- 标题
- 摘要
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- 实验方案
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Beam steering characteristics of highly directive photoconductive dipole phased array antenna for terahertz imaging application
摘要： In this paper, the beam-steering characteristics of photoconductive dipole phased array antenna configuration at 1.95 THz is presented. The proposed array antenna configuration with frequency selective surface favourably improves its gain and directivity which is useful to upsurge the imaging capabilities to address the deliberations such as limited depth-of-field (DoF) and size-weight-and-power of the THz source for imaging applications. These are important considerations for applications like stand-off imaging and surveillance of moving targets where the high angular resolution as well as extended DoF are the important parameters for successful detection of concealed explosives. The projected planar profile and compact highly directive (2 × 2) small-gap photoconductive dipole phased array antenna can be castoff for the exposure of concealed explosives such as RDX, TNT, and HMX which illustrate their substantial spectral absorption fingerprints in terahertz (1.4–2.2 THz) regime of the spectrum. A simple method of beam-steering has been explored based on phase controlled optical excitation of highly directive small-gap photoconductive dipole array antenna. Further, the effects of uniform progressive phase shift on the beam-steering of uniform linear array (along x-axis) as well as planar array (x-axis and y-axis) is investigated.
关键词： Terahertz frequency,Uniform current distribution,Photoconductive dipole antenna,Phased array,Frequency selective surface
更新于2025-09-23 15:23:52
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Polarization independent quad-bandpass frequency selective surfaces with wide-band ratio
摘要： A single layer polarization independent quad-bandpass frequency selective surface (FSS) with wide-band ratio is demonstrated theoretically as well as experimentally. The proposed structure passes four frequency bands with wide band ratio. The proposed FSS design is implemented by incorporating alternate arrangement of four units which are rotated 90° clockwise to form a unit cell of metal over a FR4 substrate. The geometrical dimensions of proposed unit cell are optimized and arranged in such a way that the structure possesses the quad bandpass characteristic and aspect dimensions of one unit is 0.11λ × 0.11λ with respect to first resonant frequency. This FSS provides stable response for different angle of incidence in transverse electric (TE) mode and transverse magnetic (TM) mode. To validate the results proposed FSS array has been fabricated and measured in free space environment. The measured results are in good agreement with the simulated results. Excellent stability is also observed for different incident angle.
关键词： quad bandpass,polarization independent,frequency selective surface,band ratio
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Auckland (2018.8.5-2018.8.8)] 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - A Broadband and Wide-angle Band-stop Frequency Selective Surface (FSS) Based on Dual-layered Fractal Square Loops
摘要： In this work, a broadband and wide-angle band-stop FSS based on dual-layered periodic arrays of fractal square loops was proposed and demonstrated. Equivalent circuit model and full-wave electromagnetic simulation were used to analyze this FSS. The sample of designed FSS with optimized structure parameters for center working frequency about 13GHz was fabricated and measured. The experimental results agree well with the simulated ones. Both of them indicated that the FSS has broad stop bands for both TE and TM polarization under incident angles from 0° to 60°. Specifically, the stop bands under incident angle 60° are over 7.35GHz and 5.91GHz for TE and TM polarization, respectively.
关键词： wide-angle,fractal Square Loop,broadband,band-stop frequency selective surface,dual-layered
更新于2025-09-23 15:22:29
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Dual-band System composed by a Photonics-based Radar and a Focal-Point/Cassegrain Parabolic Antenna
摘要： This work reports a dual-band radar system composed of a photonics-based transceiver and a unique dual-band antenna. The proposed antenna consists of an integration of conventional focal-point and Cassegrain parabolic antennas in the same structure, ensured by using a subreflector based on a frequency selective surface. Numerical and experimental results in terms of the antenna reflection coefficient, radiation pattern and gain are reported with excellent agreement over both frequency ranges. The innovative dual-band photonics-based radar transceiver operates simultaneously in the S- and X-bands. The radar system has been properly validated by multiple detections of helicopters and airplanes in real conditions.
关键词： radar,frequency selective surface,Antennas,dual-use radars
更新于2025-09-23 15:22:29
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Dual-Band High Selective Frequency Selective Surface Design and Analysis
摘要： In this paper, a second-order, dual-band, band-pass frequency selective surface (FSS) with high selectivity is presented by cascading three-layers of periodic metallic arrays. The unit cell in both two exterior layers is composed of gridded-double square loops (G-DSLs) while the element in the middle layer is consisting of wire grid. The three layers are separated by two thin F4B-2 substrates with dielectric constant of 2.65 + 0.02i. The proposed FSS can provide multi-transmission poles and multi-transmission zeros. There are two transmission poles in each pass-band. The two pass-bands are separated by two transmission zeros. On the upper side of the second pass-band, other two transmission zeros are generated also. These transmission zeros lead to a wide out of band rejection and a fast fall off response on both sides of each pass-band. The simulation is implemented using full wave electromagnetic simulator CST Microwave Studio, the central frequencies of the two pass-bands are 12.7 and 17.4 GHz. In addition, the designed principle is described using equivalent circuit model (ECM). Furthermore, the prototype of the FSS is fabricated and measured. Both simulated and measured results demonstrated that the proposed FSS has the merits of incident angle stability from 0° to 60° for both TE and TM polarizations.
