A waveguide tunable coupler and its adjustment method

Abstract

The present application discloses a waveguide adjustable coupler and its adjustment method, which belongs to the field of microwave. The coupler adopts two back-to-back waveguide bridges, and realizes the adjustable coupling amount of the waveguide coupler by cooperating with the tuning screw to tune the phase. The coupling amount can be adjusted continuously, and at the same time, good echo characteristics and isolation characteristics can be guaranteed; and the tuning screw is tuned at the empty waveguide, and the size space is large, so it can work in the millimeter wave frequency band; further, the waveguide is split from the E surface, and the narrow side of the waveguide is opened with a threaded hole, and the adjustment screw is on the front of the product, which is convenient for debugging and manufacturing.

Description

Technical Field

[0001] This application relates to the field of microwaves, and particularly to a waveguide tunable coupler and an adjustment method thereof. Background Art

[0002] Waveguides have the characteristics of low loss and large power capacity, and are widely used in various microwave and millimeter-wave communication and radar systems. In the millimeter-wave band and the E-band, the required coupling amount of the product is very small, such as -20 dB, and when the accuracy requirement of the coupling amount is relatively high, the coupling window of the waveguide coupler is very small, and it is difficult to ensure the coupling amount completely by machining, resulting in difficulty in manufacturing products with such requirements.

[0003] Adopting the method of adjustable tuning screws to compensate for machining errors is a reliable way to realize such products. At present, most waveguide tunable couplers realize adjustable coupling amount by adjusting the size of the coupling window with screws. For example, the technical solution introduced in the patent number CN201922254021.7. However, when the operating frequency band is in the millimeter-wave band, the size of the coupling window is very small and a tuning screw cannot be placed. Therefore, this method is suitable for use in lower-frequency bands and not applicable to the millimeter-wave band. At the same time, using this method to adjust the coupling window has a greater impact on the return loss and isolation of the coupler, and it is difficult to ensure a good isolation characteristic within the tuning range.

[0004] Therefore, proposing a coupler coupling amount tuning method is the key to solving the above problems. Summary of the Invention

[0005] The present invention provides a waveguide tunable coupler and an adjustment method thereof. It is used to solve the above-mentioned problems. The technical solution is as follows:

[0006] According to one aspect of the present application, a waveguide tunable coupler is provided. The coupler includes: a metal cavity, a tuning screw, and a coupling coordination structure located in the metal cavity. The tuning screw is used to tune the coupling degree;

[0007] The coupling coordination structure is designed as two back-to-back 90-degree 3 dB waveguide bridges, namely the first waveguide bridge and the second waveguide bridge. The first waveguide bridge and the second waveguide bridge are connected by a first straight waveguide and a second straight waveguide. The first straight waveguide accommodates the tuning screw;

[0008] An input waveguide port is provided at the first waveguide bridge, and an output waveguide port is provided at the second waveguide bridge.

[0009] Optionally, the metal cavity is composed of a lower cavity and an upper cavity. The lower cavity and the upper cavity are buckled and fastened by screws; the tuning screw is located on the surface of the upper cavity.

[0010] Optionally, the first straight waveguide is provided with a tuning screw hole, and the tuning screw hole is used to accommodate a tuning screw.

[0011] According to another aspect of the present application, a waveguide adjustable coupler adjustment method is provided, the method is used for the waveguide adjustable coupler of the above aspect, and the method comprises:

[0012] Input a microwave signal through an input waveguide port;

[0013] Adjust the tuning screw to set the current phase shift to 90 degrees;

[0014] Under a 90-degree phase shift, the microwave signal is divided into a first signal and a second signal by a first waveguide bridge, the first signal and the second signal have equal amplitudes and a phase difference of 90 degrees;

[0015] The first signal is input to the second waveguide electrobridge through the first straight waveguide, and the second signal is input to the second waveguide electrobridge through the second straight waveguide. The first signal and the second signal are synthesized at the second waveguide electrobridge.

