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Aperture and Phased Array Antennas
Published in Habibur Rahman, Fundamental Principles of Radar, 2019
If the amplitude of aperture distribution is constant, it is called uniform circular aperture. It is a widely used microwave antenna. The attractive feature of this configuration is its simplicity in construction. Because of the circular profile of the aperture, it is often desirable and convenient to adopt cylindrical coordinates for the analysis of fields. The uniform circular aperture is approximated by a circular opening of radius a in a ground plane illuminated by a uniform plane wave normally incident from behind. To simplify the mathematical details, the field over the aperture will be assumed to be constant at E0 and given by E¯a=x^E0r′≤a.
Excitation and Amplification of Propagating Spin Waves by Spin Currents
Published in Sergej O. Demokritov, Spin Wave Confinement, 2017
Vladislav E. Demidov, Sergej O. Demokritov
Figure 11.1 a shows a schematic of a typical experiment. A ferromagnetic film with the thickness of 5-50 nm is patterned into a stripe with the width in the range of0.1 to 5 μm serving as a magnonic waveguide. To excite spin waves, a stripe microwave antenna oriented perpendicular to the waveguide axis is manufactured on top of it. The antenna is made of highly conductive material, such as Au or Cu, and has typical width in the range of 0.5 to 2 μm and thickness of 100-150 nm. The antenna is electrically isolated from the waveguide by a 20-40 nm thick dielectric layer. The excitation of spin waves [35,36] is performed by transmitting through the antenna a microwave-frequency current. This current creates a local dynamic magnetic field, which couples to the magnetization in the waveguide underneath the antenna, resulting in a creation of a spin wave propagating away from the excitation area.
Consents and Design Guidance
Published in Jonathan Hetreed, Ann Ross, Charlotte Baden-Powell, Architect's Pocket Book, 2017
Jonathan Hetreed, Ann Ross, Charlotte Baden-Powell
Under some circumstances the following may require planning permission:The construction of a veranda, balcony or raised platform.The installation, replacement or alteration of a microwave antenna.The installation, alteration or replacement of a chimney, flue or soil pipe.
Weighted topology optimization of back-up supporting structures of antennas
Published in Engineering Optimization, 2023
Yuzheng Tan, Shuxin Zhang, Sihao Qian, Jun Song
The results of the back-up supporting structure of antennas conforming to the corresponding manufacturing characteristics are obtained through weighted level-set topology optimization. The structure is not only composed of clear components, but also relatively symmetric, which is convenient for subsequent detailed design reference. The effectiveness of the weighting method is verified with a typical reflector antenna case for microwave antenna applications. The results show that the corresponding optimized truss structure can be easily obtained by selecting different shape feature control functions. The structure satisfies the needs of the antenna supporting structure design. The weighted optimization based on the shape control function can complete the optimization of the structure shape and reflect the corresponding manufacturing characteristics.
Evaluation of the glioblastoma multiforme treatment with hyperthermia using the finite element method
Published in Numerical Heat Transfer, Part A: Applications, 2023
Ayşe Sağıroğlu, İlke Karagöz, Öznur Özge Özcan, Türker Tekin Ergüzel, Mesut Karahan, Nevzat Tarhan
Brain tissue has the ability to absorb EMR waves. SAR values show a distribution parallel to the power distribution applied to the tissue. The efficiency of the SAR distribution values in our study was compared with the values in the microwave hyperthermia simulation studies of brain tumors conducted by Saito et al. Also, The microwave antenna geometries used in the study of Saito et al. [11] and in our study had the same results. When 2.45 GHz frequency is applied with 5 W power for 10 minutes, the distribution of the SAR value in the brain tissue and the results of the application made in the thesis study with 2.45 GHz frequency and 5 W power for 10 minutes are the same. The SAR value was the same in both studies and was approximately 280 W/kg. The SAR values obtained as a result of the applications in the thesis study are in the range of approximately 0.002-55000 (W/kg). In applications where the conductor wire length is 70 mm, SAR values are taken from a distance of 2.5 mm along a line parallel to the antenna.
Design of Reconfigurable Antenna Using MSF-EBG Structure to Improve Performance Parameters
Published in IETE Journal of Research, 2022
Manasi Shrikant Kanitkar, Shankar Baburao Deosarkar
Applications of the proposed antennas are for low-frequency applications such as GSM, PCS, Bluetooth, Wi-max, and Wi-Fi. MSF-UC-EBG structure can also be integrated with a microwave antenna. The overall performance of CPW-fed SIR antenna with MSF-UC-EBG structure can be considerably improved. For this structure, simulated and measured results are in good agreement and gain of the antenna is considerably improved. Gain of the antenna is increased from without EBG (3.26 dB) to FR4_EBG (7.08 dB) in simulation results whereas gain also increases from without EBG (2.37 dB) to with FR4_EBG (6.91 dB) as shown in Table 4. With one slot inside antenna and switch, the antenna can be configured for 2.5 and 1.56 GHz. Bandwidth and directivity have been improved from 48.8 to 99.23 MHz when FR4_EBG is used. Even though gain improvement is minimal, it is observed that for the proposed antenna at 2.5 GHz frequency gain improvement is at its good range. In future work, by changing shape or dimensions or by using the innovative shape of EBG structure, gain of the antenna can be improved further for the same frequency.