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Journal articles on the topic 'Directional Microwave'

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Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

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1

Timofeeva, M. A., A. B. Ustinov, and B. A. Kalinikos. "Microwave nonlinear spin wave directional coupler." Technical Physics Letters 32, no. 11 (November 2006): 979–81. http://dx.doi.org/10.1134/s1063785006110228.

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2

Lei, Lin, and Zhi Xiong Ouyang. "Microwave Power Real-Time Soft-Measuring Based on Improved BP Neural Network." Advanced Materials Research 301-303 (July 2011): 902–7. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.902.

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There are many faults in microwave power measurement in the working spots. In this paper, the novel technique of microwave power measurement and Schottky detector and the technique of soft-measuring based on improved BP neural network are presented. Making use of directional coupler, the part of power of microwave signal in transmission line was taken in the certain proportion. Then, the microwave power meter indicated the magnitude of power. The microwave power measurement system was composed of tuneable attenuator, directional coupler, matching load, peak-peak value detector, oscillograph, thermocouple, soft-measuring algorithm and so on. The low microwave power meter obtained the sample data of training BP neuron network. Then, the output of trained BP neural network may represent the result of high microwave power measurement. The experiments and applications in practice project prove that this new method has many advantages.

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3

Khan, Tahsin Ashraf, Patrick A. Burr, David Payne, Mattias Juhl, Utshash Das, Brett Hallam, Darren Bagnall, and Binesh Puthen Veettil. "Molecular dynamic simulation on temperature evolution of SiC under directional microwave radiation." Journal of Physics: Condensed Matter 34, no. 19 (March 14, 2022): 195701. http://dx.doi.org/10.1088/1361-648x/ac553c.

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Abstract Silicon carbide (SiC) is widely used as the substrate for high power electronic devices as well as susceptors for microwave (MW) heating. The dynamics of microwave interaction with SiC is not fully understood, especially at the material boundaries. In this paper, we used the molecular dynamics simulation method to study the temperature evolution during the microwave absorption of SiC under various amplitudes and frequencies of the microwave electric field. Directional MW heating of a SiC crystal slab bounded by surfaces along [100] crystallographic direction shows significantly faster melting when the field is applied parallel to the surface compared to when applied perpendicular.

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4

Islam, S. "Multiway uniform combline directional couplers for microwave frequencies." IEEE Transactions on Microwave Theory and Techniques 36, no. 6 (June 1988): 985–93. http://dx.doi.org/10.1109/22.3623.

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5

Sangster, A. J., and H. Y. Wang. "Omni-Directional Blade Antenna for Microwave Tumour Ablation." Journal of Electromagnetic Waves and Applications 19, no. 14 (January 2005): 1935–48. http://dx.doi.org/10.1163/156939305775570549.

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6

Hu, Yuan, Aiichiro Nakano, and Joseph Wang. "Directional melting of alumina via polarized microwave heating." Applied Physics Letters 110, no. 4 (January 23, 2017): 044102. http://dx.doi.org/10.1063/1.4973698.

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7

Lobato-Morales, H., A. Corona-Chavez, and J. Rodriguez-Asomoza. "Microwave directional filters using metamaterial closed-loop resonators." Microwave and Optical Technology Letters 51, no. 5 (March 13, 2009): 1155–56. http://dx.doi.org/10.1002/mop.24275.

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8

Wu, Dong Rong, He Jun Wu, and Xiao Lu Zhu. "Microwave Directional Wireless Power Transmission for Wireless Sensor Networks." Advanced Materials Research 756-759 (September 2013): 746–50. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.746.

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Power shortage is one of critical issues stalling the development of wireless sensor networks. This paper attempts to address this issue by means of microwave power transmission. In this paper, we propose a sensor node framework using a high-frequency microwave power transmitting module to allow sensor nodes to transmit power to others. We introduce the process of exchanging power between two adjacent sensor nodes and design a power transmission routing protocol called PTR in this paper. PTR optimizes the power transmission of a whole network so that the power of energy sources can efficiently reach any sensor node in the network. We have done simulations and analysis on this framework and the results are positive.

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9

Shen, Aiguo, Yukai Lin, Chendong Yang, Guangsong Yang, Gaiyan Hong, and Dezhi Wei. "Design of branch line directional coupler for 5G millimeter wave communication." Journal of Physics: Conference Series 2384, no. 1 (December 1, 2022): 012019. http://dx.doi.org/10.1088/1742-6596/2384/1/012019.

