CN219917603U - Low-frequency ultra-wideband four-ridge horn feed source and feed source system - Google Patents
Low-frequency ultra-wideband four-ridge horn feed source and feed source system Download PDFInfo
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- CN219917603U CN219917603U CN202321413940.4U CN202321413940U CN219917603U CN 219917603 U CN219917603 U CN 219917603U CN 202321413940 U CN202321413940 U CN 202321413940U CN 219917603 U CN219917603 U CN 219917603U
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Abstract
The utility model discloses a low-frequency ultra-wideband four-ridge horn feed source and a feed source system, wherein the caliber of the feed source is larger than 500 mm, the feed source comprises a feed source skirt edge structure section, a transition section, a feed source coupling section and four ridge sheets positioned at the bottom of the feed source, and the bottom of the feed source is sealed; and a heat insulation seam is arranged between the feed source coupling section and the transition section. The low-frequency ultra-wideband four-ridge horn feed source disclosed by the utility model is used for carrying out sectional design on the current continuous four-ridge horn feed source, separating and designing the rear section of the feed source with smaller volume but larger heat loss from the front section with smaller volume but smaller heat loss, optimally designing the high-noise part of the feed source and the fixed structure of the refrigeration Du Wate, finally realizing partial refrigeration of the low-frequency ultra-wideband feed source, greatly reducing the noise of a receiver system, improving the sensitivity of a telescope, and further improving the capacity of the telescope for finding darker and weaker celestial bodies.
Description
Technical Field
The utility model relates to a low-frequency ultra-wideband four-ridge horn feed source, in particular to a low-frequency ultra-wideband four-ridge horn feed source for a radio telescope.
Background
Currently, all main radio telescopes in the world including FAST telescopes are urgently required for carrying out real-time ultra-wideband observation, so that an ultra-wideband receiver is gradually replacing a traditional single octave receiver, and more stringent requirements are put forward on the comprehensive performance of core components of the ultra-wideband receiver. The ultra-wideband feed source is one of the core components of the ultra-wideband receiver, and indexes such as frequency coverage, radiation pattern, reflection loss, polarization isolation and the like directly influence the performances such as the working bandwidth, caliber efficiency, microwave link matching, telescope polarization and the like of the ultra-wideband receiver and even the whole telescope system. The prior research adopts a log-periodic feed source technology to realize the frequency coverage exceeding 6:1 relative bandwidth, but is limited by the attribute of a log-periodic antenna, and the ultra-wideband feed source of the log-periodic type can only be applied to a reflecting surface antenna of a specific Jiao Jingbi and severely limits the wide application of the ultra-wideband feed source on different telescopes; in addition, the log periodic ultra-wideband feed needs to cooperate with a low noise differential amplifier to realize single polarization phase matching and gain equalization. Compared with a low-noise single-ended amplifier, the current low-noise differential amplifier has serious hysteresis in research, and cannot meet the wide application of an ultra-wideband receiver in the aspects of bandwidth, noise, low temperature and other performances, so that the application of a log-period ultra-wideband feed source is severely limited. In recent years, ultra-wideband feeds based on the four-ridge horn technology are studied greatly, the four-ridge horn feeds can achieve frequency coverage exceeding 6:1, the beam width of the four-ridge horn feeds is adjustable, different types of reflecting surface antennas can be matched, and only a single-port low-noise amplifier is needed to be matched for use. The characteristics enable ultra-wideband four-ridge horn feed source (Quad-Ridged Flared Horn) to be widely researched, and promote the development of ultra-wideband receivers of radio telescope, such as 0.27-1.62GHz ultra-wideband receivers of FAST telescope. The multi-octave ultra-wideband receiver gradually replaces the traditional single-octave receiver, and promotes the development of multi-octave real-time ultra-wideband astronomical observation, which is remarkable in meaning. However, the low frequency application of four-ridge horn ultra-wideband feeds at hundred megahertz faces a significant problem: the feed source has larger caliber and volume and cannot be refrigerated at low temperature, and the feed source can only be applied to a normal temperature environment, so that the noise temperature of the feed source is 5 times higher than that of the low-temperature feed source, and the overall noise performance of the receiver is greatly influenced.
Disclosure of Invention
The utility model aims to provide a low-frequency ultra-wideband four-ridge horn feed source which is novel and unique in structure, convenient to use and capable of effectively improving the overall noise performance of a receiver; the specific technical scheme is as follows:
the feed source comprises a feed source skirt edge structural section, a transition section, a feed source coupling section and four ridge sheets positioned at the bottom of the feed source, wherein the bottom of the feed source is sealed; and a heat insulation seam is arranged between the feed source coupling section and the transition section.
Further, the width of the heat insulation slit is 1 to 2 mm.
