Dual-frequency broadband negative group delay microwave circuit based on parallel coupling lines

Abstract

The invention discloses a double-frequency broadband negative group delay microwave circuit based on parallel coupling lines. The double-frequency broadband negative group delay microwave circuit comprises matching resistors, a first coupling resistor and a second coupling resistor, the matching microstrip line comprises an input matching microstrip line and an output matching microstrip line; the transmission microstrip line comprises an input transmission microstrip line and an output transmission microstrip line; the absorption resistor comprises a first absorption resistor and a second absorption resistor; one end of the first matching resistor is electrically connected with the input port, and the other end of the first matching resistor is electrically connected with one end of the connecting microstrip line through the first matching microstrip line; one end of the second matching resistor is connected with the output port, and the other end of the second matching resistor is electrically connected with the other end of the connecting microstrip line through the second matching microstrip line; one end of the connecting microstrip line is electrically connected with the first absorption resistor; the other end of the connecting microstrip line is also electrically connected with the second absorption resistor; the input end of the parallel coupling line is connected with the first absorption resistor through the input transmission microstrip line; the parallel coupling line isolation end is connected with the second absorption resistor through the output transmission microstrip line.

Description

Technical Field

[0001] The invention relates to a microwave circuit, in particular to a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines. Background Art

[0002] In recent years, negative group delay circuits have become a research hotspot. Unlike traditional microwave components, the transmission phase of negative group delay circuits within the working frequency band is proportional to the frequency. Therefore, negative group delay circuits can be cascaded with traditional microwave devices to achieve group delay flattening and thus compensate for the dispersion of the system. In addition, negative group delay circuits can also be used to construct non-Foster devices, improve amplifier performance, and improve beam squint in series-fed antenna arrays.

[0003] With the continuous deepening of the research on negative group delay circuits, scholars have proposed many new technologies to realize high-performance negative group delay circuits, such as lossy line technology, fusion filter theory, defective ground structure and interference technology, etc. However, these technologies only improve the performance of a single operating frequency and cannot adapt to the working requirements of multiple frequency bands.

[0004] In order to realize the dual-frequency characteristics of the negative group delay circuit, some scholars proposed a method of cascading two negative group delay circuits working at different frequencies to realize the dual-frequency characteristics. However, this multi-stage structure will lead to an increase in circuit size and attenuation. Later, some scholars used a multi-coupled line structure to realize the dual-frequency group delay characteristics. Other scholars have realized the dual-frequency negative group delay characteristics based on a dual-plane U-shaped defect ground structure. Although scholars have achieved certain results in the research of dual-frequency negative group delay circuits, there is a lack of circuits that can achieve flat negative group delay characteristics at two operating frequencies.

[0005] In view of this, it is necessary to propose a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines. Summary of the invention

[0006] In order to solve the above problems, the technical solution adopted by the present invention is:

[0007] A dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines, characterized in that it comprises: an input port, a matching resistor, a matching microstrip line, a connecting microstrip line, an output port, a parallel coupled line, a transmission microstrip line and an absorption resistor;

[0008] The matching resistor includes a first matching resistor and a second matching resistor;

[0009] The matching microstrip line includes an input matching microstrip line and an output matching microstrip line; the transmission microstrip line includes

[0010] An input transmission microstrip line and an output transmission microstrip line; the absorption resistor comprises a first absorption resistor and a second absorption resistor;

[0011] One end of the first matching resistor is electrically connected to the input port, and the other end of the first matching resistor is electrically connected to one end of the connecting microstrip line via the first matching microstrip line;

[0012] One end of the second matching resistor is connected to the output port, and the other end of the second matching resistor is electrically connected to the other end of the connecting microstrip line via the second matching microstrip line;

[0013] One end of the connecting microstrip line is also electrically connected to the first absorption resistor;

[0014] The other end of the connecting microstrip line is also electrically connected to the second absorption resistor;

[0015] The parallel coupling line input end is connected to the first absorption resistor via an input transmission microstrip line;

[0016] The parallel coupling line isolation end is connected to the second absorption resistor via an output transmission microstrip line.

