- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A new dual C-shaped rectangular dielectric resonator based antenna for wideband circularly polarized radiation
摘要： This article presents a new dual C-shaped rectangular dielectric resonator (DR) based antenna for generation of wideband circularly polarized (CP) radiation. The proposed antenna comprises of a pair of C-shaped rectangular dielectric DR and a metal strip with a coaxial probe. By utilization of a metal strip at the side surface of C-shaped rectangular DR, the wideband CP radiation is achieved from the proposed dielectric resonator antenna (DRA). Fundamental orthogonal modes (TEx δ11 and TEy 1δ1) are excited using the rectangular DRA with a metal strip for the generation of CP fields. The proposed antenna with dual C-shaped rectangular CP DRA provides the measured ?10 dB reflection coefficient bandwidth of 30.07% (3.22 GHz-4.36 GHz) with measured 3-dB axial ratio bandwidth of 14.81% (3.25 GHz-3.77 GHz) at the boresight. The proposed antenna covers the useful Wi-MAX band.
关键词： wideband,dielectric resonator antenna,coaxial probe,circularly polarized
更新于2025-09-23 15:23:52
-
A broadband circularly polarized monopole antenna
摘要： A compact modified C-shaped monopole antenna with broadband circular polarization is proposed, fabricated and measured. The antenna structure is simple and only consists of combined modified C-shaped radiation patch and an improved ground plane with the overall size of 25 × 25 × 1 mm3. By cutting the corner on the modified C-shaped patch and adding triangular stubs on the ground plane, the wide impedance bandwidth and axial ratio bandwidth are achieved. The design process of the antenna is given, and the circular polarization mechanism of the circularly polarized antenna is analyzed from the surface current distributions. The measured impedance bandwidth is 95.2% (4.4-12.4 GHz) with return loss better than 10 dB, and the measured 3 dB axial ratio bandwidth is 96.8% (4.42-12.72 GHz). The peak gain is above 3.0 dBi within the working band, which indicates that it is suitable for application of ultra-wideband (UWB) wireless communication systems and satellite communication systems.
关键词： axial ratio,ultra-wideband (UWB),monopole antenna,circular polarization
更新于2025-09-23 15:23:52
-
[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) - Development of a 6-18GHz Quad-Ridged Flared Horn
摘要： In this paper, the cutoff frequency of the quad-ridge flared horn (QRFH) with respect to its ridge is studied. Based on the studies, we developed a QRFH to operate from 6 GHz to 18 GHz with high efficiency. The test results show that the return loss is less than -10 dB across the whole band. When the QRFH is used to illuminate a reflector antenna, the aperture efficiency is above 55.8%.
关键词： Low return loss,Cutoff frequency,Quad-ridge flared horn,High efficiency,Wideband
更新于2025-09-23 15:23:52
-
A Low-Power, Inductorless Wideband Cryogenic Amplifier For Supercondcting Nanowire Single Photon Detector
摘要： This paper presents a low-power, inductorless wideband cryogenic amplifier for superconducting nanowire single photon detector (SNSPD). To achieve wide bandwidth, low power consumption and small chip area, a modified Cherry-Hooper amplifier topology is used. With good input and output match, at 4.2 K temperature the measurement results show that the amplifier achieves 23-dB gain with a flat gain response, a 3-dB bandwidth (BW) of over 3.4 GHz, which covers frequencies as low as 130 kHz. Fabricated in a 0.13-μm silicon germanium (SiGe) BiCMOS technology, the amplifier core occupies a silicon area of only 0.075 mm2 and consumes a power of only 4 mW.
关键词： low power,Cryogenic amplifier,wideband,Superconducting Nanowire Single Photon Detectors,SNSPD
更新于2025-09-23 15:23:52
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Coastal Application of Sea Surface Height Measurement Using Direct Broadcast Satellite Signals
摘要： This paper presents results from a proof-of-concept experiment conducted at Platform Harvest to measure Sea Surface Height (SSH) using Ku- and K-band 'Signals of Opportunity' (SoOp) from DirecTV Direct Broadcast Satellite (DBS) system. The retrieved SSH was compared with the SSH measurement from a tide gauge located at the platform; the error in retrieval of Ku-band and K-band was found to be 2.78 cm and 2.58 cm, respectively. This matched the model for error with some differences that can be attributed to the difference in spatial and temporal characteristics of the SoOp and tide gauge measurements. Finally, this paper gives an overview of temporal and spatial sampling possible from a constellation of receivers observing Ku-band SoOp to resolve mesoscale eddies in coastal regions.
关键词： bistatic radar,Wideband Signals of Opportunity,coastal altimetry
更新于2025-09-23 15:23:52
-
In-band phase deviation minimization method for wideband tunable phase shifter
摘要： This article provides a novel approach to analyze and design wideband tunable reflection-type phase shifter (RTPS) with low in-band phase deviation (IBPD) error. The proposed RTPS consists of coupled lines where through and coupled ports are terminated with varactor diodes. The coupled lines can minimize the parasitic elements of varactor diode to achieve high phase shift range (PSR). In addition, the measured frequency-dependent capacitance of varactor diode was used in the analytical analysis to obtain minimum IBPD error and high PSR. For experimental demonstration, phase shifter was fabricated at the center frequency of 2.5 GHz. The measured results show that the fabricated circuit achieved 126.85° PSR with ±6.48° IBPD error for 500 MHz bandwidth (BW). In addition, the measured maximum insertion loss variation and input/output return losses are within ±0.34 dB and higher than 16.85 dB within 500 MHz BW, respectively.
