Beam Scanning Function Research Articles

Far-field steering of beams based on dynamic encoding metasurface

Programmable metasurfaces can realize dynamic control of electromagnetic waves. We propose a 1-bit programmable metasurface based on row-column-encoded dynamic control. The programmable metasurface encodes the cell structure with a sequence of row-column patterns, and controls the on–off of diodes via a field-programmable gate array (FPGA). The proposed programmable metasurface can achieve a 180° phase change of the cell structure, and the reflectivity can reach more than 90 %. We experimentally fabricated the designed programmable metasurface and tested it for far-field scattering. When the incident electromagnetic wave frequency is 11.7 GHz, the programmable metasurface realizes the beam scanning function, and the experimental results are in good agreement with the theoretical results.

Design of a phased array with a beam scanning functionality based on the arithmetic phase difference

The demand for phased array antennas increases not only for the traditional military industry but also in commercial areas such 5G mobile network platforms, Internet of Things (IoT), and satellite communication applications. In this paper, a phased array with beam scanning function is designed based on arithmetic phase difference between array elements. In the design process, the initial complex model is simplified into a simple element model with periodic conditions, which makes the analysis faster and more efficient. Finally, two phased array designs based on microstrip patch antenna are studied, and the simulation results verify the correctness of the design method.

A Tri-Band Shared-Aperture Antenna for (2.4, 5.2) GHz Wi-Fi Application With MIMO Function and 60 GHz Wi-Gig Application With Beam-Scanning Function

This article presents the design and the realization of a tri-band shared-aperture antenna operating at 2.4, 5.2, and 60 GHz. It puts these three bands of antennas within the same radiating aperture and then realizes the Wi-Fi application with MIMO function and the Wi-Gig application with beam-scanning function simultaneously. It consists of two dual-band printed inverted-F antennas (PIFAs) and two SIW leaky wave antennas. By using the structure-reused technology, PIFA for the Wi-Fi application and the SIW antenna for the Wi-Gig application can share the same radiator without adding an extra aperture area. Thus, the ratio of the radiating aperture utilization can be improved greatly. In addition, MIMO technology is also applied to the Wi-Fi antenna design. The envelope correlation coefficients (ECCs) calculated from the simulated and measured data are all lower than 0.04. The measured radiation efficiencies are 74% to 95% and 76% to 95% within these two bands, respectively. Moreover, due to the optimal layout of the whole design, the Wi-Gig antenna can obtain high gain and wide range of beam coverage at the same time. The measured peak gain is 12.29 dBi, and the beam coverage is ±36° from 57 to 64 GHz.

Polarization-Reconfigurable Leaky-Wave Antenna With Continuous Beam Scanning Through Broadside

A simple single-layer reconfigurable leaky-wave antenna (LWA) is presented that has polarization agility and beam-scanning functionality. This LWA system realizes a scanned beam that can be switched between all of its linear polarization (LP) and circular polarization (CP) states using only one dc biasing source. A slot-loaded substrate-integrated waveguide (SIW)-based LWA is first explored to attain CP performance with continuous beam scanning through broadside. This CP LWA realizes a measured CP performance with a 3 dB gain variance within 2.75–3.35 GHz for scan angles ranging from −28.6° to +31.5°. A row of shorted stubs is then incorporated into the CP LWA to obtain similar LP performance. Finally, by introducing p-i-n diodes into this LP LWA configuration to facilitate reconfigurable connections between the main patch and the shorted stubs, the radiated fields can be switched between all of its CP and LP states. The measured results of all three antennas confirm their simulated performance. It is demonstrated that the main beam of the polarization-reconfigurable LWA can be scanned from −31.5° to +17.1° with gain variations between 9.5 and 12.8 dBic in its CP state and from −34.3° to +20° with them between 7.8 and 11.7 dBi in its LP state.

