Radio frequency impedance tuner

Abstract

The invention belongs to the technical field of radio frequency communication, and provides a radio frequency impedance tuner comprising a control unit which comprises a voltage control module, a USB module and a power supply module; the impedance amplitude tuner consists of a plurality of groups of transmission lines with different characteristic impedances and different line lengths and a radio frequency switch; the impedance phase tuner consists of a plurality of groups of transmission lines with different lengths and radio frequency switches; according to the radio frequency impedance tuner, the control unit, the impedance amplitude tuner and the impedance phase tuner are integrated, so that automatic and intelligent impedance tuning is realized, and the tuning efficiency and accuracy are remarkably improved; the impedance amplitude tuner can accurately change the impedance amplitude by flexibly switching transmission line combinations with different characteristic impedances and line lengths, and the impedance phase tuner can accurately adjust the impedance phase on the premise of not changing the impedance amplitude, so that high-efficiency transmission and stability of radio-frequency signals are ensured.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency communication technology, specifically a radio frequency impedance tuner. Background Technology

[0002] In radio frequency (RF) communication systems, impedance matching is a key factor in ensuring efficient signal transmission and reducing reflections and losses. However, existing RF impedance tuning techniques often suffer from problems such as complex operation, limited tuning range, and low automation.

[0003] Specifically, some tuners require manual adjustment of component parameters to match different load impedances, which is not only time-consuming and labor-intensive, but also makes it difficult to guarantee the accuracy and consistency of tuning. In addition, although some tuners have certain automation functions, their tuning algorithms are not intelligent enough to perform fast and accurate tuning based on real-time signal conditions, thus limiting their application in complex and ever-changing RF environments.

[0004] To address this problem, those skilled in the art have proposed a radio frequency impedance tuner. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a radio frequency impedance tuner. This addresses the issue that some existing tuners require manual adjustment of component parameters to match different load impedances, which is not only time-consuming and labor-intensive but also makes it difficult to guarantee tuning accuracy and consistency. Furthermore, while some tuners possess certain automation capabilities, their tuning algorithms are not intelligent enough to perform fast and accurate tuning based on real-time signal conditions, thus limiting their application in complex and ever-changing radio frequency environments.

[0006] A radio frequency impedance tuner, comprising:

[0007] The control unit, which includes a voltage control module, a USB module and a power module, is used to control the switching of the radio frequency switch via external computer software;

[0008] An impedance amplitude tuner, consisting of multiple sets of different characteristic impedances Z n and different line lengths L 2n It consists of a transmission line and an RF switch, which switch different Z... n and L 2n Combining different impedance amplitudes;

[0009] Impedance phase tuner, which consists of multiple sets of wires of different lengths L 1n It consists of a transmission line and an RF switch, used to adjust the impedance phase without changing the impedance amplitude;

[0010] The control unit is electrically connected to the impedance amplitude tuner and the impedance phase tuner respectively to realize automated impedance tuning.

[0011] Preferably, in the impedance amplitude tuner, Z n The value range is from 5Ω to 500Ω, L 2n The value is less than half the wavelength.

[0012] Preferably, the characteristic impedance of the transmission line of the radio frequency phase shifter is 50Ω, L 1n The value is less than half the wavelength, and by switching different L... 1n The transmission line achieves phase adjustment.

[0013] Preferably, the control unit supports connection to an external computer via a USB interface and displays the position of the impedance point on the Smith chart in real time through a software interface, enabling visual operation.

[0014] Preferably, the RF switches of the impedance amplitude tuner and the RF phase shifter are PIN diode switches or MEMS switches, respectively.

[0015] Preferably, the input impedance Z of the impedance amplitude tuner in_2 Satisfying the formula: Among them, Z L This is the load impedance.

[0016] Preferably, the input impedance Z of the radio frequency phase shifter in_1 On the Smith chart, with 50Ω as the center, along the clockwise direction with L... 1n Increase and move.

[0017] Preferably, the housing of the device is provided with an RF port, a USB port and a DC power interface.

[0018] Preferably, the software interface allows users to automatically trigger an RF switch to the corresponding Z-axis by clicking on the target impedance point in the Smith chart. n L 1n and L 2n combination.

