CN111293395B

CN111293395B - Miniaturized coupler based on thin film medium

Info

Publication number: CN111293395B
Application number: CN202010212122.2A
Authority: CN
Inventors: 修威; 田海燕; 吴迪; 杨光
Original assignee: Beijing Huameta Technology Co ltd
Current assignee: Beijing Huameta Technology Co ltd
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2025-07-22
Anticipated expiration: 2040-03-24
Also published as: CN111293395A

Abstract

The present invention discloses a miniaturized coupler based on a thin film medium, which belongs to the field of microwave communication. The coupler includes a thin film medium; four branch microstrip lines located on one side of the thin film medium; and a slotted metal ground located on the other side of the thin film medium. Among them, the thickness of the thin film medium is less than 100um, and the side length of the coupler is less than 0.08 wavelengths. The coupler is formed by alternating two sizes of miniaturized 90° microstrip lines, which makes full use of the limited space and achieves a high space utilization rate. The present invention has the following three main advantages: ① A thin film medium high impedance transmission line design is proposed to increase the width of the thin film medium microstrip line and reduce the transmission loss; ② A thin film medium transmission line based on L-C oscillation is proposed to realize a miniaturized transmission line based on a thin film medium; ③ The staggered arrangement of coupling-through branches improves the space utilization rate and realizes the miniaturized design of the coupler. The present invention uses thin film media in the radio frequency field, which provides a new idea for the design of radio frequency systems in the fields of communication and radar.

Description

Miniaturized coupler based on thin film medium

Technical Field

The invention belongs to the field of microwave communication, and particularly relates to a miniaturized coupler based on a thin film medium.

Background

The rf coupler is an indispensable component in an rf system, and is used in various wireless communication fields such as 2/3/4/5G, wiFi/bluetooth, satellite communication, and the like, and is also widely used in various radar rf systems. The performance of the coupler has great influence on the performance of the radio frequency links connected before and after the coupler, and has important effect on the index of the whole radio frequency system.

With the pursuit of miniaturization by many communication products and radar products, each of the modules faces the problem of miniaturization, including a wide range of couplers. The current couplers used in the market can be basically divided into three types of cavity filters, PCB microstrip filters and LTCC technology filters, wherein the cavity filters and the PCB microstrip filters are large in size, and the requirements of miniaturization are difficult to achieve for high-frequency use. The filter produced by the LTCC technology is complex in design, increases manufacturing difficulty and is relatively high in cost.

In view of the above, the filter should be developed to have a lower production cost, a smaller size, and a simpler structure.

Disclosure of Invention

The aim of the invention is achieved by the following technical scheme.

In view of this, the present invention provides a miniaturized coupler based on thin film media.

The technical scheme of the invention is as follows:

Firstly, the invention provides a novel thin film medium transmission line, the working principle is that a gap is arranged on the metal ground below the microstrip line, the sensibility of the microstrip transmission line is increased, then metal branches are added on two sides of the microstrip line to increase the capacity of the transmission line, and L-C resonance under different frequency bands is realized by adjusting the gap and the branches, so that the length of the microstrip line is shortened, the width of the microstrip line is increased, on one hand, the size is reduced, and on the other hand, the transmission loss of the microstrip line is reduced. The present invention illustrates the advantages of such a transmission line with a coupler, and the microstrip line of this design is equally applicable to other radio frequency components. The miniaturized coupler based on thin film media of the present invention is specifically described below.

A miniaturized coupler based on thin film media comprises thin film media, which can be liquid crystal materials or ferroelectric thin film materials. One side of the film medium is slotted metal ground, and the other side is a branch microstrip line. In order to achieve better performance, the invention designs two miniaturized 90-degree microstrip lines which are sequentially connected to form a final miniaturized coupler, thereby achieving good matching, lower loss and improving the working efficiency.

The branch microstrip line increases transmission line inductance through floor slotting, increases transmission line capacitance through open-circuit branches, and finally achieves LC oscillation in a working frequency band, thereby achieving the purpose of miniaturization of the microstrip line.

