Microwave resonator and aerosol generating device

Abstract

A microwave resonator (20) and an aerosol generating device, the microwave resonator comprising: an outer conductor (201); an inner conductor (202), one end thereof being fixed to the top of the outer conductor (201) and being in ohmic contact with the top of the outer conductor (201), and the other end thereof being spaced apart from the bottom of the outer conductor (201), the inner conductor (202) being provided with an accommodation cavity (2021) exposed from the top of the outer conductor (201) and used for accommodating an aerosol substrate (60), and the inner conductor (202) and the outer conductor (201) together defining a resonant cavity (204) around the accommodation cavity (2021); and a pin (203), one end thereof being fixed to the bottom of the outer conductor (201) and being in ohmic contact with the bottom of the outer conductor (201), and the other end thereof extending into the accommodation cavity (2021) and spaced apart from the inner conductor (202). An emitted microwave will continuously oscillate within the resonant cavity (204), thereby forming two stronger resonant electric fields around an open end (A) of the inner conductor (202) and an open end (B) of the pin (203); the inside and the outside of the aerosol substrate (60) accommodated in the accommodation cavity (2021) are respectively exposed to the two resonant electric fields, such that the inside and the outside of the aerosol substrate (60) are heated at the same time, thus generating a uniform temperature field and achieving uniform release of aerosol.

Description

Microwave resonator and aerosol generating device

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on December 21, 2023, with application number 202311780861.1 and invention name “A microwave resonator and aerosol generating device”, as well as the Chinese patent application filed with the Patent Office of China on December 21, 2023, with application number 202323508726.X and utility model name “A microwave resonator and aerosol generating device”, the entire contents of which are incorporated by reference into the application. Technical Field

[0002] The present application relates to the technical field of heating-without-burning appliances, and in particular to a microwave resonator and an aerosol generating device. Background Art

[0003] Currently, heated aerosol generating devices mostly use resistance, infrared, or electromagnetic heating. These devices contain at least one heating element. The device provides electricity to control the temperature of the heating element, which is then transferred to the aerosol matrix through contact heat transfer, reaching a temperature that continuously produces aerosol. However, the temperature difference between the heating element and the aerosol matrix causes coking reactions, which contaminate the heating element and make it difficult to clean, affecting the taste of the aerosol.

[0004] Related technologies have proposed a microwave heating device that uses a quarter-wavelength microwave resonant cavity to deliver microwave energy into the aerosol matrix through a pin. However, because the electric field intensity in the quarter-wavelength microwave resonant cavity is concentrated at the pin tip, the electric field distribution within the aerosol matrix is ​​uneven, resulting in poor temperature uniformity, affecting the puff feel and the consistency of aerosol release.

[0005] Summary of the Invention

[0006] The technical problem to be solved by the present application is to provide a microwave resonator and an aerosol generating device to solve the problem of poor temperature uniformity in the microwave resonant cavity in the related art.

[0007] The technical solutions adopted in the embodiments of this application are as follows:

[0008] In a first aspect, an embodiment of the present application provides a microwave resonator, comprising:

[0009] outer conductor;

[0010] an inner conductor, one end of which is fixed to the top of the outer conductor and in ohmic contact with the top of the outer conductor, and the other end of which is spaced apart from the bottom of the outer conductor, the inner conductor being provided with a receiving cavity exposed at the top of the outer conductor and for receiving an aerosol matrix, and the inner conductor and the outer conductor jointly defining a resonant cavity disposed around the receiving cavity; and

[0011] The pin has one end fixed to the bottom of the outer conductor and in ohmic contact with the bottom of the outer conductor, and the other end extending into the accommodating cavity and spaced apart from the inner conductor.