Further, the feed source skirt structure section and the transition section are arranged in a split mode.
Further, the low-frequency ultra-wideband four-ridge horn feed source comprises the low-frequency ultra-wideband four-ridge horn feed source; the device also comprises a Dewar; the feed source coupling section is arranged in the Dewar.
Further, a feed source supporting refrigeration platform is arranged in the Dewar; the feed source coupling section is fixedly connected with the feed source supporting refrigeration platform.
Further, a cold screen and a cold screen supporting refrigeration platform are arranged in the dewar; the cold screen is fixedly connected with the cold screen supporting refrigeration platform; the top end of the feed source coupling section is lower than the top end face of the cold screen.
Further, the feed source inner cavity is provided with an insulating and heat-insulating sealing body for sealing the transition section, and the top end surface of the insulating and heat-insulating sealing body is not higher than the top end surface of the Dewar.
The low-frequency ultra-wideband four-ridge horn feed source disclosed by the utility model is used for carrying out sectional design on the current continuous four-ridge horn feed source, separating and designing the rear section of the feed source with smaller volume but larger heat loss from the front section with smaller volume but smaller heat loss, optimally designing the high-noise part of the feed source and the fixed structure of the refrigeration Du Wate, finally realizing partial refrigeration of the low-frequency ultra-wideband feed source, greatly reducing the noise of a receiver system, improving the sensitivity of a telescope, and further improving the capacity of the telescope for finding darker and weaker celestial bodies.
Drawings
FIG. 1 is a schematic diagram of a low-frequency ultra-wideband four-ridge horn feed source structure of the utility model;
FIG. 2 is a semi-sectional view of FIG. 1;
FIG. 3 is a schematic diagram of a low frequency ultra wideband four-ridge horn feed source installation structure;
fig. 4 is a diagram of simulation results of return loss results of a feed source.
In the figure: 1. low-frequency ultra-wideband four-ridge horn feed source; 101. a feed source coupling section; 102. a transition section; 103. a feed skirt structural section; 104. a ridge sheet; 2. dewar; 3. a cold screen; 4. the feed source supports the refrigeration platform; 5. the cold screen supports the refrigeration platform; 6. an insulating heat-insulating sealing body; 601. supporting the foam; 602. and (5) vacuum sealing the film.
Description of the embodiments
The present utility model will be described more fully with reference to the following examples. This utility model may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein.
Spatially relative terms, such as "upper," "lower," "left," "right," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature's illustrated in the figures. It will be understood that the spatial terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "under" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "lower" may encompass both an upper and lower orientation. The device may be otherwise positioned (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
As shown in fig. 1 and 2, the caliber of the low-frequency ultra-wideband four-ridge horn feed source 1 in the embodiment is more than 500 mm,
the feed source comprises a feed source skirt edge structure section 103, a transition section 102, a feed source coupling section 101 and four ridge sheets positioned at the bottom of the feed source, and the bottom of the feed source is sealed; the feed source coupling section 101 and the transition section 102 are arranged in a split mode, and a heat insulation gap is arranged between the feed source coupling section 101 and the transition section 102 after assembly; the heat conduction between the feed source coupling section 101 and the transition section 102 can be greatly reduced through the heat insulation joint, and the feed source coupling section 101 is kept in a low-temperature state.
The width of the heat insulation seam is not too narrow so as to avoid heat insulation effect; too wide is not needed to influence the outward propagation of electromagnetic wave signals of the feed source coupling section 101; the range should be controlled between 1 and 2 mm.
In order to reduce the loss of signals, insulating film materials plated with gold films can be attached to the isolation joints by conductive adhesive, and the thickness of the gold films is smaller than 35 microns; the gold film is used for conducting electricity, and meanwhile, the heat conduction is reduced to be extremely low. Of course, when in pasting, the gold-plated surface should be close to the inner wall of the feed source.
The feed skirt structure section 103 may also be provided separately from the transition section 102; the transition section 102 and the feed source coupling section 101 are convenient to accurately install.
