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Three-Dimensional Electromagnetic High Frequency Concave Cavity Scars

Warne, Larry K.; Jorgenson, Roy E.; Reines, Isak C.; Coats, Rebecca S. ; Pack, Alden R.; Zinser, B.Z.

This report examines the localization of high frequency electromagnetic fields in general three-dimensional cavities along periodic paths between opposing sides of the cavity. The focus is on the case where the mirrors at the ends of the orbit are concave and have two different radii of curvature. The cases where these orbits lead to unstable localized modes are known as scars. The ellipsoidal coordinate system is utilized in the construction of the scarred modes. The field at the interior foci is examined as well as trigonometric projections along the periodic scarred ray path.

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Development of a Novel Electrical Characterization Technique for Measuring Hidden Joint Contacts in Weapons Cavities (LDRD Final Report 218470)

Wallace, Jon W.; Timmins, Ian T.; Himbele, John J.; Reines, Isak C.; Gutierrez, Roy K.; Williams, Jeffery T.

This report summarizes research performed in the context of a REHEDS LDRD project that explores methods for measuring electrical properties of vessel joints. These properties, which include contact points and associated contact resistance, are “hidden” in the sense that they are not apparent from a computer-assisted design (CAD) description or visual inspection. As is demonstrated herein, the impact of this project is the development of electromagnetic near-field scanning capabilities that allow weapon cavity joints to be characterized with high spatial and/or temporal resolution. Such scans provide insight on the hidden electrical properties of the joint, allowing more detailed and accurate models of joints to be developed, and ultimately providing higher fidelity shielding effectiveness (SE) predictions. The capability to perform high-resolution temporal scanning of joints under vibration is also explored, using a multitone probing concept, allowing time-varying properties of joints to be characterized and the associated modulation to SE to be quantified.

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Penetration through slots in cylindrical cavities with cavity modes overlapping with the first slot resonance

Electromagnetics

Campione, Salvatore; Warne, Larry K.; Langston, William L.; Gutierrez, Roy K.; Hicks, Jeorge W.; Reines, Isak C.; Pfeiffer, Robert A.; Himbele, John J.; Williams, Jeffery T.

We analyze the coupling into a slotted cylindrical cavity operating at fundamental cavity modal frequencies overlapping with the slot’s first resonance frequency through an unmatched formulation that accounts for the slot’s absorption and radiation processes. The model is validated through full-wave simulations and experimental data. We then couple the unmatched formulation to a perturbation theory model to investigate an absorber within the cavity to reduce the interior field strength, also validated with full-wave simulations and experiments. These models are pivotal to understanding the physical processes involved in the electromagnetic penetration through slots, and may constitute design tools to mitigate electromagnetic interference effects within cavities.

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Penetration through Slots in Cylindrical Cavities Operating at Fundamental Cavity Modes

IEEE Transactions on Electromagnetic Compatibility

Campione, Salvatore; Warne, Larry K.; Langston, William L.; Pfeiffer, Robert A.; Martin, Nevin S.; Williams, Jeffery T.; Gutierrez, Roy K.; Reines, Isak C.; Huerta, Jose G.; Dang, Vinh Q.

In this article, we examine the coupling into an electrically short azimuthal slot on a cylindrical cavity operating at fundamental cavity modal frequencies. We first develop a matched bound formulation through which we can gather information for maximum achievable levels of interior cavity fields. Actual field levels are below this matched bound; therefore, we also develop an unmatched formulation for frequencies below the slot resonance to achieve a better insight on the physics of this coupling. Good agreement is observed between the unmatched formulation, full-wave simulations, and experimental data, providing a validation of our analytical models. We then extend the unmatched formulation to treat an array of slots, found again in good agreement with full-wave simulations. These analytical models can be used to investigate ways to mitigate electromagnetic interference and electromagnetic compatibility effects within cavities.

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Penetration through slots in cylindrical cavities operating at fundamental cavity modes in the presence of electromagnetic absorbers

Progress In Electromagnetics Research M

Campione, Salvatore; Warne, Larry K.; Reines, Isak C.; Gutierrez, Roy K.; Williams, Jeffery T.

Placing microwave absorbing materials into a high-quality factor resonant cavity may in general reduce the large interior electromagnetic fields excited under external illumination. In this paper, we aim to combine two analytical models we previously developed: 1) an unmatched formulation for frequencies below the slot resonance to model shielding effectiveness versus frequency; and 2) a perturbation model approach to estimate the quality factor of cavities in the presence of absorbers. The resulting model realizes a toolkit with which design guidelines of the absorber’s properties and location can be optimized over a frequency band. Analytic predictions of shielding effectiveness for three transverse magnetic modes for various locations of the absorber placed on the inside cavity wall show good agreement with both full-wave simulations and experiments, and validate the proposed model. This analysis opens new avenues for specialized ways to mitigate harmful fields within cavities.