[0019] An operating method for the radio frequency impedance tuner described above includes the following steps:

[0020] S1. Select the target impedance point using external software;

[0021] S2, The control unit matches the corresponding Z according to the target impedance point. n L 2n and L 1n parameter;

[0022] S3. Switch the RF switch to the specified transmission line combination to complete impedance tuning.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. This invention achieves automation and intelligence in impedance tuning by combining a control unit with external computer software, significantly reducing the need for manual adjustment of component parameters, improving tuning efficiency and accuracy, and solving the problems of complex operation, limited tuning range and low degree of automation in the prior art.

[0025] 2. The impedance amplitude tuner of the present invention can precisely change the impedance amplitude by combining multiple sets of transmission lines with different characteristic impedances and line lengths with radio frequency switches; the impedance phase tuner can precisely adjust the impedance phase by switching transmission lines with different line lengths without changing the impedance amplitude, thus ensuring efficient transmission and stability of radio frequency signals.

[0026] 3. The control unit of this invention supports connection to an external computer via USB interface. The software interface displays the position of the impedance point on the Smith chart in real time. Users can click on the target impedance point on the Smith chart to automatically trigger the RF switch to switch to the corresponding transmission line combination, which greatly simplifies the user operation process and improves the convenience and intuitiveness of operation.

[0027] 4. This invention can accurately tune to different target impedance points over a wide range, verifying its extensive tuning capability and high precision, and is suitable for radio frequency communication systems under various load impedance conditions.

[0028] 5. Through long-term operation testing, the invention has verified its high reliability and long-term stability in continuous operation mode, ensuring the continuous and stable operation of the radio frequency communication system. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall appearance of the present invention;

[0030] Figure 2 This is a schematic diagram of the system architecture of the present invention;

[0031] Figure 3 This is a schematic diagram of the working state of the impedance amplitude tuner of the present invention;

[0032] Figure 4 The impedance Z of the present invention in_2 Movement trajectory diagram;

[0033] Figure 5 This is a schematic diagram of the working state of the impedance phase tuner of the present invention;

[0034] Figure 6 Z, the present invention in_1 One of the impedance diagrams;

[0035] Figure 7Z, the present invention in_1 Impedance diagram 2. Detailed Implementation

[0036] The embodiments of the present invention will be described in further detail below with reference to examples. These examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0037] Example 1

[0038] This invention provides a radio frequency impedance tuner, including a housing, an external interface, and a system architecture. The system architecture consists of three parts: a control unit, an impedance amplitude tuner, and a radio frequency phase shifter. The control unit connects to an external computer via a USB module and controls impedance tuning using a software interface. The impedance amplitude tuner uses different characteristic impedances Z... n And different line lengths L 2n The transmission line and RF switch are integrated to change the impedance amplitude. The RF phase shifter uses RF switches with multiple lines of different lengths L. 1n Furthermore, the transmission line with characteristic impedance Z0 enables impedance phase adjustment.

[0039] As can be seen from the above, the RF impedance tuner provided by this invention subdivides the system architecture into three parts: a control unit, an impedance amplitude tuner, and an RF phase shifter. Furthermore, the control unit connects to an external computer via a USB module to control impedance tuning through a software interface, significantly improving the automation and intelligence of the tuning process. Specifically, the impedance amplitude tuner integrates different characteristic impedances Z... n With line length L 2n The transmission lines and RF switches can flexibly change the impedance amplitude, while the RF phase shifter utilizes RF switches and multiple lines of different lengths L. 1n The transmission line configuration enables precise adjustment of impedance and phase. This design not only simplifies the operation process and improves tuning efficiency, but also ensures the accuracy and consistency of tuning, making it particularly suitable for complex and variable RF environments.

[0040] Example 2

[0041] Based on Example 1, the design of the impedance amplitude tuner is further optimized. This is achieved by accurately calculating different characteristic impedances Z. n and line length L 2n The combination of these factors makes the movement of the input impedance Zin2 on the Smith chart more precise and controllable. Simultaneously, the optimized design of the RF phase shifter allows for more precise adjustment of the impedance phase without altering the impedance amplitude.

