CN102723569A - Adjustable resonant cavity - Google Patents

Abstract

The invention discloses an adjustable resonant cavity, which mainly consists of a cavity 1 with a hollow structure, a metal ridge structure 2 arranged at the bottom of the cavity 1 , and a metal cylinder 4 penetrating through the cavity 1 and extending into the cavity 1 In this configuration, the end of the metal cylinder 4 close to the metal ridge structure 2 is also connected with a capacitor 3 , and there is a gap between the capacitor 3 and the metal ridge structure 2 . The invention has the beneficial effects of simple structure and adjustment mode, low production cost, fine adjustment function and wide adjustment range.

Description

A tuneable resonator

technical field

The invention relates to a filter, in particular to an adjustable resonant cavity that can rotate and adjust the frequency.

Background technique

As a brand-new microwave device in electronic warfare, tunable microwave filter first appeared in the 1940s. It is mainly used in microwave communication machines.

The ideal tunable filter should be: (1) has a wide tuning range and narrow passband width, and has a fast tuning speed; (2) has a small insertion loss in the passband, and in the passband There is a high degree of suppression in the stop band, so as to ensure that the microwave communication machine has a strong anti-interference ability; (3) During the entire tuning process, the absolute bandwidth and filtering characteristics should be kept unchanged. However, at the beginning, the performance of the tunable microwave filter was very poor. First, the tuning range was very narrow, and second, the passband width could not be made very narrow. The specific performance is: a larger bandwidth increases with the center The change of frequency widens rapidly, and the insertion loss in the band increases rapidly, and the suppression out of the band decreases rapidly.

Since the 1950s, foreign tunable microwave filter designers have been looking for a suitable coupling structure to obtain a large tuning range and narrow passband width (to ensure that the filter has absolute bandwidth and filtering in the entire tuning range) device characteristics remain unchanged). In the early 1960s, the tuning range of the filter was only 200MHz, and the passband width could not be made very narrow. In the mid-1960s, GL. Matthaei proposed a method to achieve absolute bandwidth invariance from the perspective of the network, but the experimental results proved that this method did not work at all. Until the 1970s, the adjustable range of the filter was close to 300MHz, and in the tuning process, the relative bandwidth has still a large change. Since the 1980s, how to ensure the absolute bandwidth and filter characteristics of tunable microwave filters in the entire tuning range has become a key issue in the design of tunable microwave filters.

Existing tunable filters can be roughly divided into four types: ferrite tunable filters, varactor diode tunable filters, micromechanical tunable filters, and cavity tunable filters.

Ferrite tunable filters adjust the frequency by changing the ferrite bias magnetic field. This filter has a wide tuning range and a Q value greater than 10,000. However, the tuning system is complex and the overall power consumption is large, which limits the application of ferrite tunable filters in wireless communication systems.

Varactor diode tunable filters have been widely studied and successfully applied in recent years, but this filter is difficult to use under high power conditions due to the limitation of diode reverse bias breakdown voltage.

Micromachined tunable filters utilize tunable micromachined capacitors to change the filter operating frequency. The bottleneck of this technology lies in the maturity and power capacity of the micro-machine manufacturing process.

The coaxial cavity tunable filter is tuned by changing the length of the inner conductor or changing the loading capacitance of the cavity. This kind of filter has simple structure, large power capacity, and can be miniaturized by capacitive loading, so it is widely used in medium and high power communication systems.

Contents of the invention

The object of the present invention is to design a mechanically tunable filter by utilizing the coupling between tunable resonant cavities.

In order to meet the above requirements, the technical solution adopted by the present invention is: an adjustable resonant cavity, which mainly consists of a cavity with a hollow structure, a metal ridge structure disposed inside the cavity and on its bottom surface, and a The metal cylinder extending into the cavity is composed of a capacitor plate connected to the end of the metal cylinder close to the metal ridge structure, and there is a gap between the capacitor plate and the metal ridge structure.

The capacitor sheet is located above the metal ridge structure.

The metal ridge structure is an arc structure fixed on the bottom of the cavity around the axis of the metal cylinder.

The height of the metal ridge structure monotonously increases or decreases clockwise.

The axis of the tuning screw is parallel to the axis of the metal cylinder.

A tuning screw is also provided through the metal ridge structure, and the axis of the tuning screw is parallel to the axis of the metal cylinder.

The number of tuning screws is at least 2.

