Radar sensor with waveguide structure

Abstract

A radar sensor comprising a waveguide structure (14) and a high frequency component (12) disposed on opposite sides of a printed circuit board (10), and a coupling device (18) for transmitting microwave signals between the high frequency component (12) and the waveguide structure (14), the coupling device (18) having a dielectric waveguide (28) fabricated separately from the printed circuit board (10).

Description

Technical Field

[0001] The present invention relates to a radar sensor comprising a waveguide structure and a high-frequency component arranged on the opposite side of a printed circuit board, and a coupling device for transmitting a microwave signal between the high-frequency component and the waveguide structure.

[0002] In particular, the present invention relates to a radar sensor for motor vehicles for detecting the traffic environment, for example in a driving assistance system or an autonomous driving system.

Background Art

[0003] From German Patent No. 10 2006 019 054 B4, a radar sensor for motor vehicles is known, in which an antenna configuration for transmitting a radar signal and receiving a radar echo is formed by a waveguide structure, and the waveguide structure is connected to a high-frequency component via a coupling device. In this radar sensor, the waveguide structure and the high-frequency component are on the same side of the printed circuit board.

[0004] Radar sensors have also been proposed in which the waveguide structure and the high-frequency component are on the opposite side of the printed circuit board, and the coupling device has to transmit the microwave signal through the printed circuit board or around the printed circuit board. In such a case, the coupling device is formed, for example, through a hole passing through the printed circuit board, the inner surface of the hole can be optionally metallized, and the inside of the hole is filled with air or another dielectric material.

[0005] In this type of coupling device, the transmission characteristics are determined by the characteristics of the printed circuit board, particularly the thickness and material of the printed circuit board, or in the case of a multilayer printed circuit board, further by its internal structure. As long as the coupling device has a metallized surface, the metallization, particularly the surface roughness, also affects the transmission characteristics. Therefore, in order to achieve low-loss transmission of microwave signals between a high-frequency component and a waveguide structure, a special matching network is required. Since manufacturing tolerances are inevitable in the production of printed circuit boards, the design of the matching network is relatively complex.

[0006] When radar sensors are manufactured in various modified embodiments with different waveguide structures and / or different high-frequency components, it is usually necessary to adapt the printed circuit board and the coupling device formed thereon to each modified embodiment.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem of the present invention is to provide a radar sensor of the type described at the beginning that can more easily adapt the coupling device to other components.

Means for Solving the Problems

[0008] According to the present invention, this problem is solved by the coupling device having a dielectric waveguide manufactured separately from the printed circuit board. The dielectric waveguide is made of a dielectric material and is a conductor through which microwaves can propagate only inside the conductor by refraction and / or reflection.

[0009] Since this dielectric waveguide is not a component of the printed circuit board, even when the dielectric waveguide extends through a hole or opening in the printed circuit board, its waveguide characteristics do not depend on the characteristics of the printed circuit board. In this way, the susceptibility to the influence of tolerances in the production of printed circuit boards, metallized surfaces, etc. is considerably reduced.

[0010] On the one hand, the coupling to the waveguide structure and, on the other hand, the coupling to the high-frequency component can be optimized by appropriately selecting the geometry of the relevant end of the dielectric waveguide, thereby providing low-loss transmission without the need to make any changes to the printed circuit board. Furthermore, this dielectric waveguide provides greater design freedom with respect to the arrangement of the coupling positions of the waveguide structure and the high-frequency component.

[0011] Advantageous forms and developments of the invention are described in the dependent claims. When the dielectric waveguide passes through a hole in the printed circuit board, the waveguide can be held in the hole such that it is kept at a distance from the inner wall of the hole over its entire circumference by means of suitable fixing elements such as spring elements or clamp elements.

[0012] For example, when the high-frequency component has a BGA / eWLB housing with electrical contacts formed by solder balls, the coupling of the waveguide to the high-frequency component is effected non-contactly via the solder balls.

[0013] Alternatively, the waveguide may contact a solder ball or another contact surface of the BGA / eWLB. In this case, an elastic design of the fixing element is necessary to always ensure contact. Alternatively, the high-frequency component may have an integrated coupling position (radiator and / or antenna) on the surface or inside its housing. In this case, the dielectric waveguide can be arranged and guided so as to be directly coupled to this coupling position.

[0014] On the side of the waveguide structure, for example, coupling can be effected by the dielectric waveguide entering the open end of the waveguide. On both the side of the waveguide structure and the side of the high-frequency component, the dielectric waveguide may protrude considerably from the hole in the printed circuit board. This protruding section of the waveguide can optionally be angled or bent and extended, and thus can reach a coupling position of the waveguide structure or the high-frequency component further away from the hole in the printed circuit board.