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Abstract A directional coupler based on a microstrip branch line for 5G millimeter wave communication is designed. The branch line structure is simple and easy to implement. The comprehensive decomposition design method of the microwave system is proposed to improve the design efficiency. Based on the theoretical analysis of microwaves, the design method of combining automatic tuning and manual tuning optimization is used to optimize the schematic simulation. The layout simulation adopts iterative optimization to approximate the design index and reduce the influence of branch line connection loss. Finally, a millimeter wave branch line directional coupler is designed with a bandwidth of 24.25ghz to 27.5ghz, a coupling degree and insertion loss of about 5dB, and an isolation degree of more than 20dB. In the coming 6G, this design method has a certain forward-looking significance.

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10

Gimpilevich, Yu, I. Afonin, V. Vertegel, and Yu Tyschuk. "Technical realization of the device for integrated monitoring of the parameters of the microwave path." Journal of Physics: Conference Series 2094, no. 3 (November 1, 2021): 032040. http://dx.doi.org/10.1088/1742-6596/2094/3/032040.

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Abstract Two designs of a microwave sensor have been developed for a device for built-in monitoring of microwave path parameters, built on the basis of a broadband quadrature measurement method. The first sensor design is made on the basis of a symmetrical strip line, the second - on the basis of a segment of a coaxial line. Each of the microwave sensor designs consists of three parts: a directional coupler and two non-directional measuring probes. The microwave sensor is designed to operate in the 1 - 2 GHz frequency range. The paper also proposes a variant of the circuitry implementation of the built-in microwave control device, which implements the procedure for broadband automatic measurement of the complex reflection coefficient and the power level in the microwave path based on the method of quadrature measurements. The device solves the problem of long-term automatic monitoring of parameters and timely detection of the beginning degradation of the antenna-feeder path.

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11

de la Fuente, Luisa, Beatriz Aja, Enrique Villa, and Eduardo Artal. "Calibration of a Polarimetric Microwave Radiometer Using a Double Directional Coupler." Remote Sensing 13, no. 11 (May 27, 2021): 2109. http://dx.doi.org/10.3390/rs13112109.

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This paper presents a built-in calibration procedure of a 10-to-20 GHz polarimeter aimed at measuring the I, Q, U Stokes parameters of cosmic microwave background (CMB) radiation. A full-band square waveguide double directional coupler, mounted in the antenna-feed system, is used to inject differently polarized reference waves. A brief description of the polarimetric microwave radiometer and the system calibration injector is also reported. A fully polarimetric calibration is also possible using the designed double directional coupler, although the presented calibration method in this paper is proposed to obtain three of the four Stokes parameters with the introduced microwave receiver, since V parameter is expected to be zero for the CMB radiation. Experimental results are presented for linearly polarized input waves in order to validate the built-in calibration system.

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12

Sarapultsev, D. A., A. A. Zolotorev, and M. L. Tsoregradskaya. "Analysis and Modeling of a Directional Microwave Coupler as SMD Component." Nano- i Mikrosistemnaya Tehnika 23, no. 3 (June 22, 2022): 137–42. http://dx.doi.org/10.17587/nmst.24.137-142.

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The article describes the calculation, modeling and layout of the directional coupler. In the course of the work the market analysis was carried out, the model of directional coupler in the frequency range of 2.9—4.5 GHz, the layout of the device and measuring equipment were developed. Directional couplers with different transient attenuation are widely used in the distribution circuits of antenna arrays, as well as to control the power of the radio signal propagating in the transmission line, in power meters, automatic gain control systems, radio receivers, etc. The choice of circuit solutions used for the construction of directional couplers is carried out depending on the specific technical requirements for electrical parameters, the range of operating frequencies and the capabilities of the technological base. Practically all variety of structures of directional couplers realized on elements is a result of modification of the simplest structures. The main types of directional taps include stub, single-stage and tandem-based. During the simulation, it turned out that the directional coupler based on a tandem connection of two connected transmissions with the location of the transmission lines on different layers of the multilayer printed section was suitable for this work. This is due to the fact that when modeling the directional coupler with transmission lines on one printed circuit board, The gap between these lines is too small (&10 nm), which is extremely difficult to perform on a microstrip structure.

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13

Bai Zhen, 白珍, 李国林 Li Guolin, and 张军 Zhang Jun. "X-band high power microwave mode-selective directional coupler." High Power Laser and Particle Beams 25, no. 7 (2013): 1747–50. http://dx.doi.org/10.3788/hplpb20132507.1747.

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14

Mori, Kazunari, Katsuyoshi Tabuse, Masami Oka, Yoshihiro Sugimoto, Takeshi Tsuji, Mikihiro Uenishi, and Takashi Ozaki. "Three directional percutaneous microwave coagulation therapy for hepatocellular carcinoma." Journal of Microwave Surgery 13 (1995): 51–56. http://dx.doi.org/10.3380/jmicrowavesurg.13.51.

