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[IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - V?ster?s, Sweden (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Toward Standard Near-Field Measurement Solutions for Stochastic Electromagnetic Fields
摘要： This paper investigates directions towards standardization of Near-Field measurement solutions for stochastic electromagnetic fields. An overview of Single-Probe, Dual-probe and Multi-Probe Array based measurements for deterministic fields is given and their capabilities and performances including test-time for industrial deployment are discussed. Importance of Field-Field correlation based analysis is underlined both from an experimental and modeling stand points and finally for combination of measurements and full-wave EM modeling.
关键词： Correlation,Field-Field Correlation,Stochastic Electromagnetic Field,Spintronic,Near Field imaging
更新于2025-09-09 09:28:46
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A 128-Pixel System-on-a-Chip for Real-Time Super-Resolution Terahertz Near-Field Imaging
摘要： This paper presents a fully integrated system-on-a-chip for real-time terahertz super-resolution near-field imaging. The chip consists of 128 sensing pixels with individual cross-bridged double 3-D split-ring resonators arranged in a 3.2 mm long 2 × 64 1-D array. It is implemented in 0.13-μm SiGe bipolar complementary metal–oxide–semiconductor technology and operated at around 550 GHz. All the functions, including sensor illumination, near-field sensing, and detection, are co-integrated with a readout integrated circuit for real-time image acquisition. The pixels exhibit a permittivity-based imaging contrast with a worst case estimated relative permittivity uncertainty of 0.33 and 10–12-μm spatial resolution. The sensor illumination is provided with on-chip oscillators feeding four-way equal power divider networks to enable an effective pixel pitch of 25 μm and a dense fill factor of 48% for the 1-D sensing area. The oscillators are equipped with electronic chopping to avoid 1/f-noise-related desensitization for the SiGe-heterojunction bipolar transistor power detectors integrated at each pixel. The chip features both an analog readout mode and a lock-in-amplifier-based digital readout mode. In the analog readout mode, the measured dynamic range (DR) is 63.8 dB for a 1-ms integration time at an external lock-in amplifier. The digital readout mode achieves a DR of 38.5 dB at 28 f/s. The chip consumes 37–104 mW of power and is packaged into a compact imaging module. This paper further demonstrates real-time acquisition of 2-D terahertz super-resolution images of a nickel mesh with 50-μm feature size, as well as a biometric human fingerprint.
关键词： terahertz,system-on-a-chip (SoC),SiGe heterojunction bipolar transistor (HBT),split-ring resonator (SRR),near-field array,3-push Colpitts oscillator,super-resolution imaging,near-field scanning optical microscopy (NSOM),power detector
更新于2025-09-09 09:28:46
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Localized Photonic Jets Generated by Step-Like Dielectric Microstructures
摘要： In this contribution we reveal how the step-like topology of a microstructure can contribute to the formation of a single high-intensity nanojet (NJ) beam located on its axis of symmetry. The proposed method for generating condensed optical NJ beams relies on the complex electromagnetic phenomenon associated with the light diffraction on the edges of step-like dielectric microstructures embedded in a host medium with lower refractive index. The possibility of NJ beam intensification in the near zone of such microstructure illuminated by a plane wave is demonstrated and explained by the recombination of multiple NJ beams associated with different edges or edge segments of the step-like microlens. We demonstrate that by changing materials of the layers we can intensify the NJ beam. We examine the dependence of the generated beam on the step size, shape and material.
关键词： near field focusing,microlens,photonic nanojet,edge diffraction
更新于2025-09-09 09:28:46
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Light-dressed states under intense optical near fields
摘要： We studied the excitation dynamics of a finite quantum system with an intense optical near field (ONF) from a perspective of light-dressed states. A simple model consisting of a single electron and a nanosized short dipole source were employed. By calculating the time-dependent wave function subjected to the ONF, we demonstrated that the optical responses involved not only the first- and third-order but also the second- and fourth-order harmonic generations that were not obtained from conventional spatially homogeneous laser fields. In order to elucidate the origins of the exotic even-order harmonic generations, the dressed states altered by the ONF were explored. The result showed that the spatial distribution of the dressed states were significantly influenced by the ONF, making forbidden optical transitions allowed by parity breaking. This was caused by the spatial inhomogeneousness of the ONF, specifically its asymmetry, that was inherited to the dressed states.
关键词： harmonic generation,parity breaking,light-dressed states,quantum system,optical near field
更新于2025-09-09 09:28:46
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REGULARIZATION IMAGING ALGORITHM WITH ACCURATE G MATRIX FOR NEAR-FIELD MMW SYNTHETIC APERTURE IMAGING RADIOMETER
摘要： In order to improve the reconstruction accuracy of near-?eld SAIR, a novel regularization imaging algorithm based on an accurate G matrix is proposed in this paper. Due to the fact that the regularization reconstruction is usually an underdetermined problem, inaccurate operation matrix G will lead to great reconstruction error in the imaging results, or even the normal imaging cannot be obtained. In this paper, we establish an accurate G matrix based on the accurate imaging model of near-?eld SAIR. Compared with the traditional G matrix with some unnecessary approximations, the proposed G matrix without approximation can improve the reconstruction accuracy e?ectively. For improving the accuracy of matrix G further, the corresponding parameters are corrected according to the RMSE between the imaging results of the regularization method and modi?ed FFT method which is not sensitive to the parameters’ change. The e?ectiveness of this calibration method has been tested by 1D simulation experiments. Moreover, the 2D simulation experiments demonstrate that the proposed accurate G matrix can improve the imaging accuracy of regularization method e?ectively. Finally, the 1D imaging experiment is performed to test the e?ectiveness of the proposed method for the actual synthetic aperture imaging further.
