Communications: radio wave antennas – Antennas – With grounding structure
Reexamination Certificate
1999-11-17
2001-04-24
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
With grounding structure
C343S713000
Reexamination Certificate
active
06222497
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an antenna device for a radio communication device, comprising a conductive first plate, having a first surface, being arranged to be connected to signal ground of the radio communication device; a conductive second plate, having first and second opposing edges partially limiting a second surface of the second plate, being arranged spaced apart from the first plate, the first and second surfaces facing each other; and a conductive grounding means interconnecting the first and second plates at least along a portion of the first edge of the second plate.
Especially it relates to an antenna device including a housing cover to be attached to a glass pane, e.g. a top portion of a wind screen or a back window of an automobile.
2. Related Art
WO-A1-97/44856 and EP-A1-0856907 disclose antenna devices of the type described in the first paragraph above. Those antenna devices are aperture-coupled planar antenna devices for mobile radio communication devices, e.g., hand-portable telephones. Antenna devices therein are fed by a feed conductor exciting an aperture, creating an electromagnetic field across the aperture. They can be made small and compact so as to fit in a mobile radio communication device, such as a hand-portable telephone. It is well known that the size of an antenna is critical for its performance (see Johnsson, Antenna Engineering Handbook, McGrawHill 1993, chapter 6). This can be expressed as a limitation of the product of the relative bandwidth (&Dgr;f/f) and the efficiency (&eegr;), which always is smaller than a constant multiplied by the efficient volume (V) of the antenna (as expressed in cubic wavelengths):
(&Dgr;
f/f
)&eegr;<constant(
V
/&lgr;
3
)
It is therefore important for small antennas that the available volume is effectively used.
Further it is disclosed through EP-A2-0 821 429, JP-A-10016646, EP-A2-0 841 715, and DE-A1-196 16 974 different solutions of how to accommodate an antenna device close to a glass pane or similar in an automobile. These antenna devices do not appear to be very efficient or they are of a complicated construction, which makes them complicated to manufacture. Further, they only provide single band operation.
SUMMARY OF THE INVENTION
It is an object of the invention to obtain an efficient antenna device, which is compact and with which the occupied space can be more efficiently used.
It is also an object of the invention to provide an efficient antenna device, which is compact and which can be adapted to efficiently use the available space.
It is a further object of the invention to provide an antenna device, which is suitable for cost effective production in large quantities.
These objects are attained by an antenna means according to the an antenna device for a radio communication device, comprising: a conductive first plate having a first surface and being arranged to be connected to signal ground of the radio communication device. There is a conductive second plate (
2
), having first (
21
) and second (
22
) opposing edges partially limiting a second surface (
2
b
) of the second plate (
2
), and being arranged spaced apart from the first plate (
1
). The first (
1
a
) and second (
2
b
) surfaces are facing each other. A conductive grounding means (
9
) interconnects the first and second plates (
1
,
2
) at least along a portion of the first edge (
21
) of the second plate (
2
), wherein a conductive third plate (
3
), having third (
33
) and fourth (
34
) opposing edges, is arranged between the first and second plates (
1
,
2
). The third plate (
3
) is provided with a feed portion (
35
), which is connected to circuitry of the radio communication device. In the invention, the received and transmitted signals in a first frequency band are capacitively coupled between the second (
2
) and third (
3
) plates, and the second plate (
2
) essentially performs the radiating function of the antenna device in the first frequency band. The third edge (
33
) is the edge of the third plate (
3
) arranged closest to the grounding means (
9
), and with a spacing therebetween.
The antenna device includes that the feed portion (
35
) is located in vicinity of the third edge (
33
).
The antenna device of the invention has the third plate (
3
) conductively connected to the first plate (
1
) at least along a portion of the fourth edge (
34
) of the third plate (
3
).
The antenna device of the invention has the third plate (
3
) arranged on the first plate (
1
) by means of a dielectric carrier (
6
), whereby a capacitive coupling between the third plate (
3
) and signal ground is achieved.
The antenna device of the invention has the first (
21
) and third (
33
) edges essentiall parallel.
The antenna device of the invention has the third plate located closer to the first plate (
1
) than to the second plate (
2
).
The antenna device of the invention has the third plate (
3
) fully overlapped by the second plate (
2
).
The antenna device of the invention has the third plate (
3
) connected, at an edge (
36
) between opposing ends of the third (
33
) and fourth (
34
) edges, to a conductive fourth plate (
4
), whereby it is achieved that the received and transmitted signals in a second frequency band are transmitted by the fourth plate (
4
) and the first plate (
1
).
The antenna device of the invention has the fourth plate (
4
) essentially not overlapped by the second plate (
2
).
The antenna device of the invention has the second frequency band at a center frequency approximately twice that of the first frequency band.
In the antenna device of the invention, the second plate.(
2
) is essentially rectangular, and the lengths of the first (
21
) and second edges (
22
), respectively, are smaller than the distance between said edges.
In the antenna device of the invention, the first (
1
) and second (
2
) plates are essentially parallel.
The antenna device of the invention has the first (
1
) and second (
2
) plates in essentially a plane, and that the planes of respective plate intersect at an angle ∝, where 0°(∝≦45°, and preferably 8°(∝≦25°.
The antenna device wherein ∝is about 10°.
The antenna device wherein the first (
1
), second (
2
), and third (
3
) plates are formed from one conductive sheet, and the first (
21
) and fourth (
34
) edges are formed by bent sections of said sheet.
The antenna device wherein the third plate (
3
) is cut out from a portion of the conductive sheet forming the first plate (
1
).
The antenna device wherein at least one of the conductive plates is provided with stabilizing longitudinal grooves.
The antenna device wherein a cover (
7
) is attached to at least one of the first plate (
1
), the second plate (
2
), or the conductive grounding means (
9
), and the cover (
7
) has one open side, possibly covered with a lid with the cover being arranged to be attached with the open side towards a glass pane (
8
) The antenna device wherein the cover (
7
) exhibits inner walls (
71
,
72
,
73
,
74
), whereof major portions are covered by a conductive ground surface.
The antenna device wherein at least two of the conductive plates are mechanically secured to each other with a predetermined spacing by means of at least one dielectric support.
By the features of the invention is also achieved an antenna means which can operate in a selected frequency band without complicated matching means.
By the features of the invention is also achieved a compact antenna device which has good directional performance and an advantageous gain.
By the features of the invention is also achieved an antenna means which is suitable for cost effective production in large quantities. The conductive portion of the antenna device can be manufactured by steps of stamping and bending, which are accurate processes through which improved mechanical tolerances are obtained.
By forming the plates of the antenna device from a conductive sheet, a stable antenna device, which is simple to manufacture is achieved.
By providing the antenna device wit
Hu Annika Yidong
Skogsfors Ola
Jacobson Price Holman & Stern PLLC
SMARTEQ Wireless AB
Wimer Michael C.
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