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15

PLANT, W. J., W. C. KELLER, A. B. REEVES, E. A. ULIANA, and J. W. JOHNSON. "Airborne microwave Doppler measurements of ocean wave directional spectra." International Journal of Remote Sensing 8, no. 3 (March 1987): 315–30. http://dx.doi.org/10.1080/01431168708948644.

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16

Mahmud, Md Zulfiker, Mohammad Tariqul Islam, Md Naimur Rahman, Touhidul Alam, and Md Samsuzzaman. "A miniaturized directional antenna for microwave breast imaging applications." International Journal of Microwave and Wireless Technologies 9, no. 10 (September 25, 2017): 2013–18. http://dx.doi.org/10.1017/s1759078717000927.

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A novel compact directional antenna with improved gain is proposed for microwave breast imaging (MBI) applications. The radiating fins are modified by etching several slots to make the antenna compact and enhance antenna performance in terms of bandwidth, gain, efficiency, and directivity. Several parameters are studied and optimized to frequency from 3.1 to 6.5 GHz, which is typically used in the breast imaging system. The electrical length of the antenna is 0.39λ × 0.46λ × 0.01λ at the lower frequency band. The result shows that the antenna exhibits −10 dB impedance bandwidth of 4.3 GHz (2.7–7 GHz) with directional radiation pattern. The peak gain of the proposed prototype is 7.8 dBi and fractional bandwidth is 92%. The time domain results show that the fidelity factor for face to face is 0.92 and for side by side is 0.62, which prove the directivity and lower distortion of the signal. The proposed prototype is successfully simulated, fabricated, and measured.

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17

Hikita, M. "Three-line microstrip directional coupler for microwave switch matrix." Electronics Letters 28, no. 10 (May 7, 1992): 960–61. http://dx.doi.org/10.1049/el:19920609.

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18

Saito, Teruo, Hirotaka Masabayashi, Tsuyoshi Kariya, Yasuhito Kiwamoto, and Syoichi Miyoshi. "Mode-Selective Directional Coupler for High Power Microwave Measurements." Japanese Journal of Applied Physics 26, Part 1, No. 8 (August 20, 1987): 1392–93. http://dx.doi.org/10.1143/jjap.26.1392.

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19

Abbosh, A. M., and M. E. Bialkowski. "Compact directional antenna for ultra wideband microwave imaging system." Microwave and Optical Technology Letters 51, no. 12 (September 23, 2009): 2898–901. http://dx.doi.org/10.1002/mop.24764.

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20

Ayik, Muratcan, Hamza Kurt, Oleg V. Minin, Igor V. Minin, and Mirbek Turduev. "Multi-Directional Cloak Design by All-Dielectric Unit-Cell Optimized Structure." Nanomaterials 12, no. 23 (November 25, 2022): 4194. http://dx.doi.org/10.3390/nano12234194.

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In this manuscript, we demonstrate the design and experimental proof of an optical cloaking structure that multi-directionally conceals a perfectly electric conductor (PEC) object from an incident plane wave. The dielectric modulation around the highly reflective scattering PEC object is determined by an optimization process for multi-directional cloaking purposes. Additionally, to obtain the multi-directional effect of the cloaking structure, an optimized slice is mirror symmetrized through a radial perimeter. The three-dimensional (3D) finite-difference time-domain method is integrated with genetic optimization to achieve a cloaking design. In order to overcome the technological problems of the corresponding devices in the optical range and to experimentally demonstrate the proposed concept, our experiments were carried out on a scale model in the microwave range. The scaled proof-of-concept of the proposed structure is fabricated by 3D printing of polylactide material, and the brass metallic alloy is used as a perfect electrical conductor for microwave experiments. A good agreement between numerical and experimental results is achieved. The proposed design approach is not restricted only to multi-directional optical cloaking but can also be applied to different cloaking scenarios dealing with electromagnetic waves at nanoscales as well as other types such as acoustic waves. Using nanotechnology, our scale proof-of-concept research will take the next step toward the creation of “optical cloaking” devices.

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21

Celik, A. R., and M. B. Kurt. "The Performance Comparison of a Dual-Ridge Horn Antenna and a Planar Monopole Antenna in the Microwave Breast Cancer Detection." Advanced Electromagnetics 9, no. 2 (November 11, 2020): 84–92. http://dx.doi.org/10.7716/aem.v9i2.1262.

