Planar Circular Array Research Articles

Efficient Phase-Only Symmetric Pattern Synthesis for Linear and Circular Planar Arrays via Phase Perturbation in Low-Dimensional Space

Efficient Phase-Only Symmetric Pattern Synthesis for Linear and Circular Planar Arrays via Phase Perturbation in Low-Dimensional Space

Synthesis of Large Ultra-wideband Sparse Circular Planar Arrays Based on Rotationally Symmetric Structure

This article aims to improve the synthesis efficiency and radiation performance of large ultra-wideband (UWB) rotationally symmetric sparse circular planar arrays by using a modified differential evolution algorithm (MDEA). In the proposed MDEA, we adopt a new encoding mechanism in which an individual represents an element position expressed in polar coordinates. Importantly, such an encoding mechanism can facilitate the multiplication calculation for the array factor in the individual being updated while making it easier to meet the given minimum element spacing constraint. Moreover, to cater to the new encoding mechanism, some low-dimensional evolution operators are introduced to avoid the prematurity. In particular, the UWB rotationally symmetric sparse planar array synthesis problem is transformed into the sidelobe suppression problem of the array pattern at the highest frequency under the given array aperture, and the minimum spacing constraints is used to guarantee enough space to place physical UWB antenna elements. Two synthesis examples of UWB sparse planar arrays based on rotationally symmetric structures are presented. The results show that the peak sidelobe level (PSL) obtained by the proposed MDEA is significantly lower than the results obtained by some existing algorithms in an acceptable CPU time, which proves the effectiveness and superiority of the proposed MDEA.

Angle-of-Arrival Sensing Using a Machine Learning Enhanced Amplitude-Only System

A low-cost, low-complexity amplitude-only angle-of-arrival (AoA) sensor system is experimentally demonstrated. The sensor embeds a machine learning (ML)-in-the-loop procedure as the processing algorithm to extract both azimuth and elevation AoA information from a planar circular array. This has not been demonstrated in the open literature with the traditional AoA approaches, the same sensor’s dimensionality, field-of-view, or with as low system complexity. A four-channel receiver is designed, built, and assembled behind a simple four-element monopole array. The sensing components and ML algorithm are integrated to experimentally validate the hypothesis that both azimuth and elevation information can be determined from this simple, low-cost sensor. Moreover, a systematic procedure is introduced for the design of a deep neural network for the amplitude-only direction-finding application. Following this approach, major system complexity reductions are found—over 99% for the azimuth network and 98% for the elevation network, while still achieving 0.75° root mean square error (RMSE) in azimuth and 1.1° RMSE in elevation. Experimental results show up to 20% accuracy improvement in azimuth estimation, and 93% accuracy improvement in elevation, when compared to a lookup table-based method.

Direction of arrival and target scale estimation based on split beamforming algorithm

Based on the theory of split beamforming algorithm and the experimental data collected by circular array, this paper analyzes the characteristics of DOA and target size estimation. In this paper, the signal receiving model of planar circular array and the split beamforming algorithm are studied. Then, based on the data collected from the lake experiment, the DOA estimation results of conventional beamforming algorithm, multiple signal classification algorithm and split beamforming algorithm are analyzed, and the target scale estimation results of split beamforming algorithm is analyzed. The experimental data analysis shows that the split beamforming algorithm has good direction finding stability, and the target scale estimation error based on the split beamforming algorithm is small.

Wideband Monostatic Co-Horizontally Polarized Simultaneous Transmit and Receive Antenna Subsystem With Integrated Beamforming Network

A wideband monostatic simultaneous transmit and receive (STAR) antenna subsystem with high isolation and Co-horizontally polarized (Co-HP) omnidirectional radiation is presented. The antenna subsystem consists of a STAR antenna and a beamforming network (BFN). The STAR antenna consists of a planar circular array having four printed dipole elements surrounded by two groups of parasitic strips. The parasitic strips are used to improve the impedance bandwidth (IMBW) and reduce the gain variation in transmit (TX) and receive (RX) modes. To achieve high isolation, the four ports of the STAR antenna are excited with two orthogonal phase modes for TX and RX using the BFN. The BFN is a six-port network consisting of two 180° hybrid couplers, one 90° hybrid coupler, and a Wilkinson power divider. The 180° hybrid coupler is elaborately designed with low imbalances since it is most key to achieve high TX/RX isolation. Measured results show that the proposed STAR subsystem achieves a TX/RX overlapping IMBW of 4.71–6.2 GHz, and a 40 dB TX/RX isolation bandwidth of 4.81–5.88 GHz, while maintaining horizontally polarized omnidirectional radiation patterns for TX and RX over the entire operating frequency band.

