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Single-Layer Multi-Via Loaded CRLH Leaky-Wave Antennas for Wide-Angle Beam Scanning with Consistent Gain
摘要： Achieving continuous backward-to-forward wide-angle beam scanning with consistent gain by employing composite right/left-handed leaky-wave antennas (LWAs) is reported. For structural and design simplicity, a single-layer 1-D structure is considered in which each unit cell consists of a patch shorted centrally to the ground plane. It was found that, when using only one via at the center of a unit cell, a continuous beam scan requires a large diameter via when all other parameters remain unchanged. To eliminate this limitation while maintaining a single-layer structure, novel unit cells are proposed using multiple vias in each unit cell. An LWA design for continuous beam scan with three vias in each unit cell is investigated and the results show good performance and design flexibility. A prototype antenna has been realized, and the measured results show that the antenna can scan the radiation beam continuously in a wide range, from ?60° to +66° with a consistent gain. The measured gain variation within the scan range is only 2.9 dB, and the 3dB gain bandwidth is 58.6%.
关键词： single-layer,leaky-wave antenna (LWA),backward and forward,consistent gain,composite right/left-handed (CRLH),Beam scanning
更新于2025-09-23 15:23:52
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Novel Phased Array-Fed Dual-Reflector Antenna with Different Orthogonal Cross-Section by Imaging Reflector Antenna and Ring-Focus Cassegrain Antenna
摘要： We propose a novel phased array-fed dual-re?ector antenna that reduces performance degradation caused by multiple re?ection. The marked feature of the proposed con?guration is that di?erent re?ector pro?les are employed for the two orthogonal directions. The re?ector pro?le in the beam-scanning section (vertical section) is set to an imaging re?ector con?guration, while the pro?le in the orthogonal non-beam-scanning section (horizontal section) is set to a ring-focus Cassegrain antenna con?guration. In order to compare the proposed antenna with the conventional antenna in which multiple re?ection was problematic, we designed a prototype antenna of the same size, and veri?ed the validity of the proposed antenna. The results of the veri?cation were that the gain in the designed central frequency increased by 0.4 dB, and the ripple of the gain frequency properties that was produced by multiple re?ection was decreased by 1.1 dB. These results demonstrated the validity of the proposed antenna.
关键词： Beam-Scanning Function,Imaging Re?ector Antenna,Ring-focus Cassegrain Antenna,Center-Fed Re?ector Antenna,Phased Array-fed Re?ector Antenna,Doubly Curved Re?ector
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Beam-Scanning Antenna Excited by Planar Spoof Surface Plasmon Polaritons
摘要： a wide-angle frequency-controlled beam-scanning antenna excited by planar spoof surface plasmon polaritons (SPPs) is proposed in this paper. The scanning angle and the gains of the proposed antenna can reach 83 degrees and 11.5dBi, respectively. The features of high gain, planar structure and wide scanning angle make this kind of antennas have great values in integrated communication systems.
关键词： antenna,beam-scanning,spoof surface plasmon polaritons (SPPs)
更新于2025-09-23 15:23:52
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Phased Transmitarray Antennas for 1-D Beam Scanning
摘要： A transmitarray antenna (TAA) fed by a phased array antenna (PAA) for one-dimensional (1-D) beam scanning is proposed at 10 GHz in this letter. The TAA is composed of two types of elements, i.e., the hexagonal subwavelength low-pass elements as well as the pure dielectric ones. The PAA feed is a 1-D printed dipole array loaded with the short-circuited dummy ones. The proposed PAA-fed TAA, with a feeding distance to TAA diameter ratio (H/D) of mere 0.375, achieves a peak simulated gain of 25.6 dBi at 0o scanning (corresponding to peak aperture efficiency of 57.5%) and a 3.13 dB gain drop for ±30o beam scanning, along with a ~2-dB beam crossover. The measured results agree reasonably well with the simulated ones, validating the proposed design.
关键词： periodic structures,phased array antennas,transmitarray antennas,Beam scanning
更新于2025-09-23 15:22:29
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - A Technique to Suppress Mutual Coupling in Densely Packed Antenna Arrays Using Metamaterial Supersubstrate
摘要： A simple and practical technique for reducing the mutual coupling between neighbouring antennas is presented for application in densely packed antenna arrays. This is achieved by locating between the radiation elements a smaller patch with metamaterial decoupling structure (MTM-DS). In this case the radiating elements are circular patches and the MTM-DS is constructed from a hexagonal slit resonator. The consequence of implementing the MTM-DS patch is significant reduction in mutual coupling between adjacent radiating patches by 60%, improvement in impedance match by 200% and substantial increase in the antenna’s fractional bandwidth by 369%. Since the ground plane is unaltered the front-to-back ratio is unaffected too. The proposed technique is easily realizable and can be used effectively in beam scanning applications.
关键词： phased antenna arrays,metamaterial,Mutual coupling,microstrip antennas,beam scanning
更新于2025-09-23 15:22:29
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Optimal Phase-Matching Strategy for Beam Scanning of Sub-Arrayed Phased Arrays
摘要： The design of phased array antennas generating two functional beams is here addressed. The first/primary beam is fixed and it is generated at the element level through the complex (amplitude and phase) weighting coefficients, while the second/secondary one is synthesized at the sub-array level by aggregating the array elements into non-overlapped clusters and using additional phase shifters at the clusters outputs. Towards this end, the sub-array configuration is determined by means of an ad-hoc iterative method aimed at reducing the unavoidable quantization lobes, while the synthesis of the sub-array phase coefficients, once the excitations at the element level have been set, is cast as a phase-matching problem whose analytic solution is optimal since it guarantees the minimum least-square error with respect to a reference phase distribution. A set of representative numerical results is reported and discussed to validate the proposed design approach and to point out its features and potentialities when addressing the synthesis of both pencil and shaped-beam power patterns.
