WO2022148210A1

WO2022148210A1 - Microstrip structure-based subminiature atomic frequency standard microwave cavity

Info

Publication number: WO2022148210A1
Application number: PCT/CN2021/137339
Authority: WO
Inventors: 王晨; 王鹏飞; 赵峰; 梅刚华
Original assignee: 中国科学院精密测量科学与技术创新研究院
Priority date: 2021-01-05
Filing date: 2021-12-13
Publication date: 2022-07-14
Also published as: CN112332840A; CN112332840B

Abstract

Disclosed is a microstrip structure-based subminiature atomic frequency standard microwave cavity, comprising a cavity body. One end of the cavity body is a light outlet; the other end is a light inlet. A line groove is provided in the circumferential direction on the outer surface of the cavity body. A C field coil is wound in the line groove. The light outlet of the cavity body is provided with an end cover. The light inlet of the cavity body is provided with a bottom cover. The bottom cover is provided thereon with a light inlet. An atomic bulb is provided within the cavity body. A microstrip substrate is provided within the cavity body. The microstrip substrate comprises a dielectric substrate and a metal conductor provided on the dielectric substrate. The dielectric substrate is bonded to the inner wall of the cavity body. The metal conductor faces the atomic bulb. The present invention has the advantages of being easy to process and simple to assemble, having a great field distribution, and being compact and inexpensive, and is applicable in the batch production of high-performance subminiature atomic frequency standards.

Description

Ultra-small Atomic Frequency Standard Microwave Cavity Based on Microstrip Line Structure

technical field

The invention belongs to the field of atomic frequency standards, and more particularly relates to an ultra-small atomic frequency standard microwave cavity based on a microstrip line structure. The microwave cavity of this structure has the characteristics of simple structure, easy processing and assembly, and convenient mass production, and is suitable for high integration degree in the ultra-small atomic frequency scale.

Background technique

With the development of social science and technology, accurate and stable time-frequency reference is required in many important areas of human social activities and daily life. Atomic frequency standard (atomic clock) is a high-reliability frequency source made by using the transition frequency between stable energy levels inside atoms or ions, which greatly improves the accuracy and stability of time-frequency measurement. Thanks to the rapid development of atomic physics and integrated circuit technology, atomic frequency standard technology has gradually matured, and more and more atomic clocks with better performance indicators and higher integration levels have gradually replaced traditional mechanical clocks and crystal oscillators. It plays an important role in the fields of punctuality, navigation and positioning, transportation and power, high-speed communication, and precision measurement.

The atomic frequency standard usually includes two parts: the physical system and the circuit system. The physical system provides a stable reference frequency. The circuit system electronically locks the output frequency of the crystal oscillator to the stable transition frequency inside the atom, so that the crystal oscillator finally The output frequency has the same stability as the atomic transition frequency. Among them, the physical system provides the standard frequency of the microwave band, which acts as a frequency discriminator and is the core of the atomic frequency standard. Among them, the atomic bubble is located in the microwave resonant cavity, which is the place where atomic transitions are generated. The microwave resonant cavity is used to store microwave energy and excite the atoms in the atomic bubble to undergo resonant transitions. The characteristics of the size, structure, resonance mode and field distribution of the microwave cavity determine the number of atoms participating in the resonance transition and determine the performance of the atomic frequency scale to a large extent. At the same time, since the physical system occupies most of the volume of the atomic frequency calibration machine, and the microwave resonator is the most important structural component in the physical system, the volume of the physical system mainly depends on the miniaturization and integration degree of the microwave cavity. , which affects the miniaturization of the atomic frequency standard machine.

