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This work introduces a reconfigurable leaky-waveguide antenna with a simplified biasing scheme for dynamic beam steering at a fixed frequency. Unlike prior metasurface-aided leaky-waveguide antennas that employ tunable metasurfaces as…

Applied Physics · Physics 2025-01-29 Sambong Jang , Minseok Kim

Standard coils can cause inhomogeneities due to the standing wave patterns at ultra high field MRI. This B1 inhomogeneity can be overcome using the travelling-wave MRI (twMRI) approach. The ma- jority of twMRI research has been done with…

Medical Physics · Physics 2015-11-12 Fabian Vazquez , Oscar Marrufo , Rodrigo Martin , Sergio Solis , Alfredo O. Rodriguez

Current wireless systems are experiencing unprecedented pressure that could be relieved by shifting carrier frequencies towards the terahertz spectrum. Yet, components are required to enable spectrally efficient communications at such high…

Optics · Physics 2021-09-24 Hichem Guerboukha , Jingwen Li

A leaky-wave antenna at optical frequencies is designed and integrated with a ring resonator at 1550 nm wavelength. The leaky wave is generated by using periodic perturbations in the integrated dielectric waveguide that excite the -1…

Optics · Physics 2015-03-26 Caner Guclu , Mehdi Veysi , Ozdal Boyraz , Filippo Capolino

The combination of surface coils and metamaterials remarkably enhance magnetic resonance imaging (MRI) performance for significant local staging flexibility. However, due to the coupling in between, impeded signal-to-noise ratio (SNR) and…

Medical Physics · Physics 2023-11-01 Qun Ren , Yuxin Lang , Yuqi Ja , Xia Xiao , Yu Liu , Xiangzheng Kong , Ruiqi Jin , Yongqing He , Jianwei You , Wei Sha , Yanwei Pang

Ultra-high field MRI offers unprecedented detail for non-invasive visualization of the human brain. However, brain imaging is challenging at 7T due to the B$_1^+$ field inhomogeneity, which results in signal intensity drops in temporal…

Medical Physics · Physics 2024-03-13 Vladislav Koloskov , Wyger Brink , Andrew Webb , Alena Shchelokova

This paper focuses on the spatial-spectral terahertz (THz) networks, where transmitters equipped with leaky-wave antennas send information to their receivers at the THz frequency bands. As a directional and nearly planar antenna, the…

Information Theory · Computer Science 2021-11-05 Zheng Lin , Lifeng Wang , Bo Tan , Xiang Li

In Magnetic Resonance Imaging (MRI), to achieve sufficient Signal to Noise Ratio (SNR), the electrical performance of the RF coil is critical. We developed a device (microcoil) based on the original concept of monolithic resonator. This…

Transmitter arrays play a critical role in ultra high field Magnetic Resonance Imaging (MRI), especially given the advantages made possible via parallel transmission (pTx) techniques. One of the challenges in design and construction of…

Wearable on-body millimeter-wave (mmWave) radars can provide obstacle detection and guidance for visually impaired individuals. The antennas, being a crucial component of these systems, must be lightweight, flexible, low-cost, and compact.…

Purpose: Low-field MRI systems operate at single MHz-range frequencies, where signal losses are primarily dominated by thermal noise from the radio-frequency (RF) receive coils. Achieving operation close to this limit is essential for…

Medical Physics · Physics 2026-03-09 Teresa Guallart-Naval , José M. Algarín , Joseba Alonso

Extraordinarily transmitting arrays are promising candidates for quasi-optical (QO) components due to their high frequency selectivity and beam scanning capabilities owing to the leaky-wave mechanism involved. We show here how by breaking…

Portable ultra-low field MRI (ULF-MRI) systems operated in unshielded environments are susceptible to electromagnetic interference (EMI). Subject presence in the imaging region will lead to substantial noise increases, yet the dominant…

Signal Processing · Electrical Eng. & Systems 2026-02-26 Jiali He , Yamei Dai , Sheng Shen , Jiamin Wu , Zheng Xu

We have used the LTLSM technique for a spatially resolved investigation of the microwave transport properties, nonlinearities and material inhomogeneities in an operating coplanar waveguide YBa_2Cu_3O_{7-\delta} (YBCO) microwave resonator…

Superconductivity · Physics 2014-01-09 A. P. Zhuravel , Steven M. Anlage , A. V. Ustinov

Inhomogeneity of the transmitted radiofrequency field B1+ is a major factor hindering the image quality in Magnetic Resonance Imaging (MRI) at high field strengths. Here, a novel approach is presented, to locally modulate the B1+ utilizing…

Ultrahigh field (UHF) Magnetic Resonance Imaging (MRI) provides a higher signal-to-noise ratio and, thereby, higher spatial resolution. However, UHF MRI introduces challenges such as transmit radiofrequency (RF) field (B1+) inhomogeneities,…

Computer Vision and Pattern Recognition · Computer Science 2025-02-07 Zhengyi Lu , Hao Liang , Xiao Wang , Xinqiang Yan , Yuankai Huo

The signal-to-noise ratio (SNR) in magnetic resonance imaging (MRI) governs the quality of signal detection and directly impacts the clarity and reliability of the acquired images. Recent advances in metamaterials have enabled lightweight…

Medical Physics · Physics 2026-01-27 Yuhan Liu , Xia Zhu , Ke Wu , Stephan W. Anderson , Xin Zhang

Objective: To develop and evaluate a bore-integrated patch antenna array designed for whole-body excitation in ultra-high-field (UHF) magnetic resonance imaging (MRI) with improved transmit efficiency and address the limitations of existing…

Theory of a high impedance coil (HIC) - a cable loop antenna with a modified shield - is discussed comprehensively for both in transmitting and receiving regimes. Understanding a weakness of the previously reported HIC in transmitting…

In this paper, a 2-D beam steering mm-wave antenna based on the leaky wave configuration is presented. Microstrip leaky wave antennas are known to exhibit beam rotation by changing the frequency. In this work, the microstrip leaky wave…

Systems and Control · Electrical Eng. & Systems 2024-10-15 Mahdi Alesheikh , Md Hedayatullah Maktoomi , Soheil Saadat , Hamidreza Aghasi