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Modeling and experiments of high-quality factor cavity shielding effectiveness

2019 International Applied Computational Electromagnetics Society Symposium in Miami, ACES-Miami 2019

Campione, Salvatore; Warne, Larry K.; Reines, Isak C.; Williams, Jeffery T.; Gutierrez, Roy K.; Coats, Rebecca S.; Basilio, Lorena I.

In this paper, we investigate the coupling from external electromagnetic (EM) fields to the interior EM fields of a high-quality factor cylindrical cavity through a small perturbing slot. We illustrate the shielding effectiveness versus frequency, highlighting bounds on the penetrant power through the slot. Because internal fields may become larger than external ones, we then introduce a small amount of microwave absorbing materials decorating the slot to improve shielding effectiveness considerably, as shown by both simulations and experiments. Although the cylindrical cavity is used for demonstration purposes in this paper, the conclusions presented here can be leveraged for use with more complex cavity structures.

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High-mobility transparent conducting oxides for compact epsilon-near-zero silicon photonic phase modulators

Optics InfoBase Conference Papers

Wood, Michael G.; Reines, Isak C.; Luk, Ting S.; Serkland, Darwin K.; Campione, Salvatore

We numerically analyze the role of carrier mobility in transparent conducting oxides in epsilon-near-zero phase modulators. High-mobility materials such as cadmium oxide enable compact photonic phase modulators with a modulation figure of merit >29 º/dB.

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Preliminary Survey on the Effectiveness of an Electromagnetic Dampener to Improve System Shielding Effectiveness

Campione, Salvatore; Reines, Isak C.; Warne, Larry K.; Williams, Jeffery T.; Gutierrez, Roy K.; Coats, Rebecca S.; Basilio, Lorena I.

This report explores the potential for reducing the fields and the quality factor within a system cavity by introducing microwave absorbing materials. Although the concept of introducing absorbing (lossy) materials within a cavity to drive the interior field levels down is well known, increasing the loading into a complex weapon cavity specifically for improved electromagnetic performance has not, in general, been considered, and this will be the subject of this work. We compare full-wave simulations to experimental results, demonstrating the applicability of the proposed method.

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Compact epsilon-near-zero silicon photonic phase modulators

Optics Express

Reines, Isak C.; Wood, Michael G.; Luk, Ting S.; Serkland, Darwin K.; Campione, Salvatore

In this paper, we analyze a compact silicon photonic phase modulator at 1.55 μm using epsilon-near-zero transparent conducting oxide (TCO) films. The operating principle of the non-resonant phase modulator is field-effect carrier density modulation in a thin TCO film deposited on top of a passive silicon waveguide with a CMOS-compatible fabrication process. We compare phase modulator performance using both indium oxide (In2O3) and cadmium oxide (CdO) TCO materials. Our findings show that practical phase modulation can be achieved only when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. The CdO-based phase modulator has a figure of merit of 17.1°/dB in a compact 5 μm length. This figure of merit can be increased further through the proper selection of high-mobility TCOs, opening a path for device miniaturization and increased phase shifts.

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A soft-landing waveform for actuation of a single-pole single-throw ohmic RF MEMS switch

Journal of Microelectromechanical Systems

Czaplewski, David A.; Dyck, Christopher D.; Sumali, Hartono S.; Massad, Jordan M.; Kuppers, Jaron D.; Reines, Isak C.; Cowan, William D.; Tigges, Chris P.

A soft-landing actuation waveform was designed to reduce the bounce of a single-pole single-throw (SPST) ohmic radio frequency (RF) microelectromechanical systems (MEMS) switch during actuation. The waveform consisted of an actuation voltage pulse, a coast time, and a hold voltage. The actuation voltage pulse had a short duration relative to the transition time of the switch and imparted the kinetic energy necessary to close the switch. After the actuation pulse was stopped, damping and restoring forces slowed the switch to near-zero velocity as it approached the closed position. This is referred to as the coast time. The hold voltage was applied upon reaching closure to keep the switch from opening. An ideal waveform would close the switch with near zero impact velocity. The switch dynamics resulting from an ideal waveform were modeled using finite element methods and measured using laser Doppler vibrometry. The ideal waveform closed the switch with an impact velocity of less than 3 cm/s without rebound. Variations in the soft-landing waveform closed the switch with impact velocities of 12.5 cm/s with rebound amplitudes ranging from 75 to 150 nm compared to impact velocities of 22.5 cm/s and rebound amplitudes of 150 to 200 nm for a step waveform. The ideal waveform closed the switch faster than a simple step voltage actuation because there was no rebound and it reduced the impact force imparted on the contacting surfaces upon closure. © 2006 IEEE.

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26 Results
26 Results