[0016] Optionally, the method further includes:

[0017] Adjust the tuning screw to set the current phase shift to 0 degrees;

[0018] Under the condition of 0 degree phase shift, the microwave signal is input to the second waveguide bridge through the first straight waveguide, and no signal is input at the second straight waveguide.

[0019] Optionally, the method further includes:

[0020] Adjust the tuning screw to set the current phase shift to 180 degrees;

[0021] Under a phase shift of 180 degrees, the microwave signal is input to the second waveguide bridge through the second straight waveguide, and no signal is input at the first straight waveguide.

[0022] On the other hand, a computer-readable storage medium is provided, wherein the storage medium stores at least one instruction, and the at least one instruction is used to be executed by a processor to implement the waveguide adjustable coupler adjustment method as described above.

[0023] The present invention provides a waveguide adjustable coupler, which is particularly suitable for the microwave field. Two back-to-back waveguide bridges are used to adjust the phase of the waveguide coupler with a tuning screw, and the coupling amount of the waveguide coupler can be adjusted continuously, while ensuring good echo characteristics and isolation characteristics; and the tuning screw is tuned at the empty waveguide, not the coupling window of the coupler, and has a large size and space, so it can work in the millimeter wave band; further, the waveguide is split from the E surface, and a threaded hole is opened on the narrow side of the waveguide, and the adjustment screw is on the front of the product, which is convenient for debugging and manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shows the product external shape diagram of the E band waveguide tunable coupler;

[0025] Figure 2 Shows the schematic diagram of the waveguide tunable coupler;

[0026] Figure 3 Schematically shows the internal structure diagram of the waveguide tunable coupler. Specific implementation manners

[0027] To make the objectives, technical solutions and advantages of the present application clearer, the following will further describe in detail the embodiments of the present application with reference to the accompanying drawings.

[0028] As used herein, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0029] Please refer to Figures 1 to 3 , Figure 1 which shows the product external shape diagram of the E band waveguide tunable coupler, Figure 2 which shows the schematic diagram of the waveguide tunable coupler, Figure 3 which schematically shows the internal structure diagram of the waveguide tunable coupler.

[0030] In a possible implementation manner, the embodiments of the present application are schematically described with the tuning screw being of M1.2 model, the first straight waveguide and the second straight waveguide being of WR-12 standard rectangular waveguide model, and the waveguide tunable coupler operating in the E band frequency band.

[0031] As Figure 1 shown, the coupler includes a metal cavity, a tuning screw and a coupling coordination structure located in the metal cavity (as Figure 3 shown), the tuning screw is used to tune the coupling degree, and in Figure 1 the tuning screw is marked as No. 3. The whole product includes two metal cavities split from the E plane.

[0032] The coupling coordination structure is designed as two back-to-back 90-degree 3dB waveguide bridges, namely the first waveguide bridge and the second waveguide bridge, which are marked as Hybrid in Figure 2 , the first waveguide bridge is marked as No. 1 in Figure 3 , and the second waveguide bridge is marked as No. 2 in Figure 3 .

[0033] The first wave conductive bridge and the second wave conductive bridge are connected through the first straight waveguide and the second straight waveguide. The first straight waveguide accommodates a tuning screw. In Figure 3 the first straight waveguide is marked as No. 3, and in Figure 3 the second straight waveguide is marked as No. 4.

[0034] An input waveguide port is provided at the first wave conductive bridge, and an output waveguide port is provided at the second wave conductive bridge. In Figure 3 the input waveguide port is marked as No. 5, and in Figure 3 the output waveguide port is marked as No. 6.

[0035] Optionally, as shown in Figure 1 , the metal cavity is composed of a lower cavity and an upper cavity. The lower cavity and the upper cavity are buckled and fastened by screws. The tuning screw is located on the surface of the upper cavity. In Figure 1 the lower cavity is No. 1, and in Figure 1 the upper cavity is No. 2.

