WO2002035644A1

WO2002035644A1 - Antenna device

Info

Publication number: WO2002035644A1
Application number: PCT/DE2001/003584
Authority: WO
Inventors: Stefan Baumann
Original assignee: Siemens Aktiengesellschaft
Priority date: 2000-10-26
Filing date: 2001-09-18
Publication date: 2002-05-02
Also published as: DE10053210A1

Abstract

The invention relates to an antenna device comprising an antenna (1) with a connection (2) for a transmitting device (4) and with a connection (3) for a receiving device (5). In this antenna device, said connections (2, 3) for the transmitting device (4) and for the receiving device (5) are arranged in an interspaced manner on the antenna (1). The antenna device is particularly suited for mobile terminals having integrated antennas.

Description

description

antenna means

The invention relates to an antenna device, in particular for mobile terminals, with an antenna, with a connection for a transmitting device and with a connection for a receiving device. In addition, the invention relates to a mobile terminal with a corresponding antenna device.

Many of the wireless communication systems used today, such as DECT, GSM, DAMPS, are mostly systems that transmit and receive alternately (half-duplex systems). The mobile terminals used in such systems are usually equipped with only one antenna, so that the antenna must be switched between the transmitting device, often also called the transmitting branch, and the receiving device, often also called the receiving branch. This is accomplished with an antenna switch, which is connected to the antenna on one side and has two outputs for the transmitting branch and the receiving branch, between which it is possible to switch back and forth. This circuit arrangement means that the output of the transmitting device and the input of the receiving device, which may be spatially far apart within the device, must be brought together to one point, namely to the changeover switch. The long lines required for the connection between the transmitting device and / or the receiving device and the antenna result in relatively high electrical losses. To compensate for this, increased power consumption is required, which in particular in the case of mobile end devices, which are generally operated by means of a rechargeable battery, reduces the standby and operating times of the device. In addition, such losses increase the cost of the power supply. It is an object of the present invention to provide an alternative to the prior art mentioned, in which the line losses from and / or to the antenna are lower. This object is achieved by an antenna device according to patent claim 1 and by a mobile terminal with such an antenna device according to claim 13.

According to the invention, the connections for the transmitting device and for the receiving device on the antenna are arranged spatially separated. This means that the antenna is no longer seen as a single-pole as before, but as a two-pole that can be operated from two different connections. In the solution according to the invention, it is therefore no longer necessary to bring the supply lines from the transmitting device and from the receiving device to the antenna into one point. The lines between the antenna and the transmitting device and between the antenna and the receiving device can be kept extremely short by a suitable position of the antenna itself or of the connections on the antenna.

The antenna can in principle have any shape, i.e. it can be a flat antenna, a spiral antenna or a PCB (Printed Circuit Board) antenna printed on a printed circuit board. However, it is often an antenna that extends essentially in a longitudinal direction and has, for example, an effective length of a fraction of the desired resonance frequency λ, for example λ / 4.

The connections for the transmitting and receiving devices are preferably located at opposite end regions of the antenna, so that the connecting lines are minimal when the receiving device and the transmitting device are positioned differently within the device.

The antenna device according to the invention is particularly suitable for devices in which the antenna is integrated into the housing. is. With such an integrated antenna, both connections are easily accessible within a short distance within the housing.

The device can be any device that requires a corresponding antenna device. It is preferably a particularly compact mobile terminal or hand-held terminal, for example a mobile radio device or a PDA (Personal Digital Assistant).

In a preferred embodiment, the antenna device has switching means for switching the connection of the antenna to the transmitting device and / or to the receiving device on and off. These can be separate on / off switches for the connection. Alternatively, a switching device can be used that switches between the two connections, i.e. at the same time the connection to the transmitting device is switched off and the connection to the receiving device is switched on and vice versa.

The switching means can be electromechanical switches, preferably micromechanical switches. Alternatively, it can also be electronic switches, for example semiconductor switches such as transistors, diodes etc.

In a further preferred exemplary embodiment, at least one of the two connections has a filter which filters out a frequency which corresponds to a transmission or reception frequency of a transmission or reception device arranged at the other end. This filter can also be switched on and off. The term “frequency” here also means a frequency range that can be narrower or wider.

