Search query: Tunable insertion loss attenuator{

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abstract: We report the development of a compact WR 4 (170260 GHz) optically tunable waveguide attenuator based on the interaction between electromagnetic waves and photo induced free carriers in semiconductors. This approach is promising for achieving superior performance, including a ~50 dB tuning range, low insertion loss, lowreturn loss (VSWR) and high tuning speed. Based on full wave simulation results, an average attenuation level of ~50 dB can be achieved using a 1 mm long Ge absorber at a light intensity of 1 W/cm. By employing an E plane taper design and energy absorption mechanism, return loss lower than 13 dB have been achieved. A prototype attenuator with Si absorber has been implemented using an E plane split waveguide design. Initial measurement results show that ~14 dB attenuation can be achieved using a single illumination spot. The attenuation level can be improved by increasing the illumination region length employing multiple fibers.
author_names: Zhenguo Jiang

Md Itrat Bin Shams

Syed M Rahman

Patrick J Fay

Cheuk-yuE Tong

Lei Liu
title: A WR 4 Optically Tunable Waveguide Attenuator with 50 dB Tuning Range and Low Insertion Loss
year: 2016

abstract: In this paper, a novel type of dynamically tunable attenuator based on graphene is proposed. This type of attenuator is composed of one or two graphene sandwich structures (GSSs) and a microstrip line. The GSSs are spread on the substrate of microstrip line near the signal strip along the direction of propagation to dissipate electromagnetic field. By the application of biased voltage, the surface impedance of graphene can be tuned, and consequently, the insertion loss of microstrip line can also be adjusted while the return loss maintains relatively low level. A transverse equivalent network and a closed form of attenuation of each attenuator are also proposed, which can be utilized to analyze the performance of attenuator with different critical parameters of graphene in detail. According to the analysis, there is a maximum value of the attenuation as the surface impedance of graphene rises from 0 to $3000~\Omega \Box As an example, a prototype of each tunable microstrip line attenuator operating at gigahertz frequencies is fabricated and measured. The fabricated attenuator present favorable attenuation ranges from 3 to 15 dB, at the operating frequency from 9 to 40 GHz, and with a stable wideband attenuation corresponding to bias voltage changing from 0 to 4.0 V.
author_names: An-Qi Zhang

Zhen-Guo Liu

Wei-Bing Lu

Hao Chen
title: Dynamically Tunable Attenuator on a Graphene Based Microstrip Line
venue: IEEE Transactions on Microwave Theory and Techniques
year: 2019

abstract: In this paper, a novel tunable attenuator based on graphene is proposed. The attenuator is composed of a graphene sandwich structure and a coplanar waveguide (CPW) By tuning the surface impedance of graphene, the insertion loss of transmission line can consequently be tuned. This attenuator present favorable attenuation ranges from 3dB to 15dB at a relatively wide frequency band from 10 GHz to 26 GHz.
author_names: An-Qi Zhang

Zhen-Guo Liu

Yang Yi

Wei-Bing Lu
title: Graphene Based Tunable Attenuator on Coplanar Waveguide
venue: 2018 IEEE International Conference on Computational Electromagnetics (ICCEM)
year: 2018

abstract: This paper presents a novel tunable microstrip attenuator, based on few layer graphene flakes. The attenuator consists of a microstrip line with two pairs of graphene pads located between the microstrip line and metal vias, positioned at the two sides of the microstrip line. In the proposed device, the insertion loss can be changed electronically by varying the applied control voltage. The structure is designed in such a way, that the attenuation is mainly due to dissipation, while minimizing the reflection contribution. A prototype of the proposed structure has been fabricated and experimentally verified. It operates in a frequency band of DC to 10 GHz, with 25 dB tunability and minimum insertion loss of 1.5 dB.
author_names: Muhammad Yasir

Maurizio Bozzi

Luca Perregrini

Silvia Bistarelli

Antonino Cataldo

Stefano Bellucci
title: Tunable and input matched attenuator based on few layer graphene
venue: 2017 47th European Microwave Conference (EuMC)
year: 2017

abstract: In this paper, a novel graphene based tunable attenuator with substrate integrated waveguide (SIW) structure is first presented. Two graphene sandwich structures insert into SIW and are utilized to constitute E plane surface impedance. By use of biased voltage, the surface impedance and the insertion loss of monolayer graphene inside SIW can be tuned. The performance of attenuator with different critical parameters of graphene sheets are analyzed in detail.
author_names: An-Qi Zhang

Wei-Bing Lu

Zhen-Guo Liu

Yang Yi

Hao Chen

Bao-Hu Huang
title: A tunable attenuator on graphene based substrate integrated waveguide
venue: 2017 Sixth Asia Pacific Conference on Antennas and Propagation (APCAP)
year: 2017

abstract: In this work, a novel tunable attenuator is presented which is based on few layer graphene flakes. The attenuator is formed of a microstrip line with metallic grounded vias on either side separated from the microstrip line by few layer graphene flakes. The insertion loss of the attenuator can be tuned by changing the bias voltage applied to the graphene flakes. It is shown that the reflection from the attenuator is minimized and its bandwidth is doubled with an increase in the tunable range. A prototype is fabricated and the simulated results are verified through experiments. The attenuator works from DC to 10 GHz with a tunable range of almost 25 dB, the value of reflection attained at maximum attenuation is around 3 dB.
author_names: Muhammad Yasir

