- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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A balloon-borne very long baseline interferometry experiment in the stratosphere: Systems design and developments
摘要： The balloon-borne very long baseline interferometry (VLBI) experiment is a technical feasibility study for performing radio interferometry in the stratosphere. The flight model has been developed. A balloon-borne VLBI station will be launched to establish interferometric fringes with ground-based VLBI stations distributed over the Japanese islands at an observing frequency of approximately 20 GHz as the first step. This paper describes the system design and development of a series of observing instruments and bus systems. In addition to the advantages of avoiding the atmospheric effects of absorption and fluctuation in high frequency radio observation, the mobility of a station can improve the sampling coverage (''uv-coverage'') by increasing the number of baselines by the number of ground-based counterparts for each observation day. This benefit cannot be obtained with conventional arrays that solely comprise ground-based stations. The balloon-borne VLBI can contribute to a future progress of research fields such as black holes by direct imaging.
关键词： Balloon,Radio telescopes,Satellite system,Interferometry,Black holes,Radio astronomy
更新于2025-09-23 15:22:29
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Compact wideband bowtie dipole orthomode transducer
摘要： A compact wideband orthomode transducer (OMT) with an octave bandwidth is proposed for a 0.56-1.12 GHz receiver system in the five hundred meter aperture spherical radio telescope. The OMT operates in a cryostat at a temperature of 70 K and therefore it is critical to minimize its dimension while insuring good electrical properties. The complete OMT comprises 2 bowtie dipoles orthogonally arranged in a circular waveguide. Because of the innovative structure, competing modes, TM01 TE21, and TE01, have been effectively suppressed, and the bandwidth of the dominate mode TE11 has achieved to 2.08:1. The final optimized OMT has a length of 300 mm, shorter than a half of the popular quardruple-ridged waveguide OMT. Measurements at room temperature agree well with simulation results, with a reflection coefficient below ?10 dB for both polarizations and cross-coupling levels of ?30.5 dB over the whole required frequency range.
关键词： wideband,radio astronomy,orthomode transducers,FAST telescope
更新于2025-09-23 15:22:29
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A Wideband Planar Aperture Array Using Interconnected Crossed Rings
摘要： A 5:1 frequency bandwidth aperture array antenna based on a new planar structure is reported. Dual polarization is implemented with high cross-polarization discrimination over ±45? scan angle from zenith. It is a low-loss cost effective approach using minimum dielectric materials. In the proposed planar antenna array design, a mutual coupled interconnected ring structure is used which extends the operational frequency band to the region where the element separation can be considerably greater than half a wavelength, unlike the previously reported interconnected array structures. Hence the total number of elements can be reduced for a speci?ed aperture size. The dual polarization have coincident-phase centers and in the implemen-tation reported here two low noise ampli?ers on the same board are integrated with a pair of dual polarized elements to form an active array. A 10 by 10 element array prototype of the design has been manufactured and the measured results con?rm it as a low cost, high performance front-end solution.
关键词： Aperture antennas,Phased arrays,Planar arrays,Radio astronomy
更新于2025-09-23 15:21:21
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Fully Metallic Anisotropic Lens Crossover-in-Antenna Based on Parallel Plate Waveguide Loaded With Uniform Posts
摘要： This paper describes a compact high-performance orthomode transducer (OMT) with a circular waveguide input and two rectangular waveguide outputs based on the superimposition of three aluminum blocks. Several prototypes operating in the band 1 (31–45 GHz) of the atacama large millimeter array have been fabricated and measured. The design is based on the use of a turnstile junction that is machined in a single block, requiring neither alignment nor a high degree of mechanical tolerances. Thus, a high repeatability of the design is possible for mass production. Across the 31–45 GHz band, the isolation is better than 50 dB and the return losses at the input and outputs of the OMT are better than ?25 dB.