In a particularly preferred exemplary embodiment, the transmitting and receiving device send or receive in different frequencies. Accordingly, a first filter is arranged at the connection of the transmitting device, which filters out the frequency of the receiving device and transmits signals with the frequency of the transmitting device to it. Correspondingly, a second filter is arranged at the connection of the receiving device, which filters out the frequency of the transmitting device and transmits signals at the frequency of the receiving device to the latter. The filters act like open or closed switches for the respective frequencies, so that it is not necessary to switch them on and off or toggle them, but rather operate the antenna from each of the connections only in the corresponding frequency range at any time can be.

The filters can be constructed as band filters or band-stop filters that only filter out a desired frequency or are permeable to a desired frequency. Alternatively, it is also possible for one filter to be a high pass and the other filter to be a low pass, and the cutoff frequency from which the high pass passes the signals and from which the low pass no longer passes the signals lies between the transmission and reception frequencies ,

It is also possible to combine the different variants in a suitable manner, for example using both filters and switches. For example, a filter can be used on the one side at the connection to the receiving device and a switch on the other side at the connection to the transmitting device or vice versa. The only thing that is decisive is that the components used are low-impedance for the desired frequencies, which are to be tapped from the antenna or fed into the antenna via the respective output, and on the other hand, for the frequencies which are to be fed or tapped via the other connection , are high impedance. The antenna device can also be constructed as a so-called dual-band or multiband antenna device for operation in a plurality of transmission and / or reception frequency ranges. Correspondingly, the connections of the antenna can also be connected with filters and / or switching means in such a way that it is also possible to switch between several frequency bands, for example GSM and PCS (Personal Communication Services).

If filters are used to connect the antenna connections, the invention is also suitable for full-duplex systems such as UMTS, AMPS or the like.

The invention is explained in more detail below with reference to the accompanying drawings using exemplary embodiments. The features shown below and the features already described above can be essential to the invention not only in the combinations mentioned, but also individually or in other combinations. In addition, it is expressly pointed out that the transmission and reception paths can also be interchanged in all the circuit variants shown, if appropriate with corresponding modifications in the circuits. They represent:

FIG. 1 shows a schematic illustration of a conventional antenna device of a mobile radio device according to the prior art,

FIG. 2 shows a schematic illustration of a first exemplary embodiment of the antenna device according to the invention,

FIG. 3a shows a more precise schematic representation of the antenna device according to FIG. 2 with the reception path closed and the transmission path open, FIG. 3b shows a more precise schematic representation as in FIG. 3a, but with the reception path open and the transmission path closed,

FIG. 4 shows a second exemplary embodiment of the antenna device according to the invention with electronic switches,

FIG. 5 shows a third exemplary embodiment of the antenna device according to the invention with an electronic switch,

FIG. 6 shows a fourth exemplary embodiment of the antenna device according to the invention with a circuit of the outputs with filters in a first variant,

Figure 7 shows a fifth embodiment of the antenna device according to the invention with a wiring of the antenna outputs with filters in a second variant.

FIG. 1 shows a conventional antenna device of a mobile radio device according to the prior art. The antenna 1 is connected to a changeover switch 6, which is connected via two connections to the transmitter 4 and receiver 5, respectively. As can be clearly seen from the figure, the connecting lines of the transmitting device 4 and the receiving device 5 must be brought together at the changeover switch 6. Since the transmitting device 4 and the receiving device 5 are generally arranged at spatially different locations within the device, a longer supply line is required for at least one of the two devices 4, 5 - here the transmitting device 4.

Figure 2 shows a first embodiment of the antenna device according to the invention. Here, the antenna 1 has separate connections 2, 3 for the transmitting device 4 and the receiving device 5 in each of the two end regions. There is a first switch 7 between the antenna 1 and the transmitting device 4 and between the antenna 1 and the receiver LU w to t J-> P ¹ Π o LΠ O σι o LΠ

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The ground potentials M and the connections for the adjustable voltages V _Tx , V _R * are each connected via coils 15 to the connecting lines from the connections 2, 3 of the antenna 1 to the transmitting device 4 and to the receiving device 5. These coils 15 act as an RF block, ie they do not pass high-frequency signals, but only direct current, which is generated by the adjustable voltages V _Tx , V _RX .

