Type Of Antenna Research Articles

Survey on performance parameters of planar microwave antennas

Planar antennas, which include microstrip antennas and printed circuit board antennas, are used in telecommunications. This study aims to provide an overview of microstrip antennas for diverse applications. Microstrip patch antenna design is a new study topic that has been established for usage in 5th-generation communication applications. An antenna is a group of connected devices that serve as a single antenna to broadcast or receive radio waves. Antennas come in a variety of designs and sizes. The paper discusses several printed microstrip antenna designs, such as rectangular to circular, broadband, dual-band, millimeter-wave and microstrip arrays. The microstrip patch is an antenna layout that is lightweight, low-profile, and results-oriented. Microstrip patch antennas may be employed in various 6G communication system applications in the future. This paper examines antenna geometric structures, antenna analysis methodologies, antenna dimensions and many different types of antennas. It will also go over the substrate materials, loss tangent, thickness, return loss, bandwidth, voltage-standing-wave-ratio (VSWR), gain, and directivity so that an optimized antenna can be designed and fabricated having excellent characteristics for use in modern applications by the promising academic researchers in the near future.

Optimal Analog Precoder Design for Hybrid Beamforming is Possible

Hybrid beamforming is a cost-effective solution for millimeter wave massive multiple-input-multiple-output communications, which highly reduces the number of required radio frequency chains by jointly using a digital precoder and an analog precoder. The digital precoder can be optimized by using the classical least squares method. However, due to the discrete resolution of analog phase shifters, the analog precoder design is a high-dimensional integer programming problem, for which the exsiting methods can only provide suboptimal solutions. In this paper, we first show that optimal analog precoder design is possible in typical antenna settings. Specifically, we show that this high-dimensional problem can be divided into multiple low-dimensional subproblems in parallel and there exists an analytical lower bound for each subproblem that can be efficiently utilized to obtain the optimal solution by using the branch and bound method. Numerical results show that the proposed hybrid precoder with an optimal analog precoder can achieve 98 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> performance of the fully digital solution in a typical antenna setting.

Experimental Optimization of the Energy Characteristics of a Ground Penetrating Radar with Continuous Linear-Frequency-Modulated Radiation

In recent years, research has been actively carried out aimed at developing the concept of construction and ways of technical implementation of ground penetrating radars with continuous wave linear-frequency-modulated (LFM) radiation. The key prerequisites for the creation of such systems are the complex consideration of the operating conditions of the radio channel in the near field, including the features associated with multichannel leakage of the probing signal components into the reception path, the presence of multipath reflections from the covering surface, the variable speed of the electromagnetic wave, and the provision of linear processing of a continuous group broadband radio signal with large dynamic range. The paper proposes and describes a scheme of a laboratory stand for LFM GPR research and optimization of the energy characteristics in modes with critical levels of reflections. The results of experiments on the analysis and optimization of the parameters of the end-to-end transfer characteristic of the radio channel are presented. Response studies were performed for two types of antennas at different suspension heights. The responses of the system to an increase in the durtion of the probing pulse and a change in the type of window function were evaluated. An empirical dependence of signal losses during propagation in radio channels of LFM GPR has been established. The conducted studies will improve the energy characteristics of ground penetrating radars with continuous LFM radiation by increasing the detection efficiency of shallow and near-surface objects.

The method of calculating the design parameters of a collinear serial antenna using the dispersion characteristics of the retarding system

