CN111092302A - FAST radio telescope 'back-lighting' observation method - Google Patents
FAST radio telescope 'back-lighting' observation method Download PDFInfo
- Publication number
- CN111092302A CN111092302A CN202010009680.9A CN202010009680A CN111092302A CN 111092302 A CN111092302 A CN 111092302A CN 202010009680 A CN202010009680 A CN 202010009680A CN 111092302 A CN111092302 A CN 111092302A
- Authority
- CN
- China
- Prior art keywords
- feed source
- angle
- fast
- noise temperature
- telescope
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
- H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/22—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the orientation in accordance with variation of frequency of radiated wave
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Telescopes (AREA)
Abstract
The invention relates to the technical field of FAST observation of giant radio telescopes, in particular to a 'retroillumination' observation method of FAST radio telescopes. The method comprises the following steps: giving a far field directional diagram and a main reflecting surface model of a feed source, and determining the position of the feed source; at each zenith angle, calculating the system noise temperature and gain value of FAST when each 'return illumination' angle is adopted; converting the gain into the effective receiving area of the telescope, and calculating the ratio of the effective receiving area to the noise temperature of the system, namely the sensitivity; at each zenith angle, the best "back-lighting" angle that maximizes sensitivity is found. The method does not need extra investment on the FAST telescope and has no additional equipment; only a feed source positioning mechanism of the FAST current feed source cabin is needed; the working range of the A-B axis of the FAST feed source cabin is reduced to a certain extent, and the deformation of the shielding cloth is reduced. Experiments show that when the best 'back illumination' angle is selected, the observation sensitivity of FAST in a large zenith angle can be remarkably improved by the method provided by the invention.
Description
Technical Field
The invention relates to the technical field of FAST observation of giant radio telescopes, in particular to a 'retroillumination' observation method of FAST radio telescopes.
Background
A500-meter Aperture Spherical radio telescope (FAST) is a major scientific device in the fifteen seasons of China, and is a single-Aperture radio telescope with the largest global Aperture and the most sensitive range of the observation frequency band. The telescope system comprises a site excavation and base construction system, an active reflecting surface system, a feed source supporting system, a measuring and controlling system, a receiver, a terminal system and the like.
The optical axis of the feed source in the original FAST design is coincident with the optical axis of the paraboloid. During observation of a large zenith angle, the system temperature rise caused by ground overflow loss is obvious, so that the FAST sensitivity is obviously reduced during observation under the large zenith angle. Therefore, how to solve the above problems becomes a difficult problem to be overcome by those skilled in the art.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide a 'retrospective' observation method of a FAST radio telescope, which aims to solve the technical problems in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a 'back-lighting' observation method of FAST radio telescope, comprising the following steps:
s1, giving a far field directional diagram and a main reflector model of the feed source, and determining the position of the feed source and the phase center of the feed source;
s2, calculating the system noise temperature and the gain value of FAST when each 'return illumination' angle is adopted at each zenith angle;
s3, converting the gain into the effective receiving area of the telescope, and calculating the ratio of the effective receiving area to the system noise temperature, namely the sensitivity;
s4, at each zenith angle, finding the best "albedo" angle that maximizes sensitivity.
As a further technical solution, step S1 specifically includes:
giving a far field directional diagram and a main reflecting surface model of a feed source, and determining the position of the feed source; the reference point of the far field directional diagram of the feed source simulation is arranged on the aperture plane of the feed source; setting the feed source at different positions in the Z direction, and calculating a far-field directional diagram; and when the axial gain is maximized, the corresponding feed source position is used as the placement position of the subsequent calculation feed source.