Low Complexity Linear Detectors for Massive MIMO with Several Antenna Array Configurations: A Comparative Study

In Multiple-Input Multiple-Output (MIMO), there is multi-user interference because of the limited number of antennas at the Base Station (BS). Deploying more antenna elements at the BS to decrease the multi-user interference is a costly solution. Therefore, changing the configuration of antenna arrays at the BS is implemented as an alternative. In this paper, the impact of BS antenna array configurations on the performance of massive MIMO detection techniques is investigated where four different antenna array configurations are implemented at the BS: Uniform Linear Array (ULA), Uniform Rectangular Planar Array (URPA), Uniform Circular Array (UCA) and Uniform Circular Planar Array (UCPA). The performance of the massive MIMO system is based on the millimeter wave (mmWave) channel that depends on the array response vector of the BS antenna array configuration. To the best of our knowledge, this is the first paper to investigate the impact of antenna array configurations at the BS on the performance and the computational complexity of massive MIMO detection techniques. Numerical results show that the implementation of URPA at the BS with MMSE detection algorithm can achieve the best performance of BER=10−4 at SNR = 9dB. The deployment of the UCA at the BS with the successive over-relaxation (SOR), the Gauss-Seidel (GS), and the conjugate-gradient (CG) detection methods provides a performance of BER=10−4 at SNR = 12dB when the number of iterations equals eight. In the case of using the UCA at BS with the Richardson (RI) detection method, the number of iterations is required to be increased to achieve the same performance. To achieve BER=10−4, the detector based on the CG method has the lowest computational complexity while the RI method has the highest complexity.

Synthesis of Planar Circular Arrays with Quantized Amplitude Weights.

A new stepwise and radially processed method for synthesizing uniformly distributed circular planar arrays with quantized weights is proposed in this paper. This method is based on a generalized analytical equation describing that for high directivity focusing arrays, minimizing the weighted mean square error between the reference pattern and the synthesized pattern is equivalent to minimizing the mean square error between the radial cumulative distributions of the reference distribution and the synthesized distribution. This principle has been successfully performed for designing large concentric ring arrays, and in this paper, we extend its use for synthesizing uniformly distributed planar circular arrays with quantized weights. Various numerical examples and comparisons with several reported statistical methods in terms of the lowest Maximum SideLobe Level (MSLL) demonstrate the effectiveness of the proposed method.

Impact of different finite MIMO array geometries on system throughput with considering mutual coupling and edge effect between array elements

In this paper, the antenna array appropriate topologies and configurations are investigated to reduce the impact of large gain variation between array elements that is produced due to the mutual coupling. Moreover, the most appropriate antenna array topology that can realize a maximum system throughput and achieve fairness between users in terms of their spectral efficiency is determined. Our analysis focuses on the comparison between various array geometries (uniform planar array (UPA), circular array (CA), conformal array (CfA), uniform planar circular array (UPCA), centric planar circular array (CPCA) and, finally, conical array (CoA)) with half-wavelength dipole elements. The simulation results show that UPA, CA, and CfA have total efficiency around 96% at 2.6GHz. Moreover, all the proposed geometries have achieved Envelope Correlation Coefficient (ECC) less than 0.5, and high Diversity Gain (DG) that makes it suitable for MIMO. The CfA geometry has been elected as the most suitable topology, which can provide minimum gain variation, maximum system throughput, and achieve fairness between users’ spectral efficiency. Finally, curl antenna is considered in the designed antenna array to study the effect of antenna gain pattern. Two array geometries have been designed using the curl antenna, which are the UPA and the CfA. The CfA curl has insertion loss -30dB between the edge elements and achieve fairness index between the users up to 0.98733. Moreover, the results show that curl antenna geometries can achieve higher system throughput compared to half-wavelength dipole based array geometries.

Communication to a spinning CubeSat using a two‐mode planar circular array

This Letter presents a novel technique for establishing a robust communication link to a spinning un-stabilised small satellite such as a CubeSat. The authors propose a system that involves a multimode excited planar circular array radio combined with a 360° phase shifter that can electronically track the spinning CubeSat antenna and establish a communication link. The transmitter comprises a mode-generating Rotman lens and a circular array of microstrip patch antennas. The authors’ proposed approach combines two spatially orthogonal modes of the circular array. They first present the system architecture, then they design and realise a proof-of-concept experimentally validated module operating in C-band at 5.8 GHz.

