CN107181056B

CN107181056B - Microwave attenuation type GNSS measurement type antenna and equipment

Info

Publication number: CN107181056B
Application number: CN201710344068.5A
Authority: CN
Inventors: 叶云裳; 姜新发
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-05-16
Filing date: 2017-05-16
Publication date: 2022-08-30
Anticipated expiration: 2037-05-16
Also published as: CN107181056A

Abstract

The invention discloses a microwave attenuation type GNSS measurement type antenna and equipment, wherein the antenna comprises a sector cross oscillator, a semi-open circular cavity, a diameter restraining plate, a microwave attenuation plate, a guide plate, a polarization isolation power division module and the like; the sector cross vibrator is arranged in the center of the bottom of the semi-open circular cavity through a supporting component; the supporting component is provided with 4 supporting columns; the sector cross-shaped vibrator comprises 4 unit vibrators which are respectively arranged at the tops of the four supporting columns and have the same height with the bottom of the cavity; the setting height of the sector cross-shaped vibrator and the depth of the semi-open circular cavity are determined through adjustment, and flat aperture surface radiation is achieved; the top of the sector cross-shaped vibrator is coaxially and insulatively installed with the guide plate through a medium ring; the diameter restraining plate is coaxially arranged at the lower bottom of the semi-open circular cavity at a certain interval, and the microwave attenuation plate is tightly close to the bottom surface of the diameter restraining plate and is coaxially arranged; the polarization isolation power division module and the LNA module are arranged at the bottom of the microwave attenuation plate. The antenna of the invention is small, light, simple and low cost.

Description

Microwave attenuation type GNSS measurement type antenna and equipment

Technical Field

The invention relates to the technical field of communication, in particular to global navigation satellite system terminal receiving

A microwave attenuation type GNSS measurement type antenna and equipment thereof.

Background

A Global Navigation Satellite System (GNSS) is a radio Navigation positioning System based on satellites, and has functions of Navigation, positioning and timing with omnipotence (sea, land, air and sky), globality, all weather, continuity and real-time; and can provide real-time dynamic precise three-dimensional space coordinates, speed and time for each user. GNSS, also known as space-based PNT (position, navigation, timing) or PNOT (position, navigation, orientation, timing) system, has become a significant spatial and information-based infrastructure in the country, and also becomes an important mark for embodying the status of modern countries and the comprehensive national strength of the country. It will become an economic new growth point of the electronic information industry that develops fastest third worldwide after mobile communication and the internet.

The navigation satellite transmission signal includes a carrier wave, a ranging code and a data code, which are often referred to as navigation messages. The receiver processes the navigation message and converts the navigation message into 7-dimensional information of position, speed and time, completes navigation and positioning and provides a time reference. Navigation positioning receivers are the basis of all applications in the satellite navigation industry, and the receiver antenna is an important and core device of the receiver. Along with popularization and deepening of application, the requirement on the positioning accuracy of a receiver system is higher and higher, the positioning accuracy of cm or even mm magnitude can be realized by a carrier phase measurement type receiver, an antenna of the carrier phase measurement type receiver is indispensable key equipment of the receiver, and the carrier phase measurement type receiver plays a very important role in improving the carrier phase measurement accuracy of the GNSS.

In the early days of GPS, the single frequency pseudo range code positioning GPS-L1(C/a code) receiver antenna mostly used a microstrip patch and a quadrifilar helix antenna. With the application of dual-frequency GPS difference, a double-layer microstrip patch antenna appears, and the antenna solves the dual-frequency point application of GPS-L1 and GPS-L2 through the lamination of microstrip dielectric plates, but cannot completely meet the application requirement of multi-frequency broadband. And the radiation of the microstrip antenna can generate surface waves at the same time, and the front-to-back ratio, circular symmetry and wide-angle circular polarization characteristics of a radiation pattern of the microstrip antenna are difficult to improve and improve due to the excitation and radiation of the surface waves. The anti-multipath capability and the phase center stability of the antenna are poor, and the requirement of high-precision carrier measurement is difficult to meet.

Then, a double short-circuit circular ring circular microstrip patch antenna is provided for suppressing surface waves, and obvious effects are obtained in GPS-L1 and L2. The design does not depart from the resonance concept, and the application to multi-frequency and broadband is still difficult. At present, diversified satellite-based resources have the defects that a single microstrip antenna is much deficient for the application of a multi-satellite coexistence and shared application environment and high-precision measurement requirements.

In 2002 NovAtel Inc (patent number: US-6445354-B1), a fire wheel Antenna ('High Performance GPS Pinwheel Antenna') for L1 frequency band was first developed to achieve stable radiation phase and a certain suppression of multipath signals, and to meet the requirement of carrier phase measurement. A typical product is GPS-601. Later, NovAtel inc, developed a broadband receiver antenna suitable for GNSS, a typical product being GPS-704X. From the actual measurement result, the gain index of the 704X antenna is unbalanced in the full frequency band, and the low-end gain is nearly 3dB lower than the high-end gain, so that the full-frequency-band GNSS signal reception is realized, and particularly, the BD-2 signal reception in China is obviously influenced.

In addition, the weak signal receiving is very easily influenced by the surrounding environment of the antenna, and the navigation positioning receiver antenna not only receives direct signals sent by satellites, but also receives indirect signals entering through reflection and scattering. The indirect signal is generally referred to as a multipath signal. Multipath signals directly cause receiver pseudorange measurements or carrier phase measurements to be skewed, resulting in degraded positioning accuracy and positioning stability. Multipath error is one of the main sources of error in GNSS receiver positioning. Multipath interference has become a problem that must be overcome to further improve the positioning accuracy, stability and reliability of the receiver. GNSS receivers can be broadly classified into spatial domain and time domain processing of multipath signals. The time domain processing of the receiver mainly aims at inhibiting the influence of multipath signals, and a narrow correlation method, a waveform decomposition method, a Fast Iterative Maximum Likelihood Algorithm (FIMLA), a multipath estimation delay phase-locked loop method and the like are commonly used, so that more resources are required to be occupied, and the receiver equipment is complicated and redundant. This is against the objectives of downsizing, weight reduction, power consumption reduction, and cost reduction of the receiver, and the receiver cannot effectively handle a time delay caused by reflection around the antenna or the like which is shorter than 1/15 chips.