[0036] Optionally, as shown in Figure 3 , the first straight waveguide is provided with a tuning screw hole position for accommodating the tuning screw. In Figure 3 the tuning screw hole position is No. 7.

[0037] Further elaboration is made on Figure 3 . Figure 3 is the internal structure diagram of the waveguide tunable coupler. In the figure, 1 is the first waveguide 3dB bridge; 2 is the second waveguide 3dB bridge; 3 is the straight waveguide with a phase tuning screw; 4 is the straight waveguide without a phase tuning screw; the two back-to-back bridges are connected through the straight waveguides marked 3 and 4; the lengths of the straight waveguides marked 3 and 4 are generally the same, but different lengths can also achieve the function of coupling amount debugging. 5 and 6 are the input and output waveguide ports; 7 is the tuning screw hole position for tuning the phase, and a tuning screw is placed in each tuning screw hole position. If the tuning screw is inserted and controlled, it is equivalent to completely closing the tuning screw hole, and the phase has a certain shift. With an M1.2 tuning screw and a WR-12 standard rectangular waveguide, each tuning screw can move the phase by about 3 degrees.

[0038] It is obtained through experiments that to complete the signal output from no output to -3dB at one port, 90 degrees is required, and about 30 tuning screws are needed. The spacing of all these tuning screws is approximately one wavelength of the operating frequency, so that the return loss can be maintained at a good level during the process of tuning the phase.

[0039] In summary, the present invention provides a waveguide tunable coupler, which is particularly suitable for the microwave field. By using two back-to-back waveguide hybrids and tuning the phase with tuning screws, the coupling amount of the waveguide coupler can be adjusted, and the coupling amount can be continuously adjusted. At the same time, good return loss characteristics and isolation characteristics can be ensured. Moreover, the position of the tuning screw for tuning is in the empty waveguide, not the coupling window of the coupler, and the size space is large, so it can operate in the millimeter wave band. Further, the waveguide is split from the E-plane, threaded holes are opened on the narrow side of the waveguide, and the tuning is on the front of the product, which is convenient for debugging and manufacturing.

[0040] Further elaboration is made on Figure 2 this. Figure 2 Fig. is the schematic diagram of the tunable coupler. The tunable coupler includes two back-to-back 90-degree 3dB waveguide hybrids, and a phase shifter (implemented by a tuning screw) is inserted into one of the transmission lines connecting the two hybrids. According to the principle of microwave network, when a microwave signal is input from P1 and passes through the first hybrid, the signal will be divided into two signals with equal amplitude and a phase difference of 90 degrees. These two signals are respectively input to the second hybrid through two transmission lines for synthesis. When the phase shift of the phase shifter is 0 degrees, the signal is completely output from the P2 port and there is no signal output from the P3 port; when the phase shift of the phase shifter is 180 degrees, the signal is completely output from the P3 port and there is no signal output from the P2 port; when the phase shift of the phase shifter is 90 degrees, the signal is output from the P2 port and the P3 port with equal amplitude. Therefore, as long as the phase shift of the phase shifter is controlled, the amplitude of the signal output from which port can be controlled, and the adjustable coupling amount can be achieved. The isolation between the P2 port and the P3 port is not affected by the phase change of the phase shifter. Therefore, good isolation characteristics can be maintained while adjusting the coupling amount.

[0041] Thus, a method for adjusting a waveguide tunable coupler can be obtained. Taking this method applied to the waveguide tunable coupler provided in the above embodiment as an example, the method includes:

[0042] Step 1, input a microwave signal through the input waveguide port.

[0043] Step 2, adjust the tuning screw to set the current phase shift to 90 degrees.

[0044] Step 3, at a 90-degree phase shift, divide the microwave signal into a first signal and a second signal through the first waveguide hybrid. The first signal and the second signal have equal amplitude and a phase difference of 90 degrees.