The thin film medium is a core technical means used by the invention, the thickness of the medium in the embodiment of the invention is only 5um, compared with the traditional medium substrate, the thickness of the medium is reduced by 50-200 times, and the ultrathin characteristic of the medium is that the bright point of the invention is located.

The slotted metal ground is an etching gap designed on the whole metal ground and matched with the microstrip line on the other side. Forming an L-C oscillation.

All the components described above are designed in a space of 1.7mm by 1.7mm, with a total thickness of only 9um, so that such a coupler is easier to use, facilitating the design of the radio frequency system.

The beneficial effects of the invention are as follows:

Based on the thin film medium design, the thickness of the device is greatly reduced. The microstrip line is improved, the length of the 90-degree microstrip line is only 0.5mm, and compared with the conventional 90-degree microstrip line under the same medium, the microstrip line is 3.8mm, and the length is reduced to be less than 1/7 of the original length.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures.

In the drawings:

FIG. 1 is a front view of a miniaturized coupler of the present invention;

FIG. 2 is a side view of the miniaturized coupler of the present invention;

FIG. 3 is a first miniaturized 90 microstrip line pattern of the present invention;

FIG. 4 is a second miniaturized 90 microstrip line pattern of the present invention;

FIG. 5 is a schematic diagram of ports of a miniaturized coupler according to the present invention;

FIG. 6 is a miniaturized coupler port S parameter result of the present invention;

FIG. 7 is a graph showing the magnitude difference results for the miniaturized coupler 2, 3 ports of the present invention;

Fig. 8 shows the results of the phase difference values of the miniaturized coupler 2 and 3 ports according to the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The invention relates to a coupler, the working center frequency of which is 14GHz, the bandwidth is more than 500MHz, and FIG. 1 is a front view of a miniaturized coupler, and the miniaturized coupler comprises a coupler peripheral dimension 1, a surface circuit part 2 of the miniaturized coupler, a metal ground etching gap 3, a rectangular gap etched on the metal ground, and the miniaturized coupler interacts with the branch microstrip to form LC oscillation, and shortens the length of the microstrip.

Fig. 2 is a side view of the miniaturized coupler of the present invention, from top to bottom, with coupler metal layer 11 (i.e., surface circuit portion 2 of fig. 1), thin film dielectric layer 12, and metal layer 13.

The principle of the coupler is the same as the traditional directional coupler, and the coupler is formed by connecting four sections of 90-degree microstrip lines, the technical means for reducing the size of the coupler is to modify the 90-degree microstrip lines, and fig. 3 and 4 are two 90-degree microstrip lines of the coupler, and the coupler is specifically described below.

Fig. 3 is a first miniaturized 90 ° microstrip line structure, which is a double-branch and three-slot microstrip line structure, wherein the microstrip line widths wt1_1=0.29 mm at the two ends, the lengths and widths of the branches are respectively equal to each other, i.e., ll1=0.21 mm, wt1_2=0.7 mm, the spacing dis 1=0.035 mm between the two microstrip branches, the three slots are the same in size, and the lengths and widths are respectively equal to each other, i.e., sl1=0.5538 mm, sw1=0.02 mm.

Fig. 4 is a second miniaturized 90 ° microstrip line structure, which is also a double-branch and three-slot microstrip line structure, wherein the microstrip line widths wl2_1=0.18 mm at two ends, the lengths and widths of branches are respectively as ll2=0.18 mm, wl2_2=0.6 mm, the spacing dis 2=0.035 mm between two microstrip branches, the three slots are the same in size, and the lengths and widths are respectively as sl2=0.692 mm, sw2=0.02 mm.

The two miniaturized 90-degree microstrip lines are sequentially connected in a rotating mode to form the surface circuit 2 of the miniaturized coupler, so that the space utilization rate is maximized, and square-sized fields are fully utilized. Fig. 5 identifies four rf ports, input <1>, pass-through <2>, coupling <3> and isolation <4>, respectively. The subsequent results are all referenced to this port.

