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1
Shaffer, David B. y John M. Gipson. "A Portable Holographic Antenna Measurement System". International Astronomical Union Colloquium 131 (1991): 94–97. http://dx.doi.org/10.1017/s0252921100013129.
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AbstractInterferometrics has developed a portable holographic antenna measurement system. The system is comprised of a small interferometer which uses satellite signals to measure the complex beam pattern of the antenna under test. A PC controls all aspects of data collection and analysis. The system produces maps of surface profile errors and the illumination power in reflector antennas.
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Baek, Jong Jin, Se Woong Kim y Youn Tae Kim. "Camera-Integrable Wide-Bandwidth Antenna for Capsule Endoscope". Sensors 20, n.º 1 (31 de diciembre de 2019): 232. http://dx.doi.org/10.3390/s20010232.
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This paper presents a new antenna design for a capsule endoscope. The proposed antenna comprises a camera hole and meandered line. These features enable the antenna to be integrated on the same side as the camera, within the capsule endoscope. Moreover, light-emitting diodes can be mounted on the surface of the antenna for illumination. The antenna achieves a wide bandwidth, despite the small size owing to its meandered line structure.
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Tripon-Canseliet, Charlotte, Cristian Della Giovampaola, Nicolas Pavy, Jean Chazelas y Stefano Maci. "Optically Controlled Gain Modulation for Microwave Metasurface Antennas". Sensors 24, n.º 6 (16 de marzo de 2024): 1911. http://dx.doi.org/10.3390/s24061911.
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Over the past decade, metasurfaces (MTSs) have emerged as a highly promising platform for the development of next-generation, miniaturized, planar devices across a wide spectrum of microwave frequencies. Among their various applications, the concept of MTS-based antennas, particularly those that are based on surface wave excitation, represents a groundbreaking advancement with significant implications for communication technologies. However, existing literature primarily focuses on MTS configurations printed on traditional substrates, largely overlooking the potential benefits of employing photosensitive substrates. This paper endeavors to pioneer this novel path. We present a specialized design of a modulated MTS printed on a silicon substrate, which acts as a photosensitive Ka-band surface wave antenna. Remarkably, the gain of this antenna can be time-modulated, achieving a variance of up to 15 dB, under low-power (below 1 W/cm²) optical illumination at a wavelength of 971 nm. This innovative approach positions the antenna as a direct transducer, capable of converting an optically modulated signal into a microwave-modulated radiated signal, thus offering a new dimension in antenna technology and functionality.
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Quintero-Torres, Rafael, Jorge Luis Domínguez-Juárez, Mariia Shutova y Alexei V. Sokolov. "Usability of Tilted Plasmon Antenna with Structured Light". Photonics 8, n.º 11 (9 de noviembre de 2021): 504. http://dx.doi.org/10.3390/photonics8110504.
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We study the effect of oblique illumination on the functioning of a plasmonic nanoantenna for chiral light. The antenna is designed to receive a structured beam of light and produce a nanosized near-field distribution that possesses nonzero orbital angular momentum. The design consists of metal (gold) microrods laid on a dielectric surface and is compatible with well-developed nanofabrication techniques. Experimental arrangements often require such an antenna to operate in a tilted geometry, where input light is incident on the antenna at an oblique angle. We analyze the limitations that the angled illumination imposes and discuss approaches to mitigate these limitations. Through our numerical simulations, we find that tilt angles require modifications to the antenna design. Our analysis can guide current and future experimental configurations to push the limits of resolution and sensitivity.
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Lampe, Bernhard, Klaus Holliger y Alan G. Green. "A finite‐difference time‐domain simulation tool for ground‐penetrating radar antennas". GEOPHYSICS 68, n.º 3 (mayo de 2003): 971–87. http://dx.doi.org/10.1190/1.1581069.
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The generation and recording of electromagnetic waves by typical ground‐penetrating radar (GPR) systems are complex phenomena. To investigate the characteristics of typical GPR antennas operating in diverse environments, we have developed a versatile and efficient simulation tool. It is based on a finite‐difference time‐domain (FDTD) approximation of Maxwell's equations that lets one simulate the radiation characteristics of a wide variety of typical surface GPR antenna systems. The accuracy of the algorithm is benchmarked and validated with respect to laboratory measurements for comparable antenna systems. Computed radiation patterns demonstrate that the illumination of the subsurface in the near‐ to intermediate‐field range varies significantly according to how the antenna is designed. Our models show the effects of varying the shapes of the antennas, adding shielding (metal box with and without absorbing material and with and without resistive loading), adding a receiver antenna, and changing the soil conditions. Given the flexibility of this modeling software, we anticipate that it will be helpful in designing GPR surveys and new GPR systems with arbitrary planar structures. It will also be useful in interpreting certain GPR data sets.