The end of the tuning screw away from the capacitor plate penetrates the cavity and extends out of the cavity. the

Based on the description of the above structure, the design principle and operation method of the present invention are as follows: For the convenience of adjustment, the original resonance structure is adjusted by several tuning devices. In order to simplify the design, the design purpose of the present invention is to use a regulating device to replace redundant tuning devices. Therefore, as mentioned above, the present invention connects the metal cylinder and the capacitor plate to form a rotary tuning structure. The upper surface of the capacitor sheet is fixedly connected with the metal cylinder, and the metal cylinder can rotate around its own axis. After the rotation, the capacitor sheet can be driven to rotate around the axis of the metal cylinder. Then, we need to design a structure corresponding to the above-mentioned rotary tuning structure, that is, the metal ridge structure. The metal ridge structure needs to meet the following conditions, condition 1: the metal ridge structure needs to be arranged under the capacitor sheet. According to the rotation track of the capacitor sheet, the present invention further designs the metal ridge structure to be an arc-shaped structure fixed on the bottom of the cavity around the axis of the metal cylinder, that is, the arc-shaped structure is connected to the bottom surface of the cavity, and the arc-shaped structure is away from the bottom surface of the cavity. The shape of one end is arc-shaped or the shape of the end of the arc-shaped structure away from the bottom surface of the cavity is consistent with the rotation track of the capacitor sheet, which can ensure that the metal ridge structure is always kept below the capacitor sheet. The above is condition 2; further, in order to make The tuning range is different, and the upper surface of the metal ridge structure close to the capacitor sheet is an uneven surface, which is described as condition 3; further, in order to make us clearly know the tendency of adjustment, therefore, the generally designed metal ridge structure The height increases or decreases in a clockwise direction. In this way, we can rotate the metal cylinder so that we can clearly know the adjustment trend, that is, when we need to increase the output frequency adjustment, we can make the metal cylinder rotate left or right. Conversely, we need to output the frequency When the adjustment becomes smaller, we can reversely rotate the metal cylinder. The specific direction of rotation varies according to the design.

Further, the above structure can only be roughly adjusted. When adjusting to the position of the value we need, in order to make the adjustment more accurate, we use the tuning screw. The tuning screw can be rotated from the outside, so that the part of the tuning screw protruding into the cavity becomes longer or shorter, thereby achieving the purpose of fine tuning.

The specific implementation method is: an adjustable resonant cavity, including a cavity, a metal cylinder passing through the cavity on the top of the cavity, and the metal cylinder can rotate around its axis; the lower end of the metal cylinder is connected to a The axis of the metal cylinder is the starting point of the capacitor sheet distributed radially, and there is a metal ridge structure arranged at the bottom of the cavity under the capacitor sheet. The metal ridge structure is an arc fixed on the bottom of the cavity around the axis of the metal cylinder. Shaped structure, the height of the metal ridge structure increases or decreases in the clockwise direction; the bottom of the cavity has tuning screws passing through the bottom of the cavity and through the metal ridge structure, and the tuning screw needs to pass through the metal ridge structure. The surface pops out and can be adjusted outside the cavity.

Compared with the prior art, the invention has the advantages of simple structure and adjustment method, low production cost, fine adjustment function and wide adjustment range.

Description of drawings

Fig. 1 is a front view of an example of the present invention.

Fig. 2 is A-A sectional view in the embodiment of the present invention

The symbols in the figure are respectively represented as: 1. Cavity body; 2. Metal ridge structure; 3. Capacitor sheet; 4. Metal cylinder; 5. Tuning screw.

Detailed ways

The present invention will be further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto.

Example 1

As shown in Figure 1 and 2. An adjustable resonant cavity mainly consists of a cavity 1 with a hollow structure, a metal ridge structure 2 arranged inside the cavity 1 and on the bottom surface thereof, and a metal cylinder 4 penetrating through the cavity 1 and extending into the cavity 1 In this configuration, the end of the metal cylinder 4 close to the metal ridge structure 2 is also connected with a capacitor 3 , and there is a gap between the capacitor 3 and the metal ridge structure 2 .

The capacitive sheet 3 is located above the metal ridge structure 2 .

The height of the metal ridge structure monotonously increases or decreases clockwise.

The metal ridge structure 2 is also provided with a tuning screw 5 , the axis of the tuning screw 5 is parallel to the axis of the metal cylinder 4 .

The number of tuning screws 5 is at least two.