At present, there are two main types of atomic frequency standard microwave cavity: standard cavity and non-standard cavity. Commonly used standard cavities mainly include two types of cylindrical cavities, TE ₀₁₁ and TE _111. These two types of microwave cavities are bulky, which is not conducive to the miniaturization of atomic frequency scales. The standard cavity with the smallest volume can be obtained by adopting the TE ₁₀₁ mode, which is realized by filling the dielectric plate with a certain thickness in the direction parallel to the Z axis by adopting the standard rectangular cavity structure of the TE ₁₀₁ mode. For related content, reference can be made to the literature Tae M.Kwon.Cavity resonator for atomic frequency standard.US Patent:4495478.1985. The cavity of this structure is characterized by a small volume, but a limited portion of the uniform microwave magnetic field.

In order to effectively reduce the volume of the microwave cavity and obtain a better field distribution in the cavity, various microwave cavities with non-standard structures have been developed, mainly including magnetron cavities, slotted cavities and coaxial TEM cavities. The common feature of this type of cavity is that the cavity structure constitutes a lumped LC model, and the resonant frequency is determined by the lumped parameters, which is easier to realize the miniaturization of the cavity compared with the standard cavity in which the resonant frequency is determined only by the cavity size. . The magnetron cavity is described by the literature G.Mileti, I.Ruedi and H.Schweda, Proc.7th EFTF, 515 (1992), and the slotted cavity is described by the literature GanghuaMei, Miniatured microwave cavity for atomic frequencystandard.US Patent:6225870B1,2001 The characteristics of these two types of microwave cavities are that several symmetrically distributed metal pole pieces are fixed in the cavity, and a lumped LC structure is formed by using the narrow grooves between the metal pole pieces and the pole pieces, and the cavity frequency is mainly determined by the pole piece and the pole piece gap. size determines. The magnetic field type of this microwave cavity is a TE ₀₁₁ -like mode, which is favorable for exciting atoms to generate transition signals. However, due to the reduction of the volume of the microwave cavity, the physical size of the pole piece and the narrow slot will decrease sharply, and the cavity frequency will also be very sensitive to the change of size, which puts forward high requirements for the machining accuracy of the structural parts. In actual operation, the actual cavity frequency of the structural parts is often far from the design requirements due to processing errors, and it is difficult to ensure good consistency, which is unfavorable for the mass production of miniaturized atomic frequency standards. The coaxial TEM cavity is described by the document J. Deng, Ultra-miniature microwave cavity, CN1452798A, 2003, which is a non-standard cavity based on the principle of coaxial oscillator, which consists of a conductive rod extending into the cavity and the rod to the cavity wall. The lumped LC structure formed by the gap between them produces resonance. The cavity frequency is mainly determined by the geometric size of the conductive rod and its distance from the cavity wall, and is basically not limited by the size and shape of the cavity. Compared with the magnetron, the cavity structure The lumen and slotted lumen are also simpler, and in principle a very small volume of microwave cavities can be made. However, since the electromagnetic field generated by the coaxial line is mainly distributed around the coaxial line, the coaxial line is located at one end of the cavity, and the atomic gas chamber is located at the other end of the cavity, the uniformity of the field distribution in the gas chamber is very limited, which is not conducive to obtaining high Intensity of atomic transition signals, so it is not suitable for the development of high-performance atomic frequency standards.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an ultra-miniature atomic frequency standard microwave cavity based on a microstrip line structure. The magnetic field direction of the transmission wave is basically parallel to the surface of the microstrip line and the uniformity is good. A microwave resonant cavity with a new structure is designed, which has the advantages of easy processing, simple assembly, good field distribution, small size and low cost. It is suitable for For mass production of high-performance ultra-small atomic frequency standards.