关键词： filter,frequency selective surface,dual-band
更新于2025-09-23 15:22:29
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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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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - A Way to Realize a Multi-Frequency Polarization Plane Rotator
摘要： In this paper, we propose a simple design of a planar-chiral screen based polarization plane rotator that enables a polarization conversion at two assigned frequency bands simultaneously. The rotator is composed of a pair of conjugated double periodic perforated screens separated by a short distance. Two groups of four rectangular slots are cut along a perimeter of the screen periodical cell. Polarization rotation frequencies are controlled by choosing appropriated dimensions and placements of the slots’ groups. At the same time, we report that even a rotator with equal slots belonging to different (outer or internal) quadruples enables a dual-frequency operation as well.
关键词： optical activity,frequency-selective surface,rotator,polarization conversion
更新于2025-09-23 15:21:21
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[IEEE 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - Erode (2018.2.15-2018.2.16)] 2018 Second International Conference on Computing Methodologies and Communication (ICCMC) - Dual-band High-gain Metamaterial Based Resonant Cavity Antenna
摘要： A technique is presented to design dual-band, high-gain metamaterial based resonant cavity antenna using frequency selective surface (FSS) layer. The radiating dielectric resonator (DR) is connected by a microstrip line and a rectangular slot is cut from the ground surface. Cylindrical dielectric resonator antenna (CDRA) is used as an elementary radiator. CDRA is excited by the microstrip line through the rectangular slot and it is radiating in the broadside direction at two adjacent frequency bands (S and C bands). Antenna simulation results confirmed it resonates in two adjacent bands centered at 3.9 GHz and 7.1 GHz. The gain of the DRA at these two bands are 2.43 dBi and 4.32 dBi respectively. With a single layer 5 X 5 array superstrate the gain of the proposed antenna increased by 8.02 dBi from 3.6 to 4.1 GHz frequency band and 1.05 dBi from 6.7 to 7.5 GHz frequency band. This high-gain dual-band DRA can be used for millimeter wave wireless communication, small satellite communication terminals.
关键词： dielectric resonator antenna,frequency selective surface,high-gain,Dual-band
更新于2025-09-23 15:21:01
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Frequency Selective Surface for Infrared Transmission Suppression at Atmospheric Window
摘要： A double screen infrared frequency selective surface (FSS) with dual transmission stopbands was proposed and numerically investigated. Simulation results show that the infrared transmittance of the structure is lower than 10% in mid-infrared band (3~5 μm) and far-infrared band(8 ~14 μm).This structure is polarization insensitive to the incident electromagnetic waves. For a wide range of incident angles from 0° to 60°, the infrared transmittance of the structure is still lower than 25% in the band of interest. Compared with black body, the radiation ratio of structure is lower in the MWIR and LWIR ranges. The structure provide the potential applications for infrared stealth.
关键词： Infrared stealth,Transmission suppression,Atmospheric windows,Frequency selective surface
更新于2025-09-23 15:21:01
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A Convoluted Structure for Miniaturized Dual-stopband Frequency Selective Surface
摘要： A miniaturized dual-bandstop frequency selective surface (FSS) using convoluted structures is proposed in this letter. The working central frequencies of the proposed FSS are 2.66 GHz and 5GHz with -3dB bandwidths of 1.5 GHz and 1.2 GHz respectively. The side length of the unit cell is 6.88mm which is about 5.9% of the wavelength at the first working frequency. The equivalent circuit and current distributions are introduced to explain the FSS frequency performance. The effects of the geometrical parameters on the frequency response of the FSS are studied. The simulated results show that the ratio of the frequencies of the two working transmission zeros can be tuned over a wide range. A prototype of the proposed FSS is fabricated and measured. The simulation and measured results show that the working frequencies, the bandwidths of the passband and two stopbands of the the proposed FSS perform excellent stabilities under different polarizations and incidence angles. This FSS is a good candidate to isolate the wireless networks.
关键词： Frequency selective surface(FSS),Miniature unit cell,Dual-band
更新于2025-09-19 17:15:36