In addition, behind the diodes 11, 12, behind the connection points to the adjustable voltages V _Tx , V _{RX, as seen} from the antenna 1, there are capacitors 13 in front of the transmitting device 4 and in front of the receiving device 5, which serve as a DC block. These DC blocks only pass the RF signals and are not continuous for direct current.

Likewise, a capacitor 14 is located on the transmission-side connection 2 of the antenna 1, directly next to the antenna 1, which, as a further DC block, prevents a direct current short circuit between the two ground connections M via the antenna 1. This capacitor could also be arranged on the receiving side of the antenna 1.

The regulation of the adjustable voltages V _Tx, V _X can determine whether the transmission path or the reception path is switched on. Both sides can be switched separately. The diodes 11, 12 are switched through when the corresponding adjustable voltages V _Tx , V _{X are} above the ground potential M. A zero potential, for example the housing potential of the device, is usually used as the ground potential. Accordingly, the transmission path is switched on under the condition V _Tx > 0 and V _RX <0 and the reception path is switched on under the condition V _Tx <0 and V _RX > 0. LU LU to to MP ¹

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If V _Tx > 0 is selected, both pin diodes 20, 21 have a low resistance. The diode 20 consequently acts like a closed switch in the direction of the transmitting device 4. The receiving connection 3 of the antenna 1, on the other hand, is connected to the ground potential M via the diode 21. This connection is transformed into an idle state by the λ / 4 transformation line. The connection 3 therefore acts like an “open connection”, ie the antenna 1 behaves like an antenna that is not connected to the receiving device 4 for the transmitting device 4. At a voltage V _Tx > 0, the transmitting path is consequently switched on and the receiving path is switched off.

Conversely, at V _Tx <0, both diodes 20, 21 are high-resistance and therefore act like open switches. Thus, the reception-side connection 3 of the antenna 1 is no longer connected to the ground potential M and the connection of the transmission-side connection 2 to the transmission device 4 is interrupted by the diode 20. In this case, the reception path is consequently switched on and the transmission path is switched off.

Instead of the ground potential, another voltage, for example an adjustable voltage, can also be applied in the two last-mentioned embodiments. In this case, the circuit depends on the potential differences between the applied voltages. If, for example in the second exemplary embodiment according to FIG. 5, a voltage V _{X is} applied to the connection of the ground potential M, then either the transmit path or the receive path is opened, depending on whether V _Tx > V ^ or vice versa.

FIGS. 6 and 7 each show exemplary embodiments in which filters 23, 24, 25, 26 are used instead of switches, which pass certain frequency ranges at the respective connection 2, 3 of the antenna and filter out other frequency ranges. The use of such in Different frequency ranges working filters instead of switches is possible because different frequency bands are usually used for sending and receiving in wireless communication systems.

In the exemplary embodiment according to FIG. 6, a filter 23, 24 is located both at the transmission-side connection 2 of the antenna 1 and at the reception-side connection 3 of the antenna 1, which filter consists of a coil 27 and a capacitor 28, which are connected by the connecting line Antenna 1 and transmitter 4 or antenna 1 and receiver 5 are connected in series against a ground potential M. These are bandpass filters 23, 24, each of which decouples a specific frequency range towards the ground potential M, so that only frequencies outside this frequency range pass the connecting line between the antenna 1 and the transmitting or receiving device 4, 5. The filter 23 on the transmission-side connection 2 of the antenna 1 is set so that exactly the frequencies in the reception area are filtered out, the filter 24 on the reception-side connection 3 of the antenna 1 is set so that exactly the frequencies in the transmission area are filtered out. The filter 23 on the transmission side is thus constructed in such a way that it has a high resistance at the transmission frequency and a low resistance at the reception frequency. The reception-side filter 24 is constructed in such a way that it is low-resistance at the transmission frequency and high-resistance at the reception frequency.

In the exemplary embodiment according to FIG. 7, filters 25, 26 are used, which are inserted directly into the connecting lines between the connections 2, 3 and the transmitting or receiving device 4, 5. These filters 24, 25 each consist of coils 29 and capacitors 30 which are connected in parallel to one another. These are band-stop filters, each of which only allows a very specific frequency range to pass. The filter 25 on the transmission-side connection 2 of the antenna 1 accordingly allows the transmission Frequency range through, and the filter 26 on the receiving end 3 of the antenna 1 passes exactly the receiving frequency range. In this exemplary embodiment, therefore, the transmission-side filter 25 is constructed in such a way that it is low-resistance at the transmission frequency and high-resistance at the reception frequency, and the reception-side filter 26 is constructed such that it is high-resistance at the transmission frequency and at the reception frequency. frequency low impedance.