A microstrip line is a planar microwave transmission line composed of a single conductor strip on a dielectric substrate. Its geometric structure is shown in Figure 1(a). Usually, a metal conductor with a width of W is printed on a thickness of d and a relative permittivity of _εr is grounded on the dielectric substrate. The microwave signal is transmitted in a TEM-like mode on the surface of the metal conductor and in the dielectric substrate. The lines of electric force E and H are both perpendicular to the propagation direction of the microwave. The distribution of the field lines is shown in Figure 1(b). It can be seen from the figure that the microwave power line starts from the upper and lower surfaces of the metal conductor and ends at the ground plane; the magnetic field line is perpendicular to the power line, and is distributed around the metal conductor in the air area above the surface of the metal conductor, and then passes through the medium covered by the conductor. The region forms a closed annular distribution. Microstrip line has the advantages of small size, light weight, wide bandwidth, high reliability, good consistency, and low manufacturing cost. However, the use of microstrip lines to transmit plane waves has a large loss. It can be used to form a resonant cavity in a metal box, and microwave energy can be coupled into the cavity in a suitable way to obtain a standing wave field. The trapping effect of the inner wall of the metal box on the microwave field is used to reduce the microwave loss and improve the Q value.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

An ultra-small atomic frequency standard microwave cavity based on a microstrip line structure, including a cavity, one end of the cavity is a light outlet, the other end is a light inlet, the inner space of the cavity is a cuboid, the outer surface of the cavity is provided with a wire groove, and a C field coil It is wound in a wire groove, the light outlet of the cavity is provided with an end cover, a photodetector is fixed on the inner surface of the end cover, the light inlet of the cavity is provided with a bottom cover, the bottom cover is provided with a light inlet hole, and the cavity is provided with There are atomic bubbles, and a microstrip line substrate is arranged in the cavity. The microstrip line substrate includes a dielectric substrate and a metal conductor arranged on the dielectric substrate. The dielectric substrate and the inner wall of the cavity are bonded, and the metal conductor faces the atomic bubble.

The ultra-small atomic frequency standard microwave cavity based on the microstrip line structure also includes that the coupling probe is a coaxial cable, the wire core of one end of the coaxial cable is exposed, and the wire core is welded on the metal conductor of the microstrip line substrate. The other end is installed in the coupling probe installation hole and extends out of the cavity. The coupling probe installation hole is located on the side wall adjacent to the cavity body and the microstrip line substrate installation wall, and is close to one end of the light outlet. The metal shield of the coaxial cable The layers are bonded to the coupling probe mounting holes by conductive glue.

As mentioned above, one end of the wire core of the coaxial cable is connected to the metal conductor by welding, and the welding point is located at the edge of the metal conductor on the side close to the light outlet.

A tuning screw mounting hole is formed on the side wall opposite to the coupling probe mounting hole of the cavity as described above at a position opposite to the coupling probe mounting hole, and the tuning screw is arranged in the tuning screw mounting hole.

The above-mentioned atomic bubble includes an atomic bubble body and a bubble tail, the bubble tail extends along the direction of the optical axis, the root of the bubble tail is located at the edge of one end face of the atomic bubble body, and the root of the bubble tail is close to the coupling probe.

The metal conductor of the above-mentioned microstrip line substrate is rectangular, and the metal conductor is provided with a slot perpendicular to the direction of the optical axis and a slot along the direction of the optical axis.

Compared with the prior art, the present invention has the following beneficial effects:

1. The shape of the cavity is a cuboid, with both ends open, and the inner space is a cuboid with a regular shape, which is less difficult to process and easy to control the accuracy to ensure consistency.

2. The dielectric substrate of the microstrip line substrate is mostly made of high dielectric constant materials such as Al ₂ O ₃ ceramics. The metal conductor can be any shape, mostly copper or gold foil, and the thickness is generally not more than tens of μm. It is made by the board process, which can well ensure the machining accuracy and consistency.

3. The atomic bubble adopts a sealed and transparent cuboid glass bubble, which can almost fill the entire inner area of the cavity. Compared with the traditional cylindrical atomic bubble, it can increase the area where the atomic vapor is active, which is helpful to obtain high-intensity atomic transition signals. , which is beneficial to improve the performance of the atomic frequency standard. The bubble tail protrudes along the optical axis, and its root is located at one end of the bubble surface near the edge, which will not block the optical path, and at the same time avoids adding a structure to install the bubble tail on the cavity, making the structure of the cavity very simple.