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Kartsan, Igor y Aleksander Zhukov. "Radar sensing of the sea surface using small spacecraft". InterCarto. InterGIS 28, n.º 1 (2022): 383–93. http://dx.doi.org/10.35595/2414-9179-2022-1-28-383-393.
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The possibility of using a constellation of small spacecraft as receiving satellites, when “highlighting” the sea surface from existing (navigational, communication) or specially created spacecraft—to form a wide-area (about 1 000 km) radar survey zone at a given resolution (about 10 m)—is under consideration. Such a constellation could provide operational monitoring of fast-moving atmospheric cyclones, measuring directly the parameters of storm waves (altitude and orbital velocity)—which would replace the existing constellation of microwave scatterometers, providing operational monitoring of the World Ocean surface in the 3 H (H—altitude of the satellite’s orbit) field of view with a resolution of about 10 km—but with calibration of the received images by wind speed and direction, which leads to huge errors when trying to introduce altitude calibration in the Small spacecraft have many advantages over large satellites. For example, they are relatively inexpensive to build, take minimal time from design to launch, are easily modified to solve a specific problem, and create less radio interference. The approach under consideration consists in redistribution of tasks to be solved between the constellation of satellites in orbit. High orbiting navigation satellites, for example, can be used as transmitter carriers (of the illumination of the surface) that use the necessary broadband signal with acceptable periodicity. Receivers of reflected signals are placed on board small spacecraft, and at formation of wide-band radar image of sea surface with necessary resolution ∼10 m (that only on order exceeds acceptable on small spacecraft size of receiving antennas)—in flight direction is necessary to use synthesized aperture of receiving antenna. This work has the character of “staged” research.
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Орлов, В., О. Коркін, С. Ковалішин y О. Наумов. "РОЗТАШУВАННЯ РОБОТИЗОВАНИХ КОМПЛЕКСІВ ПРОТИРАКЕТНОЇ ОБОРОНИ НА БЕЗПІЛОТНОМУ ПОВІТРЯНОМУ ТРАНСПОРТІ". Collection of scientific works of Odesa Military Academy, n.º 20 (14 de diciembre de 2023): 108–16. http://dx.doi.org/10.37129/2313-7509.2023.20.108-116.
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Objects of critical infrastructure of Ukraine need a multi-level anti-missile defense system, which should protect against various types of missiles with a flight range of several tens to several hundreds of kilometers. Timely detection of missiles allows for a number of measures aimed at interception and destruction of targets, the use of radio-electronic warfare, the installation of interfering and obstructing obstacles in various ranges of radio waves, as well as the inclusion of optical and thermal traps. The use of robotic complexes placed on aerostats increases the effectiveness of modern surface-to-air missile system (SAMS) many times over in the fight against low-flying targets with massed strikes of cruise missiles. The location of radar at an altitude of several kilometers ensures the detection range of low-flying targets several times greater than that of ground-based radar. This is of particular importance for SAMS when firing at targets beyond the radio horizon. The transfer of data about the location of the target from the radar of the air carrier to the air defense system and its illumination and guidance radar (at least the approximate location) provides the opportunity to bring the anti-missile to the point of inclusion of its homing head. It is proposed to modernize the radar with an active phased antenna array used on fighters to increase the range and installation on airships and balloons. This will ensure the effectiveness of defense against missile attacks, detection and tracking of up to 100 targets at distances of about 40...400 km. At the same time, the weight of the radar within the range of 200...500 kg and the dimensions of the antennas up to 1 meter are permissible for installation on large balloons. Countries for which attacks of various types of missiles are a real threat need a multi-level anti-missile system, in particular, using robotic complexes placed on air carriers. Keywords: anti-missile defense, radar station, balloon, airship.
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Sidibe, Alassane, Alexandru Takacs, Gaël Loubet y Daniela Dragomirescu. "Compact Antenna in 3D Configuration for Rectenna Wireless Power Transmission Applications". Sensors 21, n.º 9 (4 de mayo de 2021): 3193. http://dx.doi.org/10.3390/s21093193.
