阅读说明：本技术 信号转换器和微带线-波导信号转换装置 (Signal converter and microstrip line-waveguide signal conversion device ) 是由 赵奂 虞强 于 2021-08-23 设计创作，主要内容包括：本申请公开一种信号转换器和一种微带线-波导信号转换装置,所述信号转换器包括：介质基板、信号传输结构,所述信号传输结构包括传输微带线、平衡-不平衡转换器、差分微带线和阻抗变换器；所述平衡-不平衡转换器连接所述微带线和所述差分微带线,所述平衡-不平衡转换器用于延迟所述传输微带线信号的相位；所述阻抗变换器一端与所述差分微带线连接,所述阻抗变换器用于将来自所述传输微带线和所述平衡-不平衡转换器的差分信号更好地传播至所述宽带馈源；所述宽带馈源与所述阻抗变换器远离所述微带线一端连接,所述宽带馈源用于将所述差分信号通过射频电流形式,向空间辐射电磁场信号。所述信号转换器能够降低插入损耗。(The application discloses signal converter and a microstrip line-waveguide signal conversion device, signal converter includes: the signal transmission structure comprises a transmission microstrip line, a balance-unbalance converter, a differential microstrip line and an impedance transformer; the balun is connected with the microstrip line and the differential microstrip line, and is used for delaying the phase of the transmission microstrip line signal; one end of the impedance transformer is connected with the differential microstrip line, and the impedance transformer is used for better propagating the differential signals from the transmission microstrip line and the balun to the broadband feed source; the broadband feed source is connected with one end, far away from the microstrip line, of the impedance converter, and the broadband feed source is used for radiating the electromagnetic field signals to the space in a radio frequency current mode. The signal converter can reduce insertion loss.)

1. A signal converter, comprising:

a dielectric substrate having opposing first and second surfaces;

a signal transmission structure on the first surface of the dielectric substrate, the signal transmission structure comprising:

a transmission microstrip line comprising a first port and a second port;

a balun including a first switching terminal and a second switching terminal, the first switching terminal being connected to the second port of the transmission microstrip line;

a differential microstrip line including a first differential line and a second differential line, one end of the first differential line being connected to the second port of the transmission microstrip line, and one end of the second differential line being connected to the second conversion end of the balun;

the impedance converter is connected between the differential microstrip line and the broadband feed source and used for realizing impedance conversion between the first differential line and the broadband feed source and between the second differential line and the broadband feed source.

2. The signal converter according to claim 1, wherein the balun is configured to perform phase delay conversion on the signal between the transmission microstrip line and the second differential line, so that the phase of the signal between the first differential line and the second differential line is different by 180 °.

3. The signal converter according to claim 2, wherein the balun comprises a meandering and unclosed microstrip line.

4. A signal converter as claimed in claim 3 wherein the balun has a microstrip length of half the wavelength corresponding to the operating centre frequency.

5. The signal converter according to claim 3, wherein the balun comprises a U-shaped microstrip line.

6. The signal converter according to claim 1, wherein the first differential line and the second differential line are disposed in parallel with a predetermined distance therebetween.

7. The signal converter of claim 1, wherein the impedance transformer comprises a first impedance transformation path and a second impedance transformation path; one end of the first impedance transformation channel is connected to the first differential line, and the other end of the first impedance transformation channel is connected to the broadband feed source; one end of the second impedance transformation channel is connected to the second differential line, and the other end of the second impedance transformation channel is connected to the broadband feed source.

8. The signal converter of claim 7, wherein the broadband feed is a planar patch structure having first and second opposing boundaries along its length, the first boundary being connected to the first and second impedance transformation channels; the broadband feed source is provided with a third boundary and a fourth boundary which are opposite in the width direction, and the third boundary and the fourth boundary are concave towards the inner side of the broadband feed source.

9. The signal converter of claim 8, wherein the third and fourth boundaries are symmetrically curved recesses inward of the broadband feed, and wherein the depth of the curved recesses is less than 1/5 of the maximum width of the broadband feed.