Maurizio Bozzi

Luca Perregrini

Silvia Bistarelli

Antonino Cataldo

Stefano Bellucci
title: Highly tunable and large bandwidth attenuator based on few layer graphene
venue: 2017 IEEE MTT S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS AMP)
year: 2017

abstract: This paper presents the design of a graphene based electronically tunable microstrip attenuator operating at the frequency of 5 GHz. The use of graphene as a variable resistor is discussed, and the modeling of its electromagnetic properties at microwave frequencies is fully addressed. The design of the graphene based attenuator is described. The structure integrates a patch of graphene, whose characteristics can range from fairly good conductor to highly lossy material, depending on the applied voltage. By applying the proper voltage through two high impedance bias lines, the surface resistivity of graphene can be modified, thus changing the insertion loss of the microstrip attenuator.
author_names: Luca Pierantoni

Davide Mencarelli

Maurizio Bozzi

Riccardo Moro

Stefano Bellucci
title: Graphene based electronically tunable microstrip attenuator
venue: 2014 IEEE MTT S International Microwave Symposium (IMS2014)
year: 2014

abstract: Abstract A tunable all fiber optical attenuator (AOA) based on microfiber with adjustable coupling angle is reported and demonstrated. The AOA is fabricated of a microfiber probe coupled to a tapered fiber on the waist region through van der Waals and electrostatic forces. The attenuation can be tuned by adjusting the coupling angle of the two microfibers. When the coupling is fabricated of angles adjust from 8 0 o to 1 0 o the optical attenuation can be tuned in a large range from 5.7 dB to 40.1 dB with low insertion loss. The simulation and experimental show that the coupling length can be changed by increasing the coupling angle, which results in decreasing the attenuation of AOA. The attenuation of AOA is decreased linearly by increasing the coupling angle. It provides a feasible approach to achieve attenuators with miniature volume, low cost, and multiple functions in optical communication and fiber lasers.
author_names: Yan-cheng Ji

Yupei Chen

Dan Sun

Guoan Zhang

Chinhua Wang

Xiaojun Zhu
title: An all fiber optical attenuator based on adjustable coupling angle of microfiber
year: 2021

abstract: We report our recent progress toward the development of optically controlled tunable/reconfigurable THz circuits/components in waveguide configurations for advanced sensing and adaptive wireless communications. The development and demonstration of a modified WR 4.3 variable waveguide attenuator based on photo excited Si with 60 dB range and 0.7 dB insertion loss will first be reviewed. Then the investigation of a WR 5.1 reconfigurable band stop filter (BSF) prototype based on photo induced electromagnetic band gap (PI EBG) structures using semiconductor mesa arrays will be presented. The center frequency of the BSF can be reconfigured from 166 200 GHz with adjustable stop band rejection and bandwidth. Finally, the development of high performance THz integrated switches using the same optical control methodology enabling the implementation of more advanced tunable/reconfigurable THz waveguide circuits will be envisioned, investigated and discussed. Preliminary results reveal that the optically controlled RF switches show a potentially record high figure of merit (evaluated by RonCoff constant) of 153 THz, allowing them to outperform both conventional solid state device based (e.g. HEMTs) and emerging phase changing material based (e.g. VO2) counterparts, and therefore promising to compete with MEMS switches in the mmW THz region for a novel class of tunable/reconfigurable circuits/components.
author_names: Jun Ren

Yu Shi

Yijing Deng

Jeffrey L Hesler

Patrick J Fay

Longfei Liu
title: Development of Optically Controlled Tunable/Reconfigurable Terahertz Waveguide Circuits/Components For Advanced Sensing and Adaptive Wireless Communications
venue: 2019 IEEE National Aerospace and Electronics Conference (NAECON)
year: 2019

abstract: In this work, two different types of tunable attenuators based on graphene are presented and a comparative analysis of their design and functionality is performed. A preliminary solution of the tunable attenuator has been recently proposed, based on a graphene patch deposited in the gap of a microstrip line: it results in wide band functionality from DC to 20 GHz, with a tunability of 7 dB and minimum insertion loss of 5 dB. A novel enhanced design is proposed, with two graphene patches located between the main microstrip line and two metal vias, located at the two sides of the microstrip line. This solution operates in a frequency band of DC to 5 GHz, with 14 dB tunability and minimum insertion loss of 0.3 dB.
author_names: Muhammad Yasir

Maurizio Bozzi

Luca Perregrini

Silvia Bistarelli

Antonino Cataldo

Stefano Bellucci
title: Innovative tunable microstrip attenuators based on few layer graphene flakes
venue: 2016 16th Mediterranean Microwave Symposium (MMS)
year: 2016