CN106356600A - Signal transmission device - Google Patents

Abstract

The invention provides a signal transmission device which comprises a waveguide and a coupled resonator filter. A first coupling window is formed in the waveguide which is configured to transmit received signals; the coupled resonator filter comprises resonant cavities in two lines identical in number, the resonant cavity at the first end is configured to be connected with a coaxial transmission line, the resonant cavity at the second end is provided with a second coupling window formed therein, the resonant cavity is configured to be coupled to the waveguide through the first and second coupling windows, and the resonant cavity at the second end shares one volume with the waveguide. By the above mode, energy transferring (coupling) as required is realized through connection between the coupled resonator filter and the outer filter, and inherent frequency of the resonant cavities cannot be affected.

Description

signal transmission device

technical field

The present invention relates to the field of filters, in particular to a signal transmission device having a waveguide connected to a coupled resonator filter.

Background technique

Resonant cavity bandpass filters play an important role in communication systems and directly affect communication quality. With the continuous development of wireless communication technology, resonant cavity bandpass filters will be used to realize the transmission of higher power signals.

When a waveguide resonator bandpass filter has a coaxial (TEM mode) port and a waveguide type port, if it is used to transmit microwave signals, there will be some input/output coupling with frequency loading and/or keeping approximately constant related questions. When the so-called folded filter topology is realized, especially when it has two sets of resonant cavities of equal number (for example, each set is 3), or a coaxial port and a waveguide port as shown in Fig. 1 For linear topologies, the above-mentioned problems will be specifically related to: (a) frequency loading of the end resonator connected to the waveguide port, but such loading will reduce the cut-off frequency of the resonator; (b) Maintains approximately constant input/output coupling over a given filter tuning range without the need for special adjustment devices

The current technical solutions for solving these problems usually have strict requirements on the resonant cavity, or may affect the performance of the filter itself. Therefore, there is an urgent need for filter components with good coupling effects.

Contents of the invention

In view of the above problems, the present invention aims to produce the desired coupling of the filter to the attached waveguide without changing the natural resonance frequency of the end resonator.

The present invention proposes a signal transmission device, comprising: a waveguide having a first coupling window formed thereon and configured to transmit received signals; a coupled resonator filter comprising two columns of the same number of a resonant cavity, wherein the first end resonant cavity is configured to connect a coaxial transmission line, and the second end resonant cavity has a second coupling window formed thereon, the second end resonant cavity is configured to pass through the first, A second coupling window is coupled to the waveguide such that the second end resonator and the waveguide share a volume.

Preferably, the sizes of the first coupling window and the second coupling window determine a frequency range suitable for transmission therein.

Preferably, the first coupling window is formed at a first corner of the waveguide, and the second coupling window is formed at a second corner of the coupled resonator filter corresponding to the first corner.

Preferably, the first coupling window and the second coupling window are adjustable, so as to adjust the magnetic field strength at the resonant cavity at the second end.

Preferably, the waveguide further includes: a cavity; at least two separate adjusting bolts, which are located in the cavity, and are used to adjust the second-end resonant cavity by screwing in or out at least one adjusting screw. the electric field strength.

Preferably, each adjusting screw is used to adjust signals in at least partly different frequency ranges.

Preferably, the waveguide further comprises three separate adjustment bolts distributed along the centerline on the bottom side of the cavity.

Preferably, the frequency range is determined by the distance between every two regulator bolts.

Preferably, the second coupling window is L-shaped.

Preferably, the first part of the second coupling window is formed on the upper part of the second strong coupling front wall, and the second part of the second coupling window is formed on the side of the second strong coupling the upper part of the wall.

Through the technical solution of the present invention, the required energy transmission (coupling) is achieved by adjusting the connection between the coupling resonator filter and the external waveguide without affecting the natural frequency of the end resonator.

Description of drawings

The present invention will be better understood and other objects, details, features and advantages of the present invention will become more apparent by referring to the description of specific embodiments of the present invention given in the following drawings. In the attached picture:

Figure 1 shows a schematic diagram of a linear waveguide filter;

Fig. 2 shows a signal transmission device including a waveguide and a resonant cavity filter;

Fig. 3 shows the front view of the signal transmission device in Fig. 2;

Fig. 4 shows a side view of the signal transmission device in Fig. 2;

Figure 5 shows the distribution of the three adjusting bolts.

detailed description

Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In order to solve problem a, the length of the resonant cavities at both ends of the filter is usually reduced, and the subsequent resonant cavities are about half the wavelength of the resonant frequency. However, when the filter has a folded topology and different port types, for example, one port is coaxial and the other port is waveguide type, then the above technical solution will not work for this filter. In this case, it is often required that the two end resonators have the same length. Figure 1 shows the schematic diagram of a linear waveguide filter. Here, the lengths Θ1, Θn at the end filters can be adjusted to compensate the effects at X _0,1 , X _n,n+1 .