In order to improve the multipath resistance of a receiver system, the most applied receiver single antenna is in a Choke-Ring (Choke-Ring) form, and the surface wave is suppressed by using the surface impedance of a Choke coil to present a high impedance characteristic. The 2D/3D choke can effectively improve the front-to-back ratio of the single antenna. The improvement of F/B is very beneficial to the suppression of multipath and the improvement of the anti-interference capability. TOPCON introduced planar (2D) choke CR-3 and CR-4 antennas for GPS-L1 and L2 applications. To accommodate the coexistence and sharing of multiple satellites, NovAtel inc, introduced an antenna with a 3D choke ring, Nov-GNSS-750-X, which was 380mm in diameter, not less than 200mm in height, and up to 7.6kg in weight without a shroud. TOPCON then proposed a tpspn.a5 antenna with hemispherical dispersion columns 413.8mm in diameter and 288mm high and weighing no less than 7.6 kg. (NovAtel-750X antenna). Whether a choke or a hemispherical diffuser, their introduction greatly increases the size, weight and cost of the unit antenna. And the choke ring is designed based on the high impedance presented by the ring mouth to suppress stray radiation. This mechanism of action is frequency dependent, and it is limited to further expand the frequency band or to further improve the suppression capability. There are similar 3D choke antennas in China. The GNSS high-precision measurement type antenna has the same problem of serious homogenization tendency both in China and abroad, and has the common defects of large size, heavy quality and high cost. The research focus of new artificial dielectric materials appears at the end of the last century, and artificial Photonic Bandgap (PBG) and Electromagnetic Bandgap (EBG) materials are applied, and are designed to be stopped at a frequency band which needs to be suppressed by an antenna so as to prevent the propagation and radiation influence of surface waves and noise waves thereof. Since it is a periodic structure material, and its size and volume are limited, it is difficult to achieve the desired effect, so that it is not common to use this material in high-precision measuring antennas. In recent years Trimble developed a Geodetic Zephyr-2 antenna in which a ground plate is coated with a radar stealth material to form a high-impedance absorption surface to suppress spurious radiation. The height of the antenna is reduced, the diameter of the antenna still is 340mm, and the weight of the antenna is about 1.6 kg. In recent years, a design concept of forming cut-off wave attenuation on a grounding plate is applied to the design of a high-precision measurement type GNSS receiver antenna (see patent number: 20150284770.8), a small and light high-precision measurement type antenna is invented, and some favorable results are obtained at first. However, the antenna structure is complex, and the phase space uniformity still needs to be further improved.

However, from the application point of view, besides the requirements of small size, light weight and low cost, the deviation (difference) of the antenna Phase Center (PCO), the change of the antenna Phase Center (PCV) and the change of the group delay become the influencing factors of the future GNSS measurement with higher precision, and how to find a high-performance antenna with better phase and phase-frequency characteristics, simpler structure, lighter weight, smaller size and lower cost becomes an urgent problem to be solved.

Disclosure of Invention

Aiming at the defects existing in the problems, the application provides a microwave attenuation type GNSS measurement type antenna and equipment. The antenna has the advantages that the antenna characteristic is better than that of the current mainstream 3D choke coil antenna, phase center space normalization (PCO spatial dispersion in a GNSS band is approximately equal to 1 mm) is basically realized in the whole GNSS working frequency band, phase center dispersion (PCV (1 sigma)) is less than 0.5mm, more uniform phase and phase frequency characteristics are realized, the superstrong anti-multipath performance of front-to-back ratio F/B >30dB is realized, the antenna size is smaller, the quality is lighter, the structure is simpler and the cost is lower.

The application provides a microwave attenuation type GNSS measurement type antenna in a first aspect. The antenna mainly comprises a sector cross oscillator assembly with a semi-open circular cavity, a diameter restraining plate and a microwave attenuation plate assembly. The half-opening circular cavity sector cross-shaped vibrator component mainly comprises a sector cross-shaped vibrator and a half-opening circular cavity, and the diameter restraining plate and the microwave attenuation plate component mainly comprise a diameter restraining plate and a microwave attenuation plate. The semi-open circular cavity is provided with a support assembly, the support assembly is positioned in the central area of the cavity bottom of the semi-open circular cavity, and the support assembly comprises 4 support cylinders; the sector cross-shaped vibrator is arranged on the top of the supporting assembly and comprises 4 unit vibrators, and each unit vibrator is arranged on the top of one supporting column body; the setting height of the sector cross-shaped vibrator and the depth and the diameter of the semi-open circular cavity can be determined through adjustment, and the expected flat-caliber surface radiation is strived to be formed; the top of the sector cross-shaped vibrator is provided with the guide plate, and the guide plate and the sector cross-shaped vibrator are installed coaxially in an insulated manner through a medium circular ring; the diameter restraining plate is coaxially arranged at the lower bottom of the semi-open circular cavity at a certain interval, and the microwave attenuation plate is tightly abutted against the lower bottom surface of the diameter restraining plate and coaxially arranged; the polarization isolation power distribution module is arranged at the bottom of the microwave attenuation plate.

In a possible implementation manner, any unit oscillator in the sector cross oscillators is 1 fan-shaped metal corner piece (composed) bent to form an obtuse angle, 4 unit oscillators are arranged in a horizontal plane, and every two horizontal center lines are orthogonal. The height of the unit vibrator is less than lambda/4, and the unit vibrator belongs to a broadband and short vibrator design.

In a possible implementation mode, the supporting height of the central cross sector oscillator is adjusted, and the diameter and the depth of the semi-open circular cavity are adjusted to control the amplitude and the phase distribution of the aperture radiation field, so that the characteristics of the upper semi-space radiation pattern basically meet the preset pattern shaping requirement.

In a possible implementation mode, the semi-open circular cavity is provided with slots at equal intervals at the annular opening; and the generation and radiation of residual clutter loop current are suppressed by adjusting the distance between the slots and the length of the slots.

In one possible implementation, the diameter of the diameter suppressing plate is slightly larger than the diameter of the semi-open circular cavity, so as to suppress interference of (multipath and) clutter radiation as a first line of defense.

