Patent Description:
Waveguides are well known in the art for guiding electromagnetic waves, e.g., in the radiofrequency range, in a variety of apparatuses. The electromagnetic waves are often supplied to the waveguide from an emitter of electromagnetic waves coupled to a suitable electric circuit, which typically is located on a printed circuit board (PCB); an example of such waveguides can be found in <CIT>. The PCB in prior art is also used to close the waveguide on one side, which implies constraints for the PCB, as it has to correspond in size and shape to the waveguide. Furthermore, while a PCB has two opposite sides on which electronic components can be placed in principle, if the PCB is used to close the waveguide, placing electronic components on the side of the PCB towards the waveguide could interfere with the propagation of electromagnetic waves in the waveguide.

<CIT> discloses a waveguide device with a first and a second electrical conductor each having a throughhole. Electrically conductive waveguiding walls are positioned such that they include at least a portion of the space between the throughholes. The waveguiding walls allow an electromagnetic wave to propagate between the throughholes.

The article "<NPL> discloses a multi-layer waveguide structure.

<CIT> discloses a waveguide device module including plural waveguides and a circuit board. Applications in a vehicle are considered.

It therefore is an object of the invention to provide a waveguide assembly overcoming the above constraints.

This object is achieved by a waveguide assembly according to claim <NUM> or alternatively by a waveguide assembly according to claim <NUM>. Claim <NUM> relates to a corresponding radar sensor and claim <NUM> to a corresponding vehicle.

The waveguide assembly according to the invention includes a main waveguide comprising an arrangement of electrically conductive pins protruding from a basis and a circuit with an emitter for electromagnetic waves. The basis is of an electrically conductive material and may in particular be plate-shaped. The electrically conductive pins may be integral with the basis. A plate which is different from the basis and which comprises an electrically conductive material is positioned between the main waveguide and the emitter. The plate has an opening for electromagnetic waves from the emitter to pass through the plate. Furthermore, on a side of the plate opposite the main waveguide a group of electrically conductive pins is provided. The group of pins surrounds the emitter and the opening such that the group of pins forms a first transition waveguide for passing electromagnetic radiation from the emitter through the opening. The pins of the group of pins may for example be positioned such that their positions in a plane parallel to the plate trace out an open or closed polygon.

The plate closes the waveguide at least on one side, a function which in prior art was achieved by a PCB including the emitter. As the functions of closing the waveguide and carrying circuits, including the emitter, for addressing the waveguide, are now split between the plate and a separate component, like a PCB, this separate component is not subject to constraints imposed by the shape of the waveguide. Likewise, the waveguide is not constrained in shape by requirements of the prior art PCB. It is furthermore possible to independently choose suitable materials for plate and PCB or other circuit component. If a PCB is used for the circuits and emitter, as the PCB does not now close the waveguide, electronic components can be placed on opposite sides of the PCB, not just on one side of the PCB which is not towards the waveguide. The electromagnetic waves the emitter is configured to emit may for example be in the radiofrequency range or in the range of millimetre waves.

In one alternative of the invention the pins of the group of pins surrounding the emitter, i.e., the pins forming the first transition waveguide between the emitter and the plate, extend through the plate. On the side of the plate opposite the emitter, these pins can function as additional pins of the main waveguide. Alternatively, these pins can form part of a second transition waveguide located between the plate and the main waveguide. If there is a second transition waveguide, electromagnetic waves from the emitter, guided by the first transition waveguide, are passed through the opening in the plate into the second transition waveguide, and from there the electromagnetic waves are passed on into the main waveguide.

In another alternative of the invention the waveguide assembly includes an electrically conductive block, for example a metal block, attached to the pins of the group of pins surrounding the emitter. This stabilises these pins mechanically. The conductive block is positioned in a cut-out of the plate and extends to the side of the plate where there is the main waveguide.

