Adjustable phase device based on microstrip line resonance structure

Abstract

The invention discloses an adjustable phase device based on a microstrip line resonant structure, which comprises a first resonator and a second resonator, and is characterized in that one end of the first resonator is connected with a first variable capacitance diode, and the other end of the first resonator is connected with a second variable capacitance diode; one end of the second resonator is connected with the third variable capacitance diode, and the other end of the second resonator is connected with the fourth variable capacitance diode; the first resonator and the second resonator are arranged in parallel, and a gap is formed between the first resonator and the second resonator for electromagnetic coupling; the midpoint of the first resonator is connected with a first bias resistor, and the midpoint of the second resonator is connected with a second bias resistor. The test result shows that the device can generate continuous phase deviation exceeding 100 degrees and the insertion loss change is less than 0.3 dB when the direct current bias voltage changes between 1.36 V and 1.57 V at a 380MHz working frequency point. The filter is compact in structure, easy to integrate, continuously adjustable in phase, extremely small in amplitude fluctuation and suitable for a modern communication system.

Description

Technical Field

[0001] This invention relates to the field of microwave radio frequency technology, and in particular to an adjustable phase device based on a microstrip line resonant structure, which is suitable for scenarios that require continuous and precise phase control at specific frequency points, such as phased array antennas, communication systems and radio frequency measurement devices. Background Technology

[0002] In modern communication systems, signal phase control is a key technology for achieving various functions, such as beamforming, frequency synthesis, and phase modulation, typically relying on devices like phase shifters and filters. A phase shifter is a device capable of adjusting the phase of a signal while maintaining its amplitude essentially constant, playing a crucial role in phased array radar, satellite communication, and microwave test systems. Phase shifters are mainly divided into two categories: digital and analog. Digital phase shifters provide discrete phase differences, while analog phase shifters enable continuous phase adjustment.

[0003] However, traditional analog phase shifters often suffer from problems such as complex structure, limited phase adjustment range, and large signal amplitude fluctuations during phase modulation. Specifically, many traditional designs employ complex resonator structures, resulting in large overall device sizes that are difficult to meet the miniaturization and integration requirements of modern communication equipment. Furthermore, some devices can only achieve limited discrete phase transitions during phase modulation, failing to achieve continuous phase tuning, which limits their use in applications requiring high phase accuracy. In addition, some devices, due to structural design or component characteristics, can cause significant amplitude fluctuations during phase modulation, affecting signal quality and system stability.

[0004] With the continuous development of communication technology, the performance requirements for microstrip line filter phase modulation devices are becoming increasingly stringent. To meet the demands of modern communication systems for miniaturization, high performance, and high-precision phase control, developing a compact, easily integrated, continuously adjustable phase microstrip line filter phase modulation device with minimal amplitude fluctuation is of significant practical importance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a microstrip line filter phase modulation device that is compact, easy to integrate, has a continuously adjustable phase, and has minimal amplitude fluctuation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An adjustable phase device based on a microstrip line resonant structure includes two half-wavelength open-ended transmission lines of the same size, which serve as a first resonator and a second resonator, respectively.

[0008] One end of the first resonator is connected to the cathode of the first varactor diode, and the other end is connected to the cathode of the second varactor diode; one end of the second resonator is connected to the cathode of the third varactor diode, and the other end is connected to the cathode of the fourth varactor diode; the anodes of the first varactor diode, the second varactor diode, the third varactor diode, and the fourth varactor diode are grounded.

[0009] The first resonator and the second resonator are arranged in parallel, with a gap provided for electromagnetic coupling.

[0010] Preferably, the midpoint of the first resonator is connected to a first bias resistor, and the midpoint of the second resonator is connected to a second bias resistor. The first bias resistor and the second bias resistor are respectively connected to the positive terminal of the same DC power supply.

[0011] Preferably, the resistance of the first bias resistor and the second bias resistor is greater than or equal to 100KΩ.

[0012] Preferably, the left side of the end where the first resonator is connected to the first varactor diode is connected to a first AC feed line, and a first DC blocking capacitor is provided in the middle of the first AC feed line; the right side of the end where the second resonator is connected to the third varactor diode is connected to a second AC feed line, and a second DC blocking capacitor is provided in the middle of the second AC feed line.

[0013] Preferably, the first AC feeder line serves as the radio frequency signal input terminal, and the second AC feeder line serves as the radio frequency signal output terminal.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] This invention employs two identical half-wavelength open-circuit transmission lines (a first resonator and a second resonator) arranged in parallel and electromagnetically coupled through a predetermined gap to form a second-order bandpass filter. This structural design facilitates compact device size and easy integration. By connecting varactor diodes to both ends of the resonator and changing the DC bias applied to the varactor diodes, their junction capacitance can be continuously adjusted, thereby changing the equivalent electrical length and center frequency of the resonator. This invention achieves continuous phase tuning at the target frequency, improving the flexibility and accuracy of phase tuning without altering the physical structure of the resonator. Throughout the phase tuning process, the change in insertion loss is less than 0.3 dB. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the tunable phase device based on the microstrip line resonant structure of the present invention.

[0017] Figure 2This is the equivalent circuit diagram of the tunable phase device based on the microstrip line resonant structure of the present invention.

[0018] Figure 3 The S21 amplitude response diagram of the tunable phase device based on the microstrip line resonant structure is shown under different DC bias conditions.