[0017] Furthermore: the condition for achieving dual-frequency flat broadband negative group delay characteristics is that the electrical lengths of the matching microstrip line, connecting microstrip line, parallel coupling line and transmission microstrip line are all one-fourth of the wavelength corresponding to the circuit operating center frequency.

[0018] The operating frequency and the group delay value are further adjusted by changing the characteristic impedance of the transmission microstrip line; the group delay value and the flatness of the group delay are adjusted by changing the characteristic impedance of the connecting microstrip line and the parallel coupling line and the resistance value of the absorption resistor; and the port matching characteristics are adjusted by changing the characteristic impedance of the matching microstrip line and the resistance value of the matching resistor.

[0019] Furthermore, the reflection coefficient S of the circuit 11 for:

[0020]

[0021] The transmission coefficient S of the circuit 21 for:

[0022]

[0023] Group delay τ g for:

[0024]

[0025] Where: Z0 is the characteristic impedance of input port 1 and output port 5, ω is the frequency, and the other internal parameters are as follows:

[0026]

[0027]

[0028] The internal parameters are as follows:

[0029]

[0030] The internal parameters are as follows:

[0031]

[0032]

[0033] The internal parameters are as follows:

[0034]

[0035] Among them, A, B, C, D, A1, A2, A3, A4, A c , B1, B2, B3, B4, B c , C1, C2, C3, C4, C c , D1, D2, D3, D4, D c , Y 11 , Y 12 , Y 21 , Y 22 They are all intermediate variables, θ is the electrical length of the parallel coupled line, θ1 is the electrical length of the transmission microstrip line, θ2 is the electrical length of the connecting microstrip line, and θ3 is the electrical length of the matching microstrip line.

[0036] The invention provides a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines, which has the following advantages:

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] In order to realize a dual-frequency negative group delay microwave circuit while solving the problems of narrow negative group delay bandwidth at two operating frequencies, poor input and output port matching performance, and uneven group delay within the negative group delay bandwidth, the present invention provides a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines. The negative group delay microwave circuit of the invention can realize dual-frequency broadband flat negative group delay characteristics, and has the characteristics of small group delay fluctuation and good matching of input and output ports. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0040] Figure 1This is a schematic diagram of a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines of the present invention;

[0041] Figure 2 It is a group delay curve diagram of a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines of the present invention;

[0042] Figure 3 It is an S parameter curve diagram of a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines of the present invention;

[0043] In the figure: 1, input port, 2, matching resistor, 21, input matching resistor, 22, output matching resistor, 3, matching microstrip line, 31, input matching microstrip line, 32, output matching microstrip line, 4, connecting microstrip line, 5, output port, 6, parallel coupling line, 7, transmission microstrip line, 71, first transmission microstrip line, 72, second transmission microstrip line, 8, absorption resistor, 81, first absorption resistor, 82, second absorption resistor. DETAILED DESCRIPTION

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Figure 1 This is a schematic diagram of a dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines of the present invention;

[0047] A dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines comprises: an input port 1, a matching resistor 2, a matching microstrip line 3, a connecting microstrip line 4, an output port 5, a parallel coupled line 6, a transmission microstrip line 7, and an absorption resistor 8; the operating frequency and the group delay value are adjusted by changing the characteristic impedance of the transmission microstrip line 7; the group delay value and the flatness of the group delay are adjusted by changing the characteristic impedance of the connecting microstrip line 4 and the parallel coupled line 6 and the resistance value of the absorption resistor 8; and the port matching characteristics are adjusted by changing the characteristic impedance of the matching microstrip line 3 and the resistance value of the matching resistor 2.

[0048] The input port 1 and the output port 5 are resistance units that replace the port impedance in the actual processing during the simulation process, which not only meet the signal transmission requirements but also have a certain resistance value.