In an embodiment the plate is connected to the conductive block via a structure including at least one step. This allows a more reliable bonding between the plate and the conductive block by, for instance, gluing, soldering, or welding and serves to define the position of the plate relative to the block in a more stable fashion. Also, such a structure reduces electromagnetic leakage from the waveguide assembly.

A second transition waveguide may be located between the plate and the main waveguide even if the pins of the first transition waveguide do not extend through the plate. If there is a second transition waveguide, electromagnetic waves from the emitter, guided by the first transition waveguide, are passed through the opening in the plate into the second transition waveguide, and from there the electromagnetic waves are passed on into the main waveguide.

For either alternative of the invention, in an embodiment the conductive material of the plate is a metal or a metallised plastic, i.e., a plastic substrate fully covered with a metal layer. The plate may also consist entirely of metal.

A radar sensor according to the invention has a waveguide assembly according to the invention, as described above. Such a radar sensor is less constrained in its manufacture, due to the reduced constraints on the manufacture of the waveguide assembly. This provides more freedom, for example for more efficient design.

A vehicle according to the invention has a radar sensor according to the invention, as just described. The advantages in manufacture of the radar sensor carry over to the manufacture of the vehicle. A more efficient radar sensor operates more efficiently in the vehicle and therefore contributes to safety.

Below the invention and its advantages will be described in more detail with reference to the accompanying schematic drawings.

The figures only show examples of how the invention can be implemented. In particular, the figures and the accompanying description are not to be taken as a limitation of the invention to the examples shown.

<FIG> shows an embodiment of the waveguide assembly <NUM> according to the invention. A main waveguide <NUM> with pins <NUM> protruding from a basis <NUM> is closed by an electrically conductive plate <NUM> on a side opposite to the basis <NUM>. A printed circuit board (PCB) <NUM> carries an emitter <NUM> for electromagnetic waves and has circuitry (not shown) for controlling the emitter <NUM>. Between the plate <NUM> and the PCB <NUM> a first transition waveguide <NUM> is provided for passing electromagnetic waves from the emitter <NUM> through an opening (not shown) in the plate <NUM> into the main waveguide <NUM>. The transition waveguide <NUM> has pins <NUM> which surround the emitter <NUM> at least partially.

The pins <NUM> extend through the plate <NUM> and on the side of the plate <NUM> opposite the PCB <NUM> function as additional pins of the main waveguide <NUM>.

<FIG> shows an embodiment of the waveguide assembly <NUM> according to the invention. The view here is a front view, i.e., electromagnetic waves in the main waveguide <NUM> travel in a direction orthogonal to the plane of the drawing. The main waveguide <NUM> has a basis <NUM> with pins <NUM>. On the side of basis <NUM> opposite pins <NUM> a second transition waveguide <NUM> with pins <NUM> is provided. Conductive plate <NUM> closes main waveguide <NUM> and second transition waveguide <NUM> on one side towards PCB <NUM>. A first transition waveguide <NUM> with pins <NUM> is provided between PCB <NUM> and plate <NUM>. PCB <NUM> carries an emitter <NUM> for electromagnetic waves, for example implemented as a microstrip patch. Electromagnetic waves from the emitter <NUM>, guided by first transition waveguide <NUM>, pass plate <NUM> through opening <NUM> in the plate <NUM> and reach the second transition waveguide <NUM>. From there, the electromagnetic waves are passed on into the main waveguide <NUM>. A cover <NUM> closes the main waveguide <NUM> at the side of the pins <NUM>. A conductive block <NUM> is provided between the basis <NUM> of the main waveguide <NUM> and the plate <NUM>, to stabilise pins <NUM> of the first transition waveguide <NUM>. The pins <NUM> are attached to block <NUM>. Block <NUM> extends into a cut-out <NUM> in the plate <NUM>.