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Detection of the breast cancer tumors at an early stage is very crucial to be successful in the treatment. Microwave measurement systems have gained much attention for this aim over last decades. The main principle of these systems is based on the significant difference in the dielectric properties of the malignant tumor and normal breast tissue in the microwave frequencies. In this paper, firstly several breast cancer detection techniques are mentioned. Then the advantages of the using microwaves in the detection systems are given. After that, some simulation and experimental studies of the radar-based ultra-wideband microwave measurement system are presented to detect tumor. The main purposes of these measurements are comparing the performance of a previously designed planar monopole antenna (PMA) with a dual-ridge horn (DRH) antenna and demonstrating a simple microwave breast cancer detection system. In the system, a planar breast phantom which is consisted of low dielectric constant material to represent the healthy tissue and high dielectric constant material to represent the tumor is used. Firstly, the measurements are made without tumor in the phantom. Then, the tumor-mimicking object is located to the phantom. In the measurements, both the PMA and DRH antennas are used respectively. These antennas are ultra-wideband and directional. They have narrow beamwidth and stable directional pattern at the interval of 3-10 GHz. According to the return loss results, the reflected energy increases when the antenna gets close to the tumor. Therefore, it can be said that the scattering parameters give important information about the tumor. According to the obtained results in this study, it can be said that the performance of the compact-sized PMA is better than the DRH antenna having larger size.

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22

Feng, Junfeng, Jianchun Jiang, Chung-yun Hse, Zhongzhi Yang, Kui Wang, Jun Ye, and Junming Xu. "Selective catalytic conversion of waste lignocellulosic biomass for renewable value-added chemicals via directional microwave-assisted liquefaction." Sustainable Energy & Fuels 2, no. 5 (2018): 1035–47. http://dx.doi.org/10.1039/c7se00579b.

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23

Kirihara, Soshu, and Yoshinari Miyamoto. "Selective Transmission of Electromagnetic Wave by Using Diamond Photonic Crystals with Graded Lattice Spacing." Advances in Science and Technology 45 (October 2006): 1139–44. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1139.

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Three-dimensional electromagnetic or photonic crystals with periodic variations of the dielectric constants were fabricated by using a rapid prototyping method called stereolithography. Millimeter-order epoxy lattices with a diamond structure were designed to reflect electromagnetic waves by forming an electromagnetic band gap in GHz range. Titania based ceramic particles were dispersed into the lattice to control the dielectric constant. The diamond lattice structures formed the perfect band gap reflecting electromagnetic waves for all directions. The location of the band gap agreed with the band calculation using the plane wave propagation method. The diamond structures with graded lattice spacing were successfully fabricated as well, resulting in the directional transmission of microwaves. The stretching ratio of the lattice spacing in the crystal structure was changed according to the electromagnetic band calculation. A microwave antenna head composed of the diamond structure with graded lattice spacing was fabricated which achieved the unidirectional transmission.

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24

Musa, Doaa Salim Mohammed, Ramazan Daşbaşı, and Burak Polat. "Evaluation of Radiation Performances of Various Aperture and Horn Antennas over Sea Surface." European Journal of Research and Development 2, no. 2 (June 7, 2022): 429–44. http://dx.doi.org/10.56038/ejrnd.v2i2.89.

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Directional Currents Method (DCM) is applied to various aperture and horn antennas including rectangular aperture antenna, circular aperture antenna, dielectric loaded rectangular aperture antenna and E- and H-plane sectoral horn antennas to investigate their radiation performances analytically over sea surface in microwave bands. First, the expressions of the hypothetical directional currents of these antennas are derived in free space and the total radiation patterns are generated by MATLABTM. Then, the same antennas are simulated by the commercial electromagnetic simulation software CSTTM and compared to check the parametric accuracy of DCM numerically. In the second step, these directional currents are employed in deriving the analytical radiation fields of the antennas under investigation over sea surface by incorporating Green’s functions based on Norton’s formulation. This is followed by CSTTM simulations to observe the parametric accuracy of DCM expressions for microwave radiation over sea surface.

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25

Fanyaev, I. A. "Directional microwave coupled-line couplers with high lateral coupling level." Doklady BGUIR 19, no. 6 (October 1, 2021): 5–13. http://dx.doi.org/10.35596/1729-7648-2021-19-6-5-13.

