Telecommunications – Transmitter and receiver at same station – Having particular housing or support of a transceiver
Reexamination Certificate
1999-08-06
2001-11-06
Legree, Tracy (Department: 2681)
Telecommunications
Transmitter and receiver at same station
Having particular housing or support of a transceiver
C343S702000
Reexamination Certificate
active
06314276
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a transmitter-receiver for at least two frequency ranges, in which at least one antenna arrangement is provided for each frequency range.
Furthermore, the invention relates to a mobile radiotelephone including such a transmitter-receiver.
BACKGROUND OF THE INVENTION
Transmitter-receivers for at least two different frequency ranges are used, for example, for cordless telephones or in the mobile radio domain. The various frequency ranges then relate to, for example, the transmission frequency band and reception frequency band.
FIG. 1
shows a circuit diagram of a transmitter-receiver in a mobile radiotelephone. An antenna
1
is used then for transmitting and receiving data. To avoid a transmit signal ending up in the receiver channel
2
, the transmitter channel
3
and the receiver channel
2
are to be separated. For this purpose, a duplex filter
4
may be used which comprises two sharp-edged bandpass filters
5
and
6
. A bandpass filter
5
is then tuned to the reception frequency band and the other filter
6
to the transmission frequency band. As a result, a transmit signal does reach antenna
1
, because the filter
6
has little attenuation for the transmission frequency, but does not reach the receiver channel
2
, because the filter
5
blocks this frequency band. A received signal from the antenna
1
is only slightly attenuated by the bandpass filter
5
and thus reaches the receiver channel
2
, whereas it is strongly attenuated by the filter
6
. Consequently, the duplex filter
4
is to have very small transit losses and a very sharp-edged filter behavior. Furthermore, an active electronic switch
7
(for example, realized by means of PIN diodes) may be used for separating the transmitter channel
3
and receiver channel
2
on the antenna
1
, as is represented in FIG.
2
. This type of changeover needs an additional control signal for the switch
7
, which is to be generated in a costly manner. Furthermore, very strict requirements are made on the switches because very fast switching is to be realized. Furthermore, filters are to be provided which filter the respective frequency band for the transmitter channel
3
and receiver channel
2
.
European patent application EP 0 481 986 has disclosed a communication radiotelephone which contains the transmitter and the receiver in one and the same housing, having a first antenna connected to the transmitter and tuned to the transmitter, and a second antenna connected to the receiver and tuned to the receiver, while the two antennas are separated from each other. The communication radiotelephone comprises a housing accommodating a transmitter and a receiver. The communication radiotelephone can transmit and receive simultaneously. A first antenna is connected to the receiver and a second antenna to the transmitter, while the transmitter and the receiver operate in different frequencies. The antennas tuned to the different frequencies are each connected to the receiver and transmitter, respectively via a filter. A separation of transmitter and receiver channel is then achieved in that the transmitting and receiving antennas have asymmetrical radiation characteristics and the position of the radiation characteristic is selected such that the antenna effect is always turned away from the transmitter and receiver. This, however, is highly disadvantageous in devices for transmission systems transmitting and receiving in the same direction. Furthermore, in most cases corresponding radiation characteristics for transmission and reception in a certain direction are required and/or desired.
SUMMARY OF THE INVENTION
For this purpose, it is an object of the invention to provide a better transmitter-receiver having a simpler separation of different frequency ranges.
According to the invention, the object is achieved in that at least a dielectric resonator antenna (DRA) is provided for forming at least an antenna arrangement. Due to its physical properties a dielectric resonator antenna is operable only in a narrow frequency band around its resonant frequency. Therefore, an antenna arrangement formed by a dielectric resonator antenna has a very narrow frequency band, with which a very good separation of different frequency ranges, for example, for transmission and reception, is achieved. By changing the geometry or other parameters of the DRA, the resonant frequency and the bandwidth can be adapted to the requirements of different transmission systems regarding the frequency ranges to be adhered to.
In a preferred embodiment of the invention, a first antenna is arranged for reception in a first frequency range and a second antenna for transmission in a second frequency range. This embodiment is highly suitable for use in a transmission system having different frequency ranges for transmission and reception, such as, for example, GSM900, GSM1800, DECT and so on.
A further advantageous embodiment of the invention is provided when a first antenna is arranged for reception (or transmission) in a frequency range in a first transmission system and a second antenna for reception (or transmission) in a frequency range in a second transmission system. With this arrangement, the transmitter-receiver may be operated simultaneously in different transmission systems. It is alternatively possible to use more than two antennas, so that more frequency ranges may be used. In addition, further, combinations of various antennas for different frequency ranges of various transmission systems in one transmitter-receiver are conceivable.
Furthermore, the object of the invention is achieved by a mobile radiotelephone including a transmitter-receiver, which includes at least a dielectric resonator antenna (DRA) for forming at least one antenna arrangement.
These and other aspects of the invention are apparent from and will be elucidated, by way of non-limiting example, with reference to the embodiments described hereinafter.
REFERENCES:
patent: 5557293 (1996-09-01), McCoy et al.
patent: 6011516 (2000-01-01), Minegishi et al.
patent: 6043786 (2000-03-01), Vannatta et al.
patent: 6147647 (2000-11-01), Tassoudji et al.
patent: 0481986B1 (1992-04-01), None
patent: 0801436A2 (1998-04-01), None
patent: 2754942A1 (1998-04-01), None
patent: WO9101048 (1994-01-01), None
By Fan, Z. et al.: Entitled: Slot-Coupled DR Antenna for Dual-Frequency Operation. In: IEEE Transactions on Antennas and Propagation, vol. 45, No. 2, Feb. 1997, pp. 306-308.
By Rasinger J. et al.: Entitled: Interne Antennen Fur Schnurlostelefone. In: NTZ BD. 43 (1990) Heft 5, pp. 376-379.
Derwent Abstract Accession No. 2000-081788/07, Class U23, JP 11-330818, A (Murata Mfg Co Ltd) Nov. 30, 1999.
Derwent Abstract Accession No. 1999-450578/38, Class W02, JP 11-186805 A (Sumitomo Metal Co) Jul. 9, 1999.
Heinrichs Frank
Hilgers Achim
Porath Rebekka
Halajian Dicran
Legree Tracy
U.S. Philips Corporation
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