The paper presents a technique for analyzing the electrical characteristics of series-type collinear antennas made according to the Franklin scheme, which are intended for use in radio communication systems with moving objects as basic or subscriber antenna-feeder devices. Collinear antennas belong to omnidirectional type antennas and allow to significantly increase the amplification factor in comparison with already existing types of antennas of a similar type, which is what attracts antenna technology developers today. The main element of a series-type collinear antenna is a phase-shifting device that determines both the performance of the antenna and its electrical characteristics. The most widely used phase-shifting devices were inductive chokes – a section of conductor of a certain length rolled into a spiral. The proposed engineering method of calculating the parameters of the inductive choke allows you to quickly and accurately adjust its characteristics with the calculation of the necessary phase shift. This approach takes into account the physical parameters of the conductor material and the geometry of the spiral conductor, which greatly simplifies the engineering process of developing collinear antennas. The obtained results of simulation of electrical characteristics confirm the effectiveness of the proposed method. A significant increase in the amplification factor compared to the existing types of antennas and compliance of the electrical characteristics with the specified parameters was revealed. The work has an important contribution to the development of antenna technology and has practical application in radio communication systems with moving objects. The proposed method of calculating the parameters of the inductive choke can be used by antenna developers to increase the productivity and efficiency of their radio communication system.

Compact dual‐frequency patch antenna with large beamwidth diversity at flexible frequency ratio

AbstractA compact, single‐layer, dual‐frequency patch antenna with large beamwidth diversity, that is, broad beamwidth in the lower frequency and high‐gain radiation in the higher frequency is presented and analyzed in this paper. The antenna is in general composed of a square driven patch and two T‐shaped top‐loaded monopoles that are loaded beside the two radiating edges of the driven patch. Herein, the patch antenna to be operated in the fundamental TM01 mode intrinsically provides a pair of in‐phase magnetic currents and meanwhile, the top‐loaded monopoles produce a pair of out‐of‐phase vertical electric currents. In analysis, consistent broad beamwidth and high‐gain radiation pattern are, respectively, well maintained at the lower and higher frequencies, even with a frequency ratio as small as 1.02. Moreover, the antenna preserves simple geometry and high efficiency of a typical patch antenna. For verification, a prototype is in final fabricated and measured, which has experimentally confirmed its simulated radiation results.

A Novel Shaped Four Port MIMO Antenna for Wireless Communication

This paper presents a compact novel shaped micro strip line fed four element Multiple Input Multiple Output (MIMO) antenna for wireless application at 2.4 GHz. Four vertically oriented identical rectangular patch antennas are used to form a hollow cylinder of rectangular cross section. The direction of radiation of each antenna is thus oriented at 900 with respect to its two adjacent antennas providing good isolation between adjacent antennas in this compact MIMO system. Each antenna element has the dimensions of 0.30λx0.38λx0.012λ. The whole MIMO antenna has the outer dimensions of 0.38λx0.38λx0.30λ. The uniqueness of the proposed MIMO antenna is that the inner space of the hollow cylindrical structure can be used for hosting the associated signal processing unit of the whole system. Performance parameters of the proposed MIMO antenna are investigated using Computer Simulation Technology (CST). Envelope Correlation Coefficient (ECC) less than 0.033 and almost 10dB Diversity Gain (DG) are obtained at 2.4 GHz for this simple and compact antenna system. Ratio of Mean Effective Gain (MEG) of any two antennas is less than 0.02dB. Performance parameters of the proposed MIMO antenna system are compared with similar types of antennas found in recent literature.

Double-row 16-element folded-end dipole transceiver array for 3D RF shimming of the whole human brain at 9.4 T.

Homogeneity and longitudinal coverage of transmit (Tx) human head RF coils at ultrahigh field (UHF, ≥7 T) can be improved by 3D RF shimming, which requires using multi-row Tx arrays. Examples of 3D RF shimming using double-row UHF loop transceiver (TxRx) and Tx arrays have been described previously. Dipole antennas provide unique simplicity and robustness while offering comparable Tx efficiency and signal-to-noise ratio to conventional loop designs. Single-row Tx and TxRx human head UHF dipole arrays have been previously described by multiple groups. Recently, we developed a novel type of dipole antenna, a folded-end dipole, and presented single-row eight-element array prototypes for human head imaging at 7 and 9.4 T. These studies have shown that the novel antenna design can improve the longitudinal coverage and minimize peak local specific absorption rate (SAR) as compared with common unfolded dipoles. In this work, we developed, constructed, and evaluated a 16-element double-row TxRx folded-end dipole array for human head imaging at 9.4 T. To minimize cross-talk between neighboring dipoles located in different rows, we used transformer decoupling, which decreased coupling to a level below -20 dB. The developed array design was demonstrated to be capable of 3D static RF shimming and can be potentially used for dynamic shimming using parallel transmission. For optimal phase shifts between the rows, the array provides 11% higher SAR efficiency and 18% higher homogeneity than a folded-end dipole single-row array of the same length. The design also offers a substantially simpler and more robust alternative to the common double-row loop array with about 10% higher SAR efficiency and better longitudinal coverage.