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This work presents methods for miniaturizing and characterizing a modified dipole antenna dedicated to the implementation of wireless power transmission systems. The antenna size should respect the planar dimensions of 60 mm × 30 mm to be integrated with small IoT devices such as a Bluetooth Lower Energy Sensing Node. The provided design is based on a folded short-circuited dipole antenna, also named a T-match antenna. Faced with the difficulty of reducing the physical dimensions of the antenna, we propose a 3D configuration by adding vertical metallic arms on the edges of the antenna. The adopted 3D design has an overall size of 56 mm × 32 mm × 10 mm at 868 MHz. Three antenna-feeding techniques were evaluated to characterize this antenna. They consist of soldering a U.FL connector on the input port; vertically connecting a tapered balun to the antenna; and integrating a microstrip transition to the layer of the antenna. The experimental results of the selected feeding techniques show good agreements and the antenna has a maximum gain of +1.54 dBi in the elevation plane (E-plane). In addition, a final modification was operated to the designed antenna to have a more compact structure with a size of 40 mm × 30 mm × 10 mm at 868 MHz. Such modification reduces the radiation surface of the antenna and so the antenna gain and bandwidth. This antenna can achieve a maximum gain of +1.1 dBi in the E-plane. The two antennas proposed in this paper were then associated with a rectifier to perform energy harvesting for powering Bluetooth Low Energy wireless sensors. The measured RF-DC (radiofrequency to direct current) conversion efficiency is 73.88% (first design) and 60.21% (second design) with an illuminating power density of 3.1 µW/cm2 at 868 MHz with a 10 kΩ load resistor.
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Zaman, Mohammad Asif y Md Abdul Matin. "A New Method of Designing Circularly Symmetric Shaped Dual Reflector Antennas Using Distorted Conics". International Journal of Microwave Science and Technology 2014 (17 de diciembre de 2014): 1–8. http://dx.doi.org/10.1155/2014/849194.
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A new method of designing circularly symmetric shaped dual reflector antennas using distorted conics is presented. The surface of the shaped subreflector is expressed using a new set of equations employing differential geometry. The proposed equations require only a small number of parameters to accurately describe practical shaped subreflector surfaces. A geometrical optics (GO) based method is used to synthesize the shaped main reflector surface corresponding to the shaped subreflector. Using the proposed method, a shaped Cassegrain dual reflector system is designed. The field scattered from the subreflector is calculated using uniform geometrical theory of diffraction (UTD). Finally, a numerical example is provided showing how a shaped subreflector produces more uniform illumination over the main reflector aperture compared to an unshaped subreflector.
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Gupta, Akash Kumar, Harish Chandra Mohanta, P. Satish Rama Chowdary, M. Vamshi Krishna y Heba G. Mohamed. "Design and Analysis of Fractal-Shaped High-Impedance Surface Unit Cell Characteristics". Fractal and Fractional 7, n.º 6 (14 de junio de 2023): 472. http://dx.doi.org/10.3390/fractalfract7060472.
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Fractal geometries consistently provide solutions to several electromagnetic design problems. In this paper, fractal geometries such as Hilbert and Moore curves are used to design efficient High-Impedance Surfaces. Modern communication devices have many sensors that are needed to communicate wirelessly. The critical component of wireless communications is antennas. Planar microstrip patch antennas are popular due to their low profile, compactness, and good radiation characteristics. The structural disadvantages of microstrip antennas are that they have surface waves that propagate over the ground plane. High-Impedance Surface (HIS) planes are a prominent solution to minimize and eliminate surface waves. The HIS structures behave as active LC filters that suppress surface waves at their resonance frequency. The resonance frequency of the structure is obtained by its LC equivalent or by analyzing the reflection phase characteristics. This work presents conventional HIS structures similar to mushroom HIS and fractal HIS such as Hilbert curve and Moore curve HIS. The HIS reflection phase characteristics are obtained by applying periodic boundary conditions with plane wave illumination. The results were obtained in terms of the reflection phase angle. The conventional mushroom structures show narrow band characteristics at given dimensions of 10 mm × 10 mm and 20 mm × 20 mm. These structures are helpful in the replacement of PEC ground planes for patch antennas under sub-6 GHz. The Hilbert and Moore fractals are also designed and have a multiband response that can be useful for L, S, and C band applications. Another design challenge of HIS is protrusions, which make design difficult. The work also presents the effect of having vias and the absence of vias on reflection phase characteristics. The response shows the least and no significant effect of vias under the x-band operation.
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Schmiech, Daniel, Aly Marnach y Andreas R. Diewald. "Verification and first test measurement of a microwave-based vital sign monitor". Advances in Radio Science 17 (14 de octubre de 2019): 249–56. http://dx.doi.org/10.5194/ars-17-249-2019.
