Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2002-10-02
2004-07-06
Nguyen, Hoang V. (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S846000
Reexamination Certificate
active
06759987
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns a device for sending and/or receiving radar beams, whereby at least one antenna is located on one side of a printed-circuit board, and electrical circuits are located on the other side of the printed-circuit board, and means for electromagnetically shielding the electrical circuits from the at least one antenna are provided.
Such a radar device was made known in WO 96/19737. Using the radar device described therein, objects enclosed in a wall or in the soil, for example, can be detected. To ensure that objects enclosed in a wall, such as steel reinforcements, current leads, water lines and the like, are protected against damage when holes are bored in a wall, for example, the craftsman should be provided with precise information about the location, i.e., the path position on the wall surface and the depth in the wall, of an enclosed object. As described in WO 96/19737 as well, a radar device is typically composed of a “front end”, i.e., a radar transmitting and receiving unit, and a display device. In the case of the front end disclosed in WO 96/19737, a transmitting antenna and a receive antenna are located on one side of a printed-circuit board, and electrical circuits are located on the other side of the printed-circuit board. The transmitting and receive antenna are developed as horn-like cavities in which loop-shaped wires are installed as radiating elements. An electromagnetic shielding of the electrical circuits on the side of the printed-circuit board opposite to the antenna is provided by means of the walls of the antenna horns that are attached to the side of the printed-circuit board opposite to the electrical circuits. The embodiment of the front end of a radar device described in the printed publication WO 96/19737 is relatively expensive in terms of production engineering, because it is composed of a large number of individual parts.
The invention is based on the object of providing a device for transmitting and/or receiving radar beams of the type mentioned initially, in which the shield between a transmitting and/or receive antenna and electrical circuits can be realized in a very space-saving fashion and using means that are very simple to carry out in terms of production engineering.
SUMMARY OF THE INVENTION
The object mentioned is attained in that a feeder network with which the at least one antenna is contacted and which is developed using a coplanar circuit technique is located on the antenna-side surface of the printed-circuit board and in that the connected-to-ground outer conductor of the coplanar circuit covers the antenna-side surface of the printed-circuit board to such an extent that the required shield between the antenna and the electrical circuits is produced as a result.
According to the invention, the feeder network required for the antenna simultaneously performs the function of electromagnetically shielding the antenna from the electrical circuits on the opposite of the printed-circuit board. Therefore, no additional means for electromagnetic shielding are required that would increase the production-engineering expense for the radar device and also occupy a corresponding amount of space in the device.
The feeder network is developed as a power divider, for example, having a port that is contacted with an electrical circuit on the side of the printed-circuit board opposite to the power divider, and having two further ports that are contacted with two connections of the at least one antenna.
The at least one antenna is preferably composed of a conductive plate acting as radiating element, which said plate is located at a distance above the printed-circuit board. In a very simple embodiment, the conductive plate of the antenna has at least one support that can be fixed in position on the printed-circuit board. It is particularly advantageous that the at least one support establishes an electrical connection between the conductive plate and the feeder network.
The printed-circuit board can be composed of a plurality of stacked dielectric layers having different dielectric constants, whereby the dielectric layer on which the feeder network and the antenna are located has a lower dielectric constant than the dielectric layer on which the electrical circuits are located. In the case of a multilayer printed-circuit board, the electromagnetic shielding can be further increased by situating a grounding conductor between two dielectric layers, which said grounding conductor is interconnected with the outer conductor of the coplanar feeder network via feedthroughs in the printed-circuit board. Likewise, a greater shield effect can be obtained by placing a grounding conductor on the side of the printed-circuit board equipped with the electrical circuits, which said grounding conductor is interconnected via feedthroughs in the printed-circuit board with the outer conductor of the coplanar feeder network and/or with one or more other grounding conductors located inside the printed-circuit board.
REFERENCES:
patent: 5764189 (1998-06-01), Lohninger
patent: 41 30 493 (1993-03-01), None
patent: 0 492 357 (1992-07-01), None
patent: 0 989 628 (2000-03-01), None
patent: 96/19737 (1996-06-01), None
Patent Abstracts of Japan vol. 018, No. 464 (E-1598), Aug. 29, 1994 & JP 06 152237 A, May 31, 1994.
Hasch Juergen
Irion Hans
Pfizenmaier Heinz
Schmidt Ewald
Nguyen Hoang V.
Striker Michael J.
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