Fig. 6 shows the result of the coupler, S11 is a 1-port matching condition, and the in-band is below-18 dB, and the matching is good. S21 and S31 are transmission coefficients of pass-through end <2> and coupling end <3>, respectively, which are substantially the same and are both around-4 dB. S41 is port isolation, and the isolation is good within the band below-20 dB.

Fig. 7 shows that the amplitude difference between the through end <2> and the coupling end <3> of the miniaturized coupler of the thin film medium is kept within 0.05dB, and the consistency is good.

Fig. 8 shows the phase difference between the miniaturized coupler through-terminal <2> and the coupling terminal <3> of the thin film medium of the present invention, which varies within the range of 90 deg. + -1 deg..

The thin film medium used in the invention has the greatest advantages of thinness, thickness which is 50-200 times smaller than that of the traditional medium, obvious advantages of miniaturization and light weight of devices, capability of inhibiting generation of stray signals for high-frequency signals and pureness of useful signals. However, the physical strength is relatively weak, the risk of using the adhesive alone is high, and the adhesive should be attached to materials with high physical strength. With the continuous increase of the frequency band used in the communication field, the requirements on the size are more and more strict, and the thin film medium has more and more necessity for use.

The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A miniaturized coupler based on a thin film medium, comprising:

Thin film media;

Four sections of branch microstrip lines located on one side of the thin film dielectric; and

a slotted metal ground located on the other side of the thin film dielectric;

The slotted metal ground has slots designed and etched on the complete metal ground, which cooperates with the microstrip line on the other side to form L-C oscillation;

By setting a gap on the metal ground below the microstrip line, the inductance of the microstrip transmission line is increased, and then metal branches are added on both sides of the microstrip line to increase the capacitance of the transmission line. By adjusting the gap and branches, L-C resonance in different frequency bands can be achieved.

The branch microstrip line is a 90° branch microstrip line;

The four sections of branch microstrip lines include two sections of first branch microstrip lines and two sections of second branch microstrip lines;

The first branch microstrip line is a microstrip line structure with two branches and three gaps. The width of the microstrip line at both ends is wl1_1=0.29mm, the length and width of the branches are respectively: ll1=0.21mm, wl1_2=0.7mm, the distance between the two microstrip branches is dis1=0.035mm, and the three gaps are of the same size, and the length and width are respectively: sl1=0.558mm, sw1=0.02mm;

The second branch microstrip line is a microstrip line structure with double branches and three gaps. The width of the microstrip line at both ends is wl2_1=0.18mm, the length and width of the branches are: ll2=0.18mm, wl2_2=0.6mm, the spacing between the two microstrip branches is dis2=0.035mm, and the three gaps are of the same size, with length and width respectively: sl2=0.692mm, sw2=0.02mm.

2. A miniaturized coupler based on a thin film medium according to claim 1, characterized in that the thin film medium is a liquid crystal material or a ferroelectric thin film material, and has a thickness of less than 100 um.

3 . The miniaturized coupler based on thin film medium according to claim 1 , characterized in that the branches of the four-segment branch microstrip line are rectangular or fan-shaped.

4. A miniaturized coupler based on thin film dielectric according to claim 1, characterized in that:

The first branch microstrip line and the second branch microstrip line are rotated and connected in sequence to form a surface circuit of a miniaturized coupler.

5. A miniaturized coupler based on thin film dielectric according to claim 4, characterized in that:

The surface circuit is rectangular, the two first branch microstrip lines are located at the oblique intersection of the rectangle, and the two second branch microstrip lines are also located at the oblique intersection of the rectangle.

6. A miniaturized coupler based on thin film medium according to claim 4 or 5, characterized in that:

The surface circuit has four radio frequency ports, namely an input port, a through port, a coupling port and an isolation port.