Multifunctional Reconfigurable Antenna Research Articles

Notice of Violation: A Dual-Band Beam Steering Multifunctional Reconfigurable Antenna Optimized by Non-Dominated Sorting Genetic Algorithm (NSGA-II) for Wi-Fi 6 Applications

Notice of Violation <br><br>“A Dual-Band Beam Steering Multifunctional Reconfigurable Antenna Optimized by Non-Dominated Sorting Genetic Algorithm (NSGA-II) for Wi-Fi 6 Applications” <br> by Junlin Pu, Bing Zhang, Yanping Zhou, Kama Huang, Tiancang Zhang, and Juan Yang <br> published in the IEEE Transactions on Antennas and Propagation, Digital Object Identifier: 10.1109/TAP.3209180 <br><br>The authors of this paper violated the IEEE’s Publication Principles. An author name was included in the Early Access version of this paper who did not contribute to the work and was added without their consent. The non-contributing author’s name has been removed <br><br> <br/> A design and optimization method to realize a beam steering multi-functional reconfigurable antenna (MRA) working at two independent frequencies with an octave range frequency span is proposed. While the conventional MRAs (multi-functional reconfigurable antennas) have lacked frequency reconfigurability, the proposed design and optimization method manage to realize a beam steering MRA at two operating frequencies. To verify, a dual-band beam steering MRA working at 2.45 GHz and 5.3 GHz is designed to be compatible with the IEEE 802.11 ax for Wi-Fi 6 applications. The proposed MRA consists of a feed layer, a dual-band aperture-coupled driven patch, and a parasitic pixel layer. The driven patch is designed to ensure sufficient coupling with the parasitic layer at both two frequencies. The parasitic layer consists of a 6×6 planar array of rectangular pixels interconnected by positive-intrinsic-negative (PIN) diode switches. By optimizing the switches’ modes with the non-dominated sorting genetic algorithm (NSGA-II), the MRA’s beams are regulated at directions of θ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_xz</i> =0°, ±30° for both 2.45 GH and 5.3 GHz. This work manages to explore the potential of the traditional MRA for frequency reconfigurability applications, besides its widely-reported radiation pattern reconfigurability. The proposed MRA is a capable candidate as a Wi-Fi 6 router antenna. The design and optimization method of the MRA based on NSGA-II by Python are summarized systematically in an easy-to-follow manner, which is instructive for MRA designers.

Reconfigurable Bidirectional Beam-Steering Aperture With Transmitarray, Reflectarray, and Transmit-Reflect-Array Modes Switching

The design and experiment of an electronically reconfigurable bidirectional spatially-fed array are presented, which combines the functionalities of reconfigurable transmitarray (TA), reflectarray (RA), and transmit-reflect array (TRA). First, we demonstrate a novel bidirectional unit cell composed of a tunable resonant layer between a pair of orthogonally oriented metal gratings. Two positive-intrinsic-negative (PIN) diodes are integrated into the tunable resonant layer to achieve the 1-bit phase resolution in either transmission or reflection mode. Based on the proposed unit cell, a 16 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times16$ </tex-math></inline-formula> -element array arranged in a square grid, which can be controlled independently by a field programmable gate array (FPGA)-based digital control circuit, is excited by a linearly-polarized horn to show the beam steering ability of reconfigurable TA and RA. To realize TRA function integration with the bidirectional beam independent steering simultaneously, the method based on superposition of the aperture fields (SAF) on the aperture is used. In SAF design, the entire aperture is divided into transmission and reflection modes co-existing, and the arrangement and phase distribution are optimized by particle swarm optimization (PSO) algorithm to achieve minimum sidelobe levels (SLLs) and peak gain of bidirectional beam. The measured results of the prototype demonstrate that the antenna can steer bidirectional beam both in simultaneous and time division operating modes, which is not reported to the best of the authors’ knowledge. Our proposed method opens a new avenue for the design of high-performance multifunctional reconfigurable antenna systems.

