CN103050754A - Microstrip line-coplanar stripline broadband transitional structure - Google Patents

Abstract

The invention relates to a broadband transition structure of microstrip line-coplanar stripline, which includes a microstrip line conduction strip, a coplanar stripline, a microstrip line floor, and a circuit substrate, wherein the microstrip line conduction strip is located on the circuit substrate On the front, the coplanar stripline and microstrip floor are integrally formed on the reverse side of the circuit substrate; the coplanar stripline and the microstrip conduction strips intersect vertically to form a three-dimensional vertical intersection; the microstrip conduction strips include sequentially set The input and output ports of the microstrip line, the transmission section of the microstrip line conduction band, the transition section of the limited ground microstrip line conduction band, the three-dimensional vertical intersection, the open end of the limited ground microstrip line guide band; the microstrip line floor is equipped with a limited ground microstrip Line floor transition section and finite microstrip line floor; one end of the coplanar stripline is the input and output port of the coplanar stripline, and the other end is the short-circuit end of the coplanar stripline. The broadband transition structure of microstrip coplanar stripline has the advantages of small size, compact circuit structure, and small high-frequency insertion loss.

Description

Microstrip-Coplanar Stripline Broadband Transition Structure

technical field

The invention relates to the technical field of microwave passive devices, in particular to a broadband transition structure of microstrip coplanar stripline.

Background technique

In the field of antennas, dipole antennas are balanced antennas, and dipole antennas need balanced transmission lines such as coplanar striplines for feeding. Coplanar stripline is a balanced single-sided transmission line, which has the advantages of small size and easy integration. At present, the most commonly used signal transmission line in microwave integrated circuit design is microstrip line, which is a kind of unbalanced transmission line, so we must perform the conversion between balanced and unbalanced transmission lines when designing integrated circuit systems. Based on this background, we need to design a broadband transition structure with low loss, small size, microstrip line and coplanar stripline.

The transition structure from microstrip line to coplanar stripline has been reported in the literature:

Document 1 (Y.Qian and T.Itoh, A broadband uniplanar microstrip-to-CPS transition, 1997Asia Pacific Microwave Conf.Dig., 1997: 609-612) realized the Transition structure from microstrip to coplanar stripline.

Document 2 (Y.-H.Suh and K.Chang, A wideband coplanar stripline to microstrip transition, IEEE Microwave Wireless Compon.Lett., 2001 (11): 28-29) from microstrip line to coplanar stripline The transition structure is realized based on the principle of field matching.

Document 3 (W.-H.Tu and K.Chang, Wide-band microstrip-to-coplanar stripline/slotline transitions, IEEE Trans. Microw. Theory Tech., 2006 (54): 1084-1089) uses Chebyshev transform The transition structure from the microstrip line to the coplanar stripline is realized by using a quarter-wavelength fan-shaped matching stub line and a quarter-wavelength sector.

(1) The three transition structures from microstrip line to coplanar stripline proposed in Documents 1, 2, and 3 have relatively large insertion loss at high frequencies.

(2) The transition structure from microstrip line to coplanar stripline in Documents 2 and 3 has the disadvantage of large size due to the use of field matching section and impedance matching section.

Contents of the invention

The object of the present invention is to provide a microstrip-coplanar stripline broadband transition structure with small size, compact circuit structure and low high-frequency insertion loss.

The technical solution for realizing the present invention is: a broadband transition structure of microstrip line coplanar stripline, including microstrip line conduction belt, coplanar stripline, microstrip line floor, circuit substrate, microstrip line conductor The strip and microstrip floor forms a microstrip line, where the microstrip conduction strip is located on the front side of the circuit substrate, and the coplanar stripline and microstrip line floor are integrally formed on the opposite side of the circuit substrate; the coplanar stripline and microstrip line The conduction bands intersect three-dimensionally and vertically, and the slots of the coplanar stripline and the conduction bands of the microstrip line form a three-dimensional vertical intersection.

The broadband transition structure of the coplanar microstrip line of the present invention, the microstrip line conduction band includes the microstrip line input and output ports, the microstrip line conduction band transmission section, and the limited microstrip line conduction band The transition section, the three-dimensional vertical intersection, the open end of the conduction band of the finite microstrip line; one end of the conduction band transmission section of the microstrip line is connected to the input and output ports of the microstrip line, and the other end is connected to the transition section of the finite microstrip line conduction band, The width is consistent with the input and output ports of the microstrip line; the transition section of the finite microstrip line is from the end connected to the transmission section of the microstrip line to the three-dimensional vertical intersection, and uniformly changes from wide to narrow; the finite microstrip line The open end of the conduction strip starts from the three-dimensional vertical intersection to the end of the conduction strip of the microstrip line.

