Research

Research

We explore techniques to improve high-power and reconfigurable RF, microwave, and mm-wave devices and systems. As one viable solution, we investigate low-temperature plasma as a tuning technology for high-power applications. Our current research topics include physics and modeling of EM-microplasma interaction, high-power tunable antenna elements and arrays, frequency-selective surfaces (FSS), plasma metamaterials, electrically-small antennas, tunable high-power matching networks, and efficient plasma generators.

High-Power EM Tuning and Control

Supported by ONR and ARL

Semiconductor devices, microelectromechanical systems (MEMS), liquid crystals, and ferromagnetic materials have been conventionally employed as RF tuning elements. However, these technologies suffer from two main issues of limited tuning range and low power handling. In plasmas, both dielectric permittivity and conductivity can be widely tuned by controlling the electron density. Furthermore, varying plasma sheath thickness leads to another tuning scheme. This effort aims to investigate techniques to precisely control the electromagnetic properties of plasmas to attain high-frequency tuning for high-power scenarios.

S. N. Ramesh and A. Semnani, “A comprehensive circuit modeling approach for self-sustained capacitively-coupled microwave plasmas,” IEEE TPS, 2021.

A. Semnani, S. Macheret, and D. Peroulis, “A quasi-absorptive microwave resonant plasma switch for high-power applications,” IEEE TMTT, 2018.

A. Semnani, S. Macheret, and D. Peroulis, “A high-power widely-tunable limiter utilizing an evanescent-mode cavity resonator loaded with a gas discharge tube,” IEEE TPS, 2016.

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Supported by ONR and ARL

Semiconductor devices, microelectromechanical systems (MEMS), liquid crystals, and ferromagnetic materials have been conventionally employed as RF tuning elements. However, these technologies suffer from two main issues of limited tuning range and low power handling. In plasmas, both dielectric permittivity and conductivity can be widely tuned by controlling the electron density. Furthermore, varying plasma sheath thickness leads to another tuning scheme. This effort aims to investigate techniques to precisely control the electromagnetic properties of plasmas to attain high-frequency tuning for high-power scenarios.

S. N. Ramesh and A. Semnani, “A comprehensive circuit modeling approach for self-sustained capacitively-coupled microwave plasmas,” IEEE TPS, 2021.

A. Semnani, S. Macheret, and D. Peroulis, “A quasi-absorptive microwave resonant plasma switch for high-power applications,” IEEE TMTT, 2018.

A. Semnani, S. Macheret, and D. Peroulis, “A high-power widely-tunable limiter utilizing an evanescent-mode cavity resonator loaded with a gas discharge tube,” IEEE TPS, 2016.

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Efficient Microwave Plasma Generation

Supported by NSF

Cold plasma is a critical technology in many applications such as plasma medicine, food preservation, water treatment, reconfigurable electronics, high-quality lighting, electric propulsion systems, sterilization, and microfabrication. However, generating stable plasma is not a trivial task as bulky, expensive, and energy-hungry units are often required. This research aims to develop high efficiency and low power plasmas based on resonant microwave structures. Such plasma can potentially be powered by low-power and readily available supplies, including cell phones, solar cells, or even batteries, making it safe, low cost, portable, and readily available to many end-users.

A. Semnani and K. S. Kabir, “A highly-efficient microwave plasma jet based on evanescent-mode cavity-resonator technology,” IEEE TPS, 2021.

Z. Vander Missen, A. Semnani, and D. Peroulis, “Microwave-driven CPW microplasma generator for low-power discharge,” IMWS-AMP, 2018.

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Supported by NSF

Cold plasma is a critical technology in many applications such as plasma medicine, food preservation, water treatment, reconfigurable electronics, high-quality lighting, electric propulsion systems, sterilization, and microfabrication. However, generating stable plasma is not a trivial task as bulky, expensive, and energy-hungry units are often required. This research is aimed at developing high efficiency and low power plasmas based on resonant microwave structures. Such plasma can potentially be powered by low-power and readily available supplies, including cell phones, solar cells, or even batteries, making it safe, low cost, portable, and readily available to many end-users.

A. Semnani and K. S. Kabir, “A highly-efficient microwave plasma jet based on evanescent-mode cavity-resonator technology,” IEEE TPS, 2021.