In a possible implementation manner, the microwave attenuation plate is formed by printing a plurality of metal patches with different widths and sizes on a microwave dielectric plate in a centrosymmetric manner, and connecting the metal patches in a radial direction by using microwave resistors. Thus, the distributed microstrip patches and the lumped parameter microwave resistors are connected in series and in parallel to form a gradient magnetic high-impedance surface. The microwave attenuation plate and the grounding plate (diameter suppression plate) are combined into an independent structural module, thereby further suppressing the transmission and radiation of noise waves and effectively realizing the attenuation and suppression of multi-path signals.

In one possible implementation, the polarization isolation power division module is substantially a 3dB/90 ° microwave Hybrid component. It has two input ports and two output ports; two input ports are respectively connected with the coaxial core wire of the supporting component, one output end of the supporting component is connected with a receiver for outputting RHCP signals, and the other output end of the supporting component is connected with a 50 omega absorption resistor for absorbing LHCP signals.

In a possible implementation manner, the four supporting assemblies are also used as RF coaxial lines, wherein 2 are feed coaxial lines, and the other two are auxiliary coaxial lines; the inner conductors of the two feeding coaxial feeders extend and cross over the inner conductors of the opposite side supporting columns which also serve as auxiliary coaxial lines, the two pairs of the side supporting columns which are the short-circuit coaxial lines with open-ended terminals (the characteristic impedance of the coaxial lines is not 50 omega coaxial lines) are tuned to series resonance through the inductive end impedance of the coaxial lines and the capacitive impedance formed by the ends of the inner conductors lapped at the ends of the coaxial lines and the columns which also serve as the outer conductors, and the lapping lines are in short circuit with the sector oscillators connected on the opposite side supporting columns, so that microwave connection is realized, and 0 degree/180 degree balanced feeding of two symmetrical unit oscillators is formed. An impedance matching section with the diameter different from that of the central line is arranged at a proper position on the central line of the two feeding coaxial lines and is used together with the RF stub line and the distributed reactance formed at the opposite side, so that the self-matching of the feeding coaxial line to the 50 omega coaxial line is realized without an external matching network.

In a possible implementation manner, the antenna further includes a low noise signal module, which is connected to the RHCP output section of the polarization isolation power division module to form an active antenna.

In one possible implementation, the antenna further includes a radome; wherein, the antenna house is used for protecting the antenna body.

In one possible implementation, the antenna may be used as a high-precision survey type GNSS user-compatible receiver antenna or a network RTK base station antenna or a GNSS receiving system with high precision positioning requirements. It can be popularized to radio receiving systems with similar requirements.

A second aspect of the present application provides a Radio Frequency (RF) front-end of a high phase-stability, high-accuracy measurement type for a receiver, or a high-accuracy measurement type device, comprising a microwave-attenuated GNSS measurement type antenna as described above.

The antenna can achieve that in the whole GNSS working frequency band, the antenna gain is larger than 7dBi c, the covering gain is higher than 1dBi c in an angle domain of +/-60 degrees, the RHCP circular polarization axial ratio, AR is less than or equal to 2dB, a circular symmetry ideal directional diagram with front-to-back ratio F/B larger than 30dB, the phase center space normalization (the space deviation of PCO in the whole GNSS band is about 1 mm), the phase center dispersion (PCV (1 sigma) is smaller than 1mm, more uniform phase and phase frequency characteristics are achieved, the size of the antenna is smaller, the quality is lighter, the structure is simpler, the cost is lower, the excellent performance of the antenna completely exceeds that of the first-class antenna applied at present, and the antenna can be used as a first choice for high-end market and future higher-requirement application of the GNSS receiver antenna in a brand-new mode.

Drawings

Fig. 1 is a schematic cross-sectional view of a microwave-attenuated GNSS surveying antenna according to an embodiment of the present invention;

FIG. 2a is a schematic partial cross-sectional view of a microwave-attenuated GNSS measurement antenna according to an embodiment of the present invention;

FIG. 2b is a schematic top view of a microwave-attenuated GNSS measurement antenna according to an embodiment of the present invention;

fig. 3a is a schematic top view of a diameter-restraining plate according to an embodiment of the present invention;

fig. 3b is a schematic bottom view of a diameter-restraining plate according to an embodiment of the present invention;

FIG. 4a is a schematic top view of a microwave attenuating panel according to an embodiment of the present invention;

fig. 4b is a schematic bottom view of a microwave attenuation panel according to an embodiment of the present invention.

In the drawings: the antenna house 1, lead to board 2, sector cross oscillator 3, half opening circle chamber 4, the board 5 of reducing, microwave attenuation board 6, the polarization is kept apart the merit and is divided module 7, radio frequency joint 8, LNA module 9.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The embodiment of the invention aims to synthesize a novel high-precision measurement type GNSS receiver antenna by only using a single antenna through the updating of a design concept and a design method under the conditions of not increasing the receiver configuration, not adopting a multi-antenna unit processing system and a self-adaptive antenna, and not adopting a 2D/3D choking loop structure (because the design can obviously increase the volume, the weight and the cost of the antenna, and is not suitable for the design targets of miniaturization, light weight and low cost). The stability of the phase center and the space normalization of the phase center are improved, and the phase center is simpler, smaller, high-light, more reliable and lower in cost as far as possible under the condition of meeting the requirement of high-end application. A brand-new antenna is created by a brand-new design concept, so that the antenna can better adapt to the high requirements in the future.

The embodiment of the invention adopts the cross sector oscillator and the half-opening circular cavity component to jointly form the flat aperture radiation source, and utilizes the design concept of feed source radiation to realize ideal directional diagram and phase center space normalization of the antenna of the navigation terminal receiver (the PCO space position is only 1mm along with the maximum difference of frequency in the whole GNSS navigation frequency band), phase center dispersion (PCV (1 sigma)) is less than 1mm, and very uniform phase and phase frequency characteristics.

The computer simulation profiling data of an embodiment of the antenna of the present invention further illustrates the role and performance of each component. The antenna of the invention is divided into: (1) a semi-open circular cavity cross sector vibrator assembly; (2) a diameter restraining plate; (3) a microwave attenuation plate assembly. The results of computer simulations of the antenna embodiments of the present invention using Ansof HFSS software are shown in the following table: the BD-2-B1/B2 and the GPS-L1/L2 are taken as examples to illustrate the effects and the efficiencies of the BD-2-B1/B2 and the GPS-L1/L2 on directional diagram shaping and multipath interference suppression respectively.

