Antenna Array Elements Research Articles

A Diagnosing Method for Phased Antenna Array Element Excitation Amplitude and Phase Failures Using Random Binary Matrices

A diagnosing method for phased antenna array element failures is proposed. The element excitation amplitudes and phases are reconstructed by a compressed sensing based approach, in which the radiated electric fields of the array are sampled by a single fixed receiving antenna. The diagnosing can be processed when the phased array is still in service. Particularly, it can be specialized for detecting faults only. Element excitation phases are designed to follow Bernoulli distribution, which is difficult to be realized in conventional geometric sampling methods. It is capable to provide effective and simultaneous detection for different types of failures with phase control means that are simpler comparing with other methods in which excitation phase adjustment is required. Especially, a two-step detection strategy is proposed to effectively detect phase failures due to faultily short-circuited phase shifters. Numerical results illustrate the effective sensing range of a single receiving antenna. Full-wave simulations validate the diagnosing performance in the presence of mutual couplings between array elements.

3D-Printed Low-Profile Single-Substrate Multi-Metal Layer Antennas and Array With Bandwidth Enhancement

This paper presents a few single-substrate multi-metal layer antennas using additively manufactured electronics (AME) solution based on piezoelectric additive fabrication. By vertically stacking metal layers in a 3D printed single substrate, the designed antenna prototype exhibits the advantages of wide bandwidth and ultra-low profile. For proof-of-concept, multi-layer linear polarization (LP) patch antenna elements and 2 × 2 LP antenna arrays are designed, fabricated, and measured. It verifies that the feeding network can be integrated into the same substrate of the antenna array element without increasing the size and profile of the array. Compared with the traditional single-layer LP patch antenna, the proposed LP patch antenna can improve the impedance bandwidth from 5.9% to 10.6% (three layers) and 83% (seven layers), respectively. All these designs can be fabricated in a single substrate with a thickness of 1.5 mm (0.031 λg), which is an ideal solution for the applications where ultra-low profile and wideband patch antenna are expected. Finally, circular polarization (CP) patch antenna elements and 2 × 2 CP antenna arrays are fabricated and measured. Good agreements between the simulated and the measured results verify that wider impedance bandwidth and broader frequency range of under 3-dB axial ratio can be obtained by vertically stacking metal layers. The antennas are designed at sub-6GHz, which have great potentials for 5G consumer mobile electronics.

High Gain UWB Four Elements Antenna Array for C-Band and X-Band Application

The C-band is allocated for commercial telecommunications via satellites. Amateur satellite operations in the frequency range 5.830 to 5.850 GHz for down-links and 5.650 to 5.670 GHz for up-links are allowed by International Telecommunication Union. The X-band is used for terrestrial broadband communication, radar applications, and portions of the X-band are assigned for deep space telecommunications. In this paper, a design of 4 × 1 Ultra Wide Band (UWB) antenna array for C-band and X-band applications is introduced. Metamaterial sixteen-unit cells are incorporated into each antenna element for radiation characteristics enhancement purposes. Permeability and permittivity of metamaterial unit cells are obtained all over the operating bandwidth. UWB unequal power divider is used to feed the proposed four elements antenna array based on Chebyshev excitation method. The proposed antenna has a suitable 3 dB beam width and gains all over the operating bandwidth which extends from 5.6 GHz to 10.9 GHz. The proposed antenna covers 60% and 72.5% of the C-band and X-band, respectively. The proposed antenna is fabricated, measured, and good agreement is obtained between simulated and measured results. The obtained performance ensures the suitability of the proposed antenna array for C-band and X-band applications.

A 2×2 Antenna Array for L Band Phased Array RADAR Applications

A Four element antenna array for the Phase array RADAR applications in the L Band with an operating frequency of 1.32GHz is presented. The four patches are been connected to four different transmitter circuit with which we can control the phase of the input signal. The antenna is having a size of 212mm×212mm×1.6mm with a gain of 8.78dB and directivity of 10.31dB at the operating frequency of 1.32GHz.. Low cost FR4 material is been used as the laminate base for the antenna which will act as the dielectric material.