To solve problem b, the usual solution is a tunable device, eg a tuned tunable coupling loop. For high power filters, this approach usually affects the power handling of the filter.

The coupling between the waveguide-type resonator and the external waveguide is usually inductive, ie the energy is coupled through equal magnetic fields in the filter resonator and waveguide. At the position X _0,1 in Figure 1, the magnetic field has a maximum and the coupling is achieved through a simple opening, commonly referred to here as the "aperture". However, this opening has a strong influence on the eigenfrequency of the cavity frequency. Thus, the invention aims to produce the desired coupling of the filter to the attached waveguide without changing the natural resonance frequency of the end resonator.

According to an embodiment of the present invention, the technical scheme of coupling the external waveguide and the resonant cavity of the waveguide filter through a coupling window can be used to eliminate the influence of undesired frequency loading.

Fig. 2 shows a signal transmission device comprising a waveguide and a coupled resonator filter.

As shown in FIG. 2, the signal transmission device includes a coupled resonator filter 210 and a waveguide 212, wherein the coupled resonator filter 210 is a so-called folded resonator filter and includes two columns of the same number of resonant cavities, for example, each Group contains 3 resonators. The input port 211 is arranged at the first end resonant cavity 213 and is configured to be electrically connected with a TEM mode transmission line (not shown), and the output port 212 is arranged at the corner of the second end resonant cavity 214 and is coupled to at least a part The external waveguide 212 of the external waveguide 212, so that the influence caused by the arrangement of the external waveguide 212 is minimized, and the required energy transfer (coupling) will not affect the natural frequency of the resonant cavity too much.

When the second-end resonant cavity 214 and the external waveguide 212 are coupled through respective coupling windows, the resonant cavity 214 and the external waveguide 212 have a common cavity. In particular, a first coupling window is formed at a first corner of the outer waveguide 212 and a second coupling window is formed at a second corner of the coupled resonator filter 212 corresponding to the first corner. The two coupling windows may have sizes suitable for different signal frequencies, and the size of the coupling windows is inversely proportional to the suitable signal frequency, which means that the larger the coupling window, the lower the suitable signal frequency.

Both the input port and the output port are arranged at the same surface S1, and the external waveguide 212 shares a volume with the second end resonant cavity 214, so that the connection of the external waveguide 212 to the second resonant cavity 213 is only for energy transfer from the filter way to the waveguide without other unwanted side effects.

In addition, in the coupled resonant cavity filter 210, there is also an opening between the resonant cavities 213 and 214, which can provide inductive or capacitive coupling between the two to suit the required filter transfer function. Thus, external waveguides placed at the corners of the resonator filter 21 are able to adjust the magnetic and/or electric fields at the resonator 214 to provide near constant coupling. When the input port receives a signal, the signal will sequentially flow through the resonant cavities 213, 215, 217, 218, 216 and 214, and output at the outer waveguide 212, so that the directions of input and output are substantially parallel.

As shown in Figure 3, the first adjusting bolt b1 is located in the cavity of the external waveguide to adjust the electric field intensity by changing its height in the cavity, and the first part of the second coupling window CW is formed on the front wall of the resonant cavity 214 upper part. In order to reduce the influence caused by the arrangement of the waveguides, the width W1 of the first part of the second coupling window CW is smaller than λ/4, while the width W2 of the outer waveguide is larger than λ/2. In addition, the resonant cavity 214 has a substantially square cross-section and a width greater than λ/2, that is, the width of the front wall of the resonant cavity 213 is greater than λ/2. [lambda] as used here is the maximum wavelength suitable for the signal transmitted in the resonant cavity. In addition, the adjustment screw is able to work with or act as a small "capacitive load", which facilitates impedance matching and minimizes reflection effects, thereby maximizing the power transfer from the filter to the waveguide, vice versa.

As shown in FIG. 4 , there are three adjustment bolts b1 - b3 in the cavity of the external waveguide 212 , and the second portion of the second coupling window CW is formed on the upper portion of the sidewall of the resonant cavity 214 .