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Classic сoupled-line couplers with a high lateral coupling level by type of directivity are counterdirectional. Restrictions on their synthesis are imposed by the gap between transmission lines, which must be extremely small (tens of microns), the difference in the phase velocities of even and odd modes, which must be compensated and others. This makes it difficult of manufacturing couplers. Described in technical literature сoupled-line couplers with a high lateral coupling level with changed types of directivity are either quite bulky or have small dimensions due to the use of discrete inductors and capacitances, which complicates the technological process with surface mounting when implementing the final device. In this article we propose a compact сoupledline coupler with a high lateral coupling level, which implements power transfer to a single port (0 dB, crossover). The coupler topology uses periodic loops that are located between сoupled-line. The equivalent circuit of the coupled lines was calculated and analyzed for a single periodic stub. This allowed us to determine the necessary parameters and dimensions of the topology. The device is narrow-band (3 GHz ± 5 %), transmission coefficient minus 0.44 dB at the center frequency of 3 GHz, isolation for isolated ports is not less than 35 dB. The proposed compact coupler with a coupling level of 0 dB suits building distribution circuits in which it is necessary to exclude the intersection of transmission lines. The information on the synthesis of the 3 dB co-directional microwave coupler on coupled strip lines with lateral electromagnetic coupling is given. The coupler is characterized by a high isolation level with an isolated port, not less than 40 dB. The imbalance of the amplitudes between the working (through and connected) and the input port is minus (3.4 ± 0.8) dB.

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26

Cuesta, F., A. Griol, A. Martínez, and J. Martí. "Experimental demonstration of photonic crystal directional coupler at microwave frequencies." Electronics Letters 39, no. 5 (2003): 455. http://dx.doi.org/10.1049/el:20030317.

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27

Cao, Kaicheng, Yongqiang Cheng, Kang Liu, Hongqiang Wang, Jianqiu Wang, and Hongyan Liu. "Off-Grid Microwave Coincidence Imaging Based on Directional Grid Fission." IEEE Antennas and Wireless Propagation Letters 19, no. 12 (December 2020): 2497–501. http://dx.doi.org/10.1109/lawp.2020.3037100.

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28

Liu, Jinchang, Lili Zhang, Ping Gao, Jun Ma, Chuanfu Xia, and Renjie Lin. "Automatic UAV Relay Communication System Based on Microwave Directional Antenna." Journal of Physics: Conference Series 1650 (October 2020): 022019. http://dx.doi.org/10.1088/1742-6596/1650/2/022019.

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29

Andersson, I. L. "High-speed microwave switching using laser-controlled microstrip directional coupler." Electronics Letters 25, no. 5 (1989): 368. http://dx.doi.org/10.1049/el:19890255.

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30

Sebek, Jan, Sergio Curto, Radoslav Bortel, and Punit Prakash. "Analysis of minimally invasive directional antennas for microwave tissue ablation." International Journal of Hyperthermia 33, no. 1 (July 5, 2016): 51–60. http://dx.doi.org/10.1080/02656736.2016.1195519.

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31

Lobato-Morales, Humberto, Alonso Corona-Chavez, Tatsuo Itoh, and José L. Olvera-Cervantes. "Dual-Band Multi-Pole Directional Filter for Microwave Multiplexing Applications." IEEE Microwave and Wireless Components Letters 21, no. 12 (December 2011): 643–45. http://dx.doi.org/10.1109/lmwc.2011.2172683.

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32

Ojaroudi, Nasser, Mouhammad Ojaroudi, and Yasser Ebazadeh. "UWB/OMNI-DIRECTIONAL MICROSTRIP MONOPOLE ANTENNA FOR MICROWAVE IMAGING APPLICATIONS." Progress In Electromagnetics Research C 47 (2014): 139–46. http://dx.doi.org/10.2528/pierc14010804.

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33

Hadj Aissa Fekhar, Youcef, Faouzi Salah-Belkhodja, Didier Vincent, Enrique Bronchalo, Wassila Tebboune, and Rafah Naoum. "Microwave non-reciprocal coplanar directional coupler based on ferrite materials." Journal of Electromagnetic Waves and Applications 34, no. 5 (March 9, 2020): 623–33. http://dx.doi.org/10.1080/09205071.2020.1733102.

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34

Levy, Benzion, Ely Levine, and Yosef Pinhasi. "Super Directional Antenna—3D Phased Array Antenna Based on Directional Elements." Electronics 11, no. 14 (July 17, 2022): 2233. http://dx.doi.org/10.3390/electronics11142233.

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This paper describes an antenna design approach for achieving super directivity in an AESA (Active Electronic Scanned Array) radar using an unconventional 3D phased array (PA) antenna concept based on directional Yagi–Uda elements. The proposed scheme is shown to have a wider scanning feature, with higher directivity in comparison to the same geometry dipole array without increasing the element number. The antenna’s microwave design includes an antipodal Yagi–Uda antenna element that is implemented efficiently on a microstrip PCB using a balun (balance–unbalance)-fed network. This type of antenna is valuable in restricted aperture scans for achieving a narrow antenna beam that increases the angular resolution and measurement precision of tracked targets and also enlarges the detection range or, alternatively, achieves the same performance with a lower number of elements—meeting the goal of low-cost production. The notable result of the high antenna directivity was obtained by both the element and the array architecture, which allowed for improvements in the Array Factor (AF) directivity by increasing the element’s spacing and broadening the scan sector, achieved via the suppression of the element’s Grating Lobe (GL). Another important benefit of this antenna design is the superior coupling reduction caused by its enlarged element distances, which are very significant in electronic scans. An outstanding opportunity to exploit this low coupling can be found in separated MIMO radar architecture. Other benefits of this design’s architecture are the support of a combined module and antenna on a unified board thanks to the End-Fire radiation pattern, its low frequency sensitivity, and its low-cost manufacturing.

