Communications: radio wave antennas – Antennas – With vehicle
Reexamination Certificate
1999-06-07
2001-05-01
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With vehicle
C343S711000, C343S712000
Reexamination Certificate
active
06225954
ABSTRACT:
TECHNICAL FIELD OF INVENTION
The present invention relates generally to an antenna means for receiving and transmitting RF signals arranged for being mounted in a vehicle, for instance in a car. More specifically the present invention relates to an antenna means comprising a reflector means for receiving and transmitting RF signals arranged for being mounted in a vehicle.
DESCRIPTION OF RELATED ART
Operating hand-held radio communication devices in a motor vehicle may result in bad performance as the metallic plates in the roof, walls and the floor act as a radiation shield. There is also an increased risk that transmitted RF energy from the hand-held radio communication device may interact with other electronic equipment in the car through EMC (Electro-Magnetic Coupling). Recent research indicates that it would be beneficial to reduce SAR values for radiating equipment operated in a motor vehicle, especially in a car.
All these problems are a result of operating a radiating device inside a metallic cage. The motor vehicle acts as a metallic cage with the driver and passengers inside and the only way out for radiation being substantially through the windows. The electromagnetic radiation is held within the cage reflecting back and forth affecting electronic equipment and persons in the car.
Modern hand-held radio communication devices are capable of transmitting and receiving RF signals in more than one RF band or in a very broad RF band. An antenna device for receiving and transmitting RF signals in multiple bands is disclosed in the Swedish patent application SE-9801169-5 ‘WIDE BAND ANTENNA MEANS INCORPORATING A RADIATING STRUCTURE HAVING A BAND FORM’ assigned to the present assignee and which is hereby incorporated in the present application by reference. It is also a desirable characteristic of an antenna device to be small.
One solution to the problems with EMC in the compartment of a car is to position the radiating device outside the compartment, for instance with a separate antenna. The separate antenna may then be coupled to the hand-held radio communication device and secured, for instance, on the outside of the roof of the motor vehicle. Recent development indicates that car producers prefer to provide new models with antennas integrated in the car assembly. A connection may be provided for connecting the hand-held radio communication device to the integrated antenna.
Such arrangement are shown in, for instance the German gebrauchsmuster DE 296 06 475 which disclose a low profile antenna with a covering ground plane mounted for instance to a window. Such a low profile antenna is not suitable for receiving or transmitting RF signals in a broadband application or in multiple RF bands.
The German gebrauchsmuster DE 296 15 060 disclose radiating elements integrated in parts of a car, such as in a rear light or rear bumpers. No antenna means suitable for transmitting and receiving RF signals in multiple bands are disclosed.
It is beneficial to have the antenna as close as possible to the actual hand-held radio communication device so a minimum loss occur in the transfer of signals between the antenna and the circuitry of the hand-held device. Since the radio communication device is operated by a passenger or driver it would thus be beneficial to have the antenna in the passenger compartment, however this would then, according to the prior art, result in the problems described above.
SUMMARY OF INVENTION
The main object of the present invention is to provide a wide band antenna device integrated in a vehicle for receiving and transmitting RF signals, without transmitting electromagnetic radiation into the compartment of the vehicle.
The problems described, with how to achieve an antenna device for receiving and transmitting RF signals arranged to be mounted on a vehicle comprising an compartment, without transmitting electromagnetic radiation into the compartment of the vehicle and taking a limited amount of space are solved by providing a housing being transparent to RF radiation in at least on direction, the housing being arranged inside the compartment, the housing comprising means for suppressing RF radiation in substantially all directions facing substantially inwards the compartment of the motor vehicle seen from a radiating element being arranged in the housing.
The problems described above, according to a first embodiment of the invention, with how to achieve an antenna device for receiving and transmitting RF signals in multiple bands, which is integrated into a part of a vehicle, and arranged in the passenger compartment, without transmitting electromagnetic radiation into the compartment of the vehicle and taking a limited amount of space are solved by providing an broadband radiating element arranged in a housing, the housing having conductive surfaces on all sides facing substantially inwards the compartment of the motor vehicle seen from the radiating device and, at least one of the conductive surfaces being conductivly or capacitivly connected to a larger metal surface substantially covering at least one side of the compartment.
The housing constitutes a reflector reflecting RF energy, transmitted from the radiating element towards the compartment, outwards to the free air, thus increasing the efficiency of the antenna means as well as reducing the amount of radiation in the compartment of the car.
The problems described above, according to a second embodiment of the invention, are solved by further to the above providing a radiating element having a substantially accordion form.
An advantage with the present invention is that an antenna means integrated into a part of a motor vehicle, which is capable of receiving and transmitting RF signals in multiple bands, is achieved.
Another advantage according to a preferred embodiment of the invention is that the antenna device can be arranged inside the compartment of the vehicle.
Another advantage with the present invention is obtained by positioning the radiating device in a housing, which has conductive surfaces facing inwards the compartment, so that no electromagnetic radiation is transmitted into, and lost in, the compartment effectively eliminating EMC with other electronic equipment and substantially reducing SAR values for driver and passengers.
Yet another advantage with the present invention is that a better gain is achieved since no radiation is transmitted into the compartment.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 4229744 (1980-10-01), Luedtke et al.
patent: 5649316 (1997-07-01), Prudhomme et al.
patent: 6024382 (2000-02-01), Baumann
patent: 4403643 (1995-08-01), None
patent: 19530617 (1997-02-01), None
patent: 19616974 (1997-10-01), None
Edvardsson Olov
Hellgren Mattias
Jacobson Price Holman & Stern PLLC
Le Hoang-anh
SMARTEQ Wireless AB
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