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Abstract. The authors present a microwave-based vital sign monitoring system to detect the breathing rate of premature infants in a baby incubator. The sensor is a four channel I/Q-radar system with adapted antennas to cover the predefined region of interest on the patient surface of the incubator. In order to prove the correct illumination of the reclining area an electromotive actuator and a pneumatic dummy is used. With a periodic and repeatable breathing simulation the reflected signal in the sensor system is measured and evaluated. In the publication the radar system in the baby incubator, the electromotive actuator and the infant dummy are presented.
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Cacocciola, Riccardo, Badreddine Ratni, Nicolas Mielec, Emmanuel Mimoun y Shah Nawaz Burokur. "Metasurfaces for Far-Field Radiation Pattern Correction of Antennas under Dielectric Seamed-Radomes". Materials 15, n.º 2 (16 de enero de 2022): 665. http://dx.doi.org/10.3390/ma15020665.
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A high-index dielectric radome seam is camouflaged with respect to a low-index dielectric radome panel by tuning the seam with carefully engineered metasurfaces. A transmission-line approach is used to model the metasurface-tuned seam and analytically retrieve the corresponding surface impedance, from which the unit-cell design is then tailored. Full-wave simulations and microwave antenna measurements performed on a proof-of-concept prototype validate the undesired scattering suppression effect in the case of normally and obliquely incident transverse electric and transverse magnetic wave illuminations. Robustness of the proposed solution to fabrication tolerances is also reported. The study presents metasurface-tuning as an easily implementable, frequency adjustable, and polarization insensitive solution to reduce the scattering of dielectric mechanical seams and improve the overall transparency performance of radome structures.
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Nguyen, Van Quan. "Coastal Shipping Radar Monitoring System with Satellites as Transmitters of Opportunity". Journal of the Russian Universities. Radioelectronics 25, n.º 1 (21 de febrero de 2022): 6–16. http://dx.doi.org/10.32603/1993-8985-2022-25-1-6-16.
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Introduction. With the development of technology and science, passive radar systems operating on the basis of third-party transmitters of illumination signal sources are increasingly attracting research interest. The use of satellite systems as transmitters of opportunity for a radar station makes it possible to monitor coastal sea areas, where the ground sources of illumination signals are absent. Satellite systems can cover any point on the Earth's surface. Passive radar systems can be used to determine the location of ships and monitor navigation. They are also promising as part of vessel traffic control systems.Aim. To develop a model of a passive radar system that uses satellite systems as third-party sources of illumination signals and to conduct an experimental study of a system for monitoring ships in coastal waters.Materials and methods. The AA2-KKС antennas of satellite signals and radio recording tools based on the universal USRP B210 board were used. Signal processing was performed using a program developed in the MATLAB environment.Results. An algorithm for processing satellite signals of the GPS global navigation system in a passive radar system is proposed. An experimental model of the receiving station for such a radar monitoring system was created on the basis of a data input device for a universal USRP board of the B210 series. Experimental results for the receiving station using the satellite signal GPS L1 C/A-code for coastal monitoring were obtained.Conclusion. The developed experimental model of a passive radar receiving station using third-party transmitters of GPS satellitebased illumination signals on the L1 frequency range of the C/A-code type can be used for detecting ships and monitoring coastal navigation. Future research will consider a multiposition modification of such a monitoring system for improving its detection quality and increasing its target positioning accuracy.
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Bertone, Stefano, Erwan Mazarico, Michael K. Barker, Matthew A. Siegler, Jose M. Martinez-Camacho, Colin D. Hamill, Allison K. Glantzberg y Nancy L. Chabot. "Highly Resolved Topography and Illumination at Mercury’s South Pole from MESSENGER MDIS NAC". Planetary Science Journal 4, n.º 2 (1 de febrero de 2023): 21. http://dx.doi.org/10.3847/psj/acaddb.
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Abstract Mercury’s south polar region is of particular interest since Arecibo radar measurements show many high-reflectance regions consistent with ice deposits. However, current elevation information in Mercury’s southern hemisphere is not sufficient to perform detailed modeling of the illumination and thermal conditions at these radar-bright locations and to constrain properties of the volatiles potentially residing there. In this work, we leverage previously existing elevation maps of Mercury’s surface from stereo-photogrammetry at 665 m pix−1, Mercury Dual Imaging System Narrow Angle Camera images, and Shape-from-Shading tools from the Ames Stereo Pipeline, to provide the first high-resolution topographic maps of the south pole with a resolution of 250 m pix−1 poleward of 75°S. We show that the increased resolution and level of detail provided by our new elevation model allow for a more realistic recovery of illumination conditions in Mercury’s south polar region, thus opening the way to future thermal analyses and for the characterization of potential ice and volatile deposits. We compare both the old and new topographic models to the Mercury Dual Imaging System Narrow Angle Camera images to show the higher level of fidelity with our products, and we assess the improved consistency of derived permanently shadowed regions with reflectance measurements by Arecibo’s antennas.