[0049] The matching resistor 2 includes a first matching resistor 21 and a second matching resistor 22;

[0050] The matching microstrip line 3 includes an input matching microstrip line 31 and an output matching microstrip line 32; the transmission microstrip line 7 includes an input transmission microstrip line 71 and an output transmission microstrip line 72; the absorption resistor 8 includes a first absorption resistor 81 and a second absorption resistor 82;

[0051] One end of the first matching resistor 21 is electrically connected to the input port 1, and the other end of the first matching resistor 21 is electrically connected to one end of the connecting microstrip line 4 via the first matching microstrip line 31;

[0052] One end of the second matching resistor 22 is connected to the output port 5, and the other end of the second matching resistor 22 is electrically connected to the other end of the connecting microstrip line 4 via the second matching microstrip line 32;

[0053] One end of the connecting microstrip line 4 is also electrically connected to the first absorption resistor 81;

[0054] The other end of the connecting microstrip line 4 is also electrically connected to the second absorption resistor 82;

[0055] The input end of the parallel coupling line 6 is connected to the first absorption resistor 81 via the input transmission microstrip line 71;

[0056] The isolation end of the parallel coupling line 6 is connected to the second absorption resistor 82 via the output transmission microstrip line 72 .

[0057] The resistance of the matching resistor 2 is R2,

[0058] The characteristic impedance of the matching microstrip line 3 is Z3,

[0059] The characteristic impedance of the connecting microstrip line 4 is Z2,

[0060] The odd-mode characteristic impedance of the parallel coupled line 6 is Z 0o , the even-mode characteristic impedance is Z 0e ,

[0061] The characteristic impedance of the transmission microstrip line 7 is Z1,

[0062] The resistance of the absorption resistor 8 is R1.

[0063] Furthermore, the condition for achieving dual-frequency flat broadband negative group delay characteristics is that the electrical lengths of the matching microstrip line 3, the connecting microstrip line 4, the parallel coupling line 6 and the transmission microstrip line 7 are all one-fourth of the wavelength corresponding to the circuit operating center frequency.

[0064] It also includes: adjusting the operating frequency and the group delay value by changing the characteristic impedance of the transmission microstrip line 7; adjusting the group delay value and the flatness of the group delay by changing the characteristic impedance of the connecting microstrip line 4 and the parallel coupling line 6 and the resistance value of the absorption resistor 8; and adjusting the port matching characteristics by changing the characteristic impedance of the matching microstrip line 3 and the resistance value of the matching resistor 2.

[0065] The reflection coefficient S of this circuit 11 for:

[0066]

[0067] The transmission coefficient S of the circuit 21 for:

[0068]

[0069] Group delay τ g for:

[0070]

[0071] Where: Z0 is the characteristic impedance of input port 1 and output port 5, ω is the frequency, and the other internal parameters are as follows:

[0072]

[0073]

[0074] The internal parameters are as follows:

[0075]

[0076] The internal parameters are as follows:

[0077]

[0078]

[0079] The internal parameters are as follows:

[0080]

[0081] Among them, A, B, C, D, A1, A2, A3, A4, A c , B1, B2, B3, B4, B c , C1, C2, C3, C4, C c , D1, D2, D3, D4, D c , Y 11 , Y 12 , Y 21 , Y 22They are all intermediate variables, θ is the electrical length of the parallel coupled line, θ1 is the electrical length of the transmission microstrip line, θ2 is the electrical length of the connecting microstrip line, and θ3 is the electrical length of the matching microstrip line.

[0082] Specific example: This example cites a dual-band broadband negative group delay microwave circuit based on parallel coupled lines when its central operating frequency is 0.85 GHz for illustration.

[0083] like Figure 2 As shown, the two operating frequencies of the flat broadband negative group delay microwave circuit based on parallel coupled lines described in the present invention are 0.3GHz and 1.4GHz respectively. The group delay value at the first operating frequency of 0.3GHz is -0.47ns, and the group delay is negative in the frequency range of 0.236GHz to 0.417GHz; in the frequency range of 0.266GHz to 0.363GHz, the fluctuation of the group delay is ±5%, achieving a broadband flat negative group delay characteristic.

[0084] The group delay value at the second operating frequency of 1.4GHz is -0.47ns, and in the frequency range of 1.283GHz to 1.464GHz, the group delay is negative; in the frequency range of 1.337GHz to 1.434GHz, the fluctuation of the group delay is ±5%, achieving a broadband flat negative group delay characteristic, thereby confirming the dual-band broadband characteristics of the negative group delay circuit.