10. The signal converter of claim 8, wherein the first boundary is a distance from the second boundary of the wideband feed length L,wherein L is the length of the broadband feed source, lambda₀Is the wave guide wavelength, epsilon_rIs the dielectric constant of the dielectric substrate.

11. The signal converter of claim 1, further comprising: the first metal grounding patch, the second metal grounding patch and the metal via hole are arranged on the substrate; the first metal grounding patch is positioned on the first surface of the dielectric substrate, the second metal grounding patch is positioned on the second surface of the dielectric substrate, and the metal via hole penetrates through the dielectric substrate and is electrically connected with the first metal grounding patch and the second metal grounding patch; the first metal grounding patch is arranged around the two sides of the coplanar waveguide structure along the signal transmission direction and the periphery of the side where the broadband feed source is located, and a signal gap is formed between the first metal grounding patch and the coplanar waveguide structure.

12. The signal converter of claim 11, wherein a spacing between adjacent ones of said metal vias is less than 1/10 for a wavelength corresponding to a center operating frequency.

13. A microstrip line-waveguide signal conversion apparatus, characterized by comprising:

the signal converter of any one of claims 1 to 12;

the broadband feed source comprises a waveguide, wherein the waveguide is provided with a first waveguide port and a second waveguide port, the first waveguide port is arranged on the first surface of the signal conversion device, the broadband feed source is located in the coverage area of the first waveguide port, and the second waveguide port is used for being connected to a load.

14. The microstrip-waveguide transition device according to claim 13, wherein the waveguide is a rectangular waveguide, the first waveguide port and the second waveguide port are both rectangular, and the waveguide is orthogonally disposed on the first surface of the dielectric substrate; the first waveguide port is coincident with the outer edges of the signal slots around the broadband feed and the impedance transformer.

Technical Field

The application relates to the technical field of signal transmission, in particular to a signal converter and a microstrip line-waveguide signal conversion device.

Background

With the high-speed development of intelligent automobile technology, the requirements on the application technology of the automotive millimeter wave radar are higher and higher, and particularly the 4D imaging millimeter wave radar technology can assist an automobile in detecting the surrounding environment in the driving process and is of great importance for the development of automatic driving of the intelligent automobile.

The traditional radar antenna has the disadvantages of narrow bandwidth coverage, large standing wave, low efficiency, high cost of a high-frequency circuit board and the like, and cannot meet the automatic driving requirement of an automobile. The radar antenna is connected with the waveguide antenna through the microstrip-waveguide converter, and the traditional microstrip line waveguide converter adopts a structural design that a microstrip probe is inserted into a rectangular waveguide or a microstrip line and the rectangular waveguide are connected in series, so that the structure cannot be compact, the insertion loss is large, and the engineering technical requirements cannot be met.

Therefore, how to solve the transition matching between the transmitting and receiving end of the millimeter wave radar chip and the waveguide transmitting and receiving antenna and reduce the insertion loss is a problem which needs to be solved urgently at present.

Disclosure of Invention

In view of this, the present application provides a signal converter and a microstrip line-waveguide signal conversion apparatus to solve the problems of transition matching between the transmitting and receiving end of the existing millimeter wave radar chip and the waveguide transmitting and receiving antenna and reducing the insertion loss.

The present application provides a signal converter comprising: a dielectric substrate having opposing first and second surfaces; a signal transmission structure on the first surface of the dielectric substrate, the signal transmission structure comprising: a transmission microstrip line comprising a first port and a second port; a balun including a first switching terminal and a second switching terminal, the first switching terminal being connected to the second port of the transmission microstrip line; a differential microstrip line including a first differential line and a second differential line, one end of the first differential line being connected to the second port of the transmission microstrip line, and one end of the second differential line being connected to the second conversion end of the balun; the impedance converter is connected between the differential microstrip line and the broadband feed source and used for realizing impedance conversion between the first differential line and the broadband feed source and between the second differential line and the broadband feed source.

Optionally, the balun is configured to perform phase delay conversion on the signal between the transmission microstrip line and the second differential line, so that a phase difference between the signal between the first differential line and the second differential line is 180 °.

Optionally, the balun comprises a length of meandering and unclosed microstrip line.