A 2×2 Antenna Array for L Band Phased Array RADAR Applications

A Four element antenna array for the Phase array RADAR applications in the L Band with an operating frequency of 1.32GHz is presented. The four patches are been connected to four different transmitter circuit with which we can control the phase of the input signal. The antenna is having a size of 212mm×212mm×1.6mm with a gain of 8.78dB and directivity of 10.31dB at the operating frequency of 1.32GHz.. Low cost FR4 material is been used as the laminate base for the antenna which will act as the dielectric material.

Performance Analysis of Low-Cost Printed Antenna Array Elements for 5G LOS-MIMO Arrays at 60 GHz

Design of 5G and beyond 5G telecommunication systems relies on utilization of diverse solutions for different envisioned applications and different constituents of an entire system. One of the research directions is the utilization of a global unlicensed millimeter wave frequency band from 57 to 66 GHz for the high throughput data transfer. Apart from the wide spectrum availability at 60 GHz, there are many problems to be resolved before the concept can become fully functional; one of the requirements is the design of low-cost, energy efficient, wideband antennas with enhanced gain, capable of overcoming propagation losses at 60 GHz. We investigate the benefits and shortcomings of four types of low-cost, printed antennas as the constituents of sub-array elements for the large line-of-sight MIMO arrays. The results are put into perspective by comparison with the most used low-cost microstrip patch sub-array element. The state-of-the-art method-of-moments computations were employed in the highly accurate analyses of the four compared antenna array elements. Although the gains of such sub-arrays can be boosted by the increases in antenna numbers, this does not hold for the efficiency or bandwidth of operation; therefore, radiation patterns and characteristics at the level of individual antennas cannot be ignored as these translate directly into the behavior of an array. Careful choice of antenna type and initial efforts in the sub-array design should be seen as a necessary first step in the design of a large line-of-sight MIMO array of superior characteristics.

ВЛИЯНИЕ СЕЗОННЫХ ВАРИАЦИЙ ПАРАМЕТРОВ ГРУНТА НА ЧУВСТВИТЕЛЬНОСТЬ ЭЛЕМЕНТА АКТИВНОЙ ФАЗИРОВАННОЙ АНТЕННОЙ РЕШЕТКИ РАДИОТЕЛЕСКОПА ГУРТ

ВЛИЯНИЕ СЕЗОННЫХ ВАРИАЦИЙ ПАРАМЕТРОВ ГРУНТА НА ЧУВСТВИТЕЛЬНОСТЬ ЭЛЕМЕНТА АКТИВНОЙ ФАЗИРОВАННОЙ АНТЕННОЙ РЕШЕТКИ РАДИОТЕЛЕСКОПА ГУРТ

Performance Analysis of LMS, RLS, CMA Algorithms for Beamforming in Smart Antenna Systems

Smart antenna systems strengthen wireless mobile communication, with enhancement over conventional systems, by projecting the signal power in narrow beams towards the desired users and suppressing the signal power towards unwanted users or interferers. Different DOA estimation and beamforming algorithms play crucial role in smart antenna system. In beamforming algorithms, using different techniques complex weights are calculated and applied to the signals from the smart antenna array elements to enhance signals of interest and suppress signals not of interest. In this article Least Mean Square(LMS) technique, Recursive Least Square(RLS)technique and Constant Modulus (CMA)technique adaptive beamforming algorithms are implemented, analyzed and compared using MATLAB simulations to help users to choose amongst them as per the their need, ease and suitability.

Flexible and Beam Steerable Planar UWB Quasi-Yagi Antenna for WBAN

An Ultra-Wide Band (UWB) Quasi Yagi antenna with beam steering property is reported in this paper for Wireless Body Area Network (WBAN) application. The proposed antenna has a driver dipole, micro-strip line to slot-line transition and four parasitic strips printed on a very thin substrate of thickness 0.2 mm. The coplanar strip-line (CPS) is used to connect the driver dipole to the slot-line. The proposed antenna has an improved bandwidth of 7.4 GHz along with unidirectional radiation pattern. The parasitic strips act as directors to attain high gain of 7.8 dBi with better directionality. The flexible and compact geometry with footprint of 34 mm × 30 mm makes the antenna suitable for body worn devices. Further to improve the communication between the sensor and the cluster node in WBAN, design of two element antenna array with footprint of 34 mm x 52.3 mm, is constructed to achieve beam steering and the performance metrics are evaluated. The proposed flexible antenna offers large gain and high impedance bandwidth simultaneously. The prototype of the simulated antenna is fabricated and the simulation results are validated using experimental measurements. The measurement and simulation results are found in good agreement.

