Communications: radio wave antennas – Antennas – Balanced doublet - centerfed
Reexamination Certificate
2000-11-16
2001-11-27
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
Balanced doublet - centerfed
C343S795000, C343S822000, C343S876000
Reexamination Certificate
active
06323820
ABSTRACT:
The invention relates to a multiband antenna in accordance with the precharacterizing clause of claim
1
.
The mobile radio field is mostly dealt with over the GSM 900 network, that is to say in the 900 MHz range. In addition, the GSM 1800 standard has also become established, where signals can be received and transmitted in an 1800 MHz range.
For such multiband base stations, multiband antenna devices for transmitting and receiving various frequency ranges are therefore required which usually have dipole structures, that is to say a dipole antenna device for transmitting and receiving the 900 MHz band range and a further dipole antenna device for transmitting and receiving the 1800 MHz band range.
An antenna device known from the prior art is schematically shown in FIG.
1
.
Such a known antenna device comprises a common antenna input
1
which has a combiner circuit
3
arranged downstream of it on the antenna side, in order to permit appropriate decoupling of the signals transmitted in the various frequency ranges.
Arranged downstream of this combiner or branch circuit
3
are two branch lines
5
′ and
5
″ which are respectively connected to the first antenna device
7
′ and to the second antenna device
7
″ in order to use them to handle the radio traffic in the first and second band ranges.
To this end, the branch circuit
3
is provided with integrated frequency-selective components, for example of bandpass filter type, which cause each of the two branch lines
5
′ and
5
″ to reject the band range of the other antenna device.
The object of the present invention is to provide, on the basis of the prior art illustrated, a comparatively simple dual-band antenna which is of economical design.
The invention achieves the object on the basis of the features specified in claim
1
. Advantageous refinements of the invention are specified in the dependent claims.
It must be hailed as thoroughly amazing and surprising that it is possible to dispense with a conventional combiner or branch circuit. This is because the frequency-selective components, which are also required in accordance with the invention, need not be produced by separate components integrated in the combiner circuit, unlike in the prior art, but rather can, in accordance with the invention, be integrated in the antenna device itself.
The components concerned can be integrated in the antenna device merely as a result of an appropriate design for the balun and the relevant antenna device's effective electrical line length starting from the branch point, without requiring separate components for this, as in the prior art.
It has been found to be particularly beneficial to adapt the balun using shorting devices which can be incorporated between the balun. The size and arrangement of these shorting devices can be used to adapt the effective electrical length of the balun such that each frequency-selective component (for example of bandpass filter type) integrated in the relevant antenna device rejects, that is to say is operated as an open circuit for, the respective frequency of the second antenna device for the other frequency band range.
REFERENCES:
patent: 2619596 (1952-11-01), Kolster
patent: 2886813 (1959-05-01), Hings
patent: 5485167 (1996-01-01), Wong et al.
patent: 5977928 (1999-11-01), Ying et al.
patent: 6025811 (2000-02-01), Canora et al.
patent: 6211840 (2001-04-01), Wood et al.
patent: 963 794 (1956-11-01), None
patent: 37 14 382 (1989-11-01), None
patent: 0 823 751 (1998-02-01), None
patent: 0 887 880 (1998-12-01), None
Kathrein-Werke KG
Nixon & Vanderhye
Phan Tho
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