Optionally, the microstrip length of the balun is half of the wavelength corresponding to the working center frequency.

Optionally, the balun comprises a U-shaped microstrip line.

Optionally, the first differential line and the second differential line are arranged in parallel, and a preset distance is provided between the first differential line and the second differential line.

Optionally, the impedance transformer includes a first impedance transformation channel and a second impedance transformation channel; one end of the first impedance transformation channel is connected to the first differential line, and the other end of the first impedance transformation channel is connected to the broadband feed source; one end of the second impedance transformation channel is connected to the second differential line, and the other end of the second impedance transformation channel is connected to the broadband feed source.

Optionally, the broadband feed source is of a planar patch structure, and a first boundary and a second boundary which are opposite to each other are arranged in the length direction of the broadband feed source, and the first boundary is connected to the first impedance transformation channel and the second impedance transformation channel; the broadband feed source is provided with a third boundary and a fourth boundary which are opposite in the width direction, and the third boundary and the fourth boundary are concave towards the inner side of the broadband feed source.

Optionally, the third boundary and the fourth boundary are symmetrically arc-shaped recesses towards the inner side of the broadband feed source, and the recess depth of the arc-shaped recesses is less than 1/5 of the maximum width of the broadband feed source.

Optionally, the distance from the first boundary to the second boundary is the broadband feed length L,wherein L is the length of the broadband feed source, lambda₀Is the wave guide wavelength, epsilon_rIs the dielectric constant of the dielectric substrate.

Optionally, the method further includes: the first metal grounding patch, the second metal grounding patch and the metal via hole are arranged on the substrate; the first metal grounding patch is positioned on the first surface of the dielectric substrate, the second metal grounding patch is positioned on the second surface of the dielectric substrate, and the metal via hole penetrates through the dielectric substrate and is electrically connected with the first metal grounding patch and the second metal grounding patch; the first metal grounding patch is arranged around the two sides of the coplanar waveguide structure along the signal transmission direction and the periphery of the side where the broadband feed source is located, and a signal gap is formed between the first metal grounding patch and the coplanar waveguide structure.

Optionally, the spacing between adjacent metal vias is smaller than 1/10 of the wavelength corresponding to the central operating frequency.

The present application also provides a microstrip line-waveguide signal conversion device, including: the signal converter of any of the above; the broadband feed source comprises a waveguide, wherein the waveguide is provided with a first waveguide port and a second waveguide port, the first waveguide port is arranged on the first surface of the signal conversion device, the broadband feed source is located in the coverage area of the first waveguide port, and the second waveguide port is used for being connected to a load.

Optionally, the waveguide is a rectangular waveguide, the first waveguide port and the second waveguide port are both rectangular, and the waveguide is orthogonally disposed on the first surface of the dielectric substrate; the first waveguide port is coincident with the outer edges of the signal slots around the broadband feed and the impedance transformer.

The signal converter comprises a medium substrate and a signal transmission structure; the signal transmission structure comprises a transmission microstrip line, a balance-unbalance converter, a differential microstrip line, an impedance converter and a broadband feed source which are sequentially connected, wherein a signal for driving the broadband feed source is derived from the differential microstrip line, the differential signal forms electromagnetic waves on the broadband feed source, the insertion loss can be reduced, and the structure of the signal transmission structure is compact.

Furthermore, the balun is configured to delay a phase of the transmission microstrip line signal by 180 degrees, and generate a differential signal with a phase difference of 180 degrees in the two differential lines, and the broadband feed source has a third boundary and a fourth boundary which are opposite in a width direction and are recessed toward an inner side of the broadband feed source, so that the electromagnetic signals can be gathered more and radiate toward a space perpendicular to the dielectric substrate. The differential signal can form electromagnetic field radiation on two arc edges, the direction of the radiation electromagnetic field is watermelon seed shape, and can be well matched with the rectangular waveguide cavity, thereby reducing insertion loss.

Further, the bandwidth of the electromagnetic signal can be adjusted by adjusting the arc radius of the arc-shaped recess of the broadband feed source.