<FIG> shows the waveguide assembly <NUM> shown in <FIG> in a side view. The direction of propagation of electromagnetic waves in the main waveguide <NUM> is parallel to the plane of the drawing. All elements shown have already been discussed in the context of <FIG>. It can be seen that the second transition waveguide <NUM> with pins <NUM> extends longer along the main waveguide <NUM> than the first transition waveguide <NUM> with pins <NUM>. Together with <FIG> it is also shown how the pins <NUM> of the first transition waveguide <NUM> surround the emitter <NUM> for electromagnetic waves.

<FIG> shows a portion of a waveguide assembly <NUM> according to the invention, seen from the side of the emitter <NUM> for electromagnetic waves. Emitter <NUM> is supplied with energy via supply line <NUM>. Pins <NUM> of the first transition waveguide <NUM> here surround emitter <NUM> on three sides, the positions of the pins <NUM> tracing out a rectangle open on one side, corresponding to a "U"-shape. Pins <NUM> are attached to a conductive block <NUM>, stabilising the pins <NUM> mechanically. On the other side of conductive plate <NUM>, from the perspective of the drawing behind plate <NUM>, is second transition waveguide <NUM> with pins <NUM>, part of which is also visible through opening <NUM> in plate <NUM>.

<FIG> shows a portion of a waveguide assembly <NUM> according to the invention, seen from the side of the emitter <NUM> for electromagnetic waves. Emitter <NUM> is supplied with energy via supply line <NUM>. Most of the structure shown is covered by the PCB <NUM>. Pins <NUM> of first transition waveguide <NUM> surround emitter <NUM> in a "U"-shape fashion as in the case of <FIG>. Shown also is opening <NUM> in plate <NUM>, for passing electromagnetic waves into second transition waveguide <NUM> with pins <NUM>. Conductive block <NUM> is partially inserted in a corresponding cut-out <NUM> of plate <NUM>. Also indicated is part of the main waveguide <NUM>.

<FIG> shows a portion of a waveguide assembly <NUM> according to the invention. Shown are pins <NUM> of the first transition waveguide, and conductive block <NUM> mechanically stabilising these pins <NUM>. Further shown are pins <NUM> of the second transition waveguide and basis <NUM> of main waveguide <NUM>. Also shown is plate <NUM>, however not in its mounted position. Arrows <NUM> indicate how plate <NUM> is to be set into recesses or steps <NUM> provided in conductive block <NUM> for increased robustness and mechanical stability of the assembly.

<FIG> show various possibilities of connecting the plate <NUM> to the conductive block <NUM>. The connection has to be electrically conductive and can for example be realised by welding, soldering or gluing. <FIG> shows a simple butt joint. <FIG> shows a profiled connection, more precisely a single step <NUM>. <FIG> shows a profiled connection, more precisely a double step <NUM>. Single step and double step provide additional stability due to their shape and increase the contact surface between plate <NUM> and block <NUM> available for, e.g., soldering, welding, or gluing. Furthermore, a profiled connection contributes to reducing electromagnetic leakage through the connection.

Claim 1:
Waveguide assembly (<NUM>) including
a main waveguide (<NUM>) comprising an arrangement of electrically conductive pins (<NUM>) protruding from a basis (<NUM>);
a circuit with an emitter (<NUM>) for electromagnetic waves;
a plate (<NUM>), different from the basis (<NUM>), the plate (<NUM>) comprising an electrically conductive material, the plate (<NUM>) positioned between the main waveguide (<NUM>) and the emitter (<NUM>),
the plate (<NUM>) having an opening (<NUM>) for electromagnetic waves from the emitter (<NUM>) to pass through the plate (<NUM>);
a group of conductive pins (<NUM>) on a side of the plate (<NUM>) opposite the main waveguide (<NUM>), the group of pins (<NUM>) surrounding the emitter (<NUM>) and the opening (<NUM>) such that the group of pins (<NUM>) forms a first transition waveguide (<NUM>) for passing electromagnetic radiation from the emitter (<NUM>) through the opening (<NUM>), wherein the pins (<NUM>) of the group of pins surrounding the emitter (<NUM>) extend through the plate (<NUM>).