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35

Savu, Ionel Danut. "Modification of Heat Flow Parameters during the Ceramic Assisted Microwave Heating of HDPE." Advanced Materials Research 1036 (October 2014): 240–45. http://dx.doi.org/10.4028/www.scientific.net/amr.1036.240.

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Microwave technology is more often used in large number of application. Heating polymers by microwave technology is met from domestic o industrial applications and the influences brought by the heating source, the impact between the microwaves and the polymer, to the base material is necessary to be well known to avoid different types of failure of the pieces. HDPE is polymer often used in application with interaction between material and microwaves. Because of that the analysis of the influence of such interaction on the flowing characteristics of the HDPE is proposed in this paper. Experimental programme was applied to HDPE 100 and HDPE 80, both heated by using mono-directional microwave beam with different sets of parameters (factorial experiment principles were used to establish the heating parameters). Plasticity characteristics of the heated material, as elongation and relaxation modulus, were determined by using thermal analysis. It has been recorded important influences of the heating process on the surface in contact with the ceramic powder that was used as microwave absorber. The DSC analysis revealed a decreasing of the elongation with about 16% and decreasing of the relaxation modulus with amount up to 18%, for the material located at the interface between the polymer and the ceramic powder. Each 2 mm from the interface to the interior of the polymer brought an intensity of the modification up to 15% of the values recorded for the interface. After 6 mm from the interface the intensity of the modification decreases very fast. By using DSC thermal analysis it has been analysed the crystallization rate of the polymer modified by the microwave heating and high rates were recorded. About 12% difference between the relaxation modulus of the heated and non-heated HDPE and that means local ageing transformation of the HDPE.

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36

Hirose, Sakyo, Yusuke Iguchi, Yoichi Nii, Tsuyoshi Kimura, and Yoshinori Onose. "Nonreciprocal microwave response at room temperature in multiferroic Y-type hexaferrite BaSrCo₂Fe₁₁AlO₂₂." Applied Physics Letters 121, no. 22 (November 28, 2022): 222401. http://dx.doi.org/10.1063/5.0124283.

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We investigated the microwave response in room-temperature multiferroic BaSrCo2Fe11AlO22. Microwave absorption ascribed to magnetic resonances was observed in the frequency range from 6 to 20 GHz. When the ferroelectric polarization is aligned by the electric and magnetic fields, the magnitude depends on the sign of the microwave propagation vector that indicates the nonreciprocal directional dichroism (NDD). The phenomenon can be observed even at room temperature, the sign can be controlled by the external electric and magnetic fields, and the magnitude of NDD attained is approximately 11% at 300 K and 28% at 200 K. Such microwave properties will open the avenue of practical applications for future wireless communications.

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37

Tian, Feng, Xia Ma, Han Hao, Xuewen Li, Jingdao Fan, Liang Guo, and Xiaojun Huang. "Broadband Bi-Directional Polarization-Insensitive Metamaterial Absorber." Materials 14, no. 23 (November 30, 2021): 7339. http://dx.doi.org/10.3390/ma14237339.

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Conventional metamaterial absorbers eliminate the transmitted electromagnetic wave by attaching the metal plate with the unidirectional absorption performance; these absorbers limit the practical applications to a large extent. In this paper, we present a broadband bi-directional metamaterial absorber by etching chip resistors on the resonators for expanding the bandwidth, and two orthogonal I-shaped structures are pasted on the both sides of the ultra-thin substrate (FR-4) instead of the metal plate for enhancing absorptance of the absorber. Simulated results show that absorptance of the designed absorber is larger than 0.9 in 1.43–2.51 GHz along the forward and backward directions under both TE and TM polarizations. Microwave experiments in the chamber are performed to verify the simulations, and the experimental results exhibit the excellent agreement with the simulations. Additionally, two I-shaped structures are orthogonally pasted on an ultrathin substrate, leading to the impedance-matching of both forward and backward directions, and the absorptance can be tailed dynamically via the middle layer of the substrate. The physics of the absorption are visualized by using a transmission line based on equivalent circuits. We claim that the designed bi-directional metamaterial absorber can be a good candidate for electromagnetic stealth and energy harvesting.