As a further technical solution, step S2 specifically includes:
placing the feed source at the position determined in the step S1, and calculating the system noise temperature of the telescope at different zenith angles and 'back lighting' angles by using the far-field directional diagram of the feed source, the main reflecting surface model and the heights of surrounding mountains and combining the sky background noise temperature of corresponding frequency points; under the condition of different zenith angles and 'back lighting' angles, rays emitted by taking the placement position of a feed source as a starting point are used, and if the rays are intercepted by a reflecting surface, the temperature of the part of rays to system noise is the sky noise temperature weighted by the gain of the direction; if the ray is intercepted by a peak, the contribution to the noise temperature of the system corresponds to the noise temperature of 300K on the ground; if the ray directly irradiates to the sky, the contribution to the noise temperature of the system corresponds to the noise temperature of the sky;
and (4) placing the feed source at the position determined in the step (S1), and calculating the far-field directional diagram and the gain of the telescope under each zenith angle and 'retroreflection' angle by using the far-field directional diagram and the main reflecting surface model of the feed source.
As a further technical solution, step S4 specifically includes:
at each zenith angle, the sensitivity values obtained when different 'back lighting' angles are adopted are compared, the 'back lighting' angle with the maximum sensitivity is selected, and the 'back lighting' angle is called as the optimal 'back lighting' angle.
By adopting the technical scheme, the invention has the following beneficial effects:
the FAST radio telescope 'retro-illumination' observation method provided by the invention does not need extra investment on the FAST telescope and does not have additional equipment; only a feed source positioning mechanism of the FAST current feed source cabin is needed; the working range of the A-B axis of the FAST feed source cabin is reduced to a certain extent, and the deformation of the shielding cloth is reduced. Experiments show that when the best 'back illumination' angle is selected, the observation sensitivity of FAST in a large zenith angle can be remarkably improved by the method provided by the invention.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a graph of the variation of the FAST gain at 1.1GHz frequency with the feed source position according to the embodiment of the present invention;
FIG. 2 is a graph of system noise temperature as a function of zenith angle at 1.1GHz frequency for FAST provided by embodiments of the present invention at various "back-lighting" angles;
FIG. 3 is a graph of gain as a function of "back-lighting" angle at various zenith angles at a frequency of 1.1GHz using FAST provided by an embodiment of the present invention;
FIG. 4 is a graph of the sensitivity as a function of "back-illuminated" angle at various zenith angles at a frequency of 1.1GHz for FAST provided by embodiments of the present invention;
FIG. 5 is a graph of the sensitivity of FAST provided by embodiments of the present invention at 1.1GHz, with the best "back-illumination" angle and without back-illumination, as a function of zenith angle.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The embodiment provides a FAST radio telescope 'back-lighting' observation method, which comprises the following steps:
s1, giving a far field directional diagram and a main reflector model of the feed source, and determining the position of the feed source;
s2, calculating the system noise temperature and the gain value of FAST when each 'return illumination' angle is adopted at each zenith angle;
s3, converting the gain into the effective receiving area of the telescope, and calculating the ratio of the effective receiving area to the system noise temperature, namely the sensitivity;
s4, at each zenith angle, finding the best "albedo" angle that maximizes sensitivity.
In this embodiment, as a further technical solution, step S1 specifically includes:
giving a far field directional diagram and a main reflecting surface model of a feed source, and determining the position of the feed source; the reference point of the far field directional diagram of the feed source simulation is arranged on the aperture plane of the feed source; setting the feed source at different positions in the Z direction, and calculating a far-field directional diagram; and when the axial gain is maximized, the corresponding feed source position is used as the placement position of the subsequent calculation feed source.
In this embodiment, as a further technical solution, step S2 specifically includes:
placing the feed source at the position determined in the step S1, and calculating the system noise temperature of the telescope at different zenith angles and 'back lighting' angles by using the far-field directional diagram of the feed source, the main reflecting surface model and the heights of surrounding mountains and combining the sky background noise temperature of corresponding frequency points; under the condition of different zenith angles and 'back lighting' angles, rays emitted by taking the placement position of a feed source as a starting point are used, and if the rays are intercepted by a reflecting surface, the temperature of the part of rays to system noise is the sky noise temperature weighted by the gain of the direction; if the ray is intercepted by a peak, the contribution to the noise temperature of the system corresponds to the noise temperature of 300K on the ground; if the ray directly irradiates to the sky, the contribution to the noise temperature of the system corresponds to the noise temperature of the sky;
and (4) placing the feed source at the position determined in the step (S1), and calculating the far-field directional diagram and the gain of the telescope under each zenith angle and 'retroreflection' angle by using the far-field directional diagram and the main reflecting surface model of the feed source.