[0012] In a second aspect, the present application also provides an aerosol generating device, comprising:

[0013] power supply;

[0014] A microwave resonator for accommodating an aerosol matrix, the microwave resonator comprising: an outer conductor; an inner conductor having one end fixed to the top of the outer conductor and in ohmic contact with the top of the outer conductor, and the other end spaced apart from the bottom of the outer conductor; the inner conductor having a cavity exposed at the top of the outer conductor and for accommodating the aerosol matrix, and the inner conductor and the outer conductor jointly defining a resonant cavity disposed around the cavity; and a pin having one end fixed to the bottom of the outer conductor and in ohmic contact with the bottom of the outer conductor, and the other end extending into the cavity and spaced apart from the inner conductor.

[0015] a radio frequency component, electrically connected to the power supply and the microwave resonator;

[0016] a temperature measuring component, disposed in the microwave resonator, and configured to measure the temperature of the aerosol matrix; and

[0017] The controller is electrically connected to the radio frequency component, the power supply and the temperature measurement component.

[0018] In the present application, one end of the inner conductor in ohmic contact with the top of the outer conductor and one end of the pin in ohmic contact with the bottom of the outer conductor are both short-circuited ends, and one end of the inner conductor spaced apart from the bottom of the outer conductor and one end of the pin spaced apart from the inner conductor are both open-circuited ends, so that microwaves can be transmitted through the outer conductor to the open-circuited end of the inner conductor and the open-circuited end of the pin and emitted. The emitted microwaves oscillate continuously in the resonant cavity, thereby forming two strong resonant electric fields around the open-circuited end of the inner conductor and the open-circuited end of the pin, and the interior of the aerosol matrix accommodated in the accommodating cavity is exposed to the resonant electric field formed by the open-circuited end of the pin, and the outside is exposed to the resonant electric field formed by the open-circuited end of the inner conductor, so that heat is generated simultaneously inside and outside the aerosol matrix, thereby generating a uniform temperature field and realizing uniform release of the aerosol. In addition, the open end of the inner conductor is located inside the outer conductor, which can prevent the microwaves emitted from the open end of the inner conductor from leaking out of the resonant cavity, reducing the loss of microwave energy and avoiding radiation damage to the user; moreover, the inner conductor is higher than the pin, so that the open end of the pin is blocked by the inner conductor, thereby preventing the magnetic field formed by the pin from leaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0020] FIG1 is a structural block diagram of an aerosol generating device provided in an embodiment of the present application;

[0021] FIG2 is a schematic structural diagram of an aerosol generating device provided in an embodiment of the present application;

[0022] FIG3 is a cross-sectional view of the microwave resonator and the aerosol matrix when assembled according to an embodiment of the present application.

[0023] In the accompanying drawings, the various reference numerals represent: 10, power supply; 20, microwave resonator; 201, outer conductor; 202, inner conductor; 2021, accommodating cavity; 203, pin; 204, resonant cavity; 205, RF connector; 30, RF component; 40, temperature measurement component; 50, controller; 60, aerosol matrix. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be understood as limiting the present application. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application without making any creative efforts shall fall within the scope of protection of the present application.

[0025] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "circumferential", "radial", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0027] Example:

[0028] Referring to Figures 1 and 2, an embodiment of the present application provides an aerosol generating device, comprising a power supply 10, a microwave resonator 20, a radio frequency component 30, a temperature measurement component 40, and a controller 50. The microwave resonator 20 is used to accommodate an aerosol matrix 60. The radio frequency component 30 is electrically connected to the power supply 10 and the microwave resonator 20. The temperature measurement component 40 is disposed within the microwave resonator 20. The controller 50 is electrically connected to the power supply 10 and the radio frequency component 30. The power supply 10 is used to provide power to the radio frequency component 30. When powered on, the radio frequency component 30 transmits microwave energy into the microwave resonator 20. The microwave energy resonates within the microwave resonator 20, heating and atomizing the aerosol matrix 60 contained within the microwave resonator 20 to generate an aerosol. The temperature measurement component 40 is used to measure the temperature of the aerosol matrix 60. The controller 50 controls the power supply 10 to the radio frequency component 30 based on the temperature data transmitted by the temperature measurement component 40, thereby controlling the heating temperature of the aerosol matrix 60 and achieving uniform release of the aerosol.