[0019] Figure 4 The image shows the S21 phase response of the tunable phase device based on the microstrip line resonant structure under the same DC bias conditions. Detailed Implementation

[0020] Example 1:

[0021] This embodiment provides a microstrip filter phase modulation device operating in the approximately 380MHz frequency band. For example... Figure 1 As shown, the tunable phase device based on a microstrip line resonant structure provided by this invention includes two half-wavelength open-circuit transmission lines of the same size, namely a first resonator and a second resonator. The two resonators are arranged in parallel and electromagnetically coupled through a predetermined gap, together forming a second-order bandpass filter.

[0022] The first resonator is connected to the cathodes of the first varactor diode VD1 and the second varactor diode VD2, respectively. The second resonator is connected to the cathodes of the third varactor diode VD3 and the fourth varactor diode VD4, respectively. The anodes of all varactor diodes are grounded through vias. By changing the DC bias voltage applied to the varactor diodes, their junction capacitance can be continuously adjusted, thereby changing the equivalent electrical length and center frequency of the resonator, ultimately achieving continuous phase tuning at the target frequency.

[0023] The center of the first resonator is connected to the positive terminal of a DC power supply via a first bias resistor R1; the center of the second resonator is connected to the same positive terminal of a DC power supply via a second bias resistor R2. This center point is at AC ground potential, ensuring that the resonator's resonance mode is not affected during DC bias. Both the first and second bias resistors are high-resistance resistors to achieve AC isolation of the radio frequency signal. In this embodiment, the resistance of both the first and second bias resistors is 100 kΩ.

[0024] A first AC feed line is connected to the top left side of the first resonator as the RF signal input terminal. A first DC blocking capacitor C1 is provided at the RF signal input terminal and placed in a slot in the middle of the first AC feed line. A second AC feed line is connected to the top right side of the second resonator as the RF signal output terminal. A second DC blocking capacitor C2 is provided at the RF signal output terminal and placed in a slot in the middle of the second AC feed line. The first DC blocking capacitor C1 and the second DC blocking capacitor C2 are used to prevent DC components from entering the external RF circuit. In this embodiment, their value is preferably 100 pF.

[0025] In this embodiment, the two half-wavelength open-circuit transmission lines are microstrip lines with a length of 33 mm, a width of 4.7 mm, and a thickness of 0.5 ounces, with a predetermined gap of 2.9 mm. The cathodes of four varactor diodes (SMV1236-004LF) are soldered to the ends of the two transmission lines, and the anodes are connected to the system ground plane through grounding vias.

[0026] Ignoring ohmic losses in the microstrip line, the AC equivalent circuit diagram of the microstrip circuit is as follows: Figure 2 As shown in the figure. L and C0 in the figure represent the equivalent parallel capacitance and inductance of a half-wavelength open-circuit transmission line; C in the figure... coup This is the coupling capacitance between the two half-wavelength open-circuit transmission lines. The input-output relationship of this circuit satisfies:

[0027]

[0028] in M=K+1, C=C0+2C VD. C VD This is the capacitance value of the varactor diode.

[0029] The phase response is:

[0030]

[0031] The tunable phase device based on the microstrip line resonant structure was tested, and the test results are as follows: Figure 3 and Figure 4 As shown. The results show that at a working frequency of 380 MHz, when the applied DC bias varies between 1.36 V and 1.57 V, the device can produce a continuous phase shift of more than 100°, while the change in insertion loss (i.e., amplitude fluctuation) is less than 0.3 dB throughout the phase modulation process.

[0032] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A tunable phase device based on a microstrip line resonant structure, comprising two half-wavelength open-circuit transmission lines of identical size, serving as a first resonator and a second resonator, respectively; characterized in that: One end of the first resonator is connected to the cathode of the first varactor diode, and the other end is connected to the cathode of the second varactor diode; one end of the second resonator is connected to the cathode of the third varactor diode, and the other end is connected to the cathode of the fourth varactor diode; the anodes of the first varactor diode, the second varactor diode, the third varactor diode, and the fourth varactor diode are grounded. The first resonator and the second resonator are arranged in parallel, with a gap provided for electromagnetic coupling.

2. The tunable phase device based on a microstrip line resonant structure according to claim 1, characterized in that: The midpoint of the first resonator is connected to a first bias resistor, and the midpoint of the second resonator is connected to a second bias resistor. The first bias resistor and the second bias resistor are respectively connected to the positive terminal of the same DC power supply.

3. The tunable phase device based on a microstrip line resonant structure according to claim 2, characterized in that: The resistance of the first bias resistor and the second bias resistor is greater than or equal to 100KΩ.

4. The tunable phase device based on a microstrip line resonant structure according to claim 1, characterized in that: The left side of the first resonator connected to the first varactor diode is connected to a first AC feed line, and a first DC blocking capacitor is provided in the middle of the first AC feed line; the right side of the second resonator connected to the third varactor diode is connected to a second AC feed line, and a second DC blocking capacitor is provided in the middle of the second AC feed line.

5. The tunable phase device based on a microstrip line resonant structure according to claim 4, characterized in that: The first AC feeder line serves as the radio frequency signal input terminal, and the second AC feeder line serves as the radio frequency signal output terminal.

6. The tunable phase device based on a microstrip line resonant structure according to claim 4 or 5, characterized in that: The capacitance values ​​of the first DC blocking capacitor and the second DC blocking capacitor are 100 pF.

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