Nonreciprocal Components With Distributedly Modulated Capacitors

Qin, Shihan

doi:10.1109/tmtt.2014.2347935

Cited by 225 publications

(106 citation statements)

References 30 publications

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“…The concept is based on imparting a suitable form of momentum biasing that breaks time-reversal symmetry, achieved with mechanical motion or with spatiotemporal modulation (20)(21)(22)(23)(24)(25)(26)(27)(28)(29). In this paper, for the first time to our knowledge, we apply these concepts to emitting/absorbing systems, showing that it is possible to realize magnetic-free nonreciprocal structures that can emit without absorbing from the same direction over a broad frequency range.…”

mentioning

confidence: 99%

Breaking temporal symmetries for emission and absorption

Hadad

Soric

Alù

2016

Proc. Natl. Acad. Sci. U.S.A.

261

177

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Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff's law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω, θ) = a(ω, θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies.

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confidence: 99%

Breaking temporal symmetries for emission and absorption

Hadad

Soric

Alù

2016

Proc. Natl. Acad. Sci. U.S.A.

261

177

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“…These shortcomings keep them from being utilized in systems that require wide dynamic ranges678. The realization of non-reciprocity without exploiting magnetic material properties has been introduced in a number of past works9101112131415161718192021. In these previous works, the dielectric property of a conventional transmission line was modulated in time and space to break the material property symmetry.…”

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confidence: 99%

“…Time-modulation architectures were also applied to parametrically coupled resonators1516 and a staggered commutating switched capacitor device17 to achieve non-reciprocity over a very narrow bandwidth. Broadband non-reciprocity at RF has been demonstrated on a printed circuit board and on a monolithic microwave integrated circuit (MMIC) based on the concept of Time-Varying Transmission Line (TVTL)18192021. The lowest operating frequency of the device is dictated by the longest delay of the TVTL one can implement.…”

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confidence: 99%

Ultra-Wide Band Non-reciprocity through Sequentially-Switched Delay Lines

Biedka

Zhu

et al. 2017

Sci Rep

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Achieving non-reciprocity through unconventional methods without the use of magnetic material has recently become a subject of great interest. Towards this goal a time switching strategy known as the Sequentially-Switched Delay Line (SSDL) is proposed. The essential SSDL configuration consists of six transmission lines of equal length, along with five switches. Each switch is turned on and off sequentially to distribute and route the propagating electromagnetic wave, allowing for simultaneous transmission and receiving of signals through the device. Preliminary experimental results with commercial off the shelf parts are presented which demonstrated non-reciprocal behavior with greater than 40 dB isolation from 200 KHz to 200 MHz. The theory and experimental results demonstrated that the SSDL concept may lead to future on-chip circulators over multi-octaves of frequency.

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“…Although nonreciprocal devices can in general provide greater field control than reciprocal devices, they require either nonlinear materials [1], or a complicated biasing mechanism such as a static magnetic field [2], static electric field [3], or time-varying electric field [4,5]. This has motivated the development of reciprocal devices that can mimic nonreciprocal effects.…”

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confidence: 99%

“…Several conclusions can be drawn from (5). In contrast to the 3D surface parameters, the 2D surface parameters depend upon the transverse wavenumber of the incident field, [23].…”

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confidence: 99%