[0029] In some embodiments, the power supply 10 can be a battery pack, which is integrated with a buck-boost circuit and a voltage stabilizing circuit to ensure the stability of the power provided by the power supply 10; the RF component 30 can be a RF source, which is integrated with a RF oscillation circuit, a RF amplification circuit, a self-excited circuit, etc. The RF source can transmit a certain frequency or frequency band in the range of 100MHz-20GHz; the controller 50 can be a circuit board, which can control the start and stop of the RF source, the microwave frequency and the microwave power, etc.

[0030] Referring to Figures 2 and 3 , the microwave resonator 20 includes an outer conductor 201, an inner conductor 202, and a pin 203. One end of the inner conductor 202 is fixed to the top of the outer conductor 201 and makes ohmic contact with the top of the outer conductor 201, while the other end is spaced apart from the bottom of the outer conductor 201. The inner conductor 202 defines a cavity 2021, exposed at the top of the outer conductor 201, for accommodating the aerosol matrix 60. The inner conductor 202 and the outer conductor 201 together define a resonant cavity 204 surrounding the cavity 2021. One end of the pin 203 is fixed to the bottom of the outer conductor 201 and makes ohmic contact with the bottom of the outer conductor 201, while the other end extends into the cavity 2021 and is spaced apart from the inner conductor 202.

[0031] The end of the inner conductor 202 that makes ohmic contact with the top of the outer conductor 201 and the end of the pin 203 that makes ohmic contact with the bottom of the outer conductor 201 are both short-circuited ends, and the end of the inner conductor 202 that is spaced apart from the bottom of the outer conductor 201 and the end of the pin 203 that is spaced apart from the inner conductor 202 are both open-circuited ends. This allows microwaves to be conducted through the outer conductor 201 to the open-circuited end A of the inner conductor 202 and the open-circuited end B of the pin 203 and emitted. The emitted microwaves continuously oscillate within the resonant cavity 204, thereby forming two strong resonant electric fields around the open-circuited end A of the inner conductor 202 and the open-circuited end B of the pin 203. The interior of the aerosol matrix 60 contained in the accommodating cavity 2021 is exposed to the resonant electric field formed by the open-circuited end B of the pin 203, and the exterior is exposed to the resonant electric field formed by the open-circuited end A of the inner conductor 202. This causes heat to be generated both inside and outside the aerosol matrix 60, thereby generating a uniform temperature field and achieving uniform release of the aerosol. In addition, the open end A of the inner conductor 202 is located inside the outer conductor 201, which can prevent the microwaves emitted from the open end A of the inner conductor 202 from leaking out of the resonant cavity 204, reducing the loss of microwave energy and avoiding radiation damage to the user; moreover, the inner conductor 202 is higher than the pin 203, so that the open end of the pin 203 is blocked by the inner conductor 202, thereby preventing the magnetic field formed by the pin 203 from leaking.

[0032] The aerosol matrix 60 includes a matrix segment, an air intake segment and a filter segment connected in sequence. When the aerosol matrix 60 is accommodated in the accommodating cavity 2021, the matrix segment is accommodated in the accommodating cavity 2021, and the filter segment is exposed outside the accommodating cavity 2021; at the same time, the open end B of the pin 203 is inserted into the interior of the matrix segment of the aerosol matrix 60, and the open end A of the inner conductor 202 covers the outer side of the matrix segment of the aerosol matrix 60, so that the inside and outside of the matrix segment of the aerosol matrix 60 are respectively exposed to the resonant electric field formed by the open end B of the pin 203 and the resonant electric field formed by the open end A of the inner conductor 202. The open end A of the inner conductor 202 and the open end B of the pin 203 at least partially overlap in the axial direction to ensure that the open end A of the inner conductor 202 and the open end B of the pin 203 are respectively on the outside and inside of the substrate segment when the aerosol substrate 60 is inserted; for example, the open end A of the inner conductor 202 and the open end B of the pin 203 are at the same height.

