Communications: radio wave antennas – Antennas – Spiral or helical type
Reexamination Certificate
1994-10-25
2001-05-22
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
Spiral or helical type
C343S895000, C343S702000, C343S728000, C343S748000
Reexamination Certificate
active
06236378
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an antenna, comprising a first conductor having a length of substantially a quarter wavelength of electromagnetic waves to be transmitted and/or received by the antenna.
The invention further relates to a cordless telecommunication apparatus comprising an antenna, which antenna includes a first conductor having a length of substantially a quarter wavelength of electromagnetic waves to be transmitted and/or received by the antenna. A cordless telecommunication apparatus is understood to mean, for example, telecommunication apparatus exchanging information by means of radio links. Such cordless telecommunication apparatuses are, for example, a telephone operating according to the CT1 standard or a pager.
Known quarter wavelength antennas are the antennas used in cordless telephones manufactured by Hagenuk operating around 900 MHz. They consist of a PCB (Printed Circuit Board) on which a conductor functioning as an antenna is realised. The conductor consists of sections positioned in a first direction, connected to each other by means of sections positioned substantially perpendicular to the first direction. As a result, an antenna structure is obtained taking up rather much space in the first direction. Especially if such an antenna is to be accommodated in the housing of a cordless telephone or pager this is a drawback, because in view of the ever continuing miniaturization of such equipment it is desirable to keep the space to be used by the antenna as small as possible.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an antenna of the type defined in the opening paragraph, which is more compact than the antenna already known.
An antenna according to the invention is characterized in that the first conductor comprises a plurality of at least partly overlapping loops stretching out in a first direction seen from an antenna base. As a result, the antenna is more compact in the first direction than the antenna already known, so that less space for an antenna is needed in the housing of a cordless telephone or a pager. Measurements have shown that the performance of the antenna according to the invention is equivalent to that of the Hagenuk antenna. Furthermore, the antenna is rather insensitive to minor dimensional modifications. This leads to the fact that the antenna can easily be adapted to different requirements with respect to dimensions.
Therefore, an embodiment for the antenna according to the invention is characterized in that the antenna comprises a second conductor which is mirror-symmetrical relative to the first conductor, an axis of symmetry coinciding with the first direction.
A further embodiment for the antenna according to the invention is characterized in that the conductor is flexibly arranged freely. As a result, the antenna has a very simple structure.
A further embodiment for the antenna according to the invention is characterized in that the conductor is fixedly arranged, e.g. a printed circuit board. Since the overlapping loops are not to have any electrical contact, it is necessary for the printed circuit board to be double faced. The advantage of introducing the conductor on a printed circuit board is the large mechanical stability of the antenna.
A further embodiment for the antenna according to the invention is characterized in that the conductor is made of insulated copper wire. This is a very inexpensive conductor which has as an advantage, if the conductor is flexibly arranged, that has a result of the sturdiness of the material no auxiliary means are necessary to maintain the shape of the antenna.
REFERENCES:
patent: 2482767 (1949-09-01), Hansen
patent: 2755469 (1956-07-01), Etheridge
patent: 3235805 (1966-02-01), Hings
patent: 3757345 (1973-09-01), Carver
patent: 4137534 (1979-01-01), Goodnight
patent: 4780727 (1988-10-01), Seal
Phan Tho
U.S. Philips Corporation
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