4. The magnetic field lines of the microwave field in the cavity are distributed in the area above the surface of the metal conductor of the microstrip line substrate, and the direction is along the direction of the optical axis, which is basically parallel to the surface of the conductor. Since the atomic bubble is located just above the metal conductor and is in the range of the distribution of the magnetic field lines, the magnetic field lines of the microwave field have good uniformity in the region where the atomic resonance transition occurs in the atomic bubble, which is very beneficial to excite the rubidium atoms to produce clock transitions. Then, the microwave search signal with high signal-to-noise ratio can be obtained, which is beneficial to the development of high-performance ultra-small rubidium atomic frequency standard.

5. The coupling probe is a coaxial cable, one end of which is exposed, and is welded to the metal conductor of the microstrip line substrate. The welding point is located at the edge of the metal conductor near the light outlet to avoid physical interference with the atomic bubble. The other end is installed in the coupling probe installation hole of the side wall adjacent to the microstrip line substrate installation wall of the cavity, and extends out of the cavity, and the metal shielding layer of the cable is bonded to the probe installation hole with conductive glue , so that the metal shielding layer and the cavity form a good electrical contact, and at the same time play the role of reinforcing the wire to ensure the mechanical firmness of the coupling probe.

6. The tuning screw is arranged in the mounting hole of the tuning screw, which can realize the fine adjustment of the resonance frequency of the microwave cavity. The resonant frequency of the microwave cavity is mainly determined by the size of the cavity and the shape and size of the metal conductor on the microstrip line substrate. However, when a metal rod is close to the surface of the metal conductor of the microstrip line, the distribution of the magnetic field lines on the surface of the conductor will be disturbed, so The tuning screw can be screwed in or out to change its length in the cavity to fine-tune the resonant frequency.

It can be seen from the above characteristics that the microwave cavity designed in this application has a very simple cavity structure compared with the magnetron cavity and the slotted cavity. Small, low cost, suitable for mass production of high-performance ultra-small atomic frequency standards.

Description of drawings

Figure 1 (a) is a schematic diagram of the geometric structure of the microstrip line; Figure 1 (b) is a schematic diagram of the distribution of the field lines of the microstrip line;

Fig. 2(a) is a schematic diagram of the three-dimensional structure of the present invention; Fig. 2(b) is a schematic cross-sectional view of the present invention.

Figure 3 is an exploded schematic diagram of the present invention.

FIG. 4( a ) is a schematic perspective view of the cavity; FIG. 4( b ) is a schematic cross-sectional view of the cavity.

FIG. 5 is a structural diagram of a microstrip line substrate.

Fig. 6(a) is the microwave field pattern along the optical axis, the cavity is parallel to the side wall of the microstrip substrate; Fig. 6(b) is along the optical axis, the cavity and the microstrip substrate are installed Microwave field pattern in the vertical plane of the sidewall.

FIG. 7( a ) is a schematic structural diagram of the metal conductor according to the first embodiment;

FIG. 7(b) is a schematic structural diagram of the metal conductor of the second embodiment;

FIG. 7( c ) is a schematic structural diagram of the metal conductor of the third embodiment;

FIG. 7(d) is a schematic structural diagram of the metal conductor according to the fourth embodiment;

FIG. 7(e) is a schematic structural diagram of the metal conductor according to the fifth embodiment;

FIG. 7( f ) is a schematic structural diagram of the metal conductor according to the sixth embodiment;

Among them: 1-cavity; 1a-light outlet; 1b-line slot; 2-microstrip line substrate; 2a-metal conductor; 2b-dielectric substrate; Axial slot; 3-atomic bubble; 4-coupling probe; 5-tuning screw; 6-end cap; 7-photodetector; 8-bottom cap; 9-C field coil.