[0033] 3 , in some embodiments, the spacing distance between the inner conductor 202 and the bottom of the outer conductor 201 ranges from 0.1 mm to 12 mm, for example, 0.1 mm, 0.5 mm, 3 mm, 7 mm, 10 mm, 12 mm, etc., so that the spacing distance between the inner conductor 202 and the bottom of the outer conductor 201 is relatively moderate, which helps to ensure that the outer side of the matrix segment of the aerosol matrix 60 is exposed to the resonant electric field formed by the open end A of the inner conductor 202, so that the energy generated by the resonant cavity 204 acts on the aerosol matrix 60. When the spacing distance between the inner conductor 202 and the bottom of the outer conductor 201 is too small (less than 0.1 mm), the inner conductor 202 and the bottom of the outer conductor 201 are easily electrically connected. When the spacing distance between the inner conductor 202 and the bottom of the outer conductor 201 is too large (greater than 12 mm), it is not conducive to the open end of the inner conductor 202 covering the outer side of the matrix segment of the aerosol matrix 60.

[0034] Please refer to Figure 3. The outer conductor 201, the inner conductor 202, and the pin 203 are coaxially arranged, so that the microwave resonator 20 is a coaxial microwave resonator 20. The microwaves transmitted by the inner conductor 202 and the pin 203 can act more on the aerosol matrix 60, so that the aerosol matrix 60 can be heated in a shorter time by concentrating the microwaves on the aerosol matrix 60, thereby achieving rapid generation of aerosol. Among them, the outer conductor 201 is cylindrical, and the cross-sectional shape of the outer conductor 201 includes any one of a rectangle, a circle and an ellipse. For example, the outer conductor 201 can be a cylinder, and in this case, the cross-sectional shape of the outer conductor 201 is a circle; the inner conductor 202 is tubular, and the two ends of the inner conductor 202 are connected to form a receiving cavity 2021. For example, the inner conductor 202 can be a circular tube, which is conducive to ensuring that the receiving cavity 2021 is compatible with the aerosol matrix 60; the aerosol matrix 60 and the receiving cavity 2021 have an interference fit, so that the inner conductor 202 does not need to be provided with a bottom wall to support the aerosol matrix 60, so that the receiving cavity 2021 can pass through one end of the inner conductor 202 and the bottom of the outer conductor 201 spaced apart, so that the receiving cavity 2021 can accommodate aerosol matrices 60 of different lengths.

[0035] In some embodiments, the inner wall of the inner conductor 202 is provided with a plurality of clamping ribs distributed along the circumferential direction, and the length of the clamping ribs extends along the length direction of the inner conductor 202. The multiple clamping ribs work together to help clamp the aerosol matrix 60 in the accommodating cavity 2021. At the same time, a gap can be created between the aerosol matrix 60 and the inner wall of the inner conductor 202, so that air can flow into the air inlet section of the aerosol matrix 60 to carry away the aerosol.

[0036] The outer conductor 201 , the inner conductor 202 and the pin 203 are all made of metal materials. The metal materials may be materials with good electrical conductivity such as gold, silver, copper, and aluminum. The higher the electrical conductivity of the metal material, the easier it is for microwaves to conduct.

[0037] In some embodiments, the inner wall of the outer conductor 201 and the inner wall of the inner conductor 202 are both provided with a dielectric layer and a first conductive film covering the dielectric layer. The dielectric layer can be made of a low-loss (less than 0.01) dielectric material, such as plastic, ceramic, glass, aluminum oxide, zirconium oxide, silicon oxide, etc. The dielectric layer can effectively increase the frequency of microwaves in the resonant cavity 204, thereby reducing the size of the resonant cavity 204 without reducing the microwave wavelength, improving the performance of the microwave resonator 20 and achieving its miniaturization. The electrical conductivity of the first conductive film is less than or equal to that of pure aluminum. The provision of the first conductive film can ensure the electrical conductivity of the inner wall surfaces of the outer conductor 201 and the inner conductor 202, ensuring that microwaves continue to oscillate within the resonant cavity 204. The thickness of the first conductive film is determined by the microwave penetration depth at the resonant frequency of the microwave resonator 20, and the thickness of the first conductive film must ensure that microwaves can penetrate the first conductive film to act on the dielectric layer.