The end of the tuning screw 5 away from the capacitor plate 3 penetrates the cavity 1 and extends out of the cavity 1 . the

Based on the description of the above structure, the design principle and operation method of the present invention are as follows: For the convenience of adjustment, the original resonance structure is adjusted by several tuning devices. In order to simplify the design, the design purpose of the present invention is to use a regulating device to replace redundant tuning devices. Therefore, as mentioned above, the present invention connects the metal cylinder 4 and the capacitance sheet 3 to form a rotary tuning structure, the upper surface of the capacitance sheet is fixedly connected with the metal cylinder 4, and the metal cylinder 4 can rotate around its own axis. After the rotation, the capacitor sheet can be driven to rotate around the axis of the metal cylinder 4 . Then, we need to design a structure corresponding to the above-mentioned rotary tuning structure, that is, the metal ridge structure 2. The metal ridge structure 2 needs to meet the following conditions: the metal ridge structure 2 needs to be arranged under the capacitor sheet 3 to form resonance; further, in order to form different tuning ranges, the height of the metal ridge structure monotonously increases or decreases along the clockwise direction.

Further, the above structure can only be roughly adjusted. When adjusting to the position of the value we need, in order to make the adjustment more accurate, we use the tuning screw. The tuning screw can be rotated from the outside, so that the part of the tuning screw protruding into the cavity becomes longer or shorter, thereby achieving the purpose of fine tuning.

Example 2

As shown in Figures 1 and 2, on the basis of Embodiment 1, the difference between this embodiment and Embodiment 1 is that the metal ridge structure 2 is an arc-shaped structure fixed at the bottom of the cavity 1 around the axis of the metal cylinder.

The height of the metal ridge structure 2 increases or decreases clockwise.

When the rotation angle of the capacitor sheet is too large, if the metal ridge structure 2 is a straight line structure, the metal ridge structure 2 cannot always be kept under the capacitor sheet 3. Therefore, according to the rotation track of the capacitor sheet 3, the present invention further designs the metal ridge structure. 2 is an arc-shaped structure fixed on the bottom of the cavity 1 around the axis of the metal cylinder, so as to ensure that the metal ridge structure 2 is always kept under the capacitor chip 3, and the above is the condition 2.

Further, in order to enable us to clearly know the adjustment tendency, therefore, the height of the generally designed metal ridge structure 2 increases or decreases in the clockwise direction, so that we can clearly know the adjustment by rotating the metal cylinder. Trend, that is, when we need to increase the output frequency adjustment, we can make the metal cylinder rotate left or right. Conversely, if we need to adjust the output frequency to be smaller, we can rotate the metal cylinder in the opposite direction. The specific direction of rotation varies according to the design.

The specific implementation method is: an adjustable resonant cavity, including a cavity, a metal cylinder passing through the cavity on the top of the cavity, and the metal cylinder can rotate around its axis; the lower end of the metal cylinder is connected to a The axis of the metal cylinder is the starting point of the capacitor sheet distributed radially, and there is a metal ridge structure arranged at the bottom of the cavity under the capacitor sheet. The metal ridge structure is an arc fixed on the bottom of the cavity around the axis of the metal cylinder. Shaped structure, the height of the metal ridge structure increases in the clockwise direction; the bottom of the cavity has tuning screws passing through the bottom of the cavity and through the metal ridge structure, and the tuning screw will emerge from the upper surface of the metal ridge structure out and can be adjusted outside the cavity.

The present invention can be preferably carried out as described above.

Claims (8)

1. tunable cavity; It is characterized in that: mainly by the cavity (1) of hollow structure and to be arranged on cavity (1) inner and be positioned at the metal ridge structure (2) on its bottom surface and run through cavity (1) and extend into the inner metal cylinder (4) of cavity (1) and constitute; Metal cylinder (4) also is connected with capacitance sheet (3) near an end of metal ridge structure (2), has the gap between capacitance sheet (3) and the metal ridge structure (2).

2. a kind of tunable cavity according to claim 1 is characterized in that: said capacitance sheet (3) is positioned at the top of metal ridge structure (2).

3. a kind of tunable cavity according to claim 1 is characterized in that: said metal ridge structure (2) is the arcuate structure that is fixed on cavity (1) bottom around the axis of metal cylinder.

4. a kind of tunable cavity according to claim 3 is characterized in that: the height of metal ridge structure (2) is monotonic increase or successively decrease along clockwise direction.

5. according to any described a kind of tunable cavity among the claim 1-5, it is characterized in that: also run through being provided with tuning screw (5) on the said metal ridge structure (2).

6. according to claims 5 described a kind of tunable cavitys, it is characterized in that: the parallel axes of the axis of said tuning screw (5) and metal cylinder (4).

7. a kind of tunable cavity according to claim 6 is characterized in that: the number of tuning screw (5) is at least 2.

8. a kind of tunable cavity according to claim 6 is characterized in that: said tuning screw (5) runs through cavity (1) and extends to cavity (1) outside away from an end of capacitance sheet (3).

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