Hybrid precoding for mmWave massive MIMO systems with different antenna arrays

In this paper, the performance of hybrid precoding is investigated for mmWave massive MIMO systems with different antenna arrays. The hybrid precoding with partially connected architecture (PCA) is adopted. The spectral efficiency (SE) and received energy efficiency (EE) are investigated by considering four types of antenna arrays, including uniform linear array (ULA), uniform rectangular planar array (URPA), uniform hexagonal planar array (UHPA), and uniform circular planar array (UCPA), respectively. We focus on analysis at the antenna response vector and utilize the idea of orthogonal matching pursuit algorithm to seek the optimal hybrid precoder. Furthermore, the trade-off of precoding architectures is studied between SE and received EE. Simulation results show that if the uniform planar array antenna is more concentrated, the SE and receive EE will be higher. Considering SE and received EE, the performance of planar arrays outperform linear array. There exist different optimal radio-frequency chain numbers to maximize the SE for planar array and linear array. In addition, the PCA can achieve relatively higher received EE while the SE is close to the fully connected architecture and the full digital architecture.

A circular planar frequency diverse array for monostatic radar applications

ABSTRACTFrequency diverse arrays (FDAs) with scanning features have recently been of interest to radar researchers. Different frequencies with different patterns applied to the properly arranged array elements lead to the range-angle dependent beampattern. In this paper, a monostatic radar system in which the transmitter is an FDA and the receiver is a phased array is proposed, with both of which being arranged in circular planar arrays. The elements of the FDA transmitter are located at several concentric rings. The elements frequency in each ring is the same and the frequency difference between the two adjacent rings is constant. The radius of each ring is proportional to the half-wavelength of the same ring. The presented structure produces a periodic range-angle dependent beampattern. By applying a non-uniform inter-ring frequency offset, a non-periodic beampattern is radiated. In the transmitter and receiver mode, the transmitted signal to the target is reflected back to the phased array receiver. Similar to the transmitter, the receiver is composed of several concentric rings located after the last ring of the transmitter and the radius of each ring is proportional to the half-wavelength of central frequency.

Switched-Beam Endfire Planar Array With Integrated 2-D Butler Matrix for 60 GHz Chip-to-Chip Space-Surface Wave Communications

A two-dimensional Butler matrix feed network is designed, implemented, and integrated with a 60 GHz 2 × 2 circular patch planar array for chip-to-chip communications. The realized antenna module is a thin multilayer microstrip structure with a footprint small enough to fit over a typical multicore chip. The network enables endfire (azimuthal) scan of the array main beam in the four diagonal directions, which is demonstrated for the first time in this letter. The antenna module provides a seamless and practical way to achieve reconfigurable interchip communication in multicore multichip (MCMC) systems. A hybrid space-surface wave interconnect is proposed that takes advantage of surface-wave coupling. The matrix is a four-input, four-output, i.e., 4 × 4, network consisting of four interconnected quadrature (90°) hybrid couplers. A multiantenna module (MAM) consisting of five antenna modules that emulates diagonal interchip communication in MCMC systems is fabricated. The simulation and measurement of transmission coefficients between the antenna modules on the MAM are performed and compared.

Single Snapshot Super-Resolution DOA Estimation for Arbitrary Array Geometries

We address the problem of search-free direction of arrival (DOA) estimation for sensor arrays of arbitrary geometry under the challenging conditions of a single snapshot and coherent sources. We extend a method of searchfree super-resolution beamforming, originally applicable only for uniform linear arrays, to arrays of arbitrary geometry. The infinite dimensional primal atomic norm minimization problem in continuous angle domain is converted to a dual problem. By exploiting periodicity, the dual function is then represented with a trigonometric polynomial using a truncated Fourier series. A linear rule of thumb is derived for selecting the minimum number of Fourier coefficients required for accurate polynomial representation, based on the distance of the farthest sensor from a reference point. The dual problem is then expressed as a semidefinite program and solved efficiently. Finally, the searchfree DOA estimates are obtained through polynomial rooting, and source amplitudes are recovered through least squares. Simulations using circular and random planar arrays show perfect DOA estimation in noise-free cases.