[0038] The outer conductor 201 is equivalent to a capacitor, and the inner conductor 202 is equivalent to an inductor. The air and dielectric layer between the inner conductor 202 and the outer conductor 201 can affect the capacitance value. Compared with air as a medium, the dielectric layer can increase the capacitance value, thereby better controlling the size of the resonant cavity 204.

[0039] Referring to Figure 3 , the integrated design of inner conductor 202 and outer conductor 201 facilitates the formation of resonant cavity 204 and ensures good contact between the tops of inner conductor 202 and outer conductor 201, thereby ensuring ohmic contact between the tops of inner conductor 202 and outer conductor 201. The inner conductor 202 and outer conductor 201 can be made of the same metal material. An RF connector 205 is provided at the bottom of outer conductor 201. RF assembly 30 is connected to RF connector 205, establishing electrical communication between RF assembly 30 and outer conductor 201. This allows microwaves generated by RF assembly 30 to be transmitted through outer conductor 201 to the open ends of inner conductor 202 and pin 203.

[0040] In some embodiments, the material of the pin 203 includes an insulating material, such as ceramic, plastic, and quartz. The outer surface of the pin 203 is coated with a second conductive film, which makes ohmic contact with the bottom of the outer conductor 201. The second conductive film can be formed by coating the outer surface of the pin 203 with a highly conductive metal material such as gold, silver, copper, or aluminum. The pin 203 can be cylindrical, and its cross-section can be circular, rectangular, or elliptical. The pin 203 can be solid or hollow, and the end of the pin 203 away from the bottom of the inner conductor 202 can be pointed. The sharper the tip, the stronger the resonant electric field formed at the open end of the pin 203.

[0041] In some embodiments, multiple pins 203 are provided, and the pins 203 are spaced apart circumferentially to more evenly distribute the resonant electric field within the aerosol matrix 60, thereby producing a more uniform microwave heating effect on the aerosol matrix 60 and achieving uniform aerosol release. For example, the number of pins 203 can be 1-6. When there are four pins 203, the four pins 203 are spaced apart around the central axis of the outer conductor 201.

[0042] In some embodiments, the temperature measurement component 40 includes a thermocouple disposed on the pin 203, located at the end of the pin 203 away from the bottom of the inner conductor 202. The pin 203 is preferably hollow, and the wire connecting the thermocouple and the controller 50 can be routed through the pin 203 to facilitate wiring. The thermocouple is used to measure the temperature within the aerosol matrix 60 and transmit the temperature data to the controller 50. The controller 50 adjusts the power provided by the power supply 10 to the RF component 30 based on the temperature data transmitted by the thermocouple, thereby controlling the heating temperature of the aerosol matrix 60. In other embodiments, the temperature measurement component 40 can also be an infrared sensor, a thermistor sensor, etc.

[0043] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A microwave resonator, wherein: include: Outer conductor; an inner conductor, one end of which is fixed to the top of the outer conductor and in ohmic contact with the top of the outer conductor, and the other end of which is spaced from the bottom of the outer conductor, the inner conductor being provided with a receiving cavity exposed at the top of the outer conductor and used for receiving the aerosol matrix, and the inner conductor and the outer conductor jointly define a resonant cavity arranged around the receiving cavity; and, The pin has one end fixed to the bottom of the outer conductor and in ohmic contact with the bottom of the outer conductor, and the other end extending into the accommodating cavity and spaced apart from the inner conductor.

2. The microwave resonator according to claim 1, wherein: The spacing distance between the inner conductor and the bottom of the outer conductor ranges from 0.1 mm to 12 mm.

3. The microwave resonator according to claim 1, wherein: The outer conductor, the inner conductor and the pin are coaxially arranged.