Characteristic calculations of antennas for communication and retransmission placed on aircraft and helicopter unmanned aerial vehicles

The issues of increasing the communication range when organizing data transfer between two remote sites are especially important and very relevant. An increase in the communication range can be achieved by increasing the height of the antennas. One of the effective technical solutions that allow placing antennas and radio stations at high altitude in the required place is the use of modern unmanned aerial vehicles (UAV). Target. Calculations and studies of the characteristics of antennas placed on UAV of various types. The results of calculations of the energy and spatial characteristics of three types of antennas installed on UAV of various types are obtained: asymmetric whip antenna; a low-profile antenna consisting of three PIFA emitters; an annular antenna array consisting of 6 asymmetric Uda-Yagi antennas. It is shown that each of the solutions has its own advantages and disadvantages and its own scope. Based on the obtained results of calculating the characteristics of antennas, the developers of the corresponding communication systems can make a reasonable choice of the types of antennas used, depending on the requirements for the systems as a whole.

The mathematical weighting of GNSS observations based on different types of receivers/antennas and environmental conditions

Stochastic models play an important role in achieving high accuracy in positioning, the ideal estimator in the least-squares (LS) can be obtained only by using the suitable stochastic model. This study investigates the role of variance component estimation (VCE) in the LS method for Precise Point Positioning (PPP). This estimation is performed by considering the ionospheric-free (IF) functional model for code and the phase observation of Global Positioning System (GPS). The strategy for estimating the accuracy of these observations was evaluated to check the effect of the stochastic model in four modes: a) antenna type, b) receiver type, c) the tropospheric effect, and d) the ionosphere effect. The results show that using empirical variance for code and phase observations in some cases caused erroneous estimation of unknown components in the PPP model. This is because a constant empirical variance may not be suitable for various receivers and antennas under different conditions. Coordinates were compared in two cases using the stochastic model of nominal weight and weight estimated by LS-VCE. The position error difference for the east-west, north-south, and height components was 1.5 cm, 4 mm, and 1.8 cm, respectively. Therefore, weight estimation with LS-VCE can provide more appropriate results. Eventually, the convergence time based on four elevation-dependent models was evaluated using nominal weight and LS-VCE weight. According to the results, the LS-VCE has a higher convergence rate than the nominal weight. The weight estimation using LS-VCE improves the convergence time in four elevation-dependent models by 11, 13, 12, and 9 min, respectively.

Exploring the effects of directional antennas on the secure connectivity and hop count of secure multi-hop ad-hoc wireless networks