A Novel Linear Sparse Array with Reconfigurable Pixel Antenna Elements

In this paper, on the basis of multifunctional reconfigurable pixel antenna (RPA) elements, a novel linear sparse array with an attractive compound reconfigurability is presented. It has the potential advantages of its beam scanning with low gain fluctuation, low sidelobe in two orthogonal planes, and polarization reconfigurable performance. Specifically, an RPA with simultaneous polarization and pattern reconstruction capabilities, consisting of the driven patch and the parasitic pixels on the same layer of dielectric substrate, is firstly designed, which can work in several operation modes corresponding to steerable beam directions θ=0°;θxoz=25°, 45°;θyoz=15° with two circular polarizations in X-band. Cross-slot coupling feed is used to improve polarization reconstruction capability and reduce the complexity of hybrid reconstruction topology optimization. Then, those RPAs are integrated into the 1×8 linear sparse array to realize the reconfiguration of two circular polarizations and beam steering in xoz- and yoz-plane. Simulation results show that the gain fluctuation and sidelobe level of the array during beam scanning have significant advantages over the previous phased array, and the generation of antenna grating lobes is avoided. Moreover, both RPA element and RPA array prototypes have been fabricated and measured to testify the efficiency. The measured results agree well with the simulated ones, which indicates the application potential in the field of modern wireless communication system of the proposed linear sparse array.

A Beam-Steering Reconfigurable Antenna for WLAN Applications

A multifunctional reconfigurable antenna (MRA) capable of operating in nine modes corresponding to nine steerable beam directions in the semisphere space $\{-30^{\circ},0^{\circ}, 30^{\circ}\}; \phi \in \{0^{\circ}, 45^{\circ}, 90^{\circ}, 135^{\circ}\})$ is presented. The MRA consists of an aperture-coupled driven patch antenna with a parasitic layer placed above it. The surface of the parasitic layer has a grid of 3 $\,\times\,$ 3 electrically-small square-shaped metallic pixels. The adjacent pixels are connected by PIN diode switches with ON/OFF status to change the geometry of the parasitic surface, which in turn changes the current distribution on the antenna, thus provides reconfigurability in beam steering direction. The MRA operates in the IEEE 802.11 frequency band (2.4—2.5 GHz) in each mode of operation. The antenna has been fabricated and measured. The measured and simulated impedance and radiation pattern results agree well indicating an average of ${\sim} 6.5$ dB realized gain in all modes of operation. System level experimental performance evaluations have also been performed, where an MRA equipped WLAN platform was tested and characterized in typical indoor environments. The results confirm that the MRA equipped WLAN systems could achieve an average of 6 dB Signal to Noise Ratio (SNR) gain compared to legacy omni-directional antenna equipped systems with minimal training overhead.

Multi‐band and multi‐polarised reconfigurable antenna for next generation mobile communication base‐station applications

A novel multi-band reconfigurable antenna for a mobile base-station is proposed. This antenna can be operated in three bands using three radiators, but the radiators are physically combined into one body in consideration of size reduction and optimal performance. Radiator 1 is a square patch structure and is operated in 0.824-0.894 GHz for cellular service. Radiator 2 provides multiple mobile services in 1.75-2.48 GHz for personal communication service (PCS), wideband code division multiple access (WCDMA), world interoperability for microwave access (WiMAX) and WiFi, and thus has a wideband characteristic using a printed dipole structure. Finally, radiator 3 has a stacked structure composed of a radiating and a parasitic patch in 3.3-3.6 GHz for WiMAX2. Radiator 1 has a cylindrical cavity in the centre of the patch, and is designed not to degrade electrical performance, and radiator 3 is embedded in the cavity of radiator 1. Radiator 2 is composed of four printed dipoles and is vertically stacked on radiator 1 around radiator 3 with a rectangular formation. All radiators can provide dual-polarisation using multi-ports controlled by a switching circuit with a control program. In the switching circuit, there are two MEMS switches for band selection. Using the proposed structure, the authors realise a novel multi-functional reconfigurable antenna using three individual radiators.

