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A Frequency Selective Surface Based Reconfigurable Rasorber With Switchable Transmission/Reflection Band
摘要： In this letter, a reconfigurable rasorber has been designed based on switching activity of frequency selective surface (FSS) and resistive FSS. The proposed design consists of two periodic layers separated from each other by an air spacer. The upper layer comprising lumped resistors assists wide absorption band (above 90% absorption) from 3.8 to 10.3 GHz (entire C and partial X Band), whereas PIN diodes are mounted in the bottom layer to enable the switching operation of the rasorber at S-Band. The novelty of the proposed design lies in its reconfigurable transmission/reflection band, which switches from a bandpass response (at around 2.88 GHz) to perfect reflection, with the control of the biasing states of the diode. A sample prototype is also fabricated and experimentally verified. Wide absorption band along with switchable transmission/reflection band characteristics have made the proposed rasorber an excellent choice for various radar cross section (RCS) reduction applications.
关键词： Frequency Selective Surface,Rasorber,PIN Diodes,Reconfigurable Structures
更新于2025-09-23 15:21:21
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New approach to raising the resolution of position sensitive detector with moving current-voltage characteristic
摘要： Position sensitive detectors (PSD) are widely applied for determining the coordinate of an optical signal and continuously tracking it. Currently, studies concerned with the possibility of further raising the spatial resolution of PSDs remain topical. In this paper, we present the results obtained in reaching an ultrahigh resolution for a device based on the PSD Multiscan with an integral operation principle which fundamentally differs from that of the lateral PSD. The PSD Multiscan design is based on an array of back-to-back photodiodes. Its optical signal coordinate read-out is formed via the moving current-voltage characteristic of the sensor directly on the PSD as an output potential proportional to the coordinate of the optical spot median. This measurement principle provides a continuous comparison of near-equal photocurrents, which maintains a high signal-to-noise ratio over the whole sensing area. The absence of computational operations in electronic circuits of the PSD Multiscan makes it possible to introduce a nonlinear amplifier element, which substantially improves the resolution of the device based on the sensor developed in the study (as good as 0.05 μm). It has been shown that the resolution remains high for detectors with different lengths and is independent of the position of the optical spot on the sensing area.
关键词： Analogue electronic circuits,Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc),Optical detector readout concepts
更新于2025-09-23 15:21:01
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[IEEE 2019 Radiation and Scattering of Electromagnetic Waves (RSEMW) - Divnomorskoe, Russia (2019.6.24-2019.6.28)] 2019 Radiation and Scattering of Electromagnetic Waves (RSEMW) - Multitier Omnidirectional Antenna on The Circular Waveguide with The Paired Slots on The Tiers
摘要： This paper presents a recon?gurable aperture-fed patch antenna array for ±45? polarizations. First, a new method to realize the recon?gurable ±45? polarizations is proposed. It introduces controllable RF switches on a cross-aperture to excite a square patch for two orthogonal polarizations. The RF switches are controlled by two sets of DC biases, which could select the polarization through the recon?gurable aperture. Second, two patch antennas based on cross-aperture excitation are discussed. The ?rst structure uses a split ground plane with four switches, while the other one employs a united ground plane with eight switches. Both antennas operate well as the single element. However, only the antenna with a united ground is suitable for developing a recon?gurable dual-polarized antenna array, owning to its simple DC biasing lines and the recon?gurable-controlling network. Both simulation and experiment studies were examined to verify the proposed design. The measured 10-dB impedance bandwidth of the array is 9.3%, which can cover the 2.4-GHz WLAN band. The desired radiation patterns were observed with a maximum gain of 13.5 dBi. The proposed antenna array has low cross-polarization and stable gain across the entire operating bandwidth.
关键词： ±45? Polarization,Polarization recon?gurable antenna array,PIN diodes,aperture-fed patch antenna
更新于2025-09-16 10:30:52
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Substrate integrated waveguide cavity backed frequency reconfigurable antenna for cognitive radio applies to internet of things applications
摘要： In this article, a new multiband frequency reconfigurable substrate integrated waveguide cavity slot antenna was designed using Computer Simulation Technology software tool for addressing the specific design challenges posed by the internet of things (IoT) based cognitive radio networks. Reconfiguration of frequency bands is achieved using PIN diodes. The antenna resonated at 2.624, 2.664, 2.720, 2.752, 4.304, 4.532, 4.556, 5.236, 5.304, 5.368, 5.332, and 5.392 GHz. The resonant frequency capability and radiation performance are demonstrated by both simulations and measurements. The simulated and measured results were in agreement. The higher efficiency, gain and average bandwidth obtained are 90%, 8.2 dBi and 65 MHz, respectively. The compactness, integrity, reliability, and performance at various operating frequencies make the proposed antenna a good candidate for IoT applications.
