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- 摘要
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Multiple-Resonance Interference in Metallic Nanohole Arrays
摘要： In metallic nanohole arrays, the surface plasmon polaritons on the metal surfaces and the waveguide modes in the nanoholes are combined to form multipole surface plasmons. If these surface bound modes appear in a narrow frequency range, interference between multiple resonances and yields various resonant peak-dip structures in transmission, reflection and absorption spectra. In this chapter, we discuss the theoretical details of the mechanism of the multiple-resonance interference in metallic nanohole array systems using spatial and temporal coupled mode methods.
关键词： Fano resonance,surface plasmon polaritons,metallic nanohole arrays,waveguide modes,multiple-resonance interference,EIT-like phenomena
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Planar Directivity of a Dipole Array
摘要： We develop a technique for fast evaluation of superdirective performance of coupled meta-atoms. Traditionally, the directivity of a small antenna is obtained from measurements of the far-field radiated power over a spherical surface. We propose an alternative method of finding the directivity from a faster polar scan over a circular path, by introducing the “planar directivity” (D2D) for dipole arrays. We derive analytical expressions for maximum achievable values of directivity and D2D, establish the correlation between them, and identify the range of parameters (inter-element distance, coupling constant, quality factor) for which the conversion of D2D to D for superdirective dimers is possible.
关键词： dipole arrays,planar directivity,far-field measurements,metamaterials,superdirectivity
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - Sheffield (2018.7.8-2018.7.11)] 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - 2D MIMO Radar with Coprime Arrays
摘要： In this contribution, a new class of planar coprime MIMO radar systems based on quadratic integers is proposed where the antenna locations are represented by lattice points generated by prime integers in quadratic number fields. By exploiting the coprimality of certain quadratic integers, the virtual coarrays of proposed structures enjoy a quadratic gain in parameter identifiability according to the Chinese Remainder Theorem (CRT). To avoid holes in the coarray, we present Hole-free CRT arrays with guaranteed full-rank autocorrelation matrices for subspace-based target estimation. The ring of Gaussian integers and the ring of Eisenstein integers are chosen as examples of designing coprime MIMO radar systems. It is shown that the proposed arrays achieve enhanced angular resolutions and improve the side lobe suppression. In the context of target estimation, simulations show the superior performance of the coprime MIMO structures based on CRT.
关键词： quadratic integers,Coprime sensing,sparse arrays,Chinese Reminder Theorem,MIMO
更新于2025-09-10 09:29:36
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A Wideband, Single-Layer Reflectarray Exploiting A Polarization Rotating Unit Cell
摘要： We present a new technique for designing wideband, single-layer reflectarray antennas. The proposed reflectarray exploits a wideband, polarization rotating unit cell that rotates the polarization of the reflected wave with respect to that of the incident wave by 90?. This unit cell and its mirror image were used as 1-bit spatial phase shifters capable of providing a 0?/180? phase shift over a wide bandwidth of 5.4-12.7 GHz. Using this, a reflectarray antenna with 1-bit phase quantization was designed to operate at X band with aperture dimensions of 28.8 cm × 28.8 cm and a focal length of 30 cm. A prototype of the proposed reflectarray was fabricated and characterized using a spherical near-field measurement system. We determined the antenna’s 3 dB gain bandwidth to be approximately 37.4% with a maximum realized gain of 24.2 dBi. Over its entire band of operation, the polarization purity of the antenna remains better than 13 dB and side-lobe levels of better than 12 dB were achieved.
关键词： periodic structures,Reflectarray antennas,polarization rotation,antenna arrays
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Calibration of an Inductive Voltage Divider Using Pulse-Driven Josephson Arrays
摘要： We present a method for the voltage ratio calibration of inductive voltage dividers using quantum accurate pulse-driven Josephson standards. The inductive voltage divider calibration is carried out at 497 Hz with RMS amplitudes of 40 mV and 100 mV and is compared with conventional bootstrapping calibrations performed at 1 V. In these preliminary measurements, the new calibration method reached similar in-phase uncertainties as the bootstrapping method, despite the large difference in input voltages.