[0042] As shown above, by further optimizing the design of the impedance amplitude tuner, the characteristic impedances Z of different impedances can be accurately calculated. n and line length L 2nThe combination of these factors results in an input impedance Z. in_2 The more precise and controllable movement trajectory on the Smith chart significantly improves the precision and reliability of impedance tuning. At the same time, the optimized design of the RF phase shifter allows for more precise adjustment of the impedance phase while maintaining the impedance amplitude, enhancing the adaptability and flexibility of the tuner in different application scenarios and providing a more stable and efficient impedance matching solution for RF communication systems.

[0043] Specifically, the above can be achieved using the following steps:

[0044] I. System Initialization: Set the system's specific impedance Z sys =50Ω (standard RF system impedance);

[0045] Load impedance ZL = 50Ω (located at the center point of the Smith chart);

[0046] Transmission line characteristic impedance: Zn (arbitrary real value);

[0047] Transmission line length: L 2n (Adjustable parameters);

[0048] Operating frequency: f = 7 GHz (example value);

[0049] Relative permittivity of the medium: ε r (Default air medium ε) r =1);

[0050] II. Transmission Line Parameter Configuration: Select the nth transmission path, with a characteristic impedance of Zn (any real value); set the transmission line length L. 2n (must meet) (Operating frequency f = 7 GHz);

[0051] Calculate the wavelength: Where c is the speed of light (3 × 10⁻⁶) 8 m / s), ε r is the relative permittivity of the medium.

[0052] III. RF Switching: Controlling the RF switch to connect the target path n, the signal passes through the characteristic impedance Z. n

[0053] Length L 2n Transmission lines;

[0054] IV. Input impedance transformation calculation:

[0055] General transmission line input impedance formula: ;

[0056] (L 2n <1 / 2 wavelength)

[0057] Where β is the phase constant, j is the imaginary unit;

[0058] when hour

[0059] V. Steps for generating the Smith chart trajectory:

[0060] V.A. Path Selection:

[0061] The RF switch is switched to the nth path, with a characteristic impedance of Z. n ;

[0062] Set the transmission line length L 2n (The example takes λ / 4);

[0063] V.B. Normalized impedance calculation:

[0064] Normalized impedance calculation:

[0065] Normalized input impedance:

[0066] V.C. Calculation of trajectory circle parameters:

[0067] Center coordinates: Im(z c ) = 0;

[0068] radius of the trajectory circle:

[0069] V.D. Trajectory Equation:

[0070]

[0071] VI. Smith Chart Trajectory Analysis:

[0072] Case 1: Z n =50Ω;

[0073] (Fixed at the center of the Smith chart); Case 2: Z n >50Ω (such as Z1=70Ω, Z2=100Ω);

[0074] (The trajectory is located in the right half-plane and rotates clockwise); Case 3: Z n <50Ω (such as Z3=35Ω, Z4=25Ω);

[0075] (The trajectory is located in the left half-plane and rotates clockwise);

[0076] VII. Tuning Control Procedure:

[0077] VII.A. Impedance Target Location: Select the target impedance point Z on the Smith chart. target VII.B. Parameter Solving:

[0078] Solve the trajectory equation:

[0079] VII.C. Switch Control:

[0080] Control commands are sent to the digital control unit via the USB interface;

[0081] The voltage control module switches the RF switch to the target path n;

[0082] VII.D. Real-time verification:

[0083] The software interface displays the Smith chart positions of the measured impedance and the target impedance;

[0084] Impedance error tolerance: ΔZ ≤ ±2%.

[0085] Example 3

[0086] Building upon Example 2, this system adds a software interface, allowing users to visually view all possible impedance locations and select the desired impedance point with simple clicks. The system automatically adjusts the parameters of the impedance amplitude tuner and RF phase shifter based on the user's selection, achieving precise impedance adjustment. Furthermore, the device can be made available as an instruction code for third-party software systems to call and control it for other purposes, such as integrating it with a test script for greater intelligence and automation.