Specific implementation method

In order to facilitate the understanding and implementation of the present invention by those of ordinary skill in the art, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

Example:

The ultra-small atomic frequency standard microwave cavity based on the microstrip line structure includes a cavity 1, one end of the cavity 1 is a light outlet 1a, the other end is a light inlet, the inner space of the cavity 1 is a cuboid, and the outer surface of the cavity 1 is circumferentially arranged The wire slot 1b, the C field coil 9 is wound in the wire slot 1b, the light outlet 1a of the cavity 1 is provided with an end cover 6, the inner surface of the end cover 6 is fixed with a photodetector 7, and the light inlet of the cavity 1 is provided with The bottom cover 8 is provided with a light inlet hole, the cavity body 1 is provided with an atomic bubble 3, and the cavity body 1 is provided with a microstrip line substrate 2. The microstrip line substrate 2 includes a dielectric substrate 2b and a The metal conductor 2 a on the dielectric substrate 2 b is bonded to the inner wall of the cavity 1 , and the metal conductor 2 a faces the atomic bubble 3 .

The ultra-miniature atomic frequency standard microwave cavity based on the microstrip line structure further includes that the coupling probe 4 is a coaxial cable, one end of the coaxial cable is bare, and the wire core is welded on the metal conductor 2a of the microstrip line substrate 2, The other end of the coaxial cable is installed in the coupling probe mounting hole and extends out of the cavity 1. The coupling probe mounting hole is located on the side wall adjacent to the mounting wall of the cavity 1 and the microstrip line substrate 2, and is close to the light outlet 1a. At one end, the metal shielding layer of the coaxial cable is bonded to the coupling probe mounting hole through conductive glue.

One end of the wire core of the coaxial cable is connected to the metal conductor 2a by welding, and the welding point is located at the edge of the metal conductor 2a on the side close to the light outlet 1a.

A tuning screw mounting hole is opened on the side wall of the cavity 1 opposite to the coupling probe mounting hole at a position opposite to the coupling probe mounting hole, and the tuning screw 5 is arranged in the tuning screw mounting hole.

The atomic bubble 3 includes an atomic bubble body and a bubble tail, the bubble tail extends along the optical axis, the root of the bubble tail is located at the edge of one end face of the atomic bubble body, and the root of the bubble tail is close to the coupling probe 4 .

The metal conductor 2a of the microstrip line substrate 2 is rectangular, and the metal conductor 2a is provided with a slot 2c perpendicular to the direction of the optical axis and a slot 2d along the direction of the optical axis.

Cavity 1 is made of aluminum alloy material, with an external dimension of 15mm × 7.6mm × 23mm, with two open ends, one end is the light outlet 1a, the other end is the light inlet, it is cylindrical, the hollow is a rectangular waveguide, and the size is 10.6mm×5.8mm×23mm. The outer surface of the cavity 1 is provided with a wire slot 1b in the circumferential direction. The diameter of the C-field coil 9 is 0.27mm, and it is densely wound in the wire slot 1b to generate a stable static magnetic field parallel to the optical axis. The direction from the light inlet to the light outlet 1a For the direction of the optical axis, it provides the quantization axis for the atomic transition;

The microstrip line substrate 2 includes a dielectric substrate 2b and a metal conductor 2a arranged on the dielectric substrate 2b. The dielectric substrate 2b is printed with a metal conductor 2a. In this embodiment, the metal conductor 2a is copper, and the shape is 7mm×13mm Rectangular shape with a thickness of 12 μm; the dielectric substrate 2b is Al ₂ O ₃ ceramics with a thickness of 0.5 mm and a rectangular shape of 10 mm×21.5 mm. Apply appropriate silica gel to the other side surface of the microstrip line substrate 2, bond the microstrip line substrate 2 to the inner surface of the cavity 1, and the metal conductor 2a faces the atomic bubble 3 in the cavity 1; The width direction is perpendicular to the optical axis direction, and the length direction of the metal conductor 2a is parallel to the optical axis direction.