关键词： inductive voltage divider,Josephson standard,measurement techniques,pulse-driven Josephson arrays,precision measurements
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Measurement of Leakage Current to Ground in Programmable Josephson Voltage Standards
摘要： The voltage error associated with the leakage current of programmable Josephson voltage standards (PJVS) is one of the largest contributions to the uncertainty in direct comparison of voltage standards. Due to the parallel biasing scheme of the PJVS and the resulting multiple leakage paths, the quantities “leakage resistance” and “leakage current” are not necessarily equivalent. A method to measure and model the leakage current to ground for a given PJVS output voltage is presented. By upgrading simple components of the NIST system, the leakage current to ground can be reduced from 250 pA to 50 pA at 10 V.
关键词： integrated circuits,measurement,Digital-analog conversion,voltage,standards,Josephson arrays,superconducting
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - DC Comparison of a Programmable Josephson Voltage Standard and a Josephson Arbitrary Waveform Synthesizer
摘要： We present the first dc comparison of a programmable Josephson voltage standards and a pulse-driven Josephson arbitrary waveform synthesizer (JAWS) at 3 V. Both circuits are mounted side-by-side on the cold stage of a cryocooler. The relative agreement achieved was better than 1 part in 108. This measurement allowed us to identify systematic errors of the JAWS system. An undesired current injection from the JAWS isolation amplifier into the measurement circuit was responsible for an error voltage of a few nanovolts.
关键词： integrated circuits,measurement,Digital-analog conversion,voltage,standards,Josephson arrays,superconducting
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - An Optoelectronic Pulse Drive for Quantum Voltage Synthesizer
摘要： An optoelectronic pulse drive system based on commercially available telecoms optoelectronic components and a field programmable gate array (FPGA) has been developed. The system was used to drive a Josephson junction array (JJA) to synthesize quantum-accurate voltage waveforms. Results from preliminary demonstration of the system are presented showing the synthesis of a 3.1 kHz sine wave.
关键词： Josephson arbitrary waveform synthesizer,opto-electronics,metrology,voltage measurement,Measurement,Josephson arrays
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Progress on PTB's Pulse-Driven Josephson Impedance Bridge Combined with an AC Quantum Hall Resistance
摘要： Pulse-driven Josephson arrays successfully demonstrated their high potential for impedance metrology in the last years. With their high spectral purity and fundamental accuracy, they are perfectly suited for impedance measurements over the whole complex plane. PTB’s two-terminal impedance bridge is equipped with new electronics to extend the frequency range, to increase the signal amplitude and to simplify the setting of the phase angle. A 1:1 ratio measurement of 10 nF capacitance standards has been carried out between 246 Hz and 40 kHz at a signal amplitude of 75 mV (RMS). The value of a 10 nF capacitance standard is traced back to the ac quantum Hall resistor at PTB using 100 mV (RMS) signal amplitude.
关键词： quantum-Hall Josephson arrays,resistor,AC Josephson voltage standards,pulse-driven impedance measurements,capacitance standard
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Three Volt Pulse-Driven Josephson Arbitrary Waveform Synthesizer
摘要： We describe a new generation of Josephson Arbitrary Waveform Synthesizers that generate programmable ac waveforms with an rms amplitude of 3 V and, at 1 kHz, have a quantum locking range greater than 1 mA. This system has two chips with a total of 204 960 Josephson junctions (JJs) co-located on a cryocooler. To test for systematic errors, we phase-shift by 180° the waveform generated by half the JJs (102 480 JJs) to produce an approximate null. The measured residual of 51 nV rms implies a relative agreement of 3 parts in 108 between the two halves of the system.
关键词： Digital-analog conversion,signal synthesis,voltage measurement,superconducting integrated circuits,Josephson junction arrays,measurement standards
更新于2025-09-10 09:29:36