In the above table, G0 and G60 are antenna gains in the 0 ° direction and ± 60 ° angular domain; delta 70 degrees is the phase range of the phase directional diagram of the antenna and a phase plane such as a sphere in an angle domain of +/-70 degrees, PCO and Z represent the space position of the (equivalent) average phase center of the antenna; due to the symmetry of the antenna, the deviation in the plane perpendicular to the antenna axis is very small, lying substantially on the central axis, so that only the axial distance, Z, from the equivalent radiation center is indicated. AR represents the antenna circular polarization axial ratio in the angular coverage range (+ -70 °). F/B is the antenna front-to-back ratio, which is the ratio of the gain in the 0 DEG direction to the gain in the 180 DEG direction. It can be seen that:

(1) the half-opening circular cavity sector cross oscillator is used as a main radiation unit assembly of the antenna, and main radiation performance (including gain, directional diagram coverage angle domain, polarization and phase characteristics) of the upper half space of the GNSS measurement type antenna is basically realized through directional diagram shaping design. The invention is the basis of the antenna, and the design concept of forming the main radiating element of the antenna by combining the cross sector circularly polarized oscillator and circular waveguide H11 mode excitation for the first time is correct and available. The requirement of half-space radiation beams on a GNSS measurement type antenna is basically met, and particularly, the antenna disclosed by the invention has the advantages that through combined caliber amplitude and phase distribution control, a spatial phase directional diagram is in an angular domain of +/-70 degrees, the phase range delta from an ideal spherical surface is less than or equal to 1 degree, and the spatial polar difference delta is very close to an ideal spherical wave, so that the spatial normalization of the phase center of a main radiation unit is very good. However, the aperture edge of the sector cross oscillator of the semi-open circular cavity diffracts and scatters, so that the backward radiation of a radiation pattern is larger, the front-to-back ratio of the pattern, particularly the F/B-of GPS-L2/BD-B2, is only 16dB, and the main radiation unit of the antenna is not enough for restraining multipath and interference and stabilizing the phase, and a combination measure must be added.

(2) The ground plate with a limited scale is added to suppress part of the back scattering field, and computer simulation results show that the diameter suppression plate with the diameter phi of 160mm and the distance of 9mm from the bottom surface of the circular cavity can improve the front-to-back ratio F/B of a GPS-L2/BD-B2 frequency band from 16dB to 24dB, but the improvement of the front-to-back ratio of the frequency-limited ground plate to the GPS-L1/BD-B1 is not obvious.

(3) The antenna diameter suppression plate and the microwave attenuation plate component act together, the front-to-back ratio is improved by nearly 20dB compared with a single main radiation unit, the front-to-back ratio F/B of the whole GNSS navigation frequency band can reach more than 30dB, and the front-to-back ratio F/B basically does not have obvious negative effects on the radiation performance of the upper half space of the antenna. This has a significant effect on suppressing multipath and spurious interference and stabilizing the phase center characteristics.

In addition, the antenna of the embodiment of the invention has unique characteristics of inhibiting forward multipath and interference due to high polarization isolation and polarization filtering characteristics, has unique benefits for a CORS reference station receiver system in tall buildings and trees in the close proximity of cities, and ensures the receiving quality of direct waves in a complex environment. The antenna is small, light, simple and low in cost, which is incomparable with the prior similar antenna. The antenna is matched with a high-precision measurement type compatible receiver to realize the positioning precision of real-time dynamic monitoring of cm or mm magnitude, and is one of important core devices of a high-end receiver and a CORS base station.

The following describes embodiments of the present invention in detail with reference to the accompanying drawings.

Fig. 1 is a schematic cross-sectional view of a microwave-attenuated GNSS measurement antenna according to an embodiment of the present invention. As shown in fig. 1, the antenna includes a sector cross-shaped oscillator 3, a half-open circular cavity 4, a diameter-suppressing plate 5, a microwave attenuation plate 6, a directing plate 2 and a polarization isolation power division module 7.

Specifically, a support assembly is arranged on the semi-open circular cavity 4, the support assembly is positioned in the central area of the cavity bottom of the semi-open circular cavity, and the support assembly comprises 4 support (circular) cylinders; the sector cross-shaped vibrator 3 is arranged at the top of the supporting component and comprises 4 unit vibrators, and each unit vibrator is arranged at the top of one supporting (circular) cylinder; the setting height of the sector cross vibrator 3 and the depth and the diameter of the semi-open circular cavity are determined by adjustment to form (form) a flat-caliber radiation circular cavity; the top of the sector cross-shaped oscillator 3 is provided with the guide plate 2 which is used for fine tuning the impedance and the directional diagram of the antenna, and the guide plate 2 and the sector cross-shaped oscillator are coaxially installed through dielectric circular ring insulation; the diameter restraining plate 5 is arranged at the bottom of the semi-open circular cavity 4 at a preset interval, the microwave attenuation plate 6 is arranged at the bottom of the diameter restraining plate 5, and the polarization isolation power distribution module 7 is arranged at the bottom of the microwave attenuation plate 6.

In one example, as shown in fig. 1, the antenna has a diameter of 219.4mm and a radome height of 110 mm.

In one example, any unit oscillator in the fan-shaped cross oscillator is 1 metal angle sheet bent to form an obtuse angle of 133 degrees and a fan angle of 90 degrees, and 4 unit oscillators are horizontally arranged, and the horizontal central lines of the 4 unit oscillators are orthogonal in pairs (height H =34mm from a cavity bottom).

In one example, the support assembly is mounted in the center of the half-open circular cavity 4, and the sector cross-shaped dipole forms RHCP circularly polarized radiation in an operating frequency band and simultaneously excites the H11 fundamental mode by the circular waveguide.