The microstrip line-waveguide signal conversion device comprises the signal converter and the waveguide, can realize bidirectional transmission of receiving and transmitting signals in radar engineering and communication engineering application, has a simple structure, is suitable for batch product production, and has a wide working frequency range and a wide application range.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a signal converter according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a dielectric substrate of a signal converter according to an embodiment of the present application;

FIG. 3 is a cross-sectional end view of a signal converter according to an embodiment of the present application;

fig. 4 is a schematic diagram of a signal transmission structure of a signal converter according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of a balun of a signal converter according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of an impedance transformer of a signal converter according to an embodiment of the present application;

FIG. 7 is an equivalent circuit schematic diagram of an impedance transformer of the signal transformer of an embodiment of the present application;

FIG. 8 is a schematic diagram of a wideband feed of a signal converter according to an embodiment of the present application;

fig. 9 is a schematic structural diagram of a microstrip line-waveguide-signal conversion apparatus according to an embodiment of the present application;

fig. 10 is a schematic view of a waveguide structure of a microstrip line-waveguide signal conversion apparatus according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. The following embodiments and their technical features may be combined with each other without conflict.

The invention is more clearly and completely described by the following embodiments and the accompanying drawings.

Fig. 1 is a schematic diagram of a signal converter according to an embodiment of the invention.

In this embodiment, the signal converter includes a dielectric substrate 1 and a signal transmission structure 12, where the dielectric substrate 1 includes a first surface 101 and a second surface 102 (see fig. 2) opposite to each other, and the coplanar waveguide structure 12 is located on the first surface 101.

The dielectric substrate 1 is made of a material with good insulativity, strength and thermal conductivity. In one embodiment, the dielectric substrate 1 is an alumina ceramic having a thickness ranging from 10mm to 20mm, a room temperature flexural strength ranging from 300MPa to 310MPa, and a room temperature thermal conductivity ranging from 25W/m.k to 30W/m.k.

In other embodiments, the dielectric substrate 1 may be made of high frequency rogue plate, garnet ferrite, quartz high frequency plate, etc. as long as the dielectric material has certain strength and thermal conductivity.

The signal transmission structure 12 is a planar structure and can be formed by etching a metal layer formed on the surface of the dielectric substrate 1. The signal transmission structure 12 is used for transmitting electrical signals.

The signal transmission structure 12 comprises a transmission microstrip line 2, a balun 3, a differential microstrip line 4, an impedance transformer 5 and a broadband feed source 6 which are connected in sequence. Referring to fig. 4, fig. 4 is a schematic structural diagram of the signal transmission structure 12, so as to further describe the specific structure of the signal transmission structure 12 in detail.

The signal transmission structure 12 is a planar structure and is formed by microstrip lines with different shapes and functions, and the thicknesses of all parts are consistent and can be 0.1 mm-0.2 mm. In one embodiment, the thickness of the microstrip line of each portion in the signal transmission structure 12 is 0.127 mm.

The transmission microstrip line 2 includes a first port 201 and a second port 202. The design width of the transmission microstrip line 2 depends on the dielectric constant and the thickness of the dielectric substrate 1 within the operating bandwidth, and the relationship between the microstrip line width W and the impedance of the transmission microstrip line 2 can be derived from the following formula (1):

in the formula Z₀Is the conductor impedance of the transmission microstrip line 2, epsilon_rIs the dielectric constant of the dielectric substrate 1, W is the microstrip line width of the transmission microstrip line 2, T is the thickness of the transmission microstrip line 2, and H is the thickness of the dielectric substrate 1 (see fig. 3). The impedance of the transmission microstrip line 2 can be adjusted by adjusting the width of the transmission microstrip line 2.

In one embodiment, the characteristic impedance of the transmission microstrip line 2 wire is 50 ohms.

The waveguide wavelength lambda in the transmission microstrip line 2_gSatisfies formula (2):

in the formula (2), ε_rIs the dielectric constant, lambda, of the dielectric substrate 1₀Is the waveguide wavelength.

In the signal transmission structure 12, the microstrip lines of the other parts also satisfy the above-described operations (1) and (2).