[0015] Hereinafter, exemplary embodiments will be described in more detail with reference to the drawings.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0017] In FIG. 1, a part of a printed circuit board 10 (printed wiring board; PCB) of a radar sensor is shown in a cross-sectional view. A high-frequency component 12 is provided on one side (the lower side in FIG. 1) of the printed circuit board 10, and a waveguide structure 14 is provided on the opposite side. The high-frequency component 12 and the waveguide structure 14 are connected to each other via a coupling device 18 passing through a hole 16 of the printed circuit board 10, and a microwave signal generated by the high-frequency component 12 can be coupled to the waveguide structure 14. For example, the waveguide structure 14 may be a waveguide antenna that radiates a microwave signal. Conversely, a radar echo received by the waveguide antenna can be transmitted to the high-frequency component 12 via the coupling device 18 and further evaluated there.

[0018] In the illustrated example, the printed circuit board 10 has several parallel conductive layers 20 that connect various components of the radar sensor, not shown here, to each other. The waveguide structure 14 is disposed directly on the printed circuit board 10 and has a waveguide 22 for coupling to the high-frequency component 12. The waveguide 22 is aligned with a hole 16 in the printed circuit board and is open with respect to the printed circuit board 10.

[0019] The high-frequency component 12, for example an MMIC (monolithic microwave integrated circuit) or an SoC (system on chip), has a BGA / eWLB housing in the illustrated example, and this housing has a grid of solder balls 24 for contact and fixation to the printed circuit board 10. In the illustrated example, two of these solder balls 24 are in electrical contact with a shield 26, and the shield 26 surrounds the coupling device 18 at a distance.

[0020] The core part of the coupling device 18 is a pin-shaped dielectric waveguide 28. The dielectric waveguide 28 extends freely through the hole 16 in the printed circuit board 10 and is held in this hole so that its ends protrude into the waveguide 22 in a manner not shown in detail in FIG. 1. The opposite (lower) end is opposed to one of the solder balls 24 without contact, and a microwave signal is coupled to or decoupled from the waveguide 28 via the solder ball 24. The geometry of both ends of the dielectric waveguide 28 is adapted to the geometry of the waveguide 22 and the solder balls so that low-loss transmission of the microwave output is achieved.

[0021] An example of a possible method of fixing the dielectric waveguide 28 in the hole 16 of the printed circuit board 10 is shown in FIG. 2. In this example, the waveguide 28 is formed by two clamp elements 30 that face each other in the diametrical direction and a partial piece. The clamp elements 30 are in contact with the inner wall of the hole 16 and are connected to the main part of the waveguide via elastic webs 32. In this way, the waveguide 28 is positioned at the center of the hole 16 and is kept at a distance from the wall of the hole. The clamp elements 30 each have an insertion bevel at the lower end, which facilitates the insertion of the waveguide 28 into the hole 16. The clamp elements each have a stopper 34 at the opposite end, and the stopper 34 is placed on the surface of the printed circuit board 10 in the finally assembled state and determines the correct axial position with respect to the waveguide.

[0022] As can be seen in FIG. 3, the actual waveguide 28 has a rectangular cross-section in the illustrated example. The cross-section of the clamp element 30 and the contour of the elastic web 32 can also be seen in FIG. 3. However, alternative methods of fixing the dielectric waveguide 28 are also conceivable. For example, the waveguide can be fixed by filling the hole 16 with a filler having an appropriately selected dielectric constant that surrounds the waveguide.

[0023] FIG. 4 shows in perspective another exemplary embodiment of the coupling device 18'. The coupling device 18' passes through the hole 16' of the printed circuit board 10 and connects the waveguide structure 14 to a high-frequency component that is in a non-visible position below the printed circuit board 10 in FIG. 4. In this example, the waveguide structure 14 has a coupling position 36 that is arranged laterally on the side wall of the waveguide structure that extends perpendicular to the plane of the printed circuit board 10.

[0024] In this case, the core part of the coupling device 18' is also a dielectric waveguide 28' with a rectangular cross-section here. The dielectric waveguide 28' is a part that protrudes considerably from the hole 16', is angled at a right angle, and enters the coupling position 36 at the angled end.

[0025] Figs. 5 to 7 show examples of the coupling devices 18a, 18b, 18c, which are different from the coupling device 18 according to Fig. 1 by various coupling methods of the dielectric waveguide 28 to the high-frequency component 12.