The atomic bubble 3 is a sealed and transparent cuboid glass bubble. The atomic bubble 3 includes an atomic bubble body and a bubble tail. The bubble tail extends along the optical axis. The root of the bubble tail is located at the edge of one end face of the atomic bubble body, and the bubble tail faces the light outlet. . The size of the atomic bubble 3 in this embodiment is 10 mm×5 mm×17 mm, and the atomic bubble 3 is bonded in the cavity 1 through silica gel. The length of the bubble tail is 4.5mm, the root of the bubble tail is close to the coupling probe 4, and the diameter of the bubble tail is 2.5mm to avoid blocking the light path. The atomic bubble 3 is filled with working atomic rubidium metal vapor and buffer gas with a certain pressure;

The coupling probe 4 is a coaxial cable. One end of the core of the coaxial cable is exposed, and the core is welded on the metal conductor 2a of the microstrip line substrate 2. The welding point is located at the edge of the metal conductor 2a near the light outlet 1a to avoid Forms physical interference with the atomic bubble; the other end of the coaxial cable is installed in the coupling probe mounting hole and extends out of the cavity 1, and the coupling probe mounting hole is located adjacent to the mounting wall of the cavity 1 and the microstrip line substrate 2 side wall, close to one end of the light outlet 1a. Use conductive glue to bond the metal shielding layer of the coaxial cable to the mounting hole of the coupling probe, so that the metal shielding layer of the coaxial cable forms a good electrical contact with the cavity 1, and at the same time plays a role in strengthening the coaxial cable. Ensure the mechanical firmness of the coupling probe 4;

The side wall of the cavity 1 opposite to the coupling probe mounting hole is provided with a tuning screw mounting hole at the position opposite to the coupling probe mounting hole. The tuning screw mounting hole is a threaded hole, and the tuning screw 5 is a threaded metal round rod. The tuning screw is screwed in and out in the mounting hole to change the length of the tuning screw 5 extending into the cavity 1, so as to fine-tune the resonance frequency of the microwave cavity;

The end cover 6 is made of aluminum alloy material, located at the light outlet 1a of the cavity 1, and fixed on the end face of the light outlet 1a of the cavity 1 by two M1.6 screws; the inner surface of the end cover 6 is fixed with a photoelectric The detector 7 is used to detect the light signal; the bottom cover 8 is also made of aluminum alloy material and has a light inlet hole. The bottom cover 8 is fixed on the end face of the light inlet port of the cavity 1. , cavity 1 together to form a metal closed cavity.

Figures 6(a) and 6(b) show the microwave field patterns of the two surfaces along the optical axis in the cavity of the ultra-small atomic frequency standard microwave cavity based on the microstrip line structure. It can be seen from the figure that the magnetic field lines of the microwave field in the cavity 1 are distributed in the area above the surface of the metal conductor 2a of the microstrip line substrate 2, which is substantially parallel to the surface of the metal conductor 2a. Since the metal conductor 2a faces the atomic bubble 3 in the cavity 1, and the atomic bubble 3 is within the distribution range of the magnetic field lines, in the region where the atomic resonance transition occurs in the atomic bubble, the magnetic field lines of the microwave field are distributed along the axial direction, and have better uniformity It is very beneficial to excite rubidium atoms to generate clock transitions, thereby obtaining microwave search signals with high signal-to-noise ratio, which is beneficial to the development of high-performance ultra-small rubidium atomic frequency standards. In fact, using the design scheme in this embodiment, an ultra-small rubidium atomic frequency standard prototype with a height of less than 1 cm can be produced, and its short-term frequency stability can reach better than

level, τ is the measurement time.

It can be seen from the above embodiments that the ultra-small atomic frequency standard microwave cavity based on the microstrip line structure provided by the present invention combines the microstrip line technology in the field of integrated circuits, and is a microwave resonant cavity with a new structure. It has the advantages of less difficulty in machining, simple assembly process, easy adjustment of cavity frequency, good field distribution, small volume and low cost, and is suitable for mass production of high-performance ultra-small atomic frequency standards.