A New Class of Antenna Array With a Reconfigurable Element Factor

A parasitic layer-based multifunctional reconfigurable antenna array (MRAA) formed by the linear combination of four (4 × 1) identical multifunctional reconfigurable antenna (MRA) elements is presented. Each MRA produces eight modes of operation corresponding to three steerable beam directions (θ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xz</i> =-30 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> , 0 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> , 30 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> ) with linear and circular polarizations in <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> plane and another two steerable beam directions (θ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">yz</i> =-30 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> , 30 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> ) in <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> plane with linear polarization. An individual MRA consists of an aperture-coupled driven patch antenna with a parasitic layer placed above it. The surface of the parasitic layer has a grid of 4 × 4 electrically-small rectangular-shaped metallic pixels. The adjacent pixels can be connected/disconnected by means of switching resulting in reconfigurability in beam-direction and polarization. A 4 × 1 linear MRAA operating in the ~ 5.4-5.6 GHz is formed by the optimized MRA elements. MRA and MRAA prototypes have been fabricated and measured. The measured and simulated results agree well indicating ~ 13.5 dB realized array gain and ~ 3% common bandwidth. The MRAA presents some advantages as compared to a standard antenna array: MRAA alleviates the scan loss inherit to standard antenna arrays, provides higher gain, does not need phase shifters for beam steering in certain plane, and is capable of polarization reconfigurability.

A Parasitic Layer-Based Reconfigurable Antenna Design by Multi-Objective Optimization

A parasitic layer-based multifunctional reconfigurable antenna (MRA) design based on multi-objective genetic algorithm optimization used in conjunction with full-wave EM analysis is presented. The MRA is capable of steering its beam into three different directions (θi = -30°, 0°, 30°) simultaneously with polarization reconfigurability (Pj = Linear, Circular) having six different modes of operation. The MRA consists of a driven microstrip-fed patch element and a reconfigurable parasitic layer, and is designed to be compatible with IEEE-802.11 WLAN standards (5-6 GHz range). The parasitic layer is placed on top of the driven patch. The upper surface of the parasitic layer has a grid of 5 5 electrically small rectangular-shaped metallic pixels, i.e., reconfigurable parasitic pixel surface. The EM energy from the driven patch element couples to the reconfigurable parasitic pixel surface by mutual coupling. The adjacent pixels are connected/disconnected by means of switching, thereby changing the geometry of pixel surface, which in turn changes the current distribution over the parasitic layer, results in the desired mode of operation in beam direction and polarization. A prototype of the designed MRA has been fabricated on quartz substrate. The results from simulations and measurements agree well indicating ~8 dB gain in all modes of operation.

A Multifunctional Reconfigurable Pixeled Antenna Using MEMS Technology on Printed Circuit Board

A multifunctional reconfigurable pixeled antenna that uses microelectromechanical switches (MEMS) and operates within the 4-7 GHz frequency band is presented. The proposed antenna is a highly reconfigurable planar surface radiator composed of an npx × npx matrix of metallic pixels interconnected through MEMS switches. The antenna can be reconfigured to perform multiple functions such as: frequency tuning, pattern diversity, and polarization adaptation. A functional prototype using integrated MEMS switches was fabricated on a printed circuit board substrate, to show its feasibility and the impact of MEMS switches during operation. Simulated and measured data of the return loss and radiation characteristics of the antenna are presented.

Reduced Overhead Training for Multi Reconfigurable Antennas with Beam-Tilting Capability

This paper proposes low overhead training techniques for a wireless communication system equipped with a Multifunctional Reconfigurable Antenna (MRA) capable of dynamically changing beamwidth and beam directions. A novel microelectromechanical system (MEMS) MRA antenna is presented with radiation patterns (generated using complete electromagnetic full-wave analysis) which are used to quantify the communication link performance gains. In particular, it is shown that using the proposed Exhaustive Training at Reduced Frequency (ETRF) consistently results in a reduction in training overhead. It is also demonstrated that further reduction in training overhead is possible using statistical or MUSIC-based training schemes. Bit Error Rate (BER) and capacity simulations are carried out using an MRA, which can tilt its radiation beam into one of N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dir</sub> = 4 or 8 directions with variable beamwidth (≈2π/N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dir</sub> ). The performance of each training scheme is quantified for OFDM systems operating in frequency selective channels with and without Line of Sight (LoS). We observe 6 dB of gain at BER = 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> and 6 dB improvement in capacity (at capacity = 6 bits/sec/subcarrier) are achievable for an MRA with N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dir</sub> = 8 as compared to omni directional antennas using ETRF scheme in a LoS environment.