关键词： turnstile junction,orthomode transducer (OMT),polarization diplexer,Radio astronomy
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Space PV Concentrators for Outer Planet and Near-Sun Missions, Using Ultra-Light Fresnel Lenses Made with Vanishing Tools
摘要： The Kilpisj?rvi Atmospheric Imaging Receiver Array (KAIRA) is a dual array of omnidirectional VHF radio antennas located near Kilpisj?rvi, Finland. It is operated by the Sodankyl? Geophysical Observatory. It makes extensive use of the proven LOFAR antenna and digital signal-processing hardware, and can act as a stand-alone passive receiver, as a receiver for the European Incoherent Scatter (EISCAT) very high frequency (VHF) incoherent scatter radar in Troms?, or for use in conjunction with other Fenno-Scandinavian VHF experiments. In addition to being a powerful observing instrument in its own right, KAIRA will act as a pathfinder for technologies to be used in the planned EISCAT_3-D phased-array incoherent scatter radar system and participate in very long baseline interferometry experiments. This paper gives an overview of KAIRA, its principal hardware and software components, and its main science objectives. We demonstrate the applicability of the radio astronomy technology to our geoscience application. Furthermore, we present a selection of results from the commissioning phase of this new radio observatory.
关键词： receiving antennas,radio astronomy,radar antennas,Antenna arrays,phased arrays
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS) - Tel-Aviv, Israel (2019.11.4-2019.11.6)] 2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS) - Results of the Radio Optical Modeling and Application of the New Radio Holography Method of the RATAN-600 Radio Telescope Surface Diagnosis
摘要： We describe a new radio holography method of the RATAN-600 radio telescope antenna diagnosis and adjustment, using the radial movement of the reference panel. We present the results of geometric optical ray tracing of the “South + Flat” antenna system in the autocollimation mode and radio optical modeling of the hologram recording and field reconstruction procedure, taking noise into account. Estimates for necessary isolation and acceptable spatial separation between transmitting and receiving feeds, geometrical tolerances, and requirements to the reference panel motion control are discussed. The experimental results of the method application to the diagnosis of radial errors in the positioning of panels of the RATAN-600 main mirror are reported.
关键词： radio astronomy,telescopes,Antenna measurements,holography,electromagnetic modeling
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Molecular Beam Epitaxy of Wide-Bandgap InAlAsSb on InP Substrates for an All Lattice-Matched Triple-Junction Solar Cell
摘要： The Kilpisj?rvi Atmospheric Imaging Receiver Array (KAIRA) is a dual array of omnidirectional VHF radio antennas located near Kilpisj?rvi, Finland. It is operated by the Sodankyl? Geophysical Observatory. It makes extensive use of the proven LOFAR antenna and digital signal-processing hardware, and can act as a stand-alone passive receiver, as a receiver for the European Incoherent Scatter (EISCAT) very high frequency (VHF) incoherent scatter radar in Troms?, or for use in conjunction with other Fenno-Scandinavian VHF experiments. In addition to being a powerful observing instrument in its own right, KAIRA will act as a pathfinder for technologies to be used in the planned EISCAT_3-D phased-array incoherent scatter radar system and participate in very long baseline interferometry experiments. This paper gives an overview of KAIRA, its principal hardware and software components, and its main science objectives. We demonstrate the applicability of the radio astronomy technology to our geoscience application. Furthermore, we present a selection of results from the commissioning phase of this new radio observatory.
关键词： receiving antennas,radio astronomy,radar antennas,Antenna arrays,phased arrays
更新于2025-09-16 10:30:52
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Optical Fiber Communications (Principles and Applications) || Radio over Fiber
摘要： Radio over Fiber (RoF) technology can integrate advantages of both wireless networks and optical fiber networks. Recently RoF technology has found numerous applications in broadband wireless access communication networks, radio astronomy, RADAR and millimeter-wave communications, antenna array beam-forming, establishment of up- and down-converting links using photonic signals, spectroscopy, imaging, and electronic warfare.
关键词： wireless networks,RoF,radio astronomy,optical fiber networks,millimeter-wave communications,antenna array beam-forming,photonic signals,broadband wireless access,electronic warfare,Radio over Fiber,spectroscopy,RADAR,imaging
更新于2025-09-12 10:27:22