The above only provides an optional solution. In practical applications, the size of the cavity can be adjusted according to the required resonant frequency, and the shape of the metal conductor 2a of the microstrip line substrate 2 can also be designed according to the specific situation. The metal conductor 2a of the strip substrate 2 is rectangular, and Fig. 7(a)-(f) are several feasible but not limited design schemes. The metal conductor 2a is provided with a slot perpendicular to the direction of the optical axis, and There is also a notch along the optical axis. Regardless of whether the shape of the metal conductor is a complete and regular rectangle, and whether the orientation is centered, as long as the microwave field is generated in the rectangular metal box by a microstrip line similar to this kind of metal conductor on the dielectric substrate, it belongs to this design. The scope of protection for which the invention is claimed.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention pertains can make various modifications or additions to the described specific embodiments or substitute in similar manners, but will not deviate from the spirit of the present invention or go beyond the definitions of the appended claims range.

Claims

An ultra-small atomic frequency standard microwave cavity based on a microstrip line structure, comprising a cavity (1), characterized in that the right end of the cavity (1) is a light outlet (1a), the left end is a light inlet, and the cavity (1) Both the outer shape and the inner space are cuboid, the side of the cavity (1) is provided with a wire slot (1b), the C-field coil (9) is wound in the wire slot (1b), and the light outlet (1a) of the cavity (1) is provided with an end A cover (6), a photodetector (7) is fixed on the inner surface of the end cover (6), a bottom cover (8) is provided at the light inlet of the cavity (1), and a light inlet hole is opened on the bottom cover (8) , an atomic bubble (3) is arranged in the cavity (1), a microstrip line substrate (2) is arranged in the cavity (1), and the microstrip line substrate (2) comprises a dielectric substrate (2b) and a The metal conductor (2a) on the substrate (2b), the dielectric substrate (2b) and the inner wall of the cavity (1) are bonded, and the metal conductor (2a) faces the atomic bubble (3).
The ultra-miniature atomic frequency standard microwave cavity based on the microstrip line structure according to claim 1, further comprising that the coupling probe (4) is a coaxial cable, one end of the coaxial cable is bare and the wire core is welded On the metal conductor (2a) of the microstrip line substrate (2), the other end of the coaxial cable is installed in the coupling probe mounting hole and protrudes out of the cavity (1), and the coupling probe mounting hole is located in the cavity (1). ) on the side wall adjacent to the mounting wall of the microstrip line substrate (2), and close to one end of the light outlet (1a), the metal shielding layer of the coaxial cable is bonded to the coupling probe mounting hole through conductive glue.
The ultra-small atomic frequency standard microwave cavity based on the microstrip line structure according to claim 2, characterized in that, one end of the wire core of the coaxial cable is connected to the metal conductor (2a) by welding, and the welding point is located on the metal conductor (2a). ) near the edge of the light outlet (1a) side.
The ultra-miniature atomic frequency standard microwave cavity based on a microstrip line structure according to claim 2, characterized in that the cavity (1) has a side wall opposite to the coupling probe mounting hole and a position opposite to the coupling probe mounting hole A tuning screw mounting hole is opened, and the tuning screw (5) is arranged in the tuning screw mounting hole.
The ultra-small atomic frequency standard microwave cavity based on a microstrip line structure according to claim 4, characterized in that the atomic bubble (3) comprises an atomic bubble body and a bubble tail, the bubble tail extends along the optical axis direction, and the bubble tail is The root is located at the edge of one end face of the atomic bubble body, and the root of the bubble tail is close to the coupling probe (4).
The ultra-small atomic frequency standard microwave cavity based on the microstrip line structure according to claim 1, characterized in that the metal conductor (2a) of the microstrip line substrate (2) is rectangular, and the metal conductor (2a) is provided with a A groove (2c) perpendicular to the optical axis direction and a groove (2d) along the optical axis direction.