A Bidirectional Same Sense Circularly Polarized Endfire Antenna Array With Polarization Reconfigurability

In this communication, a bidirectional same sense circularly polarized (Bi-SSCP) endfire antenna array with reconfigurable polarization is proposed and implemented. First, a circular polarization (CP) reconfigurable endfire antenna element is realized by adopting two pairs of switchable electric dipoles, which have a 180° phase difference inherently. Along with the fixed magnetic dipole, the endfire antenna element can work at two CP states, i.e., left-hand CP (LHCP) and right-hand CP (RHCP) by switching the states of the two electric dipoles. Then, a Bi-SSCP endfire antenna array with polarization diversity is developed by using two identical endfire antenna elements placed back-to-back with a single feeding probe. For verification, prototypes of the designed endfire antenna element and Bi-SSCP endfire antenna array are fabricated and measured. The measured results show reasonable agreement with the simulated ones. The measured overlapped bandwidth for 10 dB return loss and 3 dB axial ratio of the Bi-SSCP endfire antenna array is from 5.7 to 5.9 GHz for the two CP states.

Analysis of phased array antenna system via spherical harmonics decomposition

Spherical phased-array antenna has hemispherical scan coverage for transmission of satellite imagery data at high bit rates to the ground station. Different conditions have been assigned based on their effects on the overall performance of the communication link. Reliability analysis consequently becomes an important requirement of any system onboard a satellite. Although the phased array and some connected algorithms have been presented in the literatures; however, there is no extensive systematic and theoretical performance evaluation framework formulated. In this work, the authors present new method that efficiently and effectively analyses the statistical performance of phased-array antenna systems using spherical harmonics expansion approach. Specifically, the errors caused by limited antenna element number, measurement noise of antenna, imprecision in phased-array antenna elements positioning, and spatial aliasing are systematically and theoretically benchmarked via simulations. Spatial sampling mechanisms for the positioning of array antenna elements on a sphere are presented and evaluated. This study proposed design guide and analysis for spherical phased-array antenna systems, and antenna arrays that do not employ spherical harmonics explicitly.

Shape Optimization of Low-Element Antenna Arrays Based on the Minimization of the Azimuthal or Elevation Angles According to the Lower Cramer-Rao Bound

This study proposes a method for designing optimally shaped antenna arrays from the perspective of error reduction of azimuthal or elevation angles for the identification of the direction of detected radio signals. The accuracy is determined by the lower Cramer–Rao bound, which is a statistical estimate of the error dispersion. It is the level below which it is impossible to access the signal regardless of the direction identification algorithm used. Thus, the purpose of this study is to build an antenna array in which the locations of the elements allow the minimization of the dispersion errors pertaining to the directionality of the detected radio signals. The proposed method minimizes the generalized expression of the lower Cramer–Rao bound. It shows that the accuracy of the identification of the radio direction is inversely proportional to the sum-of-the-squared differences between the coordinates of all omnidirectional elements along the x–, y–, and z–axes. Based on the estimated location area of the signal source, the arrangement of the antenna array elements is optimized in accordance with the maximum likelihood function that constitutes the basis of the lower Cramer–Rao bound. The optimization is based on the maximization of the probability of estimation. Accordingly, a study on the Multiple Signal Classification method is conducted and it shows that the accuracy of the direction identification can be increased up to 10-fold in comparison with similar, conventional (uniform), circular arrays.