关键词： near-field MMW synthetic aperture imaging radiometer,Regularization imaging algorithm,accurate G matrix,reconstruction accuracy
更新于2025-09-09 09:28:46
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Using CCDF statistics for characterizing the radiated power dynamics in the near field of a mobile phone operating in 3G+ and 4G+ communication standards
摘要： In this article, an original method to assess the radiated power density of the near field in the immediate vicinity of mobile terminals using both electric and magnetic field strengths determination is proposed. The complementary cumulative distribution function (CCDF) is used for the first time to assess exposure. A demonstration of the CCDF’s capabilities for providing a realistic representation of different wireless communication usage profiles is provided. Following the methodology description, an experimental setup was designed and a measurement campaign was conducted on a mobile terminal. The exposure assessment was performed for real life operating situations by selecting seven common application services used by mobile subscribers. For 4G+ communication technologies the near field power density is the highest during file upload, followed by VoIP, video call, file download, streaming services and browsing. For 3G+ networks the higher to lower power density values were associated with: file upload, file download, streaming, VoIP, video call and browsing services. The total near field radiated power density was found to be on average 34 times higher for the tested applications running in the 4G+ as compared to the 3G+, with values ranging from 180 times - during file upload, down to 1.2 times - during video streaming. Significantly higher radiated power densities were emitted while using VoIP and video call on 4G+ network as compared to 3G+ network. Present results strongly suggest that higher exposure is expected for the same application running under 4G+ rather than under 3G+. By applying an original procedure, it has been experimentally highlighted that different generations of communication technologies will lead to different exposure shapes in amplitude and in time, suggesting a future need for introducing the dose rate quantification.
关键词： 3G+,radiated power,4G+,realistic exposure,application services,CCDF,near field
更新于2025-09-09 09:28:46
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UHF Reader Antenna for Near and Far-Field RFID Operation
摘要： In order to detect the RFID tags kept inside an enclosure, the reader antenna can couple energy into another antenna kept in the near-field region. To detect the tags placed in the far-field, the reader antenna should have a good gain. Usually, these two requirements compete with each other due to the effect of coupling on the frequency of operation of the antenna system. In this work modification to a loop antenna is proposed such that it can operate in both near and far-field. Loop antenna with high impedance surface (HIS) reflector results in a low-profile antenna pair where both the antennas can interchangeably operate in near-field and far-field, with their operating frequency band independent of the spacing between the antennas. The performance of the proposed antennas is compared with that of several other antennas by measuring the read range of RFID tags. It is found that the proposed antennas perform better in comparison with the other antennas when detecting the tags placed inside an enclosure. When operating as a far-field antenna, their performance is very close to that of a conventional RFID reader antenna which is optimized only for far-field operation.
关键词： near-field coupling,far-field near-field antenna,RFID,UHF,high impedance surface,loop antennas
更新于2025-09-04 15:30:14
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A Near-Field to Far-Field RCS Measurement Method for Multiple-Scattering Target
摘要： It is challenging to perform the near-field to far-field transformation with a high precision for the multiple-scattering targets using the conventional monostatic radar cross section (RCS) measurement. In this paper, a novel near-field to far-field transformation method with bistatic RCS measurement is proposed. First, the RCS measurement is perceived as a double radiation model. Doing this, the relationship of near-field data and far-field data at different angles is derived, and the convolution function is given under the cylindrical wave. Second, the near-field scattering data are acquired using the proposed bistatic RCS measurement method that combines one transmission and multiple receptions with the rotation of a revolving table. The near-field data are then extrapolated twice with the convolution function, and the far-field RCS are obtained accordingly. Moreover, this paper also analyzes the truncation angular and sampling intervals for the measurement consideration. Finally, the effectiveness and the high precision of the proposed transformation approach for the multiple-scattering target are demonstrated using the numerical simulations and the experimental characterization with an example of dihedral structures.
关键词： near-field to far-field transformation,multiple-scattering target,sampling interval,Bistatic radar cross section (RCS) measurement,truncation angular
更新于2025-09-04 15:30:14
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Near-Field and Far-Field Thermal Emission of an Individual Patch Nanoantenna
摘要： The far-field spectral and near-field spatial responses of an individual metal-insulator-metal nanoantenna are reported, using thermal fluctuations as an internal source of the electromagnetic field. The far-field spectra, obtained by combining Fourier transform infrared spectroscopy with spatial modulation based on a light falloff effect in a confocal geometry, have revealed two distinct emission peaks attributed to the excitation of the fundamental mode of the nanoantenna at two distinct wavelengths. Superresolved near-field images of the thermally excited mode have been obtained by thermal radiation scanning tunneling microscopy. Experimental results are supported by numerical simulations showing that it is possible to excite the same mode at different wavelengths near a resonance of the insulating dielectric material forming the antenna.
关键词： near-field,nanoantenna,thermal emission,microscopy,spectroscopy,far-field
更新于2025-09-04 15:30:14
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - A Plane-Wave Synthesis Approach for 3D Monostatic RCS Prediction from Near-Field Measurements
摘要： A plane-wave synthesis approach for determining the 3D monostatic radar cross section from a set of near-field measurements is presented. Compared to image based techniques, it does not suffer from inaccuracies in the case of multiple interactions. At the same time, very general measurement setups are possible without introducing severe truncation errors and the resulting field transformation problem can still be solved efficiently, due to the implementation based on propagating plane-wave expansions of the Green’s function. The theory of the algorithm is first outlined and then validated using simulated near-field and far-field data.
关键词： plane-wave synthesis,radar cross section measurement,near-field far-field transformation
更新于2025-09-04 15:30:14