[0026] In Fig. 5, the high-frequency component 12 is arranged on the printed circuit board 10 such that its edge protrudes from the hole 16 of the printed circuit board. On the side of the housing of the high-frequency component 12 facing the printed circuit board 10, an integrated coupling position 38 (radiator and / or antenna, or optionally direct contact) is formed at a position aligned with the hole 16 and faces the end of the dielectric waveguide 28.

[0027] In Fig. 6, the arrangement is selected such that the hole 16 is located outside the outer shape of the high-frequency component 12. In this case, the coupling position 38 is on the side wall of the high-frequency component, and the dielectric waveguide 28 has a coupling section 40 protruding from the hole 16 and is formed to face the coupling position 38 at an appropriate distance.

[0028] In Fig. 7, the coupling section 38 is on the side of the high-frequency component 12 opposite to the printed circuit board 10, and the coupling section 40 of the waveguide 28 extends around the edge of the high-frequency component 12.

Claims

1. A radar sensor comprising a waveguide structure (14) and a high-frequency component (12) arranged on the opposite side of a printed circuit board (10), and a coupling device (18; 18'; 18a-c) for transmitting a microwave signal between the high-frequency component (12) and the waveguide structure (14), wherein the coupling device (18; 18'; 18a-c) has a dielectric waveguide (28; 28') manufactured separately from the printed circuit board (10), the dielectric waveguide (28; 28') extends through holes (16, 16') in the printed circuit board (10), the radar sensor, characterized in that the dielectric waveguide (28) is fixed in the hole (16) by a clamping element (30).

2. A radar sensor comprising a waveguide structure (14) and a high-frequency component (12) arranged on the opposite side of a printed circuit board (10), and a coupling device (18; 18'; 18a-c) for transmitting a microwave signal between the high-frequency component (12) and the waveguide structure (14), wherein the coupling device (18; 18'; 18a-c) has a dielectric waveguide (28; 28') manufactured separately from the printed circuit board (10), the dielectric waveguide (28; 28') extends through holes (16, 16') in the printed circuit board (10), the dielectric waveguide (28') passes through the hole (16') in the printed circuit board (10) and has a section protruding from the hole (16') on the side of the waveguide structure (14), and the section bridges the distance between the hole (16') and the coupling position (36) of the waveguide structure (14), the radar sensor, characterized in that the section of the dielectric waveguide (18') protruding from the hole (16') is angled or bent.

3. A radar sensor comprising a waveguide structure (14) and a high-frequency component (12) arranged on the opposite side of a printed circuit board (10), and a coupling device (18; 18'; 18a-c) for transmitting a microwave signal between the high-frequency component (12) and the waveguide structure (14), wherein the coupling device (18; 18'; 18a-c) has a dielectric waveguide (28; 28') manufactured separately from the printed circuit board (10), The high-frequency component (12) has an integrated coupling position (38) for coupling to the dielectric waveguide (28), and one end of the waveguide (28) faces the coupling position. The radar sensor is characterized in that the coupling position (38) is on a side surface of the high-frequency component (12) extending perpendicular to the plane of the printed circuit board (10).

4. A radar sensor comprising a waveguide structure (14) and a high-frequency component (12) arranged on opposite sides of a printed circuit board (10), and a coupling device (18; 18'; 18a-c) for transmitting a microwave signal between the high-frequency component (12) and the waveguide structure (14), wherein the coupling device (18; 18'; 18a-c) has a dielectric waveguide (28; 28') manufactured separately from the printed circuit board (10). The high-frequency component (12) has an integrated coupling position (38) for coupling to the dielectric waveguide (28), and one end of the waveguide (28) faces the coupling position. The radar sensor is characterized in that the coupling position (38) is on a surface of the high-frequency component (12) opposite to the printed circuit board (10).

5. The radar sensor according to claim 1 or 2, wherein the dielectric waveguide (28; 28') is held in the hole (16; 16') of the printed circuit board (10) so as to have a distance from the inner wall of the hole (16; 16') over its entire circumference.

6. The radar sensor according to claim 1, wherein the clamping element (30) is connected to the waveguide (28) via an elastic web (32) and is clamped to apply prestress to the peripheral surface of the hole (16).

7. The high-frequency component (12) has a housing, the housing is fixed and in contact with the printed circuit board (10) by solder balls (24), and one of the solder balls (24) forms a coupling point for coupling to the dielectric waveguide (28), and one end of the dielectric waveguide (28) faces the solder ball. The radar sensor according to any one of claims 1 to 4.

8. The radar sensor according to claim 3 or 4, wherein the coupling position (38) is on a portion of the high-frequency component (12) facing the printed circuit board (10).

Images