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38

Bi, Ping, Xiu Hua Chen, Wen Hui Ma, Cong Zhang, Kui Xian Wei, Yu Ping Li, and Xue Mei Liu. "Nucleation of Multicrystalline Silicon during Directional Solidification." Materials Science Forum 847 (March 2016): 103–8. http://dx.doi.org/10.4028/www.scientific.net/msf.847.103.

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In this work, directional solidification was performed for multicrystalline silicon (mc-Si) ingot casting. The initial nucleation at the bottom of the silicon melt could be controlled by changing the cooling rate from 9 to 20μm/s. Metallographic microscope, X-Ray Diffraction (XRD), Microwave photoconductivity decay meter (μ-PCD) and four-point probe resistivity tester were used to investigate the microstructure, crystal orientation and electrical properties of the mc-Si ingots. The obtained results showed that cooling rate at 17μm/s is the optimum condition for the mc-Si ingots casting, under which the prepared ingot has lower dislocation density of 6×10-3 cm-2, better electrical properties, more uniformer resistivity distribution with an average value of 0.68 Ω×cm and higher minority carrier lifetime with a maximum value of 1.8 μs than that of in the other cooling rate conditions.

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39

Huang, Jinhui, Buning Zhang, Paolo Valdiserri, Xue Huang, Guoqiang Yin, and Yingde Cui. "Thermal Flow Self-Assembled Anisotropic Chemically Derived Graphene Aerogels and Their Thermal Conductivity Enhancement." Nanomaterials 9, no. 9 (August 29, 2019): 1226. http://dx.doi.org/10.3390/nano9091226.

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In this study, we investigated the directional heating of graphene oxide (GO) dispersion to generate a temperature gradient and form a simulated “ocean current” inside the dispersion so that GO sheets could be aligned in a directional manner and then reduced and self-assembled into anisotropic reduced graphene oxide (rGO) gel. After freeze-drying and varying degrees of vacuum microwave treatment, anisotropic chemically derived graphene aerogels (AGAs) were obtained. Through performance detection and the analysis of the results, it was verified that the AGAs with certain characteristics of “ocean current” were prepared in this experiment, and its axial direction has obvious directional arrangement. After being treated by vacuum microwave for a short time (1 min.), the axial thermal conductivity of the composite materials (AGA-adsorbed paraffin) was observed to be 1.074 W/mK, and the thermal conductivity enhancement efficiency was 995%; as compared with similar thermal conductivity enhancement composites that were found in previous studies, the proposed method in this paper has the advantages of simple processing, high efficiency, and energy conservation.

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Cao, Yibing, Jun Sun, Zhimin Song, Zhiqiang Fan, Guangshuai Zhang, Yuchuan Zhang, and Yan Teng. "Plasma effects of the directional coupler for high-power microwave measurements." Physics of Plasmas 25, no. 7 (July 2018): 072122. http://dx.doi.org/10.1063/1.5033465.

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Lakins, D. G., C. Z. Alvarado, L. D. Thompson, M. T. Brashears, J. C. Brooks, and M. M. Brashears. "Reduction of Salmonella Enteritidis in Shell Eggs Using Directional Microwave Technology." Poultry Science 87, no. 5 (May 2008): 985–91. http://dx.doi.org/10.3382/ps.2007-00393.

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Yang, Yang, Zhipeng Fan, Tao Hong, Maoshun Chen, Xiangwei Tang, Jianbo He, Xing Chen, Changjun Liu, Huacheng Zhu, and Kama Huang. "Design of Microwave Directional Heating System Based on Phased-Array Antenna." IEEE Transactions on Microwave Theory and Techniques 68, no. 11 (November 2020): 4896–904. http://dx.doi.org/10.1109/tmtt.2020.3002831.

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Islam, Mohammad Tariqul, Md Zulfiker Mahmud, Norbahiah Misran, Jun-Ichi Takada, and Mengu Cho. "Microwave Breast Phantom Measurement System With Compact Side Slotted Directional Antenna." IEEE Access 5 (2017): 5321–30. http://dx.doi.org/10.1109/access.2017.2690671.

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Koop, B. C., Yu I. Dzhezherya, K. Demishev, V. Yurchuk, D. C. Worledge, and V. Korenivski. "Demonstration of bi-directional microwave-assisted magnetic reversal in synthetic ferrimagnets." Applied Physics Letters 103, no. 14 (September 30, 2013): 142408. http://dx.doi.org/10.1063/1.4824016.

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Mahmud, M. Z., Mohammad T. Islam, M. Samsuzzaman, Salehin Kibria, and Norbahiah Misran. "Design and parametric investigation of directional antenna for microwave imaging application." IET Microwaves, Antennas & Propagation 11, no. 6 (March 23, 2017): 770–78. http://dx.doi.org/10.1049/iet-map.2016.0774.