Directional antennas can increase the received power in specific directions while reducing it in other directions. Utilizing this unique feature, we configure directional antennas at legitimate users to obtain twofold benefits for secure multi-hop ad-hoc wireless networks (AHWNs), i.e., enhancing the secure connectivity among legitimate users and lowering the hop count of the multi-hop paths. For the quantitative evaluation of these benefits, we first use a stochastic geometry graph to model the multi-hop AHWNs under the coexistence of eavesdroppers. Then, we introduce a simulation-based analysis method comprised of two algorithms: (a) the first algorithm provides the connectivity and the hop count of the shortest path between random source–destination pairs; (b) the second algorithm utilizes the results of the first one to return the average path connectivity, the probability mass function (pmf) of the hop count distribution, and the average hop count. This simulation-based analysis method helps to exhaustively study the behaviors of connectivity, hop count distribution, average hop count, and their mutual relationship in different scenarios. To the best of our knowledge, this paper is the first research work that studies the effects of directional antennas equipped at legitimate users on both secure connectivity and hop count of secure AHWNs in four combinations of two types of practical directional antennas, i.e., uniform circular array (UCA) antenna and uniform linear array (ULA) antennas, and two beamforming schemes, i.e., centralized and randomized beamforming. Moreover, comparisons with the case of using omnidirectional antennas are also provided. From the obtained simulation results, we demonstrate that using directional antennas does not always benefit the secure connectivity and hop count of secure AHWNs, i.e., only UCA-random gives higher secure connectivity and lower hop count than the omnidirectional antenna among four combinations of antenna type — beamforming scheme. Moreover, in the cases of high-density legitimate users and low-density eavesdroppers, lowering the average hop count is more remarkable than improving secure connectivity. The critical findings in this paper are valuable for deploying secure multi-hop AHWNs with directional antennas in practice.

Design of Frequency Scanning Coupled-Resonator Two-Element Array Antenna

In this brief, we present one type of frequency scanning coupled-resonator two-element array antenna and its corresponding equivalent circuit synthesis method. This antenna consists of several series-coupled resonators, the non-radiating resonators are cascaded between two radiating resonators. Since the antenna only has resonators and coupling structures, the threeports coupled-resonator circuit model can be used to explain the working principle and predict the performance of this antenna. The analysis of circuits with different orders indicates that the fractional bandwidth can control the scanning rate and the scanning rate and range can be both affected by the number of non-radiating resonators. Finally, two antennas with three and four resonators are designed in PCB form to validate the method. The third-order (fourth-order) antenna can scan 54.1∘ (64∘) in a 5.87% (5.54%) bandwidth centered at about 3.5 GHz.

Full-Range Amplitude–Phase Metacells for Sidelobe Suppression of Metalens Antenna Using Prior-Knowledge-Guided Deep- Learning -Enabled Synthesis

A prior-knowledge-guided deep-learning-enabled (PK-DL) synthesis method is proposed to design the metacells with the full-range amplitude and phase control for suppressing the sidelobe levels of a metalens antenna. The PK-DL synthesis method is based on conditional deep convolutional generative adversarial network (cDCGAN). First, the metacells are pixelated to offer the higher degrees of design freedom and expand their transmission responses to full two-dimensional coverage of amplitude and phase responses so that a full-range metacell dataset is built up to simultaneously control the amplitude and phase of a single metacell. Conventionally, by optimizing the dimensions of predefined patterns of a metacell, only phase response of a single metacell is achieved with a specific amplitude response, vice versa. The metalens design based on the synthesized metacells has much higher degrees of freedom so that the metalens antenna has the potential to break the ceiling of performance and to realize more functions than existing metalens designs. As examples, two types of single-lens metalens antennas are designed for sidelobe suppression using the proposed metacell dataset. The first metalens is excited by a dipole antenna with an omnidirectional radiation pattern to demonstrate the simultaneous control of amplitude and phase responses using the synthesized metacells. The second metalens fed by a standard horn antenna is designed to suppress the sidelobe levels in both the E- and H-planes. The horn-fed square metalens has an aperture of 13.2 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 13.2 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 12 GHz. Measurement shows that the proposed metalens antenna realizes the gain of 26.9 dBi at 12 GHz and the first sidelobe levels in the E- and H-planes are -33.2 dB and -30.9 dB, respectively. The proposed synthesis method greatly expands the boundary of amplitude and phase responses of a single metacell so that the metacell dataset offers much higher degrees of freedom for not only metalenses but also other metasurfaces.