[0045] Step 4, input the first signal to the second waveguide hybrid through the first straight waveguide, and at the same time input the second signal to the second waveguide hybrid through the second straight waveguide. The first signal and the second signal are synthesized at the second waveguide hybrid.

[0046] In addition, other special phase shift cases are also included.

[0047] In one possible implementation, the tuning screw is adjusted to set the current phase shift to 0 degrees; at 0-degree phase shift, a microwave signal is input into the second waveguide bridge through the first straight waveguide, and no signal is input at the second straight waveguide.

[0048] In another possible implementation, the tuning screw is adjusted to set the current phase shift to 180 degrees;

[0049] At 180-degree phase shift, a microwave signal is input into the second waveguide bridge through the second straight waveguide, and no signal is input at the first straight waveguide.

[0050] In summary, in the present invention, the phase in the straight waveguide is adjusted by the depth of the tuning screw, so as to realize continuously adjustable coupling amount. Different from the way of directly adjusting the size of the coupling window, the adjustment of the coupling amount is not sensitive to the depth of the screw penetration. Each tuning screw only slightly tunes the coupling amount, which is very important in the millimeter-wave band. Therefore, the coupling amount can be accurately controlled. In addition, the tuning screw is tuned in the threaded hole on the narrow side of the waveguide to achieve full-band phase shift, and within the entire frequency band range, the phases adjusted at each frequency are basically the same, so as to ensure that the adjusted coupling amounts are also basically the same within the entire frequency band range, thereby ensuring good flatness of the coupling amount.

[0051] The present invention also provides a computer-readable medium, which stores at least one instruction, and the at least one instruction is loaded and executed by a processor to implement the waveguide adjustable coupler adjustment method of each of the above embodiments.

[0052] The above are only optional embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A waveguide tunable coupler, characterized in that, The coupler includes: a metal cavity, tuning screws, and a coupling coordination structure located within the metal cavity. The tuning screws are used to tune the coupling degree; The coupling coordination structure is designed as two back-to-back 90-degree 3dB waveguide bridges, namely the first waveguide bridge and the second waveguide bridge. The first waveguide bridge and the second waveguide bridge are connected by a first straight waveguide and a second straight waveguide. The first straight waveguide accommodates the tuning screws, and the second straight waveguide is a straight waveguide without phase tuning screws; An input waveguide port is provided at the first waveguide bridge, and an output waveguide port is provided at the second waveguide bridge; A microwave signal is input through the input waveguide port; Adjust the tuning screws to set the current phase shift to 0 degrees, or adjust the tuning screws to set the current phase shift to 180 degrees; At a phase shift of 0 degrees, the microwave signal is input to the second waveguide bridge through the first straight waveguide, and no signal is input at the second straight waveguide; At a phase shift of 180 degrees, the microwave signal is input to the second waveguide bridge through the second straight waveguide, and no signal is input at the first straight waveguide.

2. The waveguide tunable coupler according to claim 1, characterized in that, The metal cavity is composed of a lower cavity and an upper cavity. The lower cavity and the upper cavity are buckled and fastened by screws; the tuning screws are located on the surface of the upper cavity.

3. The waveguide tunable coupler according to claim 1, characterized in that, The first straight waveguide is provided with a tuning screw hole position for accommodating the tuning screws.

4. The waveguide tunable coupler according to claim 1, characterized in that, A microwave signal is input through the input waveguide port; Adjust the tuning screws to set the current phase shift to 90 degrees; At a phase shift of 90 degrees, the microwave signal is divided into a first signal and a second signal through the first waveguide bridge. The first signal and the second signal have equal amplitudes and a phase difference of 90 degrees; The first signal is input to the second waveguide bridge through the first straight waveguide, and at the same time, the second signal is input to the second waveguide bridge through the second straight waveguide. The first signal and the second signal are combined at the second waveguide bridge.

Images