The differential microstrip line 4 includes a first differential line 401 and a second differential line 402, one end of the first differential line 401 is connected to the second port 202 of the transmission microstrip line 2, and one end of the second differential line 402 is connected to the second port 202 of the transmission microstrip line 2 through the balun 3.

The signal from the transmission microstrip line 2 is converted into a differential signal by the balun 3, the signal is divided into two paths by power distribution from the second port 202 of the transmission microstrip line 2, one path passes through the balun 3 to the second differential line 402, the other path directly outputs the first differential line 401, and the two paths of signal power are equally distributed, but the balun 3 can delay the signal phase, so that the signal in the second differential line 402 and the signal in the first differential line 401 have a phase difference. In this embodiment, the balun 3 is configured to perform phase delay conversion on signals from the transmission microstrip line 2 to the second differential line 402, so that the phase of the signals between the first differential line 401 and the second differential line 402 is different by 180 °, so that a pair of differential signals is transmitted between the first differential line 401 and the second differential line 402.

The balun 3 includes a section of meandering and unclosed microstrip line, referring to fig. 5, in this embodiment, the balun 3 is a U-shaped microstrip line, and a signal slot 304 is provided between two transforming ends.

The center frequency of operation can be finely adjusted by adjusting the total length of the U-shaped portion of the balun 3, and specifically, the total length of the U-shaped portion can be adjusted to half the wavelength corresponding to the center frequency of operation by adjusting the heights of the two sides of the U-shaped portion. Compared with a circular balun, the U-shaped balun does not need a load resistor, the step of matching and debugging the load resistor is omitted, the line width and the line distance of the differential output end are adjusted, and the microstrip line impedance of the balun 3 can be adjusted.

The first differential line 401 and the second differential line 402 of the differential microstrip line 4 are two microstrip lines arranged in parallel, and a signal gap 403 is formed between the two microstrip lines.

In an embodiment, the width of the first differential line 401 and the width of the second differential line 402 are in a range of 0.2mm to 0.25mm, the width of the signal slot 403 between the first differential line 401 and the second differential line 402 is in a range of 0.1mm to 0.2mm, and the signal slot 403 of the differential microstrip line 4 is integrally connected to the signal slot 304 of the balun 3.

One end of the impedance transformer 5 is connected to one ends of the first differential line 401 and the second differential line 402, which are far away from the transmission microstrip line 2.

The impedance transformer 5 includes a first impedance transformation channel 501, a second impedance transformation channel 502 (see fig. 6), and a signal slot 503. The first impedance transformation path 501 and the second impedance transformation path 502 are microstrip lines of 1/4 wavelengths.

In this embodiment, the impedance transformer 5 is a stepped impedance transformer. Referring to FIG. 7, an equivalent circuit of the impedance transformer 5 is shown, in which the first and second impedance transformation channels each have a length of a quarter wavelength and an impedance of Z₁Of the transmission line, Z₀Is an input impedance, R_LAs the load impedance, the formula (3) is satisfied:

after obtaining Z1, the microstrip line width of the impedance transformer can be obtained by equation (1).

In an embodiment, the first and second impedance transformation channels of the impedance transformer 5 are both stepped, an included angle between the oblique side 504 of the first and second impedance transformation channels and the length direction of the impedance transformation channels is 45 ° to 60 °, and the signal slot 503 of the impedance transformer 5 is communicated with the signal slot 403 of the differential microstrip line 4 and the signal slot 304 of the balun 3.

In other embodiments, the impedance transformer 5 may also adopt impedance transformers with other structural types, as long as it can perform impedance transformation on signals in the differential microstrip line 4 for better transmission to the load broadband feed source 6.

Referring to fig. 1 and 8, the broadband feed source 6 is a microstrip patch, one end of the microstrip patch is connected to an impedance converter 5 having two channels, two differential signals output by the impedance converter 5 form radio frequency current on the broadband feed source 6, electromagnetic field signals are radiated to space, electromagnetic field transmission in the waveguide can be excited, and the electromagnetic field transmission direction is perpendicular to the plane of the broadband feed source 6.