关键词： cognitive radio,frequency reconfigurable,PIN diodes,multiband,SIW,internet of things
更新于2025-09-12 10:27:22
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Characteristics of an organic photodetector with a conjugated donor and non-fullerene acceptor for indirect X-ray detection
摘要： In this study, an organic photodetector with a small band-gap donor, PBDB-T, and a non-fullerene acceptor, ITIC, was investigated as the active element in an indirect imaging system using a scintillator of the detector for indirect X-ray imaging. Compared with the common organic photodetector with a P3HT:PC70BM active layer, higher conversion e?ciencies can be expected, because the proposed detector is advantageous for visible-light absorption and carrier transport. The absorption peak of the PBDB-T:ITIC layer was located at 640 nm and was not well-matched with the emission properties of a CsI(Tl) scintillator. Therefore, a ZnSe(Te) scintillator with an emission peak at 620 nm was also tested. Compared with the P3HT:PC70BM detector, the ZnSe(Te)-coupled detector with the PBDB-T:ITIC = 1:1 active layer was 191% higher in collected current density (CCD) and 205% higher in sensitivity. The frequency response was measured with a 520 nm green LED. The detector with the PBDB-T:ITIC layer showed the -3 dB cut-o? frequency of 31.5 kHz, which was higher than the cut-o? frequency of the P3HT:PC70BM detector.
关键词： Materials for solid-state detectors,Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs, CMOS imagers, etc),X-ray detectors
更新于2025-09-12 10:27:22
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An Electronically Mode Reconfigurable Orbital Angular Momentum Array Antenna
摘要： In this paper, an array antenna for generating multi-mode orbital angular momentum (OAM) vortex waves and having electrically controlled mode reconfigurable function is proposed. The proposed antenna is based on a reconfigurable feed network (RFN) consisting of multiple PIN diodes as reconfigurable switches, a direct current (dc) control board and a 2 × 4 radial uniform circular array. By controlling the coding sequence of the corresponding PIN diode dc bias voltage on the RFN using a programmable microcontroller, the OAM modes generated by the proposed antenna can be dynamically reconfigured between l = 0, ±1, and ±2. Moreover, the OAM beams can be generated in a wide frequency band of 5.5–6.1 GHz and 5.65–6.1GHz for l = ± 1, ±2 modes and l = 0 mode, respectively. The prototype of the proposed antenna is simulated and fabricated to validate the proposed design. Both far-field and near-field experiments were performed to verify the feasibility of the proposed design. The results of the numerical simulation and measurement have good agreement with each other.
关键词： orbital angular momentum (OAM),array antenna,Reconfigurable,PIN diodes
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Auckland, New Zealand (2018.8.5-2018.8.8)] 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Tunable Low-Frequency Broadband Dual-Polarized Rasorber
摘要： In this paper, a tunable low-frequency broadband metamaterial (MM) dual-polarized rasorber based on slot arrays has been proposed. The structure consists of one air gap sandwiched between top lossy FSS layer and bottom lossless FSS layer, which exhibits a transmission window at 1.70GHz and a -10dB broadband absorption from 0.75GHz to 3.30GHz while the thickness is less than 10% of the free space wavelength at the lowest operating frequency. A switch between absorber and rasorber can be achieved by turning PIN diodes on/off, respectively. We think the proposed rasorber can be applied in low-frequency band stealth technology. The proposed design could also be easily scaled to other frequencies if necessary.
关键词： slot arrays,metamaterial,low-frequency,broadband,rasorber,PIN diodes,tunable,FSS,dual-polarized
更新于2025-09-04 15:30:14
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Study of silicon photomultiplier performance in external electric fields
摘要： We report on the performance of silicon photomultiplier (SiPM) light sensors operating in electric field strength up to 30 kV/cm and at a temperature of 149 K, relative to their performance in the absence of an external electric field. The SiPM devices used in this study show stable gain, photon detection efficiency, and rates of correlated pulses, when exposed to external fields, within the estimated uncertainties. No visible damage to the surface of the devices was caused by the exposure.
关键词： Cryogenic detectors,Double-beta decay detectors,Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc),Noble liquid detectors (scintillation, ionization, double-phase)
更新于2025-09-04 15:30:14