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Barichello, Jessica, Paolo Mariani, Fabio Matteocci, Luigi Vesce, Andrea Reale, Aldo Di Carlo, Maurizio Lanza, Gaetano Di Marco, Stefano Polizzi y Giuseppe Calogero. "The Golden Fig: A Plasmonic Effect Study of Organic-Based Solar Cells". Nanomaterials 12, n.º 2 (14 de enero de 2022): 267. http://dx.doi.org/10.3390/nano12020267.
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An optimization work on dye-sensitized solar cells (DSSCs) based on both artificial and natural dyes was carried out by a fine synthesis work embedding gold nanoparticles in a TiO2 semiconductor and perfecting the TiO2 particle sizes of the scattering layer. Noble metal nanostructures are known for the surface plasmon resonance peculiarity that reveals unique properties and has been implemented in several fields such as sensing, photocatalysis, optical antennas and PV devices. By embedding gold nanoparticles in the mesoporous TiO2 layer and adding a scattering layer, we were able to boost the power conversion efficiency (PCE) to 10.8%, using an organic ruthenium complex. The same implementation was carried out using a natural dye, betalains, extracted from Sicilian prickly pear. In this case, the conversion efficiency doubled from 1 to 2% (measured at 1 SUN illumination, 100 mW/cm2 under solar simulation irradiation). Moreover, we obtained (measured at 0.1 SUN, 10 mW/cm2 under blue light LED irradiation) a record efficiency of 15% with the betalain-based dye, paving the way for indoor applications in organic natural devices. Finally, an attempt to scale up the system is shown, and a betalain-based- dye-sensitized solar module (DSSM), with an active area of 43.2 cm2 and a PCE of 1.02%, was fabricated for the first time.
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Volosyuk, Valeriy, Volodymyr Pavlikov, Simeon Zhyla, Eduard Tserne, Oleksii Odokiienko, Andrii Humennyi, Anatoliy Popov y Oleh Uruskiy. "Signal Processing Algorithm for Monopulse Noise Noncoherent Wideband Helicopter Altitude Radar". Computation 10, n.º 9 (31 de agosto de 2022): 150. http://dx.doi.org/10.3390/computation10090150.
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Radio altimeters are an important component of modern helicopter on-board systems. These devices currently involve the use of narrowband deterministic signals, that limits their potential technical characteristics. Given the significant breakthrough in the development of wideband and ultra-wideband radio electronics, it is promising to create on-board radio complexes capable of obtaining the necessary information using wideband stochastic signals. At the same time, when developing such complexes, it is important to use optimal synthesis methods for radio systems, which will allow optimal signal processing algorithms and potential accuracy parameters to be obtained. In this work, the algorithm to measure flight altitude for a helicopter or an unmanned aerial vehicle based on the processing of wideband and ultra-wideband pulsed stochastic signals is synthesized for the first time by the maximum-likelihood method. When formulating the problem, the mathematical model of the signal and observation is specified, and their statistical characteristics are investigated. The peculiarity of the synthesis task is the use of a noise pulse transmitter, which implements the function of an underlying surface illuminator, as well as considering the signal structure destruction during its radiation, propagation, and reflection. This signal shape destruction makes it impossible to synthesize a radar with internally coherent processing when working on one receiving antenna. In accordance with the synthesized algorithm, a simulation model of a pulsed radar with a stochastic probing signal has been developed and the results of its modeling are presented.
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Cheng, Yang, Yongfeng Li, He Wang, Jiafu Wang, Zhe Qin y Shaobo Qu. "Circular dichroism assisted bi-directional absorbers". Journal of Physics D: Applied Physics 55, n.º 9 (17 de noviembre de 2021): 095101. http://dx.doi.org/10.1088/1361-6463/ac3301.