In this embodiment, the broadband feed 6 has a first boundary 601 and a second boundary 602 opposite to each other in the length direction, and the first boundary 601 is connected to the first impedance transformation channel 501 and the second impedance transformation channel 502; the broadband feed 6 has a third boundary 603 and a fourth boundary 604 opposite to each other in the width direction, and the third boundary 603 and the fourth boundary 604 are concave towards the inner side of the broadband feed.

Further, the third boundary 603 and the fourth boundary 604 are symmetrically arc-shaped concave towards the inner side of the broadband feed source, so as to extend the working bandwidth.

The distance from the first boundary 601 to the second boundary 602 is the broadband feed length L, which can be estimated from equation (4):

wherein λ is₀Is the wave guide wavelength, epsilon_rIs the dielectric constant of the dielectric substrate.

The radiation resistance Rr of the broadband feed source 6 can be calculated according to the formula (5):

working bandwidth F of broadband feed source 6_WIt can be calculated according to equation (6):

wherein, W₁Is the width, W, of the broadband feed 6₂For a middle width, t/lambda, of the broadband feed 6₀The ratio of the thickness of the dielectric substrate to the free space wavelength is given in meters.

The depth S of the arc-shaped recess determines the resonant frequency bandwidth of the broadband feed source 6, and the larger S is, the wider the bandwidth is. Preferably, the depth of S is less than or equal to 1/5 of the width W1 of the broadband feed source 6, and if the arc-shaped recess is too deep, multipoint resonance can be caused, and the flatness in the band can be influenced. In engineering application, calculation can be performed by presetting W1-W2, and then adjusting the working bandwidth by adjusting the arc radius of the arc-shaped recess, that is, changing the width dimension of W2. When the working bandwidth is in the frequency band of 76GHz to 81GHz, in an embodiment, the arc depth S is 0.22mm, the arc of the arc opening is 1.4rad, and the arc radius is 0.65mm, and the flatness in the band is better.

Referring to fig. 1 and 3, the signal converter further includes a metal ground patch 7, including: a first metal ground patch 701, a second metal ground patch 702, and a metal via 8; the first metal ground patch 701 is located on the first surface 101 of the dielectric substrate 1, the second metal ground patch 702 is located on the second surface 102 of the dielectric substrate, and the metal via 8 penetrates through the dielectric substrate 1 and is electrically connected to the first metal ground patch 701 and the second metal ground patch 702; the first metal ground patch 701 is arranged around two sides of the signal transmission structure 12 along the signal transmission direction and the periphery of the side where the broadband feed source 6 is located, and a signal gap 10 is formed between the first metal ground patch and the signal transmission structure 12. The impedance of the microstrip line can be adjusted by adjusting the width of the signal slot 10 and the width of the microstrip line in the signal transmission structure 12, and the delay time of the signal in the microstrip line can be finely adjusted by adjusting the length of the microstrip line.

The first metal grounding patch 701 and the second metal grounding patch 702 are connected into a whole through the metal via hole 8 to generate an electromagnetic shielding field, so that transmission signals are gathered on the microstrip line more, and the transmission efficiency is improved.

And three sides of the broadband feed source 6 are surrounded with metal grounding patches to form a rectangular waveguide interface, so that the electromagnetic field radiated by the broadband feed source 6 is perpendicular to the dielectric substrate.

In one embodiment, the thickness of the conductive body of the first metal ground patch 701 and the microstrip line is 0.1mm to 0.2mm, preferably 0.127mm, and there is no requirement for the thickness of the second metal patch 702. The metal grounding patch can be made of metal materials such as copper and aluminum.

The metal vias 8 may be in a single row or multiple rows, and the spacing between adjacent metal vias 8 should be selected to be less than 1/10 center operating wavelength.

In the above embodiment, an input signal is sent to the first differential line 401 and the first conversion end 301 of the balun 3 through the transmission microstrip line 2 to generate two differential signals with a phase difference of 180 °, and the differential signals are transmitted to the impedance converter 5 through the differential microstrip line 4, and then transmitted to the broadband feed source 6 after impedance is adjusted by the impedance converter 5 to form a radio frequency current, so as to radiate an electromagnetic field signal to the rectangular waveguide space.