Verification of Performances Enhancement by Array Configuration Technique in Patch Antenna Design for Energy Harvesting Applications

This paper presented the analysis of element in designing a micro strip patch antenna. A single element of the circular patch antenna and 1x2 array elements of circular patch antennas were simulated, fabricated, measured, analyzed, and discussed in this work. Array configuration study is the essence of this research. In order to improve the performances of an antenna, the implementation of array configuration is one of the techniques in designing the patch antenna. Based on the results, it has been verified that an array configuration technique works in enhances and improves the patch antenna performances. This paper also discussed the fabrication process involves and comparison of performances between simulation and measurement.

Miniaturised MIMO antenna array of two vertical monopoles embedded inside a planar decoupling network for the 2.4 GHz ISM band

This study introduces a fundamentally new approach to suppress mutual coupling among two closely-spaced vertical monopole elements of a multiple-input multiple-output antenna array. The 40 × 40 × 1.27 mm decoupling and matching element consists of a single planar ring resonator acting as a stop-band filter along with two tuning strips printed on an ungrounded substrate surrounding a two-element co-planar waveguide-fed monopoles separated by 8 mm ( λ 0 /16) at 2.45 GHz. Measurements reveal 14.2% bandwidth centred at 2.395 GHz over which the decoupling is below 20 dB, and -10-dB impedance bandwidth of 19.5% centred at 2.36 GHz. An improvement of 43 dB in isolation is observed at a frequency of 2.38 GHz. It is shown that the decoupled array provides a total realised gain of 1.69 dBi with excellent diversity performance as demonstrated by the low envelope correlation coefficient and improved link efficiency in highly-correlated channel environments due to the spatially orthogonal 3D radiation patterns. The capacity offered by the decoupled array is enhanced by 50, 22, 18 and 12% at signal-to-noise ratios of 5, 20, 30, and 50 dB, respectively, as compared to the coupled array in an urban micro-channel spatial model.

Frequency Diverse Array Radar: New Results and Discrete Fourier Transform Based Beampattern

In the phased-array radar (PAR) signals from each antenna are transmitted at the same carrier frequency, which yields narrowly focused only angle dependent beampattern. In contrast, in the frequency-diverse-array (FDA) radar signals from antenna array are generally transmitted at linearly increasing frequencies that yields range, time, and angle dependent beampattern. Reported literature on FDA radar missed the contribution of path-differences in the signal model due to the antenna array elements, which may lead to misleading results. In this work, incorporating missed path-differences, the signal model of FDA radar is corrected. Using the corrected signal model, it is shown that the instantaneous beampattern depends on the number of transmit antenna and average beampattern depends on the product of frequency-offset and pulse-duration. Moreover, to illuminate the desired region-of-interest for longer dwell time, discrete-Fourier-transform based low-complexity algorithm is proposed. In contrast to the conventional FDA radar's 'S' shaped beampattern, the beampattern of the proposed algorithm changes linearly with range. Simulation results compare the performance of our proposed algorithm with the existing ones and show the superiority of our proposed algorithm.

Secrecy Rate Analysis of Open-Loop Analog Collaborative Beamforming Under Position Estimation Error of Virtual Antenna Array

As the importance to guarantee confidentiality against security attacks by eavesdroppers has attracted significant attention, there has been much effort to enhance the security performance through cooperative beamforming (CB) in the context of physical layer security (PLS). In particular, analog CB (ACB), which requires vastly lower overhead compared to digital CB, can provide significantly higher secrecy rate compared to the PLS methods with co-located array. In this letter, we focus on ACB with open-loop architecture that requires low complexity, and consider phase offsets across multiple virtual antenna array (VAA) elements for ACB, which are caused by position estimation error of VAA. We investigate the impact of the phase offsets in ACB in terms of the secrecy throughput loss.

Construction and Implementation of Coaxial Probe Feed Microstrip Patch Array Antenna

This project aims for the construction and implementation of the Coaxial probe feed microstrip array antenna for radar applications. As the Continuous Wave Frequency Modulated (CWFM) radar can together transfer and to accept the signals, whatever that can be used for a bistatic radar for consideration of weather and temperature. The single patch, 1x4, 2x2, 4X4 coaxial probe feed is to design at a frequency of 1.48GHz by using RT duriod (r = 2.2) dielectric substrate for a bandwidth of 15MHz. For Microstrip antenna array elements is to connect with inter-component configuration of 0.8λ. in both horizontal and vertical directions. The microstrip patch array antenna was constructed and implemented by using HFSS (High Frequency Structure Simulator) and comparison of various descriptions of array antennas by using feeder network in circuit construction and to check the isolation between the two antennas for bistatic radar.