The broadband transition structure of the microstrip coplanar stripline of the present invention, the coplanar stripline is located in the middle of the finite microstrip floor transition section and the finite microstrip floor, and is perpendicular to the finite microstrip line The floor transition section and the finite microstrip line floor, one end of the coplanar stripline is the input and output port of the coplanar stripline, and the other end after passing through the three-dimensional vertical intersection is the short-circuit end of the coplanar stripline.

The broadband transition structure of the microstrip line coplanar stripline of the present invention, the microstrip line floor is on the opposite side of the circuit substrate and along the same direction as the microstrip line conduction band: the microstrip line floor and the finite microstrip line The part vertically corresponding to the transition section of the conduction strip is set as the transition section of the finite microstrip line floor, and the part vertically corresponding to the open end of the conduction strip of the finite microstrip line is set as the finite microstrip line floor.

The microstrip-coplanar stripline broadband transition structure of the present invention, the finite microstrip conduction band transition section changes uniformly from wide to narrow from the microstrip conduction band transmission section to the three-dimensional vertical intersection, correspondingly The transition section of the finite microstrip line floor also gradually changes from wide to narrow.

The broadband transition structure of the microstrip line coplanar stripline of the present invention, the open end of the conduction belt of the finite microstrip line and the vertically corresponding finite microstrip line floor are all rectangular, and the finite microstrip line floor is three-dimensional The opposite direction of the vertical intersection extends straight to the edge of the circuit substrate.

Compared with the prior art, the present invention has significant advantages:

(1) The intersecting region of the present invention has the effect of mode conversion and impedance conversion, without using field matching section and impedance matching section;

(2) The structural size can be reduced, making the circuit simple and compact;

(3) It has the advantage of low insertion loss at high frequency.

Description of drawings

FIG. 1 is a schematic structural diagram of a broadband transition structure of a microstrip coplanar stripline according to the present invention.

FIG. 2 is a schematic diagram of the structural dimensions of Embodiment 1 of the broadband transition structure of the microstrip coplanar stripline according to the present invention.

FIG. 3 is an S-parameter simulation diagram of Embodiment 1 of the broadband transition structure of the microstrip coplanar stripline according to the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Referring to FIG. 1 , the front side of the circuit substrate is hatched with oblique lines, and the reverse side of the circuit substrate is hatched with dots. The microstrip-coplanar stripline broadband transition structure includes microstrip conduction strip 1, coplanar stripline 2, microstrip floor 3, circuit substrate 4, microstrip conduction strip 1 and microstrip line The floor 3 forms a microstrip line, wherein the microstrip conduction strip 1 is located on the front of the circuit substrate 4, and the coplanar stripline 2 and the microstrip floor 3 are integrally formed on the opposite side of the circuit substrate 4; the coplanar stripline 2 and the microstrip The stripline conduction strip 1 intersects three-dimensionally and vertically, and the slot 21 of the coplanar stripline 2 and the microstrip line conduction strip 1 form a three-dimensionally perpendicular intersection 5 .

In the broadband transition structure of the microstrip line coplanar stripline of the present invention, the microstrip line conduction band 1 includes a microstrip line input and output port 10, a microstrip line conduction band transmission section 11, a finite microstrip line Line conduction strip transition section 12, three-dimensional vertical intersection 5, finite ground microstrip line conduction strip open end 13; wherein one end of microstrip line conduction strip transmission section 11 is connected to microstrip line input and output port 10, and the other end is connected to finite ground microstrip line The strip line conduction band transition section 12 is connected, and the width is consistent with the microstrip line input and output port 10; the limited microstrip line conduction band transition section 12 is from the end connected to the microstrip line conduction band transmission section 11 to the three-dimensional vertical intersection 5, And it gradually changes from wide to narrow; limitedly, the open end 13 of the microstrip conduction strip starts from the three-dimensional vertical intersection 5 to the end of the microstrip conduction strip 1 .

The broadband transition structure of the coplanar microstrip line of the present invention, the coplanar stripline 2 is located in the middle of the finite microstrip line floor transition section 32 and the finite microstrip line floor 33, and is perpendicular to the finite ground Microstrip line floor transition section 32 and finite microstrip line floor 33, one end of the coplanar stripline 2 is the coplanar stripline input and output port 22, and the other end after passing through the three-dimensional vertical intersection 5 is the coplanar stripline Wire short-circuit terminal 23.