[0087] As can be seen from the above, by adding functionality to the software interface, users can intuitively view all possible impedance locations on the computer software interface and select the desired impedance point through simple clicks. This innovation greatly simplifies the user operation process and improves ease of use. At the same time, the system automatically adjusts the parameters of the impedance amplitude tuner and RF phase shifter according to the user's selection, achieving precise impedance adjustment. This not only improves tuning efficiency but also ensures the accuracy and consistency of tuning results, providing users with a more intuitive, efficient, and accurate impedance tuning experience.

[0088] Test case

[0089] I. To verify the basic functions of the RF impedance tuner, including the accuracy of impedance amplitude tuning and impedance phase tuning, as well as the interaction capability between the control unit and external computer software, the above-described embodiments were tested, with the following implementation steps:

[0090] Device connection: Connect the RF impedance tuner to an external computer via the USB port and connect it to a DC power supply.

[0091] Software startup: Launch the accompanying tuning software on the computer. The software interface displays the Smith chart.

[0092] Target impedance setting: Select a target impedance point on the software interface, such as 50Ω+j0Ω (pure resistance).

[0093] Automatic tuning: The control unit automatically matches the corresponding Z-axis based on the target impedance point. n L 2n and L 1n Parameters, and switch the RF switch to the specified transmission line combination.

[0094] As shown above, observing the changes in the impedance point on the software interface confirms whether the impedance point has accurately moved to the target position. Simultaneously, using a network analyzer to measure the actual impedance value verifies the accuracy of the tuning results.

[0095] II. To test the tuning capability of the RF impedance tuner under different load impedances, the above-described embodiment was tested, and the implementation steps are as follows:

[0096] Equipment preparation: Ensure that the RF impedance tuner is properly connected to the external computer and that the power is on.

[0097] Multi-target impedance setting: Select multiple representative target impedance points in sequence on the software interface, including low impedance (e.g., 25Ω), high impedance (e.g., 100Ω), and impedance points with a large reactance component (e.g., 50Ω + j30Ω).

[0098] Automatic tuning: For each target impedance point, the control unit automatically matches the parameters and switches the RF switch to complete the impedance tuning.

[0099] Pre-shipment calibration and after-sales calibration services: ensuring that every target impedance point is accurate.

[0100] Results Recording: Record the impedance point position after each tuning and compare it with the target impedance value.

[0101] As can be seen from the above, this RF impedance tuner can be accurately tuned to different target impedance points over a wide range, verifying its extensive tuning capability and high precision.

[0102] III. To test the stability of the RF impedance tuner under long-term operation, the test in this embodiment is conducted, and the implementation steps are as follows:

[0103] Equipment settings: Set the RF impedance tuner to continuous operation mode and set the target impedance point to a fixed value (e.g., 50Ω + j0Ω).

[0104] Long-term operation: Run the RF impedance tuner continuously for more than 24 hours, and record the impedance point position periodically (e.g., every hour).

[0105] Data analysis: Analyze the recorded data to assess the stability of the impedance point location.

[0106] As can be seen from the above, the RF impedance tuner can maintain the stability of the impedance point position during long-term operation, which verifies its high reliability and long-term stability.

[0107] The above embodiments will now be described in further detail with reference to the accompanying drawings.

[0108] like Figure 1 As shown, Figure 1 It refers to the overall appearance, consisting of a casing that covers the internal circuit board and components. The external interface includes RF port 1, RF port 2, USB port, and DC port. For example... Figure 2 As shown, Figure 2 This is a schematic diagram of the system architecture, which mainly consists of three parts: a control unit, an impedance amplitude tuner, and an RF phase shifter.

[0109] The first part is the digital control unit, which includes a voltage control module to control the switching of the RF switch, as well as a USB module and a power module. Its function is to allow users to conveniently operate impedance tuning through a pre-developed software interface via an external computer, reducing manual operation.

[0110] The second part is the impedance amplitude tuner, which consists of different characteristic impedances Z. n And different line lengths L 2n The purpose of integrating the transmission line with the RF switch is to change the impedance amplitude, whether by changing Z... n Or L 2n Both can change the magnitude of the impedance amplitude.