Nonreciprocal optical links based on time-modulated nanoantenna arrays: Full-duplex communication

Interference of transmitted and received signals hinders the simultaneous functionality of a conventional optical antenna as a transmitter and receiver which is required for full-duplex communication. The full-duplex communication schemes enabled by dense wavelength division multiplexed optical networks require distinct transmitter/receiver components operating at different wavelengths which increase the cost, complexity, and footprint of the physical layer. In this work, we demonstrate that an array of nanoantennas with leaky-wave architecture based on spatiotemporal modulation establishes nonreciprocal optical links which can reject the interference of transmitted and received signals by isolating the frequency of transmission and reception modes. For this purpose, we integrate indium-tin oxide into plasmonic nanodipoles which allows for realization of time-modulated nanoantennas in near-infrared frequency regime through electrical modulation of charge carrier density with radio-frequency signals. The radiation characteristics of individual nanoantennas and modal properties of nanoantenna arrays are rigorously studied through linking of charge transport and electromagnetic models. To this end, we extend the formulation of discrete dipole approximation as the standard modeling tool for electromagnetic scattering from nanoantenna arrays to treat realistic time-modulated structures with drastically different timescales between optical and modulation frequencies. The operation of spatiotemporally modulated array antennas in transmission and reception modes is investigated. Moreover, electrical beam-scanning functionality and dependence of antenna characteristics to modulation parameters and wavelength are demonstrated. It is rigorously established that such array antennas can operate as full transceivers by separating the transmitted and received signals propagating along the same direction through down conversion and up conversion of the frequency. Our results provide a route toward realization of optical antenna systems capable of full-duplex communication and real-time beam scanning which can increase the capacity and decrease the complexity of optical networks.

A Unidirectional Beam-Scanning Antenna Excited by Corrugated Metal–Insulator–Metal Ground Supported Spoof Surface Plasmon Polaritons

A unidirectional beam-scanning antenna is proposed. The antenna is constructed by placing a series of circular radiating elements on a 2-mm dielectric slab backed by a corrugated metal–insulator–metal (CMIM) ground. The CMIM structure is introduced not only as a ground but also as a waveguide for spoof surface plasmon polaritons (SSPPs). The beam-scanning function is realized through the phase difference of SSPPs fed to the radiating elements. In addition, the CMIM ground reflects downward radiation waves onto upward space, leading to a unidirectional pattern and enhanced radiation gain. Both the numerical simulation and experiment results demonstrate the good performance of the proposed antenna. They validate that the antenna achieves unidirectional radiation and scanning angle of 57° when the frequency varies from 6.2 to 9 GHz with the frequency sensitivity of 20.4°/GHz. The realized gains are higher than 8.11 dBi over the entire band. Compared with the published works, this paper provides a novel feed technology, a simpler structure, and higher frequency sensitivity. The high-frequency sensitivity is beneficial to reduce the bandwidth burden of the entire system. The antenna has potential applications in satellite communication.

A novel half mode substrate integrated waveguide leaky‐wave antenna with continuous forward‐to‐backward beam scanning functionality

A half-mode substrate integrated waveguide (HMSIW) leaky-wave antenna with a folded ground is proposed in this article to realize continuous beam scanning from backward to forward direction. This leaky-wave antenna is designed within its scanning region from −27° to 23° as the operating frequency increases from 10 to 14 GHz. In addition, this antenna has a high radiation gain even at broadside. As a folded ground is used to reduce the energy leakage from the open boundary in HMSIW, the transverse size of the proposed antenna could be further miniaturized against other reported HMSIW leaky-wave antennas. Our results show that the radiation gain of the antenna can stably vary from 10 to 11.5 dB by using the open-stopband suppressed technique at broadside. Measured results are found in good agreement with simulated ones over a wide frequency range.