According to the law that distributed capacitance is formed between any two mutually insulated conductors with voltage difference, a distributed capacitance effect is generated between the broadband feed source 6 and the conductors of the first metal grounding patch 701 and the second metal grounding patch 702, the distributed capacitance can enable the impedance characteristic of the broadband feed source 6 to deviate from capacitive reactance, impedance matching is difficult, and signal transmission loss can be increased. And the inductive components of the differential microstrip line 4 and the impedance converter 5 can be used for offsetting the capacitive effect of the broadband feed source 6, thereby reducing the loss of signal transmission and reducing the difficulty of impedance matching.

Fig. 9 and fig. 10 are schematic diagrams of a microstrip-waveguide conversion apparatus according to an embodiment of the present invention.

In this embodiment, the microstrip-line waveguide conversion device includes a signal converter 9 and a waveguide 10.

The signal converter 9 is as described in the above embodiments, and is not described herein again.

In this embodiment, the waveguide 10 transmits the electromagnetic field signal generated by the signal converter 9 to a load.

The waveguide 10 is orthogonally disposed on the dielectric substrate 1, and the waveguide 10 may be formed by processing a conductor with good conductive efficiency, such as aluminum, copper, silver, or the like, or may be formed by a plastic structure and a surface silver plating process, and has a first waveguide port 1001 and a second waveguide port 1002. The first waveguide port 1001 of the waveguide 10 coincides with a signal slot around the broadband feed 6, and the second waveguide port 1002 is used for connecting to a load end, specifically, the second waveguide port 1002 may be connected to a waveguide antenna port, and the second waveguide port 1002 may be a part of a waveguide antenna. In this embodiment, the waveguide 10 is a rectangular waveguide, and the first waveguide port 1001 and the second waveguide port 1002 are both rectangular.

The overlap ratio of the first waveguide port 1001 of the waveguide 10 and the signal gap around the broadband feed source 6 determines the transmission efficiency of the electromagnetic field signal, and the processing precision should be kept within 0.015 mm in engineering application. In one embodiment, when the broadband antenna operates in a frequency band of 76GHz to 81GHz, the signal slot 100 on both sides of the transmission microstrip line 2 is designed to be 0.115 mm, and the signal slot around the impedance transformer 5 and the broadband feed source 6 is consistent with the inner diameter of the waveguide.

The working bandwidth of the device can be adjusted by adjusting the position of the broadband feed source 6 in the first waveguide port 1001, in this embodiment, the inner diameter of the first waveguide port is 1.353mm wide and 2.706mm long, and when the broadband feed source 6 is deviated to the signal input end by 0.2mm in the plane of the waveguide port, the working bandwidth of the device is greater than 5GHz, and the device works in a frequency band from 76GHz to 81 GHz.

The above rotating device can be used for bidirectional transmission of signals, except that signals are input from the transmission microstrip line 2 and output from the broadband feed source 6 to the waveguide 10, electromagnetic waves can be input from the second waveguide port 1002, an electric field in the waveguide is coupled to the broadband feed source 6 after reaching the first waveguide port 1001, the broadband feed source 6 outputs two paths of signals with opposite phases and then reaches the differential microstrip line 4 through the impedance transformer 5, and the differential signals are connected to the balun 3 and converted into single-ended unbalanced signals which are transmitted to the transmission microstrip line 2.

The signal conversion device can be applied to the conversion of a transmission circuit between a waveguide to a microstrip line in a millimeter wave band and between the microstrip line and the waveguide, can also be applied to a conversion element between the microstrip line and the waveguide of a millimeter wave band measuring device, and is particularly suitable for a feed conversion structure between the microstrip line and a waveguide antenna array of a millimeter wave radar. The bidirectional transmission of the receiving and transmitting signals in the radar engineering and communication engineering application can be realized, the structure is simple, the mass production is suitable, the working frequency range is wide, and the application range is wide.

The above-mentioned embodiments are only examples of the present application, and not intended to limit the scope of the present application, and all equivalent structures or equivalent flow transformations made by the contents of the specification and the drawings, such as the combination of technical features between the embodiments and the direct or indirect application to other related technical fields, are also included in the scope of the present application.