The second coupling window CW is L-shaped, and realizes coupling on two adjacent surfaces through the first and second parts. When the microwave signal is transmitted from the resonant cavity 214 to the external waveguide 212, the energy can be transmitted through the first and second parts of the second coupling window CW. The lengths of both the first part and the second part are less than λ/4, thus reducing the influence of frequency load on coupling. When the height of the second coupling window CW increases, the field coupling amount associated with the size of the second coupling window CW will also increase accordingly.

When the size of the second coupling window CW is determined, the magnetic field strength at the second end resonant cavity 214 is also determined accordingly. Therefore, adjusting the coupling between the resonator and the waveguide can be achieved by adjusting the electric field strength at the outer waveguide. The three separate adjustment bolts provide a means to adjust the electric field strength there by screwing in or out at least one of the three bolts.

Referring to Figures 4 and 5, three adjusting bolts are arranged in a row. Based on the distribution of the electric field at the outer waveguide 212, three adjustment bolts are preferably arranged on the bottom side of the cavity along the centerline of the bottom side of the cavity. The three bolts need to be distributed at certain intervals, for example, d1, d2, d3, so as to cover different frequency ranges respectively, so that the signal transmission device can meet the requirements of transmitting signals with different frequencies.

It can be understood that the three frequency ranges may have at least one overlapping frequency band, that is to say, each adjusting bolt corresponds to at least partly different frequency ranges. In this case, when the user wants to adjust the electric field strength for the signal with frequency F1, he can choose to turn the adjusting bolt b1, or turn the adjusting bolts b1 and b2, or even b1, b2 and b3. In the embodiment of the present invention In , when the bolt b1 is screwed in, the electric field strength is increased.

The connection between the coupled resonator filter 210 and the external waveguide 212 achieves the desired energy transfer (coupling) without affecting the natural frequency of the end resonators. This end resonator and the external waveguide share the same volume, which differs from the traditional method of connecting the waveguide to the filter end resonator via an aperture flange.

It should be understood that the above-mentioned embodiments are not intended to limit the protection scope of the present invention, and all modifications and changes that do not deviate from the concept of the present invention shall be covered by the present invention. For example, the coupled resonator filter 212 can have 4, 6, 8 or any even number or even an odd number of resonators, and the first and second coupling windows can also be adjustable, so that the resonator at the second end can be adjusted. magnetic field strength. This window can not only adjust the magnetic field length to a certain extent, but also determine the coupling strength required to realize the transfer function of the filter.

Such variations are considered to be within the scope of the invention and the appended claims. The protection scope of the present invention is defined by the claims. The verb "to comprise" indicates that other elements may be included in addition to those specified in a claim.

Claims (10)

1. A signal transmission device, comprising: a waveguide having a first coupling window formed thereon and configured to transmit the received signal; A coupled resonator filter comprising two columns of the same number of resonators, wherein a first end resonator is configured to connect a coaxial transmission line, and a second end resonator has a second coupling window formed thereon, the first end resonator The two-end resonant cavity is configured to be coupled to the waveguide through the first and second coupling windows, so that the second-end resonant cavity and the waveguide share a volume. 2. The signal transmission device according to claim 1, wherein the dimensions of the first coupling window and the second coupling window determine a frequency range suitable for transmission therein. 3. The signal transmission device according to claim 1. Wherein, the first coupling window is formed at a first corner of the waveguide, and the second coupling window is formed at a second corner of the coupled resonator filter corresponding to the first corner. 4. The signal transmission device according to claim 1, wherein the first coupling window and the second coupling window are adjustable to adjust the magnetic field strength at the second end resonant cavity. 5. The signal transmission device according to claim 1, wherein the waveguide further comprises: cavity; At least two separate adjusting bolts, which are located in the cavity, are used to adjust the electric field intensity at the resonant cavity at the second end by screwing in or out at least one adjusting bolt. 6. A signal transmission device as claimed in claim 5, wherein each adjustment bolt is used to adjust signals in at least partly different frequency ranges. 7. The signal transmission device of claim 5, wherein the waveguide further comprises three separate adjustment bolts distributed along the centerline on the bottom side of the cavity. 8. The signal transmission device according to claim 6, wherein the frequency range is determined by the distance between every two regulator bolts. 9. The signal transmission device according to claim 1, wherein the second coupling window is L-shaped. 10. The signal transmission device as claimed in claim 9, wherein the first part of the second coupling window is formed on the upper part of the second strong coupling front wall, and the second part of the second coupling window portion is formed on the upper portion of the second strong-coupling sidewall.