Non-uniform single-ring antenna array design using wavelet mutation based novel particle swarm optimization technique

Side lobe level (SLL) reduction is the key challenge in antenna array synthesis. In order to achieve low SLL in array pattern, many conventional optimization methods are proposed to handle complex, nonlinear and non-differentiable array factor of antenna array. In this article, we present an improved optimization scheme; Wavelet Mutation based Novel Particle Swarm Optimization (NPSOWM) for the synthesis of various single-ring planar arrays of isotropic antenna elements. The primary objective is to achieve the radiation pattern with minimum SLL and maximum directivity for the non-uniform, planar circular array (CA), hexagonal array (HA) and elliptical array (EA) antenna. The array pattern synthesis is done based on two parameters of the array; namely, excitation amplitude and element spacing. Two design examples are presented which illustrate the effectiveness of the NPSOWM algorithm. As compared with conventional optimization techniques like genetic algorithm (GA), simulated annealing (SA), particle swarm optimization (PSO) and its variant NPSO, NPSOWM outperforms with the goal of maximum SLL suppression.

A Beam Forming Method Based on Amplitude Weighting of Uniform Circular Array

The uniform circular planar array (UCA) has lots of advantages what linear arrays and other surface arrays don't have. However, because of its limitations, such as the high side-lobe level and low zero depth, the application on controlling array space direction by beam forming has been limited. Considering the characteristics of UCA, the receiving UCA's signal model is established in this paper. The influence factors of UCA's beam will be found out on the basis of theoretical derivation. A new method, that can improve the performance of the UCA beam directivity by amplitude weighting, is proposed in this paper. The theoretical derivation results and simulation results improved that the method could have a better ability in side-lobe suppression, and the new method could make the UCA to have a good application prospect.

Array Antennas With Jointly Optimized Elements Positions and Dimensions Part II: Planar Circular Arrays

The paper describes a deterministic algorithm based on simple analytical equations for designing planar circular sparse array antennas where the positions and the dimensions of the radiating elements are jointly exploited and optimized. The proposed solution permits addressing one of the main limitations associated to sparse arrays, i.e., their poor aperture efficiency especially when patterns with low sidelobe levels are obtained using only the density of the elements avoiding any amplitude tapering. The accuracy of the method is guaranteed by the fact that the achieved directivity differs from the target value, associated to a continuous reference aperture distribution, by a quantity asymptotically equal to the factor π/4 (corresponding to about -1.05 dB) representing the filling factor of a circular planar array organized in concentric rings populated by circular apertures. As required for several applications, the method includes the possibility to add a constraint on the maximum scanning angle with respect to the boresight direction.

Evaluation of beam steering in circular planar array of coupled microwave oscillators

A Green's function to describe the time behavior of the locking phases in a circular planar array of mutually coupled microwave oscillators is proposed. Using this Green's function the dynamic behavior of the array can be described for any arbitrary free running frequency of elements of the oscillator array. Beam steering is realized via detuning the edge oscillators of the array from a reference frequency and the beam direction is controlled by the amount of detuning for each oscillator at the edge. Some detuning functions such as sinusoidal, triangular and rectangular ones have been applied and, the resulting array patterns are compared with one another. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. © 2011 Wiley Periodicals, Inc.

Arbitrary Footprints from Arrays with Concentric Ring Geometry and Low Dynamic Range Ratio

A common method of antenna array synthesis uses least-squares approximation to fit the radiation pattern of the array to a set of samples of an ideal desired pattern Fid . However, it has long been known that discontinuities in Fid prevent close approximation, and that sampling a target pattern Ftar that approximates Fid can afford better results. Here we show, for the case of circular planar arrays, that an appropriate target pattern can be obtained by modification of a Taylor pattern for a circular aperture.

Arbitrary footprint patterns obtained by circular apertures

The proposed quasi-analytical method undertakes the shaping of a desired footprint as a composition of several /spl phi/-symmetric circular Taylor patterns exhibiting flat-topped beams. The final pattern is obtained after sampling the obtained circular aperture for circular grid planar arrays. A square and a rectangular footprint pattern, both radiated by a planar array with 1246 elements, demonstrate the performance of the technique.

Theoretical Accuracy of Doppler Navigation Sonars and Acoustic Doppler Current Profilers

This paper addresses the problem of Doppler shift estimation in Doppler sonar systems. The analysis focuses on the single-beam geometry formed by a circular planar array and considers both narrow-band (or so-called incoherent) and wide-band (or coherent) Doppler sonars, transmitting, respectively, one long continuous-wave pulse and a train of short continuous-wave pulses. The correlation function of the reverberation signal at the beam output is derived for volume reverberation. Directive transmission or reception and a combination of both is considered. Estimation theory is applied to derive the Cramer-Rao bound of the Doppler parameter estimate. The effect of pulse duration, sonar geometry, beamwidth, and signal-to-noise ratio are discussed. The accuracy of coherent and incoherent systems is compared for a specific case.