Z. Vander Missen, A. Semnani, and D. Peroulis, “Microwave-driven CPW microplasma generator for low-power discharge,” IMWS-AMP, 2018.

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Reconfigurable Antenna Elements and Arrays

Supported by ONR and NSF

This effort aims to investigate reconfigurable antenna elements and arrays that can handle high power, with tunable frequency, radiation pattern, and gain characteristics. All mechanical, electronic, and plasma tuning are being investigated. Specifically, plasma is the only natural material representing negative permittivity and so negative capacitance. Therefore, a negative plasma capacitor can compensate for the negative reactance of electrically-small antennas over a wide bandwidth. Plasma augmentation can significantly increase the bandwidth×efficiency of small antennas, and thus, this technique can be a viable solution for efficient radiation with tuning capability.

V. Podolsky, A. Semnani, and S. O. Macheret, “Experimental and numerical studies of a tunable plasma antenna sustained by RF power,” IEEE TPS, 2020.

A. Semnani, M. D. Sinanis, and D. Peroulis, “An evanescent-mode cavity-backed high-power tunable slot antenna,” IEEE TAP, 2019.

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Supported by ONR and NSF

This effort aims to investigate reconfigurable antenna elements and arrays that can handle high power, with tunable frequency, radiation pattern, and gain characteristics. All mechanical, electronic, and plasma tuning are being investigated. Specifically, plasma is the only natural material that can represent negative permittivity and so negative capacitance. Therefore, a negative plasma capacitor can compensate for the negative reactance of electrically-small antennas over a wide bandwidth. Plasma augmentation can significantly increase the bndwidth×efficiency of small antennas, and thus, this technique can be a viable solution for efficient radiation with tuning capability.

V. Podolsky, A. Semnani, and S. O. Macheret, “Experimental and numerical studies of a tunable plasma antenna sustained by RF power,” IEEE TPS, 2020.

A. Semnani, M. D. Sinanis, and D. Peroulis, “An evanescent-mode cavity-backed high-power tunable slot antenna,” IEEE TAP, 2019.

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Tunable Impedance Matching Networks

Supported by Lockheed Martin, ONR, and NSWC Crane

This effort is to mature and advance the understanding of the capabilities of plasma impedance matching networks as it relates to increasing the tunable wideband capabilities of an RF system. It is desired to understand the plasma negative permittivity characteristics and their ability to be controlled, tuned, and interfaced with other components in an RF system. It is also desired to understand the miniaturization of these components and the correlation between size and performance through analysis, simulation, and experimentation. The concept will be evaluated by the level of power, the frequency bandwidth, and the achievable efficiency of the matching network.

Z. Vander Missen, S. O. Macheret, A. Semnani, and D. Peroulis, “Plasma switch-based technology for high-speed and high-power impedance tuning,” IEEE WAMICON, 2021. 

A. Semnani, G. S. Shaffer, Y.-C. Wu, and D. Peroulis, “High-power impedance tuner utilizing substrate-integrated evanescent-mode cavity technology and external linear actuators,” IET MAP, 2019. 

A. Semnani, M. A. Khater, Y. C. Wu, and D. Peroulis, “An electronically-tunable high-power impedance tuner with integrated closed-loop control,” IEEE MWCL, 2017.

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Supported by Lockheed Martin, ONR, and NSWC Crane

This effort is to mature and advance the understanding of the capabilities of plasma impedance matching networks as it relates to increasing the tunable wideband capabilities of an RF system. It is desired to understand the plasma negative permittivity characteristics and their ability to be controlled, tuned, and interfaced with other components in an RF system. It is also desired to understand the miniaturization of these components and the correlation between size and performance through analysis, simulation, and experimentation. The concept will be evaluated by the level of power, the frequency bandwidth, and the achievable efficiency of the matching network.

Z. Vander Missen, S. O. Macheret, A. Semnani, and D. Peroulis, “Plasma switch-based technology for high-speed and high-power impedance tuning,” IEEE WAMICON, 2021. 

A. Semnani, G. S. Shaffer, Y.-C. Wu, and D. Peroulis, “High-power impedance tuner utilizing substrate-integrated evanescent-mode cavity technology and external linear actuators,” IET MAP, 2019. 

A. Semnani, M. A. Khater, Y. C. Wu, and D. Peroulis, “An electronically-tunable high-power impedance tuner with integrated closed-loop control,” IEEE MWCL, 2017.

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