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Abstract Chirality, a geometric property that is of great importance in chemistry, biology, and medicine, has spurred many breakthroughs in the field of multi-dimensional metasurfaces that provide efficient ways of flexibly manipulating amplitude and phase of circular polarization (CP) waves. As one of the most important applications, chiral metamaterials can be used to implement novel absorbers. Herein, an ultra-thin wideband circular dichroic asymmetric metasurface was implemented via loading resistive film into chiral resonators. Opposite and reversible polarization conversion and circular dichroism (CD) were realized as being illuminated by CP waves from both sides meanwhile. Theoretical derivation and simulation verify that the polarization conversion and CD enhancement utilizing multi-layer CD metasurface. It is also found that the orientation angle of the meta-atom of each layer plays an important role in the CD enhancement, which paves a new way for CD enhancement. In addition, the coupling between the CD resonators was utilized to manipulate CD. On this basis, an ultra-thin polarization-insensitive absorber was achieved by employing a C4 2 × 2 CD resonator array, which was identical illuminating from front and back sides. Circular dichroic absorbers possess great potential in practical applications, ranging from stealth technology, antenna isolation, multi-functional microwave devices, chiral sensing, and catalysis.
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Lösler, Michael, Rüdiger Haas, Cornelia Eschelbach y Ansgar Greiwe. "Gravitational deformation of ring-focus antennas for VGOS: first investigations at the Onsala twin telescopes project". Journal of Geodesy 93, n.º 10 (28 de septiembre de 2019): 2069–87. http://dx.doi.org/10.1007/s00190-019-01302-5.
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Abstract The receiving properties of radio telescopes used in geodetic and astrometric very long baseline interferometry (VLBI) depend on the surface quality and stability of the main reflector. Deformations of the main reflector as well as changes in the sub-reflector position affect the geometrical ray path length significantly. The deformation pattern and its impact on the VLBI results of conventional radio telescopes have been studied by several research groups using holography, laser tracker, close-range photogrammetry and laser scanner methods. Signal path variations (SPV) of up to 1 cm were reported, which cause, when unaccounted for, systematic biases of the estimated vertical positions of the radio telescopes in the geodetic VLBI analysis and potentially even affect the estimated scale of derived global geodetic reference frames. As a result of the realization of the VLBI 2010 agenda, the geodetic VLBI network is currently extended by several new radio telescopes, which are of a more compact and stiffer design and are able to move faster than conventional radio telescopes. These new telescopes will form the backbone of the next generation geodetic VLBI system, often referred to as VGOS (VLBI Global Observing System). In this investigation, for the first time the deformation pattern of this new generation of radio telescopes for VGOS is studied. ONSA13NE, one of the Onsala twin telescopes at the Onsala Space Observatory, was observed in several elevation angles using close-range photogrammetry. In general, these methods require a crane for preparing the reflector as well as for the data collection. To reduce the observation time and the technical effort during the measurement process, an unmanned aircraft system (UAS) was used for the first time. Using this system, the measurement campaign per elevation angle took less than 30 min. The collected data were used to model the geometrical ray path and its variations. Depending on the distance from the optical axis, the ray path length varies in a range of about $$\pm \,1\,\hbox {mm}$$±1mm. To combine the ray path variations, an illumination function was introduced as weighting function. The resulting total SPV is about $$- \,0.5$$-0.5 mm. A simple elevation-dependent SPV model is presented that can easily be used and implemented in VLBI data analysis software packages to correct for gravitational deformation in VGOS radio telescopes. The uncertainty is almost $$200\,\upmu \hbox {m}$$200μm ($$2\sigma $$2σ) and is derived by Monte Carlo simulations applied to the entire analysis process.
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Hussain, Muhammad, Kyung-Geun Lee y Dongho Kim. "Tapered high-gain Fabry–Perot cavity antenna with high sidelobe suppression for 5G industry". Scientific Reports 13, n.º 1 (21 de septiembre de 2023). http://dx.doi.org/10.1038/s41598-023-42716-8.
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AbstractWe propose a Fabry–Perot cavity (FPC) antenna to suppress a sidelobe level (SLL) while maintaining a reasonably high gain. Generally, conventional FPC antennas (FPCAs) produce a high SLL because waves in their FPC leak considerably through lateral openings, which is a primary reason for lowering antenna gains. We propose two design approaches to solve this problem: the reflection magnitude tapering of a partially reflective surface (PRS) and considering different incident modes for the PRS design. First, the proposed tapering can remarkably reduce an SLL by providing the PRS with more radiation opportunities. Second, the different incident modes of transverse electric (TE) and transverse magnetic (TM) can increase an antenna gain by considering a more realistic illumination environment of the PRS. We have proven that our antenna provides 19.8 dBi realized gain with high sidelobe suppression (SLS) of more than 23 dB. Consequently, the proposed FPCA can suppress sidelobes significantly while maintaining a high gain. Good agreement between simulations and experiments demonstrates the usefulness of our proposal.