In use, as shown in fig. 3, the feed coupling section 101 of the feed in the embodiment should be disposed within the dewar for cooling. The feed source coupling section 101 is used for coupling TEM mode electromagnetic waves in the coaxial transmission line into TE in the feed source circular waveguide 11 And (5) molding. The thermal noise of the feed coupling section 101 accounts for more than 80% of the total noise of the feed, and is mainly caused by the coaxial probe and the ridge plate. The utility model carries out low-temperature refrigeration on the feed source coupling section 101, and utilizes the primary cold head of the low-temperature Dewar to average physical property of the feed source coupling section 101The temperature is refrigerated to about 60K, thereby greatly reducing the physical temperature of the whole feed source. To prevent the heat from the external environment from passing through the upper feed section (300K), the middle section (300K) is conducted to the feed coupling section 101 (60K) (metal heat conduction), the present utility model proposes to separate a suitable gap (e.g., 2 mm) between the feed middle and lower sections. Firstly, the gap can block heat conduction, otherwise, the low-temperature Dewar refrigerator cannot refrigerate the feed source coupling section 101 due to huge heat brought by external thermal connection through metal; second, for the feed frequency, the intermetallic gap can be equivalent to a capacitance at high frequency, the capacitive reactance of which can be expressed by the formulaXc=1/jωc (where,ωfor working angular frequency, C is gap capacitance), the formula shows that at a certain frequency #ω) A smaller gap is arranged, which is beneficial to realizing higher capacitance (C), thereby leading the capacitance resistance of the gap to beXcSmaller, which is advantageous for the electromagnetic performance of the feed; on the other hand, under the condition that the area of the gap end is constant, the smaller the gap is, the larger the heat radiation between the metal end faces at the two ends of the gap is, which is unfavorable for the refrigeration of the feed source coupling section 101. The heat transferred by the heat radiation is extremely small, the utility model proposes to minimize the area of the separating end of the middle section and the lower section of the feed source, and the wall thickness of the feed source at the fracture is designed to be 1mm, so that the heat radiation quantity is further reduced.
A feed source supporting refrigeration platform 4 is arranged in the Dewar 2; the feed source coupling section 101 is fixedly connected with the feed source supporting refrigeration platform 4; the upper end of the transition section 102 is brought close to Du Wakou by the feed supporting refrigeration platform 4.
In order to reduce heat radiation, a cold screen 3 and a cold screen supporting refrigeration platform for installing the cold screen 3 are also arranged in the dewar; the cold screen 3 is fixedly connected with the cold screen supporting refrigeration platform 5; after installation, the top end of the feed coupling section 101 should be lower than the top end face of the cold screen. The cold screen is also cooled to an average physical temperature of about 60K.
An insulating and heat-insulating sealing body 6 for sealing the transition section 102 can be arranged in the feed source cavity, and the top end surface of the insulating and heat-insulating sealing body 6 is preferably not higher than the top end surface of the Dewar; to improve the heat insulating performance. The insulating sealing body 6 can adopt a scheme that a vacuum sealing film 602 is matched with a supporting foam 601. In use, the trapezoidal structure of the support foam 601 will be strongly supported by the feed transition section 102 and provide sufficient support for the vacuum sealing membrane 602, and the support stopper layer will be vacuum sealed with the vacuum sealing membrane 602. The vacuum sealing film 602 and the supporting foam 601 are transparent to electromagnetic waves, and do not affect the propagation of electromagnetic waves of the feed source.
The lower end face of the feed source skirt structure section 103 or the upper end face of the transition section 102 can be welded and connected with the opening of the Dewar 2; when the lower end surface of the feed source skirt edge structure section 103 or the transition section 102 is arranged in a split mode, the lower end surface of the feed source skirt edge structure section 103 and the upper end surface of the transition section 102 are welded and connected with the opening of the Dewar 2, so that a continuous feed source inner metal surface is formed, and continuous conduction of electromagnetic waves is guaranteed.
In order to test the overall electromagnetic performance of the segmented feed source, the utility model carries out return loss simulation on the segmented ultra-wideband feed source with the frequency of 0.5-3.3GHz, and the return loss result is shown in figure 4. Therefore, in the ultra-wideband, the return loss in 95% of the bandwidth is better than-10 dB, which indicates that the electromagnetic wave can be effectively transmitted through the gap capacitor, thereby meeting the application requirements.