The broadband transition structure of the microstrip line coplanar stripline of the present invention, the microstrip line floor 3 is on the opposite side of the circuit substrate 4 and along the same direction as the microstrip line guide strip 1: wherein the microstrip line floor 3 and the limited The part vertically corresponding to the transition section 12 of the ground microstrip line is set as the transition section 32 of the finite microstrip line floor, and the part vertically corresponding to the open end 13 of the microstrip line floor 3 is set as the finite microstrip line. Wired floor33.

The broadband transition structure of the coplanar microstrip line of the present invention, the finite microstrip conduction band transition section 12 from the microstrip conduction band transmission section 11 to the three-dimensional vertical intersection 5 changes uniformly from wide to narrow, The corresponding finite microstrip line floor transition section 32 also gradually changes from wide to narrow.

In the broadband transition structure of the coplanar microstrip line of the present invention, the open end 13 of the conduction band of the finite microstrip line and its vertically corresponding finite microstrip line floor 33 are all rectangular, and the finite microstrip line floor 33 extends straight to the edge of the circuit substrate 4 in the direction opposite to the three-dimensional vertical intersection 5 . The three-dimensional vertical intersection 5 is close to the finitely grounded microstrip conduction strip open end 13 of the microstrip line conduction strip 1 , and is close to the coplanar stripline short-circuit end 23 of the coplanar stripline 2 .

The working process of the broadband transition structure of the microstrip line-coplanar stripline of the present invention is as follows: the electromagnetic signal enters the microstrip line 1 from the input and output port 10 of the microstrip line, passes through the conduction band transmission section 11 of the microstrip line, and finally passes through the limited microstrip line. The line conduction strip transition section 12 reaches the three-dimensional vertical intersection 5 , is coupled to the coplanar stripline 2 , and is transmitted to the coplanar stripline input and output port 22 along the coplanar stripline 2 . Similarly, when the electromagnetic signal enters the coplanar stripline 2 from the coplanar stripline input and output port 22, it is coupled to the microstrip line 1 through the three-dimensional vertical intersection 5, and along the finite microstrip line conduction band transition section 12, The conduction band transmission section 11 of the microstrip line is transmitted to the input and output port 10 of the microstrip line, which can also realize the transmission of electromagnetic signals. By adjusting the length of the open end 13 of the conduction strip of the finite microstrip line, the length of the short-circuit end 23 of the coplanar strip line, and the size of the transition section 32 of the floor of the finite microstrip line, the position and transition performance of the passband can be adjusted.

Structurally, the width of the input and output port 10 of the microstrip line is determined according to the impedance of the port, and is generally designed to be the width corresponding to a 50-ohm microstrip line. The line width and slot width of the coplanar stripline input and output port 22 are determined according to the port impedance, and are generally designed as the line width and slot width corresponding to the high characteristic impedance (such as 155 ohms), and the lines of other parts of the coplanar stripline 2 Width and slot width remain the same as for coplanar stripline ports. The coplanar stripline 2 and the microstrip line 1 form a three-dimensional vertical intersection 5, and the intersection angle is generally 90 degrees. The width of the microstrip conduction band at the three-dimensional vertical intersection 5 has a certain value in order to ensure the best energy coupling. Different from microstrip line input and output port 10. The width of the finite microstrip floor 33 and the width of the open end 13 of the finite microstrip conduction tape are kept consistent with the three-dimensional vertical intersection 5 . The finite microstrip line conduction strip transition section 12 changes uniformly from wide to narrow from the microstrip line conduction strip transmission section 11 to the three-dimensional vertical intersection 5, and the corresponding finite microstrip line floor transition section 32 also uniformly changes from wide to narrow , to ensure the impedance matching of the circuit.

In manufacturing, the circuit on the front side of the circuit board and the circuit on the back side are processed to form the required metal patterns through the printed circuit board manufacturing process.

The present invention will be further described in detail below in conjunction with specific embodiments.

Example 1

2 and 3, taking the microstrip-coplanar stripline broadband transition structure operating at 6.3-18GHz as an example, the circuit substrate 4 used has a relative dielectric constant of 2.33 and a thickness of 0.508mm. The characteristic impedance of the input and output port 10 of the microstrip line is 50 ohms, the width w1 of the input and output port 10 of the microstrip line is 1.55 mm, the characteristic impedance of the input and output port 22 of the coplanar stripline is 155 ohms, and the input and output of the coplanar stripline The line width w0 corresponding to the port 22 is 1 mm, and the slot width s is 0.2 mm. In order to couple the energy of the microstrip line 1 into the coplanar stripline 2 at the three-dimensional vertical intersection 5, the conduction strip width w4 of the microstrip line at the three-dimensional vertical intersection 5 is obtained as 0.9 mm by means of the simulation software HFSS. The length L0 of the floor transition section 32 of the finite microstrip line is 3.4 mm, and the width w2 is 5 mm and gradually gradually changes to the width w3 of 2.8 mm. The width w5 of the finite microstrip line floor 33 is 1.5mm.