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Han, Yajuan, Jiafu Wang, Xinmin Fu, Hongya Chen, Chang Ding y Shaobo Qu. "Broadside Radiation Antenna Based on Tightly-Coupled Spoof Surface Plasmon Polaritons". Journal of Physics D: Applied Physics, 25 de agosto de 2023. http://dx.doi.org/10.1088/1361-6463/acf3f7.
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Abstract Spoof surface plasmon polariton (SSPP) is a hybrid mode of surface wave in the air and electron oscillation within artificial electromagnetic (EM) media, with dispersion curve lying below the light line, giving rise to many unique EM properties. In this paper, we investigate EM properties of tightly-coupled SSPP (TC-SSPP) modes and propose a slender broadside antenna based on the TC-SSPP. With the comb structure (CS), dispersion properties of different SSPP modes are firstly analyzed under plane wave illumination, and then we introduce a modified SSPP structure, the broadside-coupled comb structure (BC-CS), to excite and guide TC-SSPP modes. Since TC-SSPP modes can be confined tightly around the slender BC-CS, EM waves can be manipulated within much more compact space, which is favorable for miniaturization, compactness and lightweight of microwave devices. To demonstrate this, we propose a slender broadside radiation antenna based on the TC-SSPP, using a probe as the feed and a finite-length BC-CS as the radiator. Due to near-filed magnetic coupling, SSPP wave can be excited on the BC-CS. By variating geometric parameters, the antenna can radiate at broadside direction. A prototype was designed, fabricated and measured. Both the simulated and measured results verify our design.
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B., Asianuba Ifeoma y Okerulu Charles I. "Survey on Mitigating the Problems of Parabolic Reflectors for Efficient Communication". Asian Journal of Engineering and Technology 9, n.º 5 (4 de noviembre de 2021). http://dx.doi.org/10.24203/ajet.v9i5.6762.
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In this paper, various problems associated with parabolic reflectors, its causes and the approach to mitigate these problems are discussed. The problems include; side lobe radiations, edge diffraction, aperture blockage, cross polarisation, feed spill over, feed illumination taper, pointing error, surface error and phase error. These problems have adverse effect on the overall gain, efficiency and directivity of the antenna thereby inhibiting efficient communication process. The result of the survey reveals that, phase error tends to be the most difficult of the aforementioned problems due to the challenges associated with locating the phase centre at reflector’s focus. The aperture blockage seems to have the least method of solution, because the problem can be solved by changing the centre feed to an offset feed. Detailed investigation of these problems and the relevant solutions are necessary, since parabolic reflectors are among the most common antennas with diverse application.
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Tamoor, Tania, Nosherwan Shoaib, Fahad Ahmed, Tayyab Hassan, Abdul Quddious, Symeon Nikolaou, Akram Alomainy, Muhammad Ali Imran y Qammer H. Abbasi. "A multifunctional ultrathin flexible bianisotropic metasurface with miniaturized cell size". Scientific Reports 11, n.º 1 (16 de septiembre de 2021). http://dx.doi.org/10.1038/s41598-021-97930-z.
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AbstractIn this paper, a flexible bianisotropic metasurface possessing omega-type coupling is presented. The designed metasurface behaves differently when excited from either forward (port 1) or back (port 2) sides. It provides an absorption of 99.46% at 15.1 Gigahertz (GHz), when illuminated from port 1, whereas, on simultaneous illumination from port 2, it behaves like a partially reflective surface (PRS). Furthermore, the presented metasurface not only acts as an in-band absorptive surface (port 1) and partially reflective surface (port 2), but it also provides 97% out-of-band transmission at 7.8 GHz. The response of the presented metasurface remains the same for both transverse Electric (TE) and transverse magnetic (TM) polarized wave or any arbitrary linearly polarized wave. Additionally, the response of the metasurface is angularly stable for any oblique incidence up to 45º. The proposed ultrathin flexible metasurface with absorption, partial reflection and out-of-band transmission properties can be used in the Fabry Perrot cavity antenna for gain enhancement with radar cross-section (RCS) reduction both for passband and stop-band filtering, and conformal antenna applications.
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Nadi, Morteza, Seyed Hassan Sedighy y Ahmad Cheldavi. "Multimode OAM beam generation through 1-bit programmable metasurface antenna". Scientific Reports 13, n.º 1 (20 de septiembre de 2023). http://dx.doi.org/10.1038/s41598-023-42691-0.
