtenna structure exhibits a reconfigurable fractional bandwidth up to 7.74%, a peak realized gain that can reach up to 11.5 dBic, an axial ratio of less than 1 dB, and a sidelobe level that can go as low as −12 dB. The prototype filtenna is fabricated and tested, where the measured results verify the simulated data. A figure of merit is proposed to highlight the superior performance of the presented Ka-band structure in terms of the polarization, size, reconfiguration ability, and radiation characteristics as proven by the comparison with other works in the literature.