[0085] like Figure 3 As shown, the experiment proves that at the first operating frequency of 0.3GHz and the second operating frequency of 1.4GHz, the signal attenuation of the dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines described in the present invention is 18.7dB, and the return loss of the input and output ports is 38.2dB. And in the flat negative group delay frequency range of 0.266GHz to 0.363GHz and 1.337GHz to 1.434GHz, the return loss of the input and output ports is greater than 17dB, indicating that the input and output ports have achieved good matching performance in a wider frequency range. At the same time, in the flat negative group delay frequency range of 0.266GHz to 0.363GHz and 1.337GHz to 1.434GHz, the maximum change of signal attenuation is less than 1.6dB, indicating that the insertion loss also has a broadband flat characteristic.

[0086] In summary, the dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines described in the present invention realizes the dual-frequency broadband flat negative group delay characteristics, and has the characteristics of small group delay fluctuation, good matching of input and output ports, and simple circuit structure and design method, and is very suitable for application in various radio frequency microwave systems.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines, characterized in that: include: Input port (1), matching resistor (2), matching microstrip line (3), connecting microstrip line (4), output port (5), parallel coupling line (6), transmission microstrip line (7) and absorption resistor (8); The matching resistor (2) comprises a first matching resistor (21) and a second matching resistor (22); The matching microstrip line (3) comprises an input matching microstrip line (31) and an output matching microstrip line (32); the transmission microstrip line (7) comprises an input transmission microstrip line (71) and an output transmission microstrip line (72); The absorption resistor (8) comprises a first absorption resistor (81) and a second absorption resistor (82); One end of the first matching resistor (21) is electrically connected to the input port (1), and the other end of the first matching resistor (21) is electrically connected to one end of the connecting microstrip line (4) via a first matching microstrip line (31); One end of the second matching resistor (22) is connected to the output port (5), and the other end of the second matching resistor (22) is electrically connected to the other end of the connecting microstrip line (4) via a second matching microstrip line (32); One end of the connecting microstrip line (4) is also electrically connected to a first absorption resistor (81); The other end of the connecting microstrip line (4) is also electrically connected to a second absorption resistor (82); The input end of the parallel coupling line (6) is connected to the first absorption resistor (81) via an input transmission microstrip line (71); The isolation end of the parallel coupling line (6) is connected to the second absorption resistor (82) via an output transmission microstrip line (72).

2. The dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines according to claim 1, characterized in that: The condition for achieving dual-frequency flat broadband negative group delay characteristics is that the electrical lengths of the matching microstrip line (3), the connecting microstrip line (4), the parallel coupling line (6) and the transmission microstrip line (7) are all one quarter of the wavelength corresponding to the circuit operating center frequency.

3. The dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines according to claim 1, characterized in that: The operating frequency and the group delay value are adjusted by changing the characteristic impedance of the transmission microstrip line (7); the group delay value and the flatness of the group delay are adjusted by changing the characteristic impedance of the connecting microstrip line (4) and the parallel coupling line (6) and the resistance value of the absorption resistor (8); and the port matching characteristics are adjusted by changing the characteristic impedance of the matching microstrip line (3) and the resistance value of the matching resistor (2).

4. The dual-frequency broadband negative group delay microwave circuit based on parallel coupled lines according to claim 1, characterized in that: The reflection coefficient S of this circuit 11 for: The transmission coefficient S of this circuit 21 for: Group delay τ g for: Where: Z0 is the characteristic impedance of the input port (1) and the output port (5), ω is the frequency, and the other internal parameters are as follows: The internal parameters are as follows: The internal parameters are as follows: The internal parameters are as follows: Among them, A, B, C, D, A1, A2, A3, A4, A c , B1, B2, B3, B4, B c , C1, C2, C3, C4, C c , D1, D2, D3, D4, D c , Y 11 , Y 12 , Y 21 , Y 22 They are all intermediate variables, θ is the electrical length of the parallel coupled line, θ1 is the electrical length of the transmission microstrip line, θ2 is the electrical length of the connecting microstrip line, and θ3 is the electrical length of the matching microstrip line.

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