In one embodiment, the half-open circular cavity 4 has a diameter of 140mm, a cavity height of 30mm and a sector oscillator height of 34mm, the cross-shaped sector oscillator 3 excites a flat aperture surface radiation field formed by a circular polarization primary field and a circular waveguide fundamental mode field excited by circular polarization H11, and the aperture field distribution is close to an H11 mode circular polarization field in the circular waveguide. Due to the symmetrical structure, the field distribution is also centrosymmetric. The lobe width of a radiation pattern can be controlled by adjusting the geometric size (vibrator shape and fan angle) of a fan-shaped vibrator and the size (cavity diameter and cavity depth) of a semi-open circular cavity, so that the expected pattern shaping requirement is met; and meanwhile, the phase distribution of the mouth surface is controlled, so that the radiation phase of the mouth surface in a coverage angle domain is basically unchanged along with a space angle (in a GNSS frequency range, an angle domain of +/-70 degrees, the phase deviation is less than or equal to 2 degrees) and is similar to a spherical wave, and the equivalent spherical center of the mouth surface is also basically unchanged along with the frequency (in the GNSS frequency range, the PCO space position can be less than 1mm along with the frequency change). The design requirement of the phase-stabilizing antenna is met, and the technical limit of small size and light weight is maintained.

In one example, the semi-open circular cavity is provided with 8 slots at the annular opening at equal intervals, and the width of each slot is 2 mm; and adjusting the distance between the slots and the length of the slots to suppress the generation of residual clutter ring current. In principle, a slit spacing of < λ/4, slit length ≈ λ/4, an optimal ring-edge current suppression may be achieved to prevent the formation of a spindle-shaped back lobe in the backward 180 ° direction.

Furthermore, the half-open circular cavity 4 plays a role in shaping a directional diagram of a space radiation field of the cross sector oscillator 3. The semi-open circular cavity 4 conductor boundary condition shaped radiation pattern forms circular polarized semi-spherical wave beam with proper wave beam width. A group of slots are formed at the edge of the semi-open circular cavity 4 at equal intervals, so that the length of each segment of the edge of the opening is far smaller than lambda/4, and the length of each slot is as close to lambda/4 as possible, thereby effectively preventing the generation of loop current at the edge of the opening. The number and length of the slots are adjusted, edge diffraction is reduced, and the 180-degree spinning vertical rear lobe formed by residual ring current can be maximally inhibited. Finally forming a similar radiation pattern. n is equal to any number above 1, as determined by design.

In one example, the diameter D =160mm of the diameter-suppressing plate is slightly larger than the diameter of the semi-open circular cavity, and the distance between the diameter-suppressing plate and the bottom surface of the semi-open circular cavity is 9mm, so as to serve as a first defense line for suppressing multipath and interference, and adjust the distance from the bottom of the circular cavity to optimize the effectiveness of suppressing the spurious radiation under the constraint condition of small size and light weight.

In one example, the microwave attenuation plate is composed of a central symmetric microstrip transmission line and a lumped-parameter microwave component which are connected in series and in parallel to form a gradient magnetic high-impedance surface, so that transmission and radiation of clutter and multi-path signals are further attenuated.

It should be noted that the microwave attenuation plate is an important innovation, and the innovative achievement is that the diameter suppression plate and the microwave attenuation plate assembly (a special microwave plate assembly with the diameter not exceeding 200mm and the thickness not exceeding 4 mm) are adopted to replace a large and heavy 3D choke coil, so that the effective suppression of stray radiation and interference is realized,

it should be noted that an infinite metal plate is mounted at a suitable position below the radiating element to completely suppress the radiation in the lower half space and form an ideal hemispherical beam. The antenna in the embodiment of the invention is limited by the size, and the diameter restraining plate is limited in size. How to realize the function of the infinite diameter-restraining plate is the innovation of the antenna of the embodiment of the invention. The antenna of the embodiment of the invention is coaxially provided with a metal flat plate with the diameter slightly larger than the diameter of the semi-open circular cavity 4 at a proper distance from the bottom of the cavity.

In one embodiment, the diameter of the semi-open circular cavity 4 is =140mm, and due to the limitation of miniaturization and light weight, the diameter restraining plate 5 is 9mm away from the bottom of the semi-open circular cavity, and the diameter is =160 mm; immediately below the diameter-suppressing plate 5 there is a specially designed microwave-attenuating plate 6 with a diameter =200 mm. The diameter suppression plate and the microwave attenuation plate are respectively printed on an FR4 double-sided microwave dielectric plate with the thickness h =2mm and the epsilon r =2.55, and the diameter suppression plate with the diameter =160mm is printed on the upper surface of the dielectric plate; the lower surface of the microwave attenuation plate is printed with metal patch groups which are distributed centrosymmetrically. As shown in fig. 3a and fig. 3b, the patches on the microwave attenuation plate are connected in series through the lumped resistors therebetween, and the microwave attenuation plate 6 is an important innovation and is composed of a central symmetric microstrip transmission line and a lumped parameter microwave component in series and parallel connection to form a high-impedance absorption surface with gradually changed impedance.

At the edge of the wave reaching the aperture plate 5, due to the discontinuity, it will scatter and diffract the residual microwave energy into space, creating interference to the radiation. The microwave attenuation plate 6 guides the residual electromagnetic waves to the microwave attenuation plate for continuous transmission, so that the waves passing through the microwave attenuation plate are attenuated and are not radiated to the space; and is an impedance graduator, which does not generate reflection while the wave energy is absorbed.

Fig. 2a is a schematic partial cross-sectional view of a microwave attenuated GNSS surveying antenna according to an embodiment of the present invention, and fig. 2b is a schematic top view of the microwave attenuated GNSS surveying antenna according to the embodiment of the present invention. As shown in fig. 2a, the diameter of the diameter suppressing plate 5 and the microwave attenuating plate 6 may be 200 mm; the height from between the directing plate 2 and the microwave attenuation plate 6 may be 58 mm.

As shown in fig. 2b, the support assembly comprises 4 support columns, one support column is connected with one sector oscillator; the slots of the semi-open circular cavity 4 are arranged at intervals.