On-grid Adaptive Compressive Sensing Framework for Underdetermined DOA Estimation by Employing Singular Value Decomposition

In the field of Array Signal Processing, the problem of Direction of Arrival (DOA) estimation has attracted colossal attention of researchers in the past few years. The problem refers to estimating the angle of arrival of the incoming signals at the receiver end, from the knowledge of the received signal itself. Generally, an array of antenna/sensors is employed at the receiver for this purpose. In over-determined DOA estimation, the number of signal sources, whose direction needs to be estimated are usually lesser than half the number of antenna array elements, whereas the challenge is to estimate the DOAs in under-determined case, where the signal source number is quiet larger than the number of antenna array elements. This paper tackles such a problem by the application of multiple level nested array. Instead of subspace-based techniques for the estimation, sparse signal representation for Compressive Sensing (CS) framework is used, which eliminates the requirement of prior information about the source number and also the tedious task of computing the inverse of the covariance matrices. In this paper, we propose an adaptive approach for Least Absolute Shrinkage and Selection Operator (LASSO) with reduced number of computations by singular value decomposing of the received signal vector. The outcomes of this paper showcase that the presented algorithm achieves high degree of freedom (DOF), good resolution, minimum root mean square error and less computational complexity with increased speed of estimation.

Broadband planar antenna array for future 5G communication standards

This study presents a 5G antenna array for millimetre-wave communications. Overall size of the proposed antenna array is 40 × 15 mm 2 , and operates in a measured 23.76-42.15 GHz frequency range. A planar four-way feed network has been designed, optimised and used to excite the antenna array elements. The single element of the array is spiral monopole surrounded by a boundary of vias with extended ground plane in an inverted U-shaped manner. Hexagonal parasitic patches have been introduced at the backside to enhance impedance performance of the antenna element. Peak gain of the proposed antenna array is 11.5 dBi with radiation efficiency more than 83% in its entire operating band. The antenna gives a narrow beam-width of as low as 10.1°. Single element and its 1 × 4 array have been fabricated using standard printed circuit board (PCB) process. Measured results show excellent compliance with the simulated design objectives. The antenna is low cost, low profile with simple design and is capable of being deployed in future 5G communication mobile networks.

Development of an out-of-Focus Irradiator Based on a Phased Antenna Array for a Space Communications' Parabolic Reflector Antenna

Mirror antenna systems are widely used in satellite and space communication systems and radio astronomy. Development of these areas requires new efficient antenna systems' design. Possible technical solution for creating an effective mirror antenna is a “hybrid” scheme, when an adaptive phased antenna array is used as an irradiator. This paper is devoted to the development of an out-of-focus irradiator based on a phased antenna array for a space communications' parabolic reflector antenna. The aim of the work is to develop an optimal design of the irradiator with the choice of the structural element of the antenna array and experimental studies of the selected structural element.The wavefront recovery method was used as a tool for selecting the irradiator configuration. The idea of this method use is to reproduce the electromagnetic field of an incident plane wave with an irradiator in order to uniformly illuminate the aperture of the antenna mirror.In order to select the structural element of the irradiator several antennas were considered: a patch antenna, a flat spiral antenna, a conical spiral antenna. The requirements for the phased antenna array element were defined. The irradiator based on the above mentioned was simulated and the irradiator geometry was optimized according to the maximum gain criterion.The maximum gain was achieved for the irradiator based on conical spiral antennas and amounted to 30.8 dB, which for the considered mirror aperture of 2.4 m is close to traditional focal schemes. The results obtained make it possible to create an adaptive antenna system able to compensate for the deviations of the mirror's shape from the theoretical profile, as well as phase distortions in the atmosphere by changing the lattice weights coefficients.