A Method of Suppressing Higher Order Modes for Improving Radiation Performance of Metasurface Multiport Antennas Using Characteristic Mode Analysis

2018 ◽  
Vol 66 (4) ◽  
pp. 1894-1902 ◽  
Author(s):  
Feng Han Lin ◽  
Zhi Ning Chen
Keyword(s):  
Higher Order ◽  
Mode Analysis ◽  
Characteristic Mode ◽  
Higher Order Modes ◽  
Multiport Antennas

scholarly journals Electrical characterisation of higher order spin wave modes in vortex-based magnetic tunnel junctions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alex. S. Jenkins ◽  
Lara San Emeterio Alvarez ◽  
Samh Memshawy ◽  
Paolo Bortolotti ◽  
Vincent Cros ◽  
...  
Keyword(s):  
Spin Wave ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Higher Order ◽  
Spin Torque ◽  
Micromagnetic Simulations ◽  
Higher Order Modes ◽  
Spin Diode ◽  
Super High Frequency ◽  
Wave Modes

AbstractNiFe-based vortex spin-torque nano-oscillators (STNO) have been shown to be rich dynamic systems which can operate as efficient frequency generators and detectors, but with a limitation in frequency determined by the gyrotropic frequency, typically sub-GHz. In this report, we present a detailed analysis of the nature of the higher order spin wave modes which exist in the Super High Frequency range (3–30 GHz). This is achieved via micromagnetic simulations and electrical characterisation in magnetic tunnel junctions, both directly via the spin-diode effect and indirectly via the measurement of the coupling with the gyrotropic critical current. The excitation mechanism and spatial profile of the modes are shown to have a complex dependence on the vortex core position. Additionally, the inter-mode coupling between the fundamental gyrotropic mode and the higher order modes is shown to reduce or enhance the effective damping depending upon the sense of propagation of the confined spin wave.

scholarly journals Design of large mode area all-solid anti-resonant fiber for high-power lasers

2021 ◽  
Vol 9 ◽  
Author(s):  
Xin Zhang ◽  
Shoufei Gao ◽  
Yingying Wang ◽  
Wei Ding ◽  
Pu Wang
Keyword(s):  
High Power ◽  
Single Mode ◽  
Higher Order ◽  
Coupling Scheme ◽  
Resonant Coupling ◽  
Higher Order Modes ◽  
Mode Loss ◽  
Fiber Mode ◽  
Power Needs ◽  
Mode Area

Abstract High-power fiber lasers have experienced a dramatic development over the last decade. Further increasing the output power needs an upscaling of the fiber mode area, while maintaining a single-mode output. Here, we propose an all-solid anti-resonant fiber (ARF) structure, which ensures single-mode operation in broadband by resonantly coupling higher-order modes into the cladding. A series of fibers with core sizes ranging from 40 to 100 μm are proposed exhibiting maximum mode area exceeding 5000 μm2. Numerical simulations show this resonant coupling scheme provides a higher-order mode (mainly TE01, TM01, and HE21) suppression ratio of more than 20 dB, while keeping the fundamental mode loss lower than 1 dB/m. The proposed structure also exhibits high tolerance for core index depression.

scholarly journals Bandwidth Optimization of a Textile PIFA with DGS Using Characteristic Mode Analysis

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2516
Author(s):  
Bashar Bahaa Qas Elias ◽  
Ping Jack Soh ◽  
Azremi Abdullah Al-Hadi ◽  
Prayoot Akkaraekthalin ◽  
Guy A. E. Vandenbosch
Keyword(s):  
Wireless Body Area Network ◽  
Simulation Software ◽  
The Body ◽  
Mode Analysis ◽  
Area Network ◽  
Defected Ground Structure ◽  
Characteristic Mode ◽  
Antenna Structure ◽  
Rectangular Patch ◽  
Conventional Optimization

This work presents the design and optimization of an antenna with defected ground structure (DGS) using characteristic mode analysis (CMA) to enhance bandwidth. This DGS is integrated with a rectangular patch with circular meandered rings (RPCMR) in a wearable format fully using textiles for wireless body area network (WBAN) application. For this integration process, both CMA and the method of moments (MoM) were applied using the same electromagnetic simulation software. This work characterizes and estimates the final shape and dimensions of the DGS using the CMA method, aimed at enhancing antenna bandwidth. The optimization of the dimensions and shape of the DGS is simplified, as the influence of the substrates and excitation is first excluded. This optimizes the required time and resources in the design process, in contrast to the conventional optimization approaches made using full wave “trial and error” simulations on a complete antenna structure. To validate the performance of the antenna on the body, the specific absorption rate is studied. Simulated and measured results indicate that the proposed antenna meets the requirements of wideband on-body operation.

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