4. The microwave resonator according to claim 3, wherein: The outer conductor is columnar, and the cross-sectional shape of the outer conductor includes any one of a rectangular, a circular and an elliptical shape.

5. The microwave resonator according to claim 3, wherein: The inner conductor is in a tubular shape, and two ends of the inner conductor are connected to form the accommodating cavity.

6. The microwave resonator according to claim 1, wherein: The outer conductor, the inner conductor and the pin are all made of metal materials.

7. The microwave resonator according to claim 1, wherein: The inner wall of the outer conductor and the inner wall of the inner conductor are both provided with a dielectric layer and a first conductive film covering the dielectric layer, and the conductivity of the first conductive film is less than or equal to the conductivity of pure aluminum.

8. The microwave resonator according to claim 1, wherein: The inner conductor and the outer conductor are integrally arranged.

9. The microwave resonator according to claim 1, wherein: A radio frequency connector is arranged at the bottom of the outer conductor.

10. The microwave resonator according to claim 1, wherein: There are a plurality of the insertion pins, and the plurality of the insertion pins are distributed at intervals along the circumferential direction.

11. The microwave resonator according to claim 1, wherein: The material of the plug pin includes an insulating material. The outer side of the plug pin is covered with a second conductive film, and the second conductive film is in ohmic contact with the bottom of the outer conductor.

12. An aerosol generating device, characterized in that: include: power supply; A microwave resonator for accommodating an aerosol matrix, the microwave resonator comprising: an outer conductor; an inner conductor, one end of which is fixed to the top of the outer conductor and in ohmic contact with the top of the outer conductor, and the other end of which is spaced from the bottom of the outer conductor, the inner conductor being provided with a receiving cavity exposed at the top of the outer conductor and used to accommodate the aerosol matrix, and the inner conductor and the outer conductor jointly define a resonant cavity arranged around the receiving cavity; and a pin, one end of which is fixed to the bottom of the outer conductor and in contact with the outer conductor. The bottom of the conductor is in ohmic contact, and the other end extends into the accommodating cavity and is spaced apart from the inner conductor; A radio frequency component, electrically connected to the power supply and the microwave resonator; a temperature measuring component, disposed in the microwave resonator, and used for measuring the temperature of the aerosol matrix; and The controller is electrically connected to the RF component, the power supply and the temperature measurement component.

13. The aerosol generating device according to claim 12, wherein: The spacing distance between the inner conductor and the bottom of the outer conductor ranges from 0.1 mm to 12 mm.

14. The aerosol generating device according to claim 12, wherein: The outer conductor, the inner conductor and the pin are coaxially arranged.

15. The aerosol generating device according to claim 14, wherein: The outer conductor is columnar, and the cross-sectional shape of the outer conductor includes any one of a rectangular, a circular and an elliptical shape.

16. The aerosol generating device according to claim 14, wherein: The inner conductor is in a tubular shape, and two ends of the inner conductor are connected to form the accommodating cavity.

17. The aerosol generating device according to claim 12, wherein: The outer conductor, the inner conductor and the pin are all made of metal materials.

18. The aerosol generating device according to claim 12, wherein: The inner wall of the outer conductor and the inner wall of the inner conductor are both provided with a dielectric layer and a first conductive film covering the dielectric layer, and the conductivity of the first conductive film is less than or equal to the conductivity of pure aluminum.

19. The aerosol generating device according to claim 12, wherein: The inner conductor and the outer conductor are integrally arranged.

20. The aerosol generating device according to claim 12, wherein: A radio frequency connector is arranged at the bottom of the outer conductor.

21. The aerosol generating device according to claim 12, wherein: There are a plurality of the insertion pins, and the plurality of the insertion pins are distributed at intervals along the circumferential direction.

22. The aerosol generating device according to claim 12, wherein: The material of the plug pin includes an insulating material. The outer side of the plug pin is covered with a second conductive film, and the second conductive film is in ohmic contact with the bottom of the outer conductor.

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