Figures 3a-3b below are schematic views of an embodiment of a diameter plate. To explain the diameter suppressing plate, fig. 3a is a schematic top view of a diameter suppressing plate according to an embodiment of the present invention, in which a metal layer of the diameter suppressing plate is formed by printing on a microwave dielectric plate with ∈ r =2.55 and h =2 mm. Fig. 3b is a schematic bottom view of a diameter-suppressing plate according to an embodiment of the present invention. As shown in fig. 3a, 301, a non-metallized through hole, may have a diameter of 2.7 mm; 302, non-metallized through holes, which may be 2.7mm in diameter; 303, indicating that the diameter may be 160 mm; 304, indicating that the diameter may be 27.8 mm; 305, the metal copper foil is remained in the area with the diameter between 27.8mm and 160mm, and the metal copper foil is removed in other parts.

The microwave attenuation panel will be described below by taking fig. 4a to 4b as an example. Fig. 4a is a schematic top view of a microwave attenuation board according to an embodiment of the present invention, in which a microstrip patch is printed by microwave, or is applied to the back surface of a microwave dielectric board of a diameter suppression board, or is separately attached to another microwave dielectric board. Microwave resistors are soldered in place on each patch. To protect the microwave attenuation panel circuit, a dielectric plate is attached. In this embodiment, the same medium cover plate as the diameter-restraining plate is selected. The two dielectric sheets are fastened and connected at the edges by screws. Fig. 4b is a schematic bottom view of a microwave attenuating plate according to an embodiment of the present invention. And small grooves are cut at positions corresponding to the positions of the resistors arranged on the dielectric plate, so that the two plates can be seamlessly joined.

As shown in fig. 4b, the microwave attenuation plate may have a diameter of 200 mm; 401, indicating a sink at 48 is 1 mm; the metal copper foil is removed from both sides of the microwave attenuation plate.

In another embodiment, the microwave attenuation panel is obtained by periodically arranging a group of metal patches on a grounded dielectric plate. The top metal patch and the metal grounding plate are connected through a lumped resistor to form a two-dimensional high-resistance surface, so that surface wave and spurious radiation are inhibited. Also, a dielectric plate may be attached to protect the microwave attenuation panel circuit.

In one example, the polarization isolation power division module includes two input ports and two output ports; the two input ports are respectively connected with the coaxial core wires of the supporting component, one output end of the supporting component is connected with the receiver for outputting RHCP signals, and the other output end of the supporting component is connected with a 50 omega absorption resistor for absorbing LHCP signals.

At this time, the embodiment of the invention can form four-point circularly polarized self-matching feed to the oscillator without using a microstrip feed network. Besides the support, two of the four support columns connected with the vibrator are also used as coaxial feeder lines. The inner conductor of the feeder line is bridged on the opposite side supporting rod and forms a balanced feed 'balun' of 0 DEG/180 DEG with the opposite side oscillator. The coaxial core wires (inner conductors) at the bottom ends of the two support rods which are also used as the feeder lines are led out at the bottom of the circular cavity and connected with two input ends of the 3 dB/90-degree polarization isolation power division module 7. The four support cylinders and the 3dB power division network form broadband circular polarization four-point feed of the 4 vibrators of the central radiation unit. Through unique frequency band widening design and capacitance and inductance resonance impedance compensation technology, the broadband self-matching of feeding is realized under the condition that an external matching network is not arranged. Within the band of 1.1-1.7MHz, the VSWR of the port can be controlled within the range of less than or equal to 1.3. A metal flat plate serving as a director, namely a directing plate 2, is arranged at the tops of the four fan-shaped vibrators, and is coaxially and insulatively arranged with the fan-shaped cross vibrator 3 through an annular medium pad (diameter suppression plate 5) so as to further adjust the radiation pattern and the impedance characteristic of the fan-shaped cross vibrator; the direction-guiding (suppressing) plate 2 can be used to fine-tune the direction diagram and impedance to achieve the best.

The embodiment of the invention realizes the dual-polarization characteristic of the antenna, and has the polarization filtering characteristic which is not possessed by a common single antenna. The 3dB/90 degree polarization isolation power divider has 4 ports, two input ends are respectively connected with inner core of cable in the supporting column body, the other two output ends, one output RHCP signal is connected with receiver, another output end is connected with 50 omega absorption resistor, it can absorb LHCP signal led out from it. The power division network is different from a common 3dB power divider, not only realizes power distribution and 90-degree phase shift, but also can absorb an orthogonal polarization component LHCP and prevent interference on a direct signal of a receiver; the anti-multipath performance of the antenna is further improved.

In one example, 2 support columns of the support assembly are used as a coaxial feeder, an inner conductor of the feeder is bridged on an inner conductor of an opposite support column, the opposite support column is an open-circuit short-circuit coaxial line, and the inductive end impedance presented by the coaxial line and the capacitive impedance formed by lapping between the inner conductor and the outer conductor of the coaxial line are tuned to series resonance, so that the microwave connection of the lapping line and an opposite oscillator is realized, and 0 degree/180 degree balanced feeding is formed. The proper position on the center line of the two-feed coaxial line is provided with an impedance matching section with the diameter different from the center line, and the impedance matching section and the RF stub line and the distributed reactance formed on the opposite side act together, so that no external matching network is needed, and the self-matching of the antenna feed coaxial line to the 50 omega coaxial line is realized.

In one example, the antenna further comprises a low noise signal module; the low noise signal module and the polarized power division module form an active antenna.

In this step, the antenna in the embodiment of the present invention may be used as a passive antenna, or may be combined with a preselection filter and an LNA to form an active antenna; when the antenna is used as a passive antenna, an output end RHCP of the polarization isolation power division module 7 is directly connected to an RF output port 8 and led out; as an active antenna, an output end RHCP of the polarization isolation power division module 7 is connected with a filter and LNA module 9, and an output end of the LNA module 9 is connected to an RF output port and then connected with a receiver by a cable.

In one example, the antenna further comprises a radome; wherein, the antenna house is used for protecting the antenna body.

The antenna provided by the embodiment of the invention is provided with a wave-transparent antenna cover 1 made of glass fiber reinforced plastic composite materials, and is connected with an antenna microwave attenuation plate assembly 6 through a screw of a bottom flange. This antenna house 1 protection antenna body avoids with external direct contact, has increased the ability that the antenna anti-collision, anti-vibration, shocks resistance. Rain, sand, dust, moisture, salt and alkali and the like are also isolated by the sealing gasket, and the GJB150 related regulations are met.