[0111] The third part is the impedance phase tuner, which can be implemented using a specific phase shifter, and there are multiple methods for this. Its function is to change the phase of the tuning impedance without changing the impedance amplitude. In this embodiment, a switch is used in conjunction with transmission lines of different lengths and characteristic impedances Z0 (=50 Ohm). However, this patent does not limit the scope of this method.

[0112] The operating principle of this invention (an impedance tuner) is described below. When an external device is connected to RF port 2, the load impedance is typically 50 Ohms, but this patent does not limit the scope of the invention. According to transmission line theory, the input impedance Zin2 can pass through various characteristic impedances Z of the impedance amplitude tuner. n And the line length L 2nThe transmission line transforms the impedance from 50 ohms to a specific complex impedance, whose impedance amplitude is not equal to 50 ohms and has a specific phase angle, such as... Figure 3 As shown.

[0113] Explanation: Impedance Z = r + jx = |Z|∠ψ = impedance amplitude and includes impedance phase angle.

[0114] The principle is that when the RF switch is switched to a certain characteristic impedance Z... n With line length L 2n When connecting a transmission line, the input impedance Zin2 will vary depending on the different characteristic impedances Z connected. n Different movement trajectories occur due to transmission lines. For example... Figure 4 As shown, with characteristic impedances Z1 = 70 Ohm, Z2 = 100 Ohm, Z3 = 35 Ohm, Z4 = 25 Ohm and its line length L 2n These are all examples using a frequency of 7 GHz and a wavelength (less than half the wavelength). Among them, Z... n With L 2n Both can be any real values, and are not limited to them in this embodiment. Due to the load impedance Z... L The impedance is 50 Ohms, and therefore, in a Smith chart with a system impedance of 50 Ohms, it is located exactly at the center of the Smith chart. When the transmission line length L is changed... 2n When the input impedance Zin2 moves along the trajectory of the dashed circle, as shown by the dashed circles Z1, Z2, Z3 and Z4 on the Smith chart.

[0115] First, when the characteristic impedance Z n When it equals 50 Ohms, regardless of how the line length L is changed... 2n Input impedance Z in_2 It will be close to the center point. And when Z n When the input impedance Z is greater than 50 Ohm, in_2 The movement trajectory will rotate clockwise from the center point of the Smith chart to the right half, as shown by the dashed circles marked Z1 and Z2 on the Smith chart. Conversely, when the characteristic impedance Z... n When less than 50 Ohm, the input impedance Z in_2 The movement trajectory will rotate clockwise from the center point of the Smith chart to the left half, as shown by the dashed circles Z3 and Z4 on the Smith chart.

[0116] Furthermore, the third part is the impedance phase tuner, or RF phase shifter, which needs to change the impedance phase without changing the impedance amplitude. There are multiple ways to design a phase shifter, and this embodiment is not limited to any particular method. One method can utilize an RF switch with multiple wires of different lengths L. 1n And a transmission line with characteristic impedance Z0 (=50 Ohm), such as Figure 5As shown, its working principle is as follows: when the RF switch is switched to a certain line length L of the shifter... 1n When the characteristic impedance Z0 (500 Ohm) is a transmission line, the input impedance Zin1 will be reduced by the output impedance Z. in_2 The position moves clockwise from the center point of the Smith chart. When L 1n The longer the length, the longer the path of movement. Here, L 11 ,L 12 ,L 13 These represent the lengths of different transmission lines. Their function is to allow the input impedance Zin_1 at each frequency to move clockwise around the system impedance of 50 Ohms (i.e., the center of the Smith chart), as shown by the dashed circle in the figure. When the line length L... 1n The longer the length, the greater the impedance Z at each frequency. in_1 The greater the distance traveled on the Smith chart, the longer the distance will be, such as Figure 6 As shown. Figure 6 As an example, and without limitation in this embodiment, it is based on a transmission line whose characteristic impedance Z2 (=100OHm) is switched to the previous stage impedance amplitude tuner and whose line length is exactly 7GHz wavelength (less than 1 / 2 wavelength) (impedance Z2 = 7GHz in the Smith chart). in_1 It will fall exactly in (100) 2 The position is 50 Ohm (the red dot on the rightmost real impedance line). The principle of impedance conversion for wavelengths less than half a wavelength is as follows: Z in_2 =(Z n 2 ) / ZL.