Instead of the capacitors and coils, any other components can also be used to construct the filters. For example, ceramic filters or surface wave filters (SAW filters; surface acoustic wave filters) are possible.

For the function of the antenna device, it is not absolutely necessary that bandstops or bandpasses are used as filters. It is only important that the components for the corresponding frequencies are low-resistance or high-resistance. Instead of bandstops or bandpasses, high and low passes can also be used, which filter everything above or below a certain cutoff frequency.

For example, in a GSM 900 system with the above-mentioned transmission and reception frequency ranges, a low-pass filter can be used at the transmission-side connection of the antenna, which passes all frequencies below 920 MHz and cuts off all frequencies above 920 MHz. There is then a corresponding high pass on the receiving side, which passes all frequencies above 920 MHz and cuts off all frequencies below 920 MHz.

In the case of a GSM 1800 system which has a transmission frequency between 1.71 and 1.785 GHz and a reception frequency range between 1.805 and 1.88 GHz, a low pass up to 1.8 GHz and a high pass above 1.8 GHz is used at the start.

In a UMTS / CDMA (Code Division Multiple Access) system with a transmission frequency between 1.92 and 1.98 GHz and a reception frequency between 2.11 and 2.17 GHz, a low pass up to 2 GHz can be transmitted and a high pass from 2 on the receive side GHz are used.

When building a multiband system with two (dual-band system) or even more different transmission and reception frequency ranges, the circuit variants only have to be changed accordingly in order to pass the different frequency bands. When using filters, it is also possible in particular to use adjustable filters in which the filter properties can be changed, for example, by means of suitable control voltages.

Claims

claims

1. Antenna device with an antenna (1), with a connection for a transmitting device (4) and with a connection for a receiving device (5), characterized in that the connections (2, 3) for the transmitting device (4) and the receiving device (5) are spatially separated on the antenna (1).

2. Antenna device according to claim 1, characterized in that the connections (2, 3) for the transmitting device (4) and the receiving device (5) are arranged on opposite end regions of the antenna (1).

3. Antenna device according to claim 1 or 2, characterized in that the antenna is integrated in a device.

4th Antenna device according to one of Claims 1 to 3, characterized by switching means (7, 8, 9, 10, 16, 17) for switching a connection of the antenna (1) to the transmitting device (4) and / or on and off to the receiving device (5) and / or to switch between these connections.

5. Antenna device according to claim 4, characterized in that the switching means (7, 8) comprise an electromechanical switch (7, 8).

6. Antenna device according to claim 4 or 5, characterized in that the switching means (9, 10, 16) comprise an electronic switch.

7. Antenna device according to claim 6, characterized in that the switching means (9, 10, 16) comprise a diode (11, 12, 20, 21) acting as a switch.

8. Antenna device according to one of claims 1 to 7, characterized by a filter (23, 24, 25, 26) arranged on one of the connections (2, 3), which filters out a frequency that corresponds to a transmission or reception frequency of one at the other connection arranged transmitting or receiving device (4, 5) corresponds.

9. Antenna device according to claim 8, characterized in that the transmitting device (4) and the receiving device (5) transmit or receive at different frequencies, and at the connection (2) of the transmitting device (4) a first filter (23, 25) is arranged, which filters out the frequency of the receiving device (5) and passes signals at the frequency of the transmitting device (4) to the transmitting device (4), and a second filter (24, 26) is arranged on the connection (3) of the receiving device (5) , which filters out the frequency of the transmitting device (4) and transmits signals at the frequency of the receiving device (5) to the receiving device (5).

10. Antenna device according to claim 9, characterized in that the filters (23, 24, 25, 26) comprise band filters which only filter out a desired frequency or are permeable to a desired frequency.

11. Antenna device according to claim 8 or 9, characterized in that the one filter comprises a high pass and the other filter comprises a low pass.

12. Antenna device according to one of claims 1 to 11, characterized in that the antenna device is a multiband antenna device.

13. Mobile terminal with an antenna device according to one of claims 1 to 12.