Furthermore, the antenna of the embodiment of the present invention is RF-connected to the receiver only through a sealed socket (tnc (f)) on the bottom plate of the radome 1; while being connected to the antenna support pole only through a screw hole (5/8-11) in the center of the bottom of the housing.

In one example, the antenna may be used as a high-precision survey type GNSS user-compatible receiver antenna or a network RTK base station antenna or a GNSS receiving system with high precision positioning requirements. It can be popularized to radio receiving systems with similar requirements.

A second aspect of the present application provides a high-precision measurement-type apparatus including the high-precision measurement-type antenna as described in any one of the above.

The antenna in the embodiment of the invention is different from a short-circuit circular microstrip patch antenna, a 2D/3D choking loop antenna used at home and abroad and a GNSS receiving antenna of a TOPCON hemispherical scatterer, and is also different from a Trimble Zephyr-2 antenna. The original microwave attenuation plate component and the diameter restraining plate jointly act to replace a 3D-choke coil which is commonly used at home and abroad, and the microwave attenuation plate has simple structure, light weight and low cost; and the phase frequency characteristic of antenna stable phase center and phase center space normalization is realized by using the design concept of the high-efficiency plain-flat feed source.

The antenna in the embodiment of the invention has the following beneficial effects:

the approaches and methods for suppressing multipath and interference are completely different from the previous ones. Short-circuit circular microstrip patch antennas are not used, nor are widely used 2D/3D choke structures. The antenna of the embodiment of the invention creatively designs the microwave attenuation plate assembly, organically combines the microwave attenuation plate with the diameter suppression plate, tightly installs the microwave attenuation plate assembly below the diameter suppression plate, attenuates wave energy passing through the microwave attenuation plate assembly again to prevent the radiation of the wave energy, effectively inhibits surface wave and clutter interference, and improves the anti-multipath interference efficiency of the antenna. Compared with the hook Ring loop antenna, the antenna has the advantages of lighter and more compact structure, lower cost, better phase center stability and space normalization;

2, hemispherical beam radiation is realized by a fan-shaped cross oscillator of a semi-open circular ring cavity instead of a common radiating unit and a metal grounding plate. And adjusting the cross-linking between the oscillator field and the waveguide mode by adjusting the diameter and the depth of the semi-open circular cavity to obtain a semi-spherical beam with a preset beam width. It not only realizes the shaping of the directional diagram. The antenna of the embodiment of the invention belongs to a short antenna and a complete central symmetry structure, and the flat aperture surface radiation is beneficial to stable phase center and phase center space normalization, so that the antenna of the invention has better phase frequency characteristic and stable radiation phase center;

3, the complete centrosymmetric structure brings the circular symmetry and wide-angle circular polarization of the radiation pattern. In the whole navigation frequency band (1.1-1.7 GHz), a full-space single lobe is basically realized, a side back lobe with a level exceeding-30 dB is avoided, single RHCP main polarization coverage is realized in a 30dB range, and a heart-shaped hemispherical RHCP circularly polarized beam is formed;

4, adopt the further beneficial effect of above-mentioned scheme to be: and the broadband self-matching of the antenna is realized without a network. The central radiation unit of the antenna of the invention is composed of 4 orthogonal broadband sector oscillators, belongs to short and short antennas, and realizes the broadband self-matching of feed by unique broadening frequency band design and capacitance and inductance resonance impedance compensation technology without an external matching network. In the band of 1.1-1.7MHz, the VSWR of the port is controllable to be less than or equal to 1.2. The requirement of multi-frequency and multi-mode application shared by multiple satellites is completely met;

5, adopt the further beneficial effect of above-mentioned scheme to be: the feed loss is reduced, and polarization filtering is realized. The antenna of the embodiment of the invention has the remarkable characteristic that the feed network does not adopt a microwave dielectric slab network, but is formed by a coaxial 0-degree/180-degree feed 'Balun' + 3 dB/90-degree polarization isolation power dividing device. The circular polarization feed device unique to the antenna provided by the embodiment of the invention not only realizes the four-point circular polarization feed to the radiation center unit, but also can isolate the cross polarization (LHCP) component. The unique characteristics of the feed device are compact structure, high integration level, low feed RF loss and easy integration with the antenna and the receiver.

Compared with the similar antenna, the antenna in the embodiment of the invention has the following beneficial effects:

1, the antenna has a wide frequency band and is suitable for being matched with a multi-satellite and multi-mode GNSS compatible receiver without a matched broadband oscillator design. The microstrip patch antenna and the quadrifilar helix antenna are common GPS receiver antennas, both belong to resonant antennas, and are suitable for single-frequency or narrow-band operation. The antenna in the embodiment of the invention realizes the broadband self-matching characteristic, namely, no additional network is required to be allocated, and the VSWR can be less than 1.2 in a 1.1GHz-1.6GHz band: 1;

2, the complete central symmetry design enables the antenna directional diagram to have good circular symmetry and good wide-angle circular polarization characteristics. The antenna of the embodiment of the invention has a complete central circular symmetry structure, the radiation pattern is circularly symmetric, and the circular asymmetry is less than or equal to plus or minus 0.5dB in a working angle range of plus or minus 60 degrees; the wide-angle circular polarization, in the working angle range of +/-60 degrees, AR is less than or equal to 2dB;

3, the antenna of the embodiment of the invention has the obvious characteristics that the microwave attenuation plate component is creatively designed, so that the multipath and the interference are effectively inhibited, and the antenna becomes lighter, smaller and simpler. The attenuation plate component is composed of a microstrip line with central symmetry and a microwave component with lumped parameters in series and parallel connection, a high-impedance grounding surface with gradually changed impedance is formed, and the attenuation plate component and the grounding surface are combined to effectively inhibit the interference of multipath, clutter, surface waves and the like to a receiving field. The multi-path effect is greatly inhibited, and the high roll-off, high front-to-back ratio and good wide-angle circular polarization characteristics of the directional diagram are realized. The multi-path resistant effect of the Ckoke loop is achieved, and the Ckoke loop antenna is superior to a Choke loop antenna in the aspects of frequency band widening, small structure and compactness;