A Compact, Wideband, Two-Port Substrate-Integrated Waveguide Antenna With a Central, Double-Slotted, Metallic Plate Flanked by Two Paired of Corrugations for Radar Applications

This communication proposes a compact, wideband, two-port substrate-integrated waveguide (SIW) antenna with a central, double-slotted metallic plate flanked by two paired corrugations for radar applications. The proposed antenna uses a two-layer structure, with a slotted metallic plate with corrugations on the top layer and an FR-4 substrate SIW on the bottom layer. The antenna has compact dimensions of 63 mm $\times$ 54 mm ( $2.32\lambda _{0} {\times}\,\, 1.99\lambda _{0}$ ) with a low profile of 7 mm ( $0.26\lambda _{0}$ ). To understand the operating principle of the two-port SIW antenna clearly, modal analysis is performed for single-port SIW antenna. The antenna satisfies a −10 dB reflection coefficient from 10.15 to 11.58 GHz. Although the separation between the two central slots is minimized to 4 mm ( $0.14\lambda _{0}$ ), the isolation performance remains excellent (less than −30 dB). The gain enhancement, with a narrow beam pattern for radar applications, is realized using constructive superposition of in-phase electromagnetic energy from the two slots. In addition, because the antenna has two ports, it also has a beam scanning function from −12° to +12° in its boresight direction. The experimental and simulated results from the proposed antenna are in good agreement.

Low-Profile Spoof Surface Plasmon Polaritons Traveling-Wave Antenna for Near-Endfire Radiation

This paper proposes a low-profile and highly efficient endfire radiating travelling-wave antenna based on spoof surface plasmon polaritons (SSPPs) transmission line. The aperture is approximately $0.32\lambda_0\times0.01\lambda_0$ where $\lambda_0$ is the space wavelength at the operational frequency 8 GHz. This antenna provides an endfire radiation beam within 7.5-8.5 GHz. The maximum gain and total efficiency reaches 9.2 dBi and $96\%$, respectively. In addition to the endfire operation, it also provides a beam scanning functionality within 9-12 GHz. Measurement results are finally given to validate the proposed SSPPs antenna.

Determining Projections of Grain Boundaries from Diffraction Data in Transmission Electron Microscope.

Grain boundaries (GB) are characterized by disorientation of the neighboring grains and the direction of the boundary plane between them. A new approach presented here determines the projection of GB that can be used to determine the latter one. The novelty is that an additional parameter of GB is quantified in addition to the ones provided by the orientation maps, namely the width of the projection of the GB is measured from the same set of diffraction patterns that were recorded for the orientation map, without the need to take any additional images. The diffraction patterns are collected in nanobeam diffraction mode in a transmission electron microscope, pixel-by-pixel, from an area containing two neighboring grains and the boundary between them. In our case, the diffraction patterns were recorded using the beam scanning function of a commercially available system (ASTAR). Our method is based on non-negative matrix factorization applied to the mentioned set of diffraction patterns. The method is encoded in a MATLAB environment, making the results easy to interpret and visualize. The measured GB-projection width is used to determine the orientation of the GB-plane, as given in the study by Kiss et al.

One way optical waveguides for matched non-reciprocal nanoantennas with dynamic beam scanning functionality

Matching circuits for waveguide-nanoantenna connections are difficult to implement. However, if the waveguide permits only one-way propagation, the matching issue disappears since back-reflections cannot take place; the feed signal is converted to radiation at high efficiency. Hence, a terminated one-way waveguide may serve as an assembly consisting of a waveguide, a matching mechanism, and an antenna. Since one-way structures are inherently non-reciprocal, this antenna possesses different transmit and receive patterns. We test and demonstrate this concept on a recently suggested new class of one-way plasmonic waveguides and present an additional significant dynamic beam scanning functionality.

