An ultrahigh-frequency (UHF) radio frequency identification (RFID) tag antenna that can be placed on a metal surface with stable performance is proposed. It is made of a modified dipole with two ...cylindrical metal grounds on both ends. The cylindrical metal grounds not only enable the antenna to roll freely on a metal surface with a stable reading performance, but also reduce the antenna's length. The proposed tag antenna maintains a small size with a diameter of 10 mm (0.031λ) and a length of 45 mm (0.137λ). With an effective isotropic radiated power (EIRP) of 4 W, experimental results demonstrate that the proposed tag can achieve a maximum read distance ranging from 9.1 to 11.7 m when the tag rolls on a metal surface. The tag has the advantages of a more compact size, better reading range, and excellent rolling capability on a metal surface in comparison with the state-of-the-art. These features fulfill the emerging demands in the industrial Internet of Things field.
We propose and experimentally demonstrate a photonic measurement approach of microwave frequency with adjustable measurement ranges and low errors based on a silicon microring resonator (MRR). The ...key factor is that microwave photonic filters (MPFs) with high rejection ratios could be realized by a phase modulator, an optical filter, and a silicon MRR. In the experiment, by adjusting the wavelength of the laser diode, tunable MPFs with rejection ratios beyond 60 dB are realized in order to construct different amplitude comparison functions (ACFs) with high frequency resolutions (30 dB/GHz). According to the mapping relationships between the microwave frequency and power ratio of the ACF, the unknown microwave frequency could be measured. The experimental results show that microwave frequency could be measured from 10 to 19 GHz with a measurement resolution of 0.08 GHz. In the future, the measurement ranges and frequency resolutions could be manipulated according to the practical requirements. The photonic measurement method and compact device are significant in microwave systems.
A microwave microfluidic sensor for detecting binary liquid mixtures with a dielectric method at RF/microwave frequencies is presented in this article. The sensor is based on a split-ring resonator ...(SRR) that is implemented in a microstrip transmission line, with interdigitated electrodes (IDEs) being integrated into the ring for liquid detection. Based on the equivalent circuit of the IDE-SRR device and with a series of finite element simulations, the detection theory is developed, and the device design optimization is investigated. The validation measurements on water-isopropanol liquid mixtures with various concentrations show that the proposed IDE-SRR sensor has higher sensitivity than the previous standard SRR sensor. The IDE-SRR sensor is then used to detect two binary liquids, i.e., water-methanol mixtures and water-tetrahydrofuran mixtures. The measured effective permittivity results of the binary mixtures at RF/microwave frequency range are compared with the existing mixing models for binary dielectric mixtures at zero frequency.
In this letter, an ultracompact substrate integrated waveguide (SIW)-based hexaplexing antenna, operating at six distinct frequencies (4, 5.8, 6.6, 7.8, 9.8, 10.68 GHz) is proposed. It is made up of ...four compacted square-like quarter-mode SIW (S-QMSIW) resonators, and two triangular (T-QMSIW) elements. Their compactness is accomplished through the inclusion of rectangular slots at the closed-off ends of each resonator, resulting in increased shunt capacitance. As such, the resonance frequencies shift to the lower spectrum of their fundamental frequency ranges, forming the full hexaband system, with only 0.14<inline-formula><tex-math notation="LaTeX">\lambda _{g}^{2}</tex-math></inline-formula> in size. In addition, the minimum attained isolation level is 27 dB. At the intended frequencies, the maximum realized gain and efficiency are 4.9, 5.11, 5.4, 5.43, 5.32, and 5.3 dBi, for gain; 94%, 94.3%, 95%, 96.5%, 94%, and 95.7% for efficiency, at 4, 5.8, 6.6, 7.8, 9.8, and 10.68 GHz, respectively. In addition, a reliable equivalent circuit model is designed to confirm the proposed methodology, and the final design is fabricated. The simulation results are in good agreement with the measured ones. The proposed design proved its flexibility in terms of independent frequency tuning, thus making it an appealing choice for ultracompact communication systems.
A circular-slot-inscribed square-shaped metal-free superwideband absorber is presented. It comprises a silicon dioxide substrate sandwiched between the circular-slot-loaded square-shaped and square ...graphite slabs. It has an overall volume of <inline-formula> <tex-math notation="LaTeX">5\times 5\times 6.77\,\,\mu \text{m} </tex-math></inline-formula> with an operating frequency spectrum ranging from 5.1 to > 80 THz (> 176.03% for <inline-formula> <tex-math notation="LaTeX">{A}\ge {90} </tex-math></inline-formula>%). The periodicity and substrate thickness are <inline-formula> <tex-math notation="LaTeX">{\sim }\lambda _{\text {o}} /{12} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">{\sim }\lambda _{\text {o}} / {76} </tex-math></inline-formula> respectively at 5.1 THz. The proposed absorber's performance is insensitive to the polarization angle (<inline-formula> <tex-math notation="LaTeX">\Phi </tex-math></inline-formula>) variations due to symmetric geometry. In addition to this, the incidence angle (<inline-formula> <tex-math notation="LaTeX">\theta </tex-math></inline-formula>) variations between 0° and 45° also had insignificant effects on the absorption. The presented absorber has advantages of metal-free geometry, polarization angle insensitiveness to <inline-formula> <tex-math notation="LaTeX">\Phi </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">{0}^{\circ }\le \theta \le {45}^{\circ } </tex-math></inline-formula> along with compact dimensions over previously reported absorbers operating in terahertz (THz)/infrared frequency ranges. The proposed absorber-based sensor has a peak sensitivity of 9 THz/RIU for refractive index (RI) sensing and 7 THz/RIU for cancer and tuberculosis detection.
