JP2003324314A - Multifrequency antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multifrequency antenna which can transmit and receive signals of a plurality of frequencies and has simple constitution as one antenna system which has a plurality of antenna elements stored in one housing. <P>SOLUTION: A 2.4 GHz-band antenna element 20 and a 5.2 GHz-band antenna element 22 are included. One port 26a of a filter 26 which passes a signal of the 2.4 GHz band, but blocks a signal of the 5.2 GHz band is connected to the antenna element 20. One port 28a of a filter 28 which passes the signal of the 5.2 GHz band, but blocks the signal of the 2.4 GHz band is connected to the antenna element 22. A matching part 30 is provided between other-side ports 26b and 28b of the filters 26 and 28 and an external connection terminal 32. The filters 26 and 28 and a matching part 30 are formed on one substrate 17. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

The present invention relates to a single antenna device having a plurality of antenna elements in a single housing, for example.

[0002]

2. Description of the Related Art In recent years, personal computers have become quite popular in general homes and workplaces, and LANs for connecting a plurality of personal computers to each other have been actively used. A wireless LAN is used for LAN connection in order to avoid the trouble of wiring. In wireless LAN,
The 2.4 GHz band is mainly used. However, due to legal regulations, it is not possible to take a too wide band and take a high transmission rate. The use of higher frequency bands, for example the 5.2 GHz band, is also considered. 2.4G
When using both the Hz band and the 5.2 GHz band,
For example, as shown in FIG. 7, the antenna 2 in the 2.4 GHz band and the antenna 4 in the 5.2 GHz band can be switched by the antenna switching device 6 and connected to the personal computer 10 via the access point 8. Conceivable. These antennas 2 and 4 are housed in separate housings.

[0003]

However, in such a configuration, not only a housing for the two antennas 2 and 4 is required, but also an antenna switching device has to be provided, which complicates the configuration. .

The present invention provides, for example, a multi-frequency antenna which is a single antenna device in which a plurality of antenna elements are housed in a single housing and which can transmit and receive signals of a plurality of frequencies and has a simple structure. With the goal.

[0005]

A multi-frequency antenna according to the present invention comprises a first frequency antenna element and a second frequency antenna element. The first and second frequencies are different frequencies. The first frequency antenna is not limited to the one that transmits and receives only the radio wave of the first frequency, but may be the one that can also transmit and receive the radio wave of the first frequency band including the first frequency, for example. . Similarly, the second frequency antenna may be capable of transmitting and receiving radio waves in the second frequency band including the second frequency. Although various elements can be used as these antenna elements, it is desirable to use patch antenna elements from the viewpoint of miniaturization. It is desirable to house these