Damage study of UAV cluster by high-power electromagnetic radiation

With regard to the threat of Unmanned Aerial Vehicle(UAV) clusters, the mechanism and rule of the damage to UAV cluster caused by electromagnetic wave is explored in this paper. A typical satellite navigation antenna high power electromagnetic radiation is studied with the experimental and simulation, in which, the damage sensitive parts and threshold of damage is obtained, which provides support for interference and damage UAV cluster of enemy and protection research for UAV of our own.

Design and Analysis of the Hexagonal-Shaped Antenna with Multi-Band Feature for WLAN, WiMAX, and LTE Applications

Developing and researching antenna designs are analogous to excavating in an undiscovered mine. This paper proposes a multi-band antenna with a new hexagonal ring shape, theoretically designed, developed, and analyzed using a CST before being manufactured. The antenna has undergone six changes to provide the best performance. The results of the surface current distribution and the electric field distribution on the surface of the hexagonal patch were theoretically analyzed and studied. The sequential approach taken to determine the most effective design is logical, and prevents deviation from the work direction. After comparing the six theoretical results, the fifth model proved to be the best for making a prototype. Measured results represent that the proposed antenna can operate well in three bands with a return loss of -11.24 dB at 2.9 GHz, -25.99 dB at 4.9 GHz, and -21.26 dB at 5.4 GH. This type of antenna belongs to various wireless communication systems, including 2G, 3G, 4G, and 5G.

Comparative evaluation of implementation options for partial radiators for antenna systems of urban radio centers under severe restrictions on placement conditions

In connection with the active development of urban infrastructure and the expansion of residential areas, it becomes necessary to provide corporate mobile radio communications with a large coverage area. In this regard, a number of problems arise, since in most cases special television towers and cellular communication masts are already occupied, and the location on high-rise buildings that are not adapted for antenna placement has rather severe restrictions. Calculation and study of the characteristics of PIFA type antennas placed on high-rise buildings under severe restrictions on placement conditions. Results. The results of calculations of antennas of the PIFA type are obtained, taking into account the environment. A technical solution for a dual-band PIFA VHF antenna is proposed. It is shown that with duplex operation isolation of at least 20 dBm, VSWR of no more than 2 with a bandwidth of 3 MHz is achieved.

Design of a compact patch antenna with bandwidth and efficiency improvement for UWB applications

The demand of small, lightweight and high effectiveness antennas has increased significantly with the development of communication technologies. Microstrip patch antennas (MPAs) are one of the most widely used types of antenna that can satisfy these requirements. MPAs have numerous benefits, including tiny size and weight, ease of fabrication, and inexpensive. In addition to these advantages, MPAs also have some drawbacks such as limited bandwidth and low efficiency. In this paper, a compact rectangular patch microstrip antenna employing hybrid technique (HT) is designed to enhance the bandwidth and efficiency and its performance is compared with that of a conventional antenna. The HT is formed by combining a slotted patch with a defected partial ground structure. A low-cost FR-4_epoxy substrate material with a dielectric constant of 4.4, a thickness of 0.8 mm and a loss tangent of 0.02 is used to make both antennas designed. The antennas are designed, analyzed and simulated at the operating frequency of 6.85 GHz for ultra-wideband (UWB) (3.1-10.6GHz) applications using high-frequency structure simulator (HFSS) software. The overall size of the proposed antenna is 30 mm × 20 mm × 0.8 mm. A 50 Ω microstrip feedline is used to excite the patch. The outcomes of the simulation reveal that the suggested and conventional antennas achieved a bandwidth of 19.7 GHz and 2.53 GHz with an efficiency of 95.779% and 92.296% respectively. The recommended antenna has boosted in bandwidth and efficiency by 17.17 GHz (137.24%) and 3.483% respectively as compared to the traditional antenna.