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Abstractmodern wireless communication, the orbital angular momentum (OAM) beam is considered as an important technology. Some considerable efforts have been devoted to using this technology for channel capacity enhancement as much as possible. Nowadays, programmable metasurfaces provide an innovational scenario for generating multi-mode OAM beams due to their ability for digital electromagnetic waves modulation. However, the current programmable metasurfaces for generating OAM beams are typically based on reflective and transmissive modes, which have low aperture efficiency due to spillover and illumination effects. In this paper, a 1-bit programmable metasurface antenna is proposed with capability of producing highly efficient dynamic multi-mode OAM beams. The proposed structure is consisted of electronically reconfigurable meta-radiating elements loaded by PIN diodes to generate two-phase states of electric field. The designed Field Programmable Gate Array (FPGA) can assign a code sequence of 0 or 1 to the metasurface antenna in real-time to generate multi-mode OAM beams. Hence, a dynamical surface is obtained by switching PIN diodes to change the phase distribution on the surface. To verify the concept, the metasurface antenna is fabricated and measured with different OAM beam states, which are in agreement with the full-wave simulations, properly. The designed structure introduces a capable multi-mode OAM alternative for high throughput mm-wave communications.
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Kiryushkin, V. V., S. I. Babusenko, A. V. Zhuravlev y V. A. Shuvaev. "Goniometric-elliptical multi-position radar system built into spatially distributed radio interference system". Radioengineering 7 (1 de julio de 2023). http://dx.doi.org/10.18127/j00338486-202307-02.
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Problem statement. In multi-position radar systems (MPRS) built into a spatially distributed system of radio interference, a total-range or difference-range method of positioning is used to determine the coordinates of an air target. For their implementation, it is necessary that, at the stage of primary processing in the MPRS, the target response be detected in at least two or three bistatic links "transmitter-target-receiver". Under conditions of low power radio links "transmitter-receiver" and the use of small airborne targets with a small effective scattering surface, it is more likely that the target will be detected in only one channel, for which the total range "transmitter - target - receiver" will be minimal. In this case, the determination of the target coordinates using the total-range or difference-range methods of positioning becomes impossible. Purpose. To develop a method for determining the coordinates of the target in the MPRS, built into a spatially distributed system of radio interference, based on the analysis of the response received in a single bi-static link "transmitter - target - receiver". Results. A method for determining the coordinates of the target based on the analysis of the response recorded in the only bistatic link "transmitter - target - receiver" in the MPRS, the receiving position of which is equipped with an antenna array, is proposed. The developed method provides a target positioning accuracy of 30-50 m with a total range of the bistatic link "transmitter - target - receiver" of 15-20 km and a bearing error of no more than 1 °. Practical significance. The use in the developed method of the phase distribution on the elements of the antenna array, obtained after the correlation processing of the phase-coded keyed signal reflected from the target, provides separate observation at the receiving position of the responses received from illumination signals from transmitters with different codes. This makes it possible to implement, on the basis of this method, a cellular MPRL with transmitters at the nodes of the cell and a receiving position in its center.
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Đặng, Duy Hoàng, Cường Văn Anh Lê, Trung Hoài Đặng y Vấn Thành Nguyễn. "Data analysis of two-dimensional ground penetration radar profiles in three-dimensional space to study of underground objects". Science and Technology Development Journal - Natural Sciences 3, n.º 3 (9 de enero de 2020). http://dx.doi.org/10.32508/stdjns.v3i3.720.
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The Ground Penetrating Radar can be effectively applied in ground surface exploration geophysics. Underground anomalies are shown in the ground penetratingradar slices in the form of signals having similarity in amplitude and phase. Typically, each point-scattering object can be seen as a form of hyperbola. During the Ground Penetrating Radar measurement in an urban environment, the data including information of high frequency electromagnetic waveforms were easily affected by civil noise (human activities, etc.). Shielded antennas could help to eliminate mostly the civil noise, but processing and analysis of the data were still difficult because of attenuation of electromagnetic waves and wave energy dispersion during their propagation in the ground environment. Due to the field geometry condition, 2D profiles were conducted. In order to analyze and interpret data effectively, we processed each 2D profile separately and located all the 2D profiles into the 3D dimensional space for enhancing the ability of illuminating potential 3D anomalies and confirming the reliability of the data interpretation. We studied the data measured at an industrial company at Nhon Trach district, Dong Nai province, Vietnam. Results from the data analysis of ground penetration radar reflected the object in three-dimensional space.