In this embodiment, as a further technical solution, step S4 specifically includes:
at each zenith angle, the sensitivity values obtained when different 'back lighting' angles are adopted are compared, the 'back lighting' angle with the maximum sensitivity is selected, and the 'back lighting' angle is called as the optimal 'back lighting' angle.
When the best "back-lighting" angle is selected, the sensitivity of FAST observation at the zenith angle can be significantly improved by the method of the present invention, as shown in fig. 1 to 5.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (4)
1. A FAST radio telescope 'back-lighting' observation method is characterized by comprising the following steps:
s1, giving a far field directional diagram and a main reflector model of the feed source, and determining the position of the feed source and the phase center of the feed source;
s2, at each zenith angle, rotating the feed source around the phase center to the center of the main reflecting surface, namely 'irradiation back'; calculating the system noise temperature and gain value of FAST when each 'return illumination' angle is adopted;
s3, converting the gain into the effective receiving area of the telescope, and calculating the ratio of the effective receiving area to the system noise temperature, namely the sensitivity;
s4, at each zenith angle, finding the best "albedo" angle that maximizes sensitivity.
2. The FAST radio telescope "retro-illumination" observation method according to claim 1, wherein step S1 specifically comprises:
giving a far field directional diagram and a main reflecting surface model of a feed source, and determining the position of the feed source; the reference point of the far field directional diagram of the feed source simulation is arranged on the aperture plane of the feed source; setting the feed source at different positions in the Z direction, and calculating a far-field directional diagram; and when the axial gain is maximized, the corresponding feed source position is used as the placement position of the subsequent calculation feed source.
3. The FAST radio telescope "retro-illumination" observation method according to claim 1, wherein step S2 specifically comprises:
placing the feed source at the position determined in the step S1, and calculating the system noise temperature of the telescope at different zenith angles and 'back lighting' angles by using the far-field directional diagram of the feed source, the main reflecting surface model and the heights of surrounding mountains and combining the sky background noise temperature of corresponding frequency points; under the condition of different zenith angles and 'back lighting' angles, rays emitted by taking the placement position of a feed source as a starting point are used, and if the rays are intercepted by a reflecting surface, the temperature of the part of rays to system noise is the sky noise temperature weighted by the gain of the direction; if the ray is intercepted by a peak, the contribution to the noise temperature of the system corresponds to the noise temperature of 300K on the ground; if the ray directly irradiates to the sky, the contribution to the noise temperature of the system corresponds to the noise temperature of the sky;
and (4) placing the feed source at the position determined in the step (S1), and calculating the far-field directional diagram and the gain of the telescope under each zenith angle and 'retroreflection' angle by using the far-field directional diagram and the main reflecting surface model of the feed source.