[0117] Finally, based on the desired application frequency and the number and relative positions of the impedance points, it is only necessary to use the characteristic impedance Z of the impedance amplitude tuner. n With L 2n Two variables, and different line lengths L of the phase shifter. 1n A transmission line can ensure that the impedances at the desired frequency are all aligned in a neat and uniform manner, such as... Figure 7 As shown, its working principle is: if the Z-axis of the impedance amplitude tuner... n Without restrictions, the phase can be adjusted arbitrarily by adding a phase shifter, resulting in any impedance position and applicability to all frequency points.

[0118] In actual operation, users can refer to the software interface displayed on the computer, such as... Figure 7 All impedance positions are available for user selection. Users simply need to select an impedance point on the diagram via computer, and the device will be automatically controlled and set to the corresponding correct impedance position before use.

[0119] In summary, this RF impedance tuner achieves automated and intelligent impedance tuning by integrating a control unit, impedance amplitude tuner, and impedance phase tuner, significantly improving tuning efficiency and accuracy. Its impedance amplitude tuner can precisely change the impedance amplitude by flexibly switching between transmission line combinations with different characteristic impedances and line lengths, while the impedance phase tuner can precisely adjust the impedance phase without changing the impedance amplitude, ensuring efficient and stable RF signal transmission. Furthermore, the control unit supports connection to an external computer via USB interface, enabling visual operation through a software interface, simplifying the user's workflow and improving the convenience and intuitiveness of the tuning process, making it particularly suitable for complex and variable RF environments.

[0120] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A radio frequency impedance tuner, characterized in that, include: The control unit, which includes a voltage control module, a USB module and a power module, is used to control the switching of the radio frequency switch via external computer software; An impedance amplitude tuner, consisting of multiple sets of different characteristic impedances Z n and different line lengths L 2n It consists of a transmission line and an RF switch, which switch different Z... n and L 2n Combining different impedance amplitudes; Impedance phase tuner, which consists of multiple sets of wires of different lengths L 1n It consists of a transmission line and an RF switch, used to adjust the impedance phase without changing the impedance amplitude; The control unit is electrically connected to the impedance amplitude tuner and the impedance phase tuner respectively to realize automated impedance tuning.

2. The radio frequency impedance tuner as described in claim 1, characterized in that: In the impedance amplitude tuner, Z n The value range is from 5Ω to 500Ω, L 2n The value is less than half the wavelength.

3. The radio frequency impedance tuner as described in claim 1, characterized in that: The characteristic impedance of the transmission line of the radio frequency phase shifter is 50Ω, L 1n The value is less than half the wavelength, and by switching different L... 1n The transmission line achieves phase adjustment.

4. The radio frequency impedance tuner as described in claim 1, characterized in that: The control unit supports connection to an external computer via USB interface and displays the position of the impedance point on the Smith chart in real time through a software interface, enabling visual operation.

5. The radio frequency impedance tuner as described in claim 1, characterized in that: The RF switches for the impedance amplitude tuner and the RF phase shifter are either PIN diode switches or MEMS switches, respectively.

6. The radio frequency impedance tuner as described in claim 1, characterized in that: The input impedance Z of the impedance amplitude tuner in_2 Satisfying the formula: Among them, Z L This is the load impedance.

7. The radio frequency impedance tuner as described in claim 1, characterized in that: The input impedance Z of the radio frequency phase shifter in_1 On the Smith chart, with 50Ω as the center, along the clockwise direction with L... 1n Increase and move.

8. The radio frequency impedance tuner as described in claim 1, characterized in that: The device's casing is equipped with an RF port, a USB port, and a DC power interface.

9. The radio frequency impedance tuner as described in claim 1, characterized in that: The software interface allows users to automatically trigger an RF switch to the corresponding Z-axis by clicking on the target impedance point in the Smith chart. n L 1n and L 2n combination.

10. A method of operating the radio frequency impedance tuner according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Select the target impedance point using external software; S2, The control unit matches the corresponding Z according to the target impedance point. n L 2n and L 1n parameter; S3. Switch the RF switch to the specified transmission line combination to complete impedance tuning.

Images