关键词： Beam Scanning,Contiguous Partition Method,Sub-Arraying,Phase Matching,Active Electronically Scanned Array (AESA)
更新于2025-09-23 15:21:01
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MALDI MS Imaging at Acquisition Rates Exceeding 100 Pixels per Second
摘要： The practicality of matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) applied to molecular imaging of biological tissues is limited by the analysis speed. Typically, a relatively low speed of stop-and-go micromotion of XY stages is considered as a factor substantially reducing the rate with which fresh sample material can be supplied to the laser spot. The sample scan rate in our laboratory-built high-throughput imaging TOF mass spectrometer was significantly improved through the use of a galvanometer-based optical scanner performing fast laser spot repositioning on a target plate. The optical system incorporated into the ion source of our MALDI TOF mass spectrometer allowed focusing the laser beam via a modified grid into a 10-μm round spot. This permitted the acquisition of high-resolution MS images with a well-defined pixel size at acquisition rates exceeding 100 pixel/s. The influence of selected parameters on the total MS imaging time is discussed. The new scanning technique was employed to display the distribution of an antitumor agent in 3D colorectal adenocarcinoma cell aggregates; a single MS image comprising 100 × 100 pixels with 10-μm lateral resolution was recorded in approximately 70 s.
关键词： MSI,TOF,Mass spectrometry imaging,High throughput,Laser beam scanning,Colorectal adenocarcinoma,3D cell aggregates,Spheroids,Grid ion source,MALDI
更新于2025-09-23 15:21:01
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Infrared-controlled programmable metasurface
摘要： Programmable metasurface enables controlling electromagnetic (EM) waves in real time. By programming the states of active device embedded in metasurface element, the EM properties of the digital metasurface can be changed quickly without redesigning their structures. However, large numbers of long-distance wires are required to connect the programmable metasurface to provide the coded signals from field programmable gate array (FPGA) when controlling the metasurface at a long distance, which is complicated and inconvenient. Here, we propose an infrared-controlled programmable metasurface that can be programmed remotely. The infrared transceiver is able to switch the coding sequences stored in the FPGA controller, thus controlling the voltage on the varactors integrated in the metasurface. Experiment is performed at microwave frequencies, and the measured results verify that the scattering beams of the metasurface sample can be changed remotely by using infrared ray. The proposed infrared-controlled programmable metasurface opens up avenues for constructing a new class of remotely-tuning dynamic metasurfaces.
关键词： remotely-tuning,beam splitting,infrared-controlled programmable metasurfaces,beam scanning
更新于2025-09-23 15:19:57
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Contour scanning, multi-leaf collimation and the combination thereof for proton pencil beam scanning
摘要： In proton therapy, the lateral fall-off is often used to spare critical organs. It is therefore crucial to improve the penumbra for proton pencil beam scanning. However, previous work has shown that collimation may not be necessary for depths of >15 cm in water. As such, in this work we investigate the effectiveness of a thin multi leaf collimator (just thick enough to completely stop protons with ranges of <15 cm in water) for energy layer specific collimation in patient geometries, when applied in combination with both grid and contour scanned PBS proton therapy. For this, an analytical model of collimated beam shapes, based solely on data available in the treatment planning system, has been included in the optimization, with the resulting optimised plans then being recalculated using Monte Carlo in order to most accurately simulate the full physics effects of the collimator. For grid based scanning, energy specific collimation has been found to reduce the V30 outside the PTV by 19.8% for an example patient when compared to the same pencil beam placement without collimation. V30 could be even reduced by a further 5.6% when combining collimation and contour scanning. In addition, mixed plans, consisting of contour scanning for deep fields (max range >15 cm WER) and collimated contour scanning for superficial fields (<15 cm), have been created for four patients, by which V30 could be reduced by 0.8% to 8.0% and the mean dose to the brain stem by 1.5% to 3.3%. Target dose homogeneity however is not substantially different when compared to the best un-collimated scenario. In conclusion, we demonstrate the potential advantages of a thin, multi leaf collimator in combination with contour scanning for energy layer specific collimation in PBS proton therapy.
关键词： collimation,optimisation,pencil beam scanning,proton therapy,penumbra
更新于2025-09-19 17:15:36
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SIW Based Leaky-Wave Antenna Supporting Wide Range of Beam Scanning through Broadside
摘要： In this letter, a substrate integrated waveguide (SIW) based leaky wave antenna with wide beam scanning is presented to mitigate open stopband (OSB). The unit cell of this proposed antenna consists of a longitudinal slot and a post placed oppositely offset from the center line. By introducing inductive post along with longitudinal slot in each unit cell, the open stopband is suppressed resulting continuous beam scanning. An equivalent circuit of the proposed unit cell is developed to explain impedance matching technique used here to suppress OSB. Dispersion diagram is also used to analyze this seamless scanning. This antenna can scan from -49° to +69° through broadside because of wide impedance matching. Finally, the antenna is prototyped and experimentally verified. Measured results are in accord with simulated results. This antenna provides maximum gain of 14.2dBi and low level of cross-polarization.
关键词： SIW,wide beam-scanning,impedance matching,leaky wave antenna,open stopband
更新于2025-09-19 17:15:36