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Debicki, P. S., M. Okoniewski, E. Okoniewska, P. N. Shrivastava, A. M. Debicka, L. V. Baert, and Z. Petrovich. "Cooled microwave transrectal applicator with adjustable directional beam for prostate treatment." International Journal of Hyperthermia 11, no. 1 (January 1995): 95–108. http://dx.doi.org/10.3109/02656739509004951.

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47

Latif, Saeed I., Daniel Flores Tapia, Diego Rodriguez Herrera, Mario Solis Nepote, Stephen Pistorius, and Lotfollah Shafai. "A Directional Antenna in a Matching Liquid for Microwave Radar Imaging." International Journal of Antennas and Propagation 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/751739.

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The detailed design equations and antenna parameters for a directional antenna for breast imaging are presented in this paper. The antenna was designed so that it could be immersed in canola oil to achieve efficient coupling of the electromagnetic energy to the breast tissue. Ridges were used in the horn antenna to increase the operating bandwidth. The antenna has an exponentially tapered section for impedance matching. The double-ridged horn antenna has a wideband performance from 1.5 GHz to 5 GHz (3.75 GHz or 110% of impedance bandwidth), which is suitable for breast microwave radar imaging. The fabricated antenna was tested and compared with simulated results, and similar bandwidths were obtained. Experiments were conducted on breast phantoms using these antennas, to detect a simulated breast lesion. The reconstructed image from the experiments shows distinguishable tumor responses indicating promising results for successful breast cancer detection.

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Glushechenko, E. N. "Microstrip doubler microwave with non-traditional implementation." Технология и конструирование в электронной аппаратуре, no. 1-2 (2019): 20–26. http://dx.doi.org/10.15222/tkea2019.1-2.20.

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Frequency multipliers are used in electronic devices to generate spectrally pure sinusoidal signals in the frequency range from a few to tens of GHz. The multipliers are used to multiply the frequency of highly stable but more low-frequency devices with the subsequent extraction of the necessary harmonics from the frequency spectrum of the received microwave range. The frequencies selected after multiplication (set) have significantly higher energy, spectral and range characteristics, which allows them to be used as local oscillators and synthesizers in receiving and transmitting systems. The authors of this paper theoretically substantiate and practically demonstrate the possibility of an unconventional implementation of a microstrip multiplier of the microwave range based on a directional traveling wave filter. The proposed implementation does not require the use of active semiconductor elements. The well-known circuit and technological principles for the creation of microstrip microwave multipliers are considered in the paper. The features, problems and shortcomings arising from their implementation are analyzed. The effectiveness of using the balanced circuit for frequency multiplication is confirmed. A list of mandatory requirements and conditions necessary for the implementation of the microwave multipliers is given. It is demonstrated that the features of the microstrip travelling-wave filter are identical to the conditions and requirements for the implementation of balanced multipliers. It is shown and substantiated how an unconventional implementation of a passive microwave multiplier is possible due to the electromagnetic interaction of the input and output nodes of such a filter with an annular travelling-wave resonator. Using the example of modifying a block diagram of a directional filter into a multiplier circuit, the possibility of creating a microwave doubler is confirmed by separating a given frequency from the frequency spectrum of a traveling-wave ring resonator.

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Pushpakaran, Sarin Valiyaveettil, Jayakrishnan M. Purushothama, Manoj Mani, Aanandan Chandroth, Mohanan Pezholil, and Vasudevan Kesavath. "A metamaterial absorber based high gain directional dipole antenna." International Journal of Microwave and Wireless Technologies 10, no. 4 (April 3, 2018): 430–36. http://dx.doi.org/10.1017/s1759078718000454.

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AbstractA novel idea for generating directional electromagnetic beam using a metamaterial absorber for enhancing radiation from a microwave antenna in the S-band is presented herewith. The metamaterial structure constitutes the well-known stacked dogbone doublet working in the absorption mode. The reflection property of the dogbone metamaterial absorber, for the non-propagating reactive near-field, is utilized for achieving highly enhanced and directional radiation characteristics. The metamaterial absorber converts the high-spatial reactive spectrum in the near-field into propagating low-spatial spectrum resulting in enhanced radiation efficiency and gain. The gain of a printed standard half-wave dipole is enhanced to 10 dBi from 2.3 dBi with highly directional radiation characteristics at resonance.

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Cheng, Yang, Yongfeng Li, He Wang, Jiafu Wang, Zhe Qin, and Shaobo Qu. "Circular dichroism assisted bi-directional absorbers." Journal of Physics D: Applied Physics 55, no. 9 (November 17, 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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