The lengths of the open end 13 of the conduction tape of the finite microstrip line and the short-circuit end 23 of the coplanar strip line have the function of branch matching: the length L1 corresponding to the open end 13 of the conduction tape of the finite microstrip line is 4mm, that is, the 1/4 center The wavelength of the finite microstrip line waveguide corresponding to the frequency; the length L2 corresponding to the short-circuit end 23 of the coplanar stripline is 6 mm, and the wavelength of the coplanar stripline waveguide corresponding to 1/4 of the center frequency.

Fig. 3 is the S-parameter simulation diagram of the broadband transition structure of the microstrip line-coplanar stripline of this embodiment, as can be seen from the figure, in the 6.3-18GHz frequency band, the insertion loss is less than 3dB, and the reflection coefficient of the feed port is less than -13dB, the relative bandwidth is 96%, and it has the advantage of low high-frequency insertion loss.

Claims (6)

1. A broadband transition structure of microstrip-coplanar stripline, characterized in that it comprises microstrip conduction band (1), coplanar stripline (2), microstrip floor (3), circuit substrate (4), the microstrip line conduction strip (1) and the microstrip line floor (3) form a microstrip line, wherein the microstrip line conduction strip (1) is located on the front side of the circuit substrate (4), and the coplanar stripline (2 ) and the microstrip line floor (3) are integrally formed on the opposite side of the circuit substrate (4); The slot (21) forms a three-dimensional vertical intersection (5) with the microstrip conduction strip (1). 2. the broadband transition structure of microstrip line-coplanar stripline according to claim 1, is characterized in that: described microstrip line conduction band (1) comprises the microstrip line input-output port ( 10), microstrip line conduction band transmission section (11), finite microstrip line conduction band transition section (12), three-dimensional vertical intersection (5), finite microstrip line conduction band open end (13); One end of the strip line conduction band transmission section (11) is connected to the microstrip line input and output port (10), and the other end is connected to the finite microstrip line conduction band transition section (12), and the width is the same as the microstrip line input and output port (10) Consistent; the finite microstrip conduction band transition section (12) is from one end connected to the microstrip conduction band transmission section (11) to the three-dimensional vertical intersection (5), and uniformly changes from wide to narrow; finite microstrip The open-circuit end (13) of the line conduction strip starts from the three-dimensional vertical intersection (5) to the end of the microstrip line conduction strip (1). 3. The broadband transition structure of microstrip line-coplanar stripline according to claim 1, characterized in that: said coplanar stripline (2) is located at the limited microstrip line floor transition section (32) and the middle of the limited ground microstrip line floor (33), and perpendicular to the limited ground microstrip line floor transition section (32) and the limited ground microstrip line floor (33), one end of the coplanar stripline (2) is a common The other end of the stripline input and output port (22) passing through the three-dimensional vertical intersection (5) is the coplanar stripline short-circuit terminal (23). 4. The broadband transition structure of microstrip-coplanar stripline according to claim 1 or 2, characterized in that: the microstrip floor (3) is on the opposite side of the circuit substrate (4) and along the The same direction of the microstrip line guide strip (1): the part vertically corresponding to the microstrip line floor (3) and the finite microstrip line conduction strip transition section (12) is set as the finite microstrip line floor transition section (32) , the part of the microstrip line floor (3) vertically corresponding to the finite microstrip line conduction strip open end (13) is set as the finite microstrip line floor (33). 5. the broadband transition structure of microstrip line-coplanar stripline according to claim 4, is characterized in that: described finitely microstrip line conduction band transition section (12) is from microstrip line conduction band transmission section (11) to the three-dimensional vertical intersection (5) uniformly and gradually changes from wide to narrow, and the corresponding finite microstrip line floor transition section (32) also uniformly and gradually changes from wide to narrow. 6. The broadband transition structure of microstrip-coplanar stripline according to claim 4, characterized in that: said finite microstrip conduction band open end (13) and its vertically corresponding finite microstrip The line floors (33) are all rectangular, and the limited microstrip line floors (33) extend straight to the three-dimensional vertical intersection (5) to the edge of the circuit substrate (4).

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