4, the antenna of the embodiment of the invention has another remarkable characteristic that: has a very stable radiation phase center. In the whole navigation frequency band, the phase center dispersion PCV (1 sigma) is less than 1mm, the phase center is basically kept unchanged along with the frequency, the phase frequency characteristic is better, and the smaller group delay change can meet the higher requirement of a higher-precision carrier phase measurement type receiver antenna;

5, the antenna of the embodiment of the invention has the following salient points: the antenna has dual circular polarization characteristics. The feed device of the antenna not only realizes four-point RHCP circularly polarized feed to the central radiation unit, but also provides a reverse-rotation LHCP channel isolated from a receiver for forward primary reflection and scattering, and the interference of forward primary multipath signals to received signals is effectively isolated due to unique polarization filtering performance.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A microwave attenuation type GNSS measurement type antenna is characterized by comprising a sector cross oscillator, a semi-open circular cavity, a diameter restraining plate, a microwave attenuation plate, a conductor guide plate and a polarization isolation power division module; wherein the content of the first and second substances,

the central area of the bottom of the semi-open circular cavity is provided with a supporting component, the supporting component is provided with 4 supporting columns, the sector cross-shaped vibrator comprises 4 unit vibrators, and each unit vibrator is arranged at the top of one supporting column and keeps the same height with the bottom of the cavity;

the conductor guide plate is installed at the top of the sector cross-shaped vibrator, and the conductor guide plate and the sector cross-shaped vibrator are coaxially and insulatively installed through a medium circular ring;

the diameter restraining plates are arranged on the lower bottom surface of the semi-open circular cavity at intervals of a preset distance and are coaxially arranged, and the microwave ground potential is kept between the diameter restraining plates and the semi-open circular cavity through the supporting assembly; the microwave attenuation plate is closely arranged on the lower bottom surface of the diameter restraining plate; the diameter restraining plate and the microwave attenuation plate are respectively printed on the microwave dielectric plate, and two microwave modules are coaxially arranged in pairs to form an independent microwave module;

the polarization isolation power division module is arranged at the bottom of the microwave attenuation plate;

the diameter suppression plate and the microwave attenuation plate are organically combined into an independent structural module, so that the ultra-strong suppression of interference such as diffraction waves, multipath signals and the like is realized; the diameter restraining plate is a metal circular plate with the diameter slightly larger than that of the semi-open circular cavity, the diameter restraining plate forms a first restraining defense line for multi-path signals and clutter radiation, the microwave attenuation plate is tightly connected to the lower surface of the diameter restraining plate, and a second restraining defense line is formed for transmission and radiation of residual diffraction signals and clutter, so that ultra-strong anti-multi-path and anti-interference performance is achieved;

the microwave attenuation plate is obtained by periodically arranging a group of metal patches on a grounded dielectric plate, and the top metal patch and the metal grounded plate are connected through a lumped resistor to form a two-dimensional high-resistance surface so as to inhibit surface wave and spurious radiation.

2. The microwave attenuated GNSS surveying antenna of claim 1, wherein the sector cross dipole is composed of 4 unit dipoles; any unit oscillator is a fan-shaped metal angle piece with 1 fan-shaped angle close to 90 degrees and bent into an obtuse angle, 4 unit oscillators are arranged in a horizontal plane, every two horizontal center lines are orthogonal, and the two orthogonal fan-shaped oscillators realize feeding through the supporting component.

3. The microwave attenuated GNSS surveying antenna of claim 1, wherein the geometry and support height of the sector cross dipole and the diameter and depth of the half-open circular cavity are adjusted to control the amplitude and phase of the aperture radiation field to achieve a desired shaping requirement for the upper half-space radiation pattern, the shaping requirement including a predetermined bandwidth, gain, coverage angle, wide-angle circular polarization, phase center and phase frequency characteristics.

4. The microwave attenuated GNSS surveying antenna of claim 1, wherein the semi-open circular cavity is provided with axial slots at its opening at equal intervals; the distance between the slots is smaller than lambda/4, the length of the slots is close to lambda/4, and the distance between the slots and the length of the slots are adjusted to optimally inhibit the generation and radiation of residual clutter ring edge current.

5. The microwave attenuated GNSS surveying antenna of claim 1, wherein the optimal fusion of structural support and microwave feed, without external feed network, achieves its self-matching; 4 support columns are also used as RF coaxial lines, wherein 2 support columns are feed coaxial lines, and the other 2 support columns are auxiliary coaxial lines; the inner conductors of the two feeding coaxial feeders extend and are bridged on the inner conductors of the opposite side supporting columns and also used as auxiliary coaxial lines, the two pairs of the auxiliary coaxial lines of the side supporting columns are short-circuit coaxial lines with open-ended terminals, the short-circuit coaxial lines are tuned to series resonance through the inductive end impedance of the coaxial lines and the capacitive impedance formed by the inner conductors lapped at the ends of the coaxial lines and the column ends used as the outer conductors, the lapping lines are short-circuited with the sector oscillators connected on the opposite side supporting columns, microwave connection is realized, and balanced feeding of 0 degree/180 degrees is formed;

an impedance matching section with the diameter different from that of the central line is arranged at a preset position on the central line of the two feeding coaxial lines and is used together with the RF stub line and the distributed reactance formed at the opposite side, and the self-matching of the antenna feeding coaxial line to the 50 omega coaxial line is realized without an external matching network.

6. The microwave attenuated GNSS surveying antenna of claim 1, wherein the support assembly doubling as an RF coaxial line is combined with a polarization isolation power division module, so that the antenna has dual polarization filtering characteristics; the polarization isolation power distribution module is a 3dB/90 DEG Hybrid microwave component in essence, and comprises two input ports and two output ports; wherein, the first and the second end of the pipe are connected with each other,

two input ports are respectively connected with the feed coaxial core wire of the supporting component, one output end is connected with a receiver for outputting RHCP signals, and the other output end is connected with a 50 omega absorption resistor to absorb LHCP signals.

7. The microwave attenuated GNSS surveying antenna of claim 1, further comprising a low noise amplification module coupled to the polarization isolation power division module to form an active antenna for direct coupling to a GNSS receiver.

8. The microwave-attenuated GNSS surveying antenna of claim 1, further comprising a radome for protecting the antenna body.

9. A high-precision surveying-type device comprising the microwave-attenuated GNSS surveying-type antenna according to any one of claims 1 to 8.