A Typical Slotted SIW Cavity-backed Antenna for Dual frequency operations in U-NII Bands

A low profile circular shaped cavity-backed substrate integrated waveguide (SIW) antenna with two-typical intersecting rectangular slots on the ground plane is designed to operate in the dominant TM010 mode at a frequency of 5.19 GHz in U-NII-1 band for wireless applications. The initially designed antenna produces a gain of 4 dBi with a narrow impedance bandwidth extending from 5.17 – 5.22 GHz. The antenna design is further modified by insertion of another shifted two-typical intersecting rectangular slots to finally resemble that of Hash shape; resulting in dual band antenna operation at 4.9 and 5.93 GHz. The gains obtained are 3.7 dBi and 1.4 dBi for 4.9 and 5.93 GHz respectively with an impedance bandwidth covering 4.88 - 4.92 GHz and 5.92 – 5.94 GHz respectively. The antenna prototype is fabricated using Arlon AD270 substrate material. Parametric studies are performed in terms of return loss and gain of the antenna. All simulations are carried out using HFSS v19.0 and show similar behavior to their experimentally measured counterparts.

Energy Efficient Enhancement in a 5.8 GHz Batteryless Node Suitable for Backscattering Communications

This work presents a compact batteryless node architecture suitable with the backscattering communication (BackCom) approach. The key functional blocks are demonstrated at 5.8 GHz, making use of commercially available components involving a DC/DC step-up converter, a 3.3 V data generator, and an ASK backscattering modulator based on a single GaAs HEMT in a cold-FET configuration. The node integrates a patch antenna exhibiting a non-50 Ω optimal port impedance; the value is defined by means of a source pull-based optimization technique aimed at maximizing the DC/DC input current supplied by the RF to DC converter. This approach maximizes the node compactness, as well as the wireless power conversion efficiency. A prototype was optimized for the −5 dBm power level at the input of the RF to DC converter. Under this measurement condition, the experimental results showed a 63% increase in the harvesting current, rising from 145 to 237 μA, compared to an identical configuration that used a microstrip matching network coupled with a typical 50-Ω patch antenna. In terms of harvested power, the achieved improvement was from −13.2 dBm to −10.9 dBm. The conversion efficiency in an operative condition improved from 15% to more than 25%. In this condition, the node is capable of charging a 100 μF to the operative voltage in about 27 s, and operating the backscattering for 360 ms with a backscattering modulation frequency of about 10 MHz.

Wireless Surface Strain Mapping by Passive Electromagnetic Resonators

A wireless multipoint strain sensing system is demonstrated via compact and passive electromagnetic-coupling based array of resonators. The system incorporates nested split-ring resonators (NSRR) as the sensing element, since this geometry is known to enable higher sensitivity and miniaturization. The strain sensing system can be configured in two ways: 1) A single-antenna system where the near-field coupling of the antenna creates high field localization on the array, 2) A two-channel system (TX and RX), where the transmitter can be placed at a distant location to allow remote illumination of the array. Both configurations are validated by measurements, which demonstrate that the system exhibits at least 10-μm-level displacement resolution, corresponding to 1000 microstrains, and a sensitivity of 100 Hz/microstrain. Results of experiments with various antenna types, different number of elements and array alignments are presented, along with simulations to understand the system characteristics. The results prove that frequency shifts of the sensors can be tracked without complex processing as long as the initial resonance frequency and allocated bandwidth of each sensor are selected so as to avoid overlaps. The system is particularly advantageous for Structural Health Monitoring (SHM) applications, where measurement of two-dimensional strain is critical in assessment of the deformation in concrete, metal or composite materials.

Cross Dipole Antennas Solution for Angle of Arrival Estimation

The Multiple Signal Classification (MUSIC) algorithm is the most popular algorithm to estimate the Angle of Arrival (AOA) of the received signals. The analysis of this algorithm (MUSIC) with typical array antenna element ( ) shows that there are two false direction indication in the planaligned with the axis of the array. In this paper a suggested modification on array system is proposed by using two perpendiculars crossed dipole array antenna in spite of one array antenna. The suggested modification does not affect the AOA estimation algorithm. The simulation and results shows that the proposed solution overcomes the MUSIC problem without any effect on the performance of the system.