Design of a T-shaped terahertz imager

为了获得较高的帧速率以及降低成本，提出了一种带有波束扫描功能的T形太赫兹成像系统.系统包含两个共极化扇形波束扫描天线，它们以T字形正交摆放.收发天线具有基本相同的内部结构，由角锥喇叭馈源、产生扇形波束的椭圆主反射体以及用于实现波束扫描功能的旋转次反射体构成，而所有这些元件都镶嵌在两个平行金属板之间.给出了T形太赫兹成像系统的具体设计，提出了设计高性能扇形波束扫描天线的系统化方法，最后给出了一些实验的成像结果，以论证系统的功能.;To achieve relatively high frame rates with relatively low costs, a Tshaped terahertz imaging system with beamscanning function is presented. The system employs two orthogonally oriented copolarized scanning fanbeam antennas arranged in a Tshaped configuration. Both transmitting and receiving antennas consist of a pyramid horn feed, a fixed elliptical mainreflector to generate thin fan beam, and a rotating subreflector to realize beam scanning function, all of which are embedded between two parallel metal plates. In this paper, specific design details of such a system were discussed, especially for the systematic method proposed to design a fanbeam scanning antenna with high performance. In addition, some experimental imaging results were shown, which demonstrated the capability of the system.

The Improvement of the Performence of Microstrip Leaky-Wave Antenna Based on Symmetrical CRLH-TL

In this paper we propose a novel structure for CRLH-TL,that is symmetrical CRLH-TL structure,used in microstrip leaky-wave(MLWA) ,which will have more advantages than asymmetric structure.because the symmetrical structure allows the unit always in balanced state, microstrip leaky-wave antenna(MLWA)based on symmetrical structure CRLH-TL in balanced state can realize the seamless transition from left hand to right hand , expanding the scope of beam scanning,realizing the beam scanning function of the electromagnetic wave from backward to forward and miniaturization.The phenomenon will be explained theoretically and validated through the measurement and simulation in this paper.

Design, Analysis and Measurement of a Millimeter Wave Antenna Suitable for Stand off Imaging at Checkpoints

A systematic method is proposed to design a novel beam-scanning antenna with fan-beam, which is suitable for stand off imaging at millimeter wave band. The antenna has not only an elliptical main-reflector to generate thin fan beam, but also a rotating sub-reflector to realize beam scanning function. All these structures are embedded between two parallel metal plates. A Reversed Ray Tracing Algorithm (RRTA) was introduced to optimize the positions and dimensions of the subreflector and the feed horn. A modified Physical Optics method based on Discrete Real Mirror Image theory (DRMI-PO) was developed to efficiently analyze and optimize the field patterns of the antenna with specific structures. Based on above methods, an antenna working at 200 GHz is designed and fabricated. The measured patterns are in well agreement with the calculated results. It’s found that, the total beam scanning range is about 60 cm with its minimum half -power beam widths about 1.7 cm in the scanning direction. All the results validate the design method and potential applications of the antenna in the stand off imaging systems.

A dual-mode surface encoder for position measurement

A surface encoder incorporating an angle grid and two two-dimensional (2D) slope sensors is presented. The angle grid is a plate inscribed with periodic sinusoidal waves in the X and Y directions as a position reference, and the position of the plate is detected uniquely using two slope-sensor units. One of the slope sensors is fitted with a beam scanning function to probe and read the angle grid. The system provides two measurement modes: a high-speed measurement mode that measures the XYθ z position at a fast sampling rate, and a multiple degree-of-freedom (DOF) measurement mode that measures the XYθ xθ yθ z position at a lower sampling rate by probe scanning. The linearity, cross-talk and resolution of a prototype encoder system are evaluated, and the system is shown to be acceptable for application as a precise dual-mode measurement scheme for a planar stage.

ハイブリッド集積ピエゾ素子駆動ミラーによるレーザビーム走査制御ユニットの基礎検討

The hybrid-integration of electro-mechanical components and opto-electronic devices have been designed and put through initial trial tests. The beam scanning unit, which guides the laser beam by tilting a micro-mirror prism with a piezoelectric actuator, has been fabricated and its basic performance has been confirmed. By applying 300Vp-p sinusoidal signal to the piezoelectric device, the laser beam scanning function has been stable up to 1kHz. The result suggests that it is possible to use the laser beam scanning function to control the optical spot's high-speed fine tracking.