This work presents a broadband linear-cross polarizer for K- and Ka-band applications. The design consists of a simple asymmetric width-based meander-line metasurface printed on a thin FR-4 grounded ...dielectric substrate. Normal incidence demonstrates 90% polarization conversion ratio (PCR) bandwidth (BW) of 20.64 GHz from 18.31 to 38.95 GHz with 72.1% fractional BW (FBW). Due to the destructive interference involved at greater oblique angles, reflective polarizers experience severe degradation of 90% PCR BW response. The proposed polarizer's performance is obliquely stable up to 43° for transverse electric (TE) and 45° for transverse magnetic (TM) incidence with minimal 90% PCR BW reduction of only 13.95% (TE) and 15.25% (TM) compared with normal incidence. For the first time, transfer matrix method (TMM)-based equivalent surface impedance technique is modeled for oblique incidence analytically, closely resembling the full-wave analysis. The design is compact with a periodicity of <inline-formula> <tex-math notation="LaTeX">\lambda \text{o} </tex-math></inline-formula>/5.98 and a thickness of <inline-formula> <tex-math notation="LaTeX">\lambda \text{o} </tex-math></inline-formula>/13.69. The surface current patterns at resonant frequencies illustrate the reason behind broadband behavior. Bistatic radar cross section (RCS) analysis of the proposed converter is studied with reference to PEC. To the best of the author's knowledge, this structure demonstrates broadband response with wide angular stability with less than 90% PCR BW reduction at higher oblique angles reported so far.
Microresonator soliton dual-comb spectroscopy Suh, Myoung-Gyun; Yang, Qi-Fan; Yang, Ki Youl ...
Science (American Association for the Advancement of Science),
11/2016, Letnik:
354, Številka:
6312
Journal Article
Recenzirano
Odprti dostop
Measurement of optical and vibrational spectra with high resolution provides a way to identify chemical species in cluttered environments and is of general importance in many fields. Dual-comb ...spectroscopy has emerged as a powerful approach for acquiring nearly instantaneous Raman and optical spectra with unprecedented resolution. Spectra are generated directly in the electrical domain, without the need for bulky mechanical spectrometers. We demonstrate a miniature soliton-based dual-comb system that can potentially transfer the approach to a chip platform. These devices achieve high-coherence pulsed mode locking. They also feature broad, reproducible spectral envelopes, an essential feature for dual-comb spectroscopy. Our work shows the potential for integrated spectroscopy with high signal-to-noise ratios and fast acquisition rates.
A UHF RFID Tag Embeddable in Small Metal Cavities Michel, Andrea; Franchina, Vittorio; Nepa, Paolo ...
IEEE transactions on antennas and propagation,
02/2019, Letnik:
67, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A compact in-metal ultrahigh frequency radio frequency identification tag for identification of metal components is described. The radiating element is printed on a <inline-formula> <tex-math ...notation="LaTeX">23\times 23 \times 1 </tex-math></inline-formula> mm 3 copper-clad alumina (Al 2 O 3 ) substrate (<inline-formula> <tex-math notation="LaTeX">\varepsilon _{\mathbf {r}} = 9 </tex-math></inline-formula>, tan<inline-formula> <tex-math notation="LaTeX">\delta = 0.0003 </tex-math></inline-formula>) and consists of two rectangular quarter-mode patch antennas properly arranged to make the tag performance as robust as possible even when the tag is embedded in small cavities carved out of metal objects. The entire structure has been optimized by taking into account the presence of a thin superstrate of commercial epoxy resin used to protect the tag. The effect of the cavity size on the tag performance is numerically analyzed. Measurements on a tag prototype are also described and discussed.
High-Resolution UHF Near-Field Imaging Probe Abou-Khousa, Mohamed A.; Muhammed Shafi, K. T.; Xingyu, Xie
IEEE transactions on instrumentation and measurement,
10/2018, Letnik:
67, Številka:
10
Journal Article
Recenzirano
Imaging probes which work at relatively low microwave frequencies in the ultrahigh frequency band (UHF) facilitate imaging through high loss dielectric materials and yield manageable imaging system ...complexity. However, acquiring images with resolutions on the order of few millimeters at frequencies within the UHF band requires super-resolution imaging methods and probes. In this paper, a compact near-field imaging probe working in the UHF band is proposed for high-resolution noninvasive imaging applications. The proposed probe is based on an electrically small loop loaded with a miniaturized spiral resonator. The probe is analyzed in this paper using numerical electromagnetic simulations and its equivalent circuit model is consequently developed. A prototype of the proposed probe operating at 426 MHz is fabricated and its spatial resolution as well as sensitivity are experimentally verified. A spatial resolution of around <inline-formula> <tex-math notation="LaTeX">\lambda </tex-math></inline-formula>/140 is demonstrated in simulations and verified experimentally. In order to highlight the utility of the probe for practical applications, images of many test samples including multilayer dielectric composite structures and corroded metallic substrate are acquired using the fabricated prototype. It will be shown that the images obtained using the proposed probe is comparable with those produced using an open-ended rectangular waveguide operating at 24 GHz. The salient features of the proposed probe include its high sensitivity and resolution while operating at relatively low frequency.
Scanner manufacturers, and several small companies, produce MRI compatible headphones which operate under various physical principles including air tubes, magnet-less electrodynamic ...(http://www.mr-confon.de/) and electrostatic transducers (http://www.nordicneurolab.no/). The principle of operation is that, with respect to the figure, with the main magnetic field running horizontally, an audio current flowing vertically through the aperture-spanning wires causes a force on these wires and attached membrane in and out of the page.
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