Low-Loss Modes in Dielectric Lined Waveguide

Carlin, J. W.; D’Agostino, P.

doi:10.1002/j.1538-7305.1971.tb02572.x

Cited by 21 publications

(2 citation statements)

References 3 publications

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“…The dielectric lining and the bore form a closed waveguide with a reactive wall . In waveguide literature such a dielectric lined waveguide is known as a low attenuation waveguide . To investigate the effect of dielectric lining to improve travelling wave MR efficiency, the modes in the scanner bore with a load and with the dielectric lining were studied with an analytical model for a range of relative permittivity values of the dielectric lining.…”

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confidence: 99%

Improved RF performance of travelling wave MR with a high permittivity dielectric lining of the bore

et al. 2012

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Application of travelling wave MR to human body imaging is restricted by the limited peak power of the available RF amplifiers. Nevertheless, travelling wave MR advantages like a large field of view excitation and distant location of transmit elements would be desirable for whole body MRI. In this work, improvement of the B1+ efficiency of travelling wave MR is demonstrated. High permittivity dielectric lining placed next to the scanner bore wall effectively reduces attenuation of the travelling wave in the longitudinal direction and at the same time directs the radial power flow toward the load. First, this is shown with an analytical model of a metallic cylindrical waveguide with the dielectric lining next to the wall and loaded with a cylindrical phantom. Simulations and experiments also reveal an increase of B1+ efficiency in the center of the bore for travelling wave MR with a dielectric lining. Phantom experiments show up to a 2-fold gain in B1+ with the dielectric lining. This corresponds to a 4-fold increase in power efficiency of travelling wave MR. In vivo experiments demonstrate an 8-fold signal-to-noise ratio gain with the dielectric lining. Overall, it is shown that dielectric lining is a constructive method to improve efficacy of travelling wave MR.

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Improved RF performance of travelling wave MR with a high permittivity dielectric lining of the bore

et al. 2012

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“…Much of the original theory of propagation in dielectric lined waveguides was derived by Unger, who demonstrated that the waveguides could be approximated with an effective wall impedance model [9,10,18]. Later, Carlin and D'Agonstino expanded on the attenuation of certain modes in DLWGs [19,20]. Bell Labs later proposed a TE 01 transmission line network based on DLWGs [11].…”

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Dielectric Lined Waveguides for Low Loss Millimeter Wave and Terahertz Transmission

Thackston

Doane²,

Anderson

et al. 2022

Preprint

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By coating the inside of an overmoded, smooth wall metallic waveguide with a thin dielectric layer, one can obtain similar boundary conditions to corrugated waveguides and achieve extremely low transmission loss propagating the HE11 mode. As presented here, dielectric lined waveguides are a cost-effective alternative to corrugated waveguides for broadband microwave transmission, particularly at frequencies above 300 GHz. A theoretical model provides an analytic method for computing attenuation. The propagation mode of a prototype dielectric lined waveguide is characterized using low power transmission measurements to analyze the beam radiated from the waveguide aperture. Results indicate HE11 mode purity of approximately 98%. Furthermore, we quantified attenuation with low power Fabry-Perot measurements, verifying low loss performance of the experimental prototype. These results demonstrate that dielectric lined waveguides could have applications in many fields demanding low attenuation millimeter and terahertz transmission, such as radar, high-frequency communication systems, THz dynamic nuclear polarization, and electron cyclotron heating in magnetically confined fusion experiments.

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A Relation for the Loss Characteristics of Circular Electric and Magnetic Modes in Dielectric Lined Waveguide

Carlin¹

1971

Bell System Technical Journal

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Low-Loss Modes in Dielectric Lined Waveguide

Cited by 21 publications

References 3 publications

Improved RF performance of travelling wave MR with a high permittivity dielectric lining of the bore

Improved RF performance of travelling wave MR with a high permittivity dielectric lining of the bore

Dielectric Lined Waveguides for Low Loss Millimeter Wave and Terahertz Transmission

A Relation for the Loss Characteristics of Circular Electric and Magnetic Modes in Dielectric Lined Waveguide

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