The feed source in the embodiment greatly reduces the thermal noise of the traditional feed source working at normal temperature: taking 1GHz working frequency as an example, the ohmic loss of a traditional continuous surface ultra-wideband four-ridge horn feed source is about 0.15dB, and then the noise introduced at normal temperature (300K) is calculated by the following formula (1):
Te=（10 LdB⁄10 -1）T p =（10 0.15/10 -1）*300K=10.5K （1）
wherein, the liquid crystal display device comprises a liquid crystal display device,Tethe equivalent noise temperature of the feed source is;L dB the insertion loss of the feed source is in dB;T p physical temperature of feed source. Calculations indicate that: the equivalent noise temperature of the feed source at normal temperature is about 10.5K. And for the novel sectional feed source and the sectional refrigeration scheme thereof provided by the utility model: the upper section and the middle section of the feed source are connected with the outer wall of the refrigeration dewar through metal, and the physical temperature of the feed source is as followsT p At an ambient temperature of 300K, and the upper part andthe middle section has a smooth continuous metal waveguide inner surface, thus having an insertion lossL dB Only 0.01dB, the introduced thermal noise can be calculated from equation (1) (10 0.01/10 -1) 300 k=0.69K; the lower section of the feed source is composed of a smooth waveguide wall, a metal ridge sheet and the like, so that the insertion loss is larger by 0.14dB (0.15 dB-0.01 dB). The utility model cools the lower section of the small-size feed source to 60K low temperature through the refrigeration Dewar (see the feed source supporting refrigeration platform 4 in figure 3), and the thermal noise introduced by the lower section of the feed source is (10) 0.14/10 -1) 60 k=1.97k, then the feed overall thermal noise is 0.69k+1.97k=2.66K. From the above calculations, it can be seen that: the utility model can reduce the thermal noise of the front-end feed source of the receiver by 7.84K and 75%. In addition, the feed source working at normal temperature needs to be connected with a low-temperature Dewar (refrigeration first-stage low-temperature amplifier) by using a normal-temperature coaxial line with a certain length (at least 250 mm), so that the thermal noise of a normal-temperature coaxial transmission line with a length of 250mm is about 10.5K at the frequency of 1 GHz; by adopting the feed source lower section refrigeration scheme of the utility model, the feed source lower section and the rear-stage low-temperature amplifier are both arranged in the low-temperature Dewar, the average physical temperature of an interconnection coaxial line between a feed source output port (60K) and a low-temperature amplifier (10K) is only 35K, and the thermal noise is only (10) 0.15 /10 -1) 35 k=1.2k. In summary, the noise introduced by the ultra-wideband feed source and the rear signal thereof at the conventional normal temperature is 21K, and the total noise introduced by the scheme provided by the utility model is only 3.86K, which is reduced by 17.14K, which is reduced by 81.6%, and the noise reduction amount and the duty ratio are definitely huge. Taking FAST telescope (300 m caliber parabolic reflecting surface) as an example, an ultra-wideband receiver is deployed, and the receiving area is 70650m 2 Telescope efficiency 60%, effective area 42390m 2 The method comprises the steps of carrying out a first treatment on the surface of the When a normal temperature ultra-wideband feed source receiver is deployed, the sensitivity of the telescope is 42390m 2 /(21k+10k (feed post-stage circuit noise))=1367m 2 When the segmented refrigeration ultra-wideband feed source receiver provided by the utility model is deployed, the sensitivity of the telescope is 42390m 2 /(2.66k+6.2k (feed back-end circuit noise))=4784m 2 and/K. It can be found that the sensitivity of the telescope is improved by 3408 and m by adopting the segmented feed source 2 K is equivalent to enlarging the caliber of a parabolic reflecting surface with the caliber of 300m to 434m, and the area of the reflecting surface is increased by 77209m 2 . Cost would be hundreds of millions, and engineering would be nearly impossible, showing the value of the inventive solution.
The above examples are for illustration of the utility model only and, in addition, there are many different embodiments which will be apparent to those skilled in the art after having the insight into the present utility model and are not explicitly recited herein.
Claims (7)
1. The feed source comprises a feed source skirt edge structural section, a transition section, a feed source coupling section and four ridge sheets positioned at the bottom of the feed source, wherein the bottom of the feed source is sealed; the heat insulation joint is characterized in that a heat insulation joint is arranged between the feed source coupling section and the transition section.
2. The low frequency ultra wideband four-ridged horn feed of claim 1, wherein said insulating slot has a width of 1 to 2 millimeters.
3. The low frequency ultra wideband four-ridged horn feed of claim 1, wherein said feed skirt structural section is provided separately from said transition section.
4. A low frequency ultra wideband four-ridge horn feed system comprising a low frequency ultra wideband four-ridge horn feed as claimed in any one of claims 1 to 3; the device also comprises a Dewar; the feed source coupling section is arranged in the Dewar.
5. The feed system of claim 4, wherein a feed support refrigeration platform is disposed within the dewar; the feed source coupling section is fixedly connected with the feed source supporting refrigeration platform.
6. The feed system of claim 4, wherein a cold screen and a cold screen support refrigeration platform are disposed within the dewar; the cold screen is fixedly connected with the cold screen supporting refrigeration platform; the top end of the feed source coupling section is lower than the top end face of the cold screen.
7. The feed system of claim 4, wherein the feed cavity is provided with an insulating seal that seals the transition section, a top end face of the insulating seal being no higher than a top end face of the dewar.
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| CN202321413940.4U CN219917603U (en) | 2023-06-06 | 2023-06-06 | Low-frequency ultra-wideband four-ridge horn feed source and feed source system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202321413940.4U CN219917603U (en) | 2023-06-06 | 2023-06-06 | Low-frequency ultra-wideband four-ridge horn feed source and feed source system |
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- 2023-06-06 CN CN202321413940.4U patent/CN219917603U/en active Active
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