关键词： varactor diode,coupled line,low in-band phase deviation error,wideband tunable reflection-type phase shifter
更新于2025-09-23 15:23:52
-
Application of metasurfaces in the design of performance-enhanced low-profile antennas
摘要： This paper presents a review of metasurface-based antennas conducted at the Microwave Communication Laboratory (MCL) of Ajou University in the Republic of Korea. In this paper, pro?le miniaturization, bandwidth enhancement, multiband operation, and radiation pattern control of metasurface-based antennas are considered. The paper ?rst presents metasurface-based antennas implemented by placing various radiators on top of the metasurface. It then presents antennas implemented by placing the radiators below the metasurface with and without the ground plane. Metasurface-based antennas are not only able to achieve high ef?ciency with a low pro?le but they are also able to generate extra resonances from the metasurface structures, which signi?cantly enhances the overall performance of the antennas. These additional resonances were utilized in multiband and/or wideband operations. In addition, the design of a planar compact wide-gain-bandwidth metasurface-based antenna and its radiation characteristics are presented at a terahertz (THz) frequency range. The THz antennas were designed with metasurfaces and a planar leaky-wave feeding structure. Finally, the outlook on future research at the MCL for antenna-related work and their applications using metasurfaces is provided.
关键词： surface wave resonance,sequential rotation,crossed dipole,arti?cial magnetic conductor,metamaterial,wideband,circular polarization,leaky-wave,Antenna,array,metasurface
更新于2025-09-23 15:23:52
-
Pattern Reconfigurable Wideband Loop Antenna for Thorax Imaging
摘要： A unidirectional loop antenna that can achieve wideband pattern re-configurability from -40 to +40 degrees in azimuth plane is presented. The antenna is designed to fulfill the multi-slice (level) scanning requirements of electromagnetic imaging (EMI) systems for thorax imaging. To overcome the need for positioning of several antenna-arrays, and hence eliminate the mutual coupling related complications, a square-loop antenna with reconfigurable pattern is designed. To create a unidirectional radiation, the loop is loaded with capacitive gaps, which convert its radiation mechanism to that of two virtual dipole arrays with quadrature phase excitation. By utilizing this feature, the location of the gaps are varied on the loop's structure to form virtual dipole arrays in different directions, thus rotating the radiation pattern without physically moving the structure of the antenna. As a proof of concept, six gaps were created on the loop and each gap is loaded with a PIN diode to electronically switch between the positions of the designed gaps, thus enabling changing the radiation direction. The proposed antenna can achieve a compact size of 0.32λ×0.32λ×0.002λ (λ is the wavelength of the lowest resonance of the antenna) and a wide fractional bandwidth of 32% at 0.8-1.15 GHz, with a peak gain and front-to-back-ratio of 2.1 dBi and 8 dB, respectively. The antenna is successfully tested on a thorax imaging platform to detect small volume of water (5 mL) inside lungs as an emulation of early pulmonary edema.
关键词： unidirectional antenna,virtual dipole array,pattern reconfigurable antenna,loop antenna,Electromagnetic imaging,wideband antenna
更新于2025-09-23 15:23:52
-
[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Recovery of UWB Radar Signals in Spectrally Restricted Environments
摘要： This paper presents a novel technique to recover the missing spectral information due to RF spectral restriction in ultra-wideband (UWB) synthetic aperture radar (SAR) imaging. We address a critical problem in UWB radar imaging: radar transmission is prohibited in reserved frequency bands specified by local frequency management agencies. We model the problem in a compressed sensing setup where a time-sparse received radar signal at each aperture is collected in the incoherent frequency domain using a stepped-frequency implementation. Using electromagnetic (EM) finite-difference, time-domain (FDTD) data of various targets and clutter objects computed at all viewing aspect angles, we show that the proposed technique can successfully recover the relevant information on targets of interest even from a large percentage of missing frequency bands.
关键词： step-frequency,sparse recovery,synthetic aperture radar,spectral restriction,Ultra-wideband
更新于2025-09-23 15:23:52
-
Dual-Layer Single-Varactor Driven Reflectarray Cell for Broad-Band Beam-Steering and Frequency Tunable Applications
摘要： A dual-layer active reflectarray configuration is proposed for broad-band beam-steering and/or frequency-tunable applications. A unit cell composed by two stacked fixed-size rectangular patches, properly loaded with a single varactor diode, is designed to realize the dynamic phase tuning mechanism. The proposed approach offers wider bandwidths, with respect to the existing varactor-based reflectarray cells, and quite good frequency reconfigurability features, as demanded by several radar or satellite communication applications. An X-band reflectarray cell is fabricated and tested, to prove the effectiveness of the proposed approach, achieving a 318° phase agility within a measured frequency range of about 14.6% with respect to the central design frequency (i.e., 11 GHz). Wideband beam-steering reflectarray designs are demonstrated, showing 1-dB gain bandwidths equal to 9–10%.
关键词： varactor,wideband,Reflectarray,beam-steering
更新于2025-09-23 15:23:52