4. The FAST radio telescope "retro-illumination" observation method according to claim 1, wherein step S4 specifically comprises:
at each zenith angle, the sensitivity values obtained when different 'back lighting' angles are adopted are compared, the 'back lighting' angle with the maximum sensitivity is selected, and the 'back lighting' angle is called as the optimal 'back lighting' angle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010009680.9A CN111092302A (en) | 2020-01-06 | 2020-01-06 | FAST radio telescope 'back-lighting' observation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010009680.9A CN111092302A (en) | 2020-01-06 | 2020-01-06 | FAST radio telescope 'back-lighting' observation method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111092302A true CN111092302A (en) | 2020-05-01 |
Family
ID=70400065
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010009680.9A Pending CN111092302A (en) | 2020-01-06 | 2020-01-06 | FAST radio telescope 'back-lighting' observation method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111092302A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109873253A (en) * | 2019-02-25 | 2019-06-11 | 中国科学院紫金山天文台 | Active Reflector face shape method of adjustment based on on-axis gain measurement |
| WO2019170827A1 (en) * | 2018-03-07 | 2019-09-12 | Technische Universiteit Eindhoven | High efficiency e-band antenna system |
| CN110334480A (en) * | 2019-07-26 | 2019-10-15 | 中国电子科技集团公司第五十四研究所 | Curve design method is extended for reducing the double offset antenna minor face of noise temperature |
-
2020
- 2020-01-06 CN CN202010009680.9A patent/CN111092302A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019170827A1 (en) * | 2018-03-07 | 2019-09-12 | Technische Universiteit Eindhoven | High efficiency e-band antenna system |
| CN109873253A (en) * | 2019-02-25 | 2019-06-11 | 中国科学院紫金山天文台 | Active Reflector face shape method of adjustment based on on-axis gain measurement |
| CN110334480A (en) * | 2019-07-26 | 2019-10-15 | 中国电子科技集团公司第五十四研究所 | Curve design method is extended for reducing the double offset antenna minor face of noise temperature |
Non-Patent Citations (2)
| Title |
|---|
| 叶文娟: "宽频带双极化多波束大型射电望远镜天线旳研究与设计", 《中国优秀硕士学位论文全文库》 * |
| 王君: "FAST 望远镜灵敏度优化及"回照"方式分析", 《中国优秀硕士学位论文全文库》 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR102591805B1 (en) | Antenna for Wearable Device | |
| US4249181A (en) | Cellular mobile radiotelephone system using tilted antenna radiation patterns | |
| KR20180134528A (en) | An electronic device comprising an antenna | |
| US20040150576A1 (en) | Secondary reflector for SHF antennae of the cassegrain type | |
| JP5709860B2 (en) | Broadband convex contact surface for multipath rejection | |
| KR20090130397A (en) | Radiation efficiency measuring device and radiation efficiency measuring method | |
| CN107528606A (en) | A kind of antenna switching method and device, mobile terminal | |
| CA2780677A1 (en) | Compact multipath-resistant antenna system with integrated navigation receiver | |
| EP3573182B1 (en) | Instrument comprising plane lens antenna and control method thereof | |
| KR102238357B1 (en) | Changeable Passive Relay, Controlling Server, and Operating Method thereof | |
| CN108039919A (en) | Adjustment method, device and the antenna system of antenna system | |
| CN111092302A (en) | FAST radio telescope 'back-lighting' observation method | |
| CN110907904A (en) | Solar method azimuth beam width correction method | |
| Yurchenko et al. | Numerical optimization of a cylindrical reflector-in-radome antenna system | |
| Saje et al. | A compact radio telescope for the 21cm neutral-hydrogen line; Radioteleskop za 21 cm vodikovo črto | |
| WO2023216595A1 (en) | Test system for active antenna | |
| RU2446522C2 (en) | Screen for inhibiting multibeam signal reception and antenna system having said screen | |
| CN103066380B (en) | Specific beam forming antenna | |
| CN206907922U (en) | Lead to antenna system during a kind of satellite is quiet | |
| WO2020011049A1 (en) | Power control method and device, and computer-readable storage medium | |
| Sloanaker et al. | Positions, intensities, and sizes of bright celestial sources at a wavelength of 10.2 CM | |
| Antar et al. | Callisto radio spectrometer construction at universiti kebangsaan malaysia [antennas and propagation around the world] | |
| Imbriale et al. | Update on the SKA offset optics design for the US technology development project | |
| Covington et al. | Radio brightness distribution of the sun at a wave-length of 10.7 centimetres, June 30, 1954 | |
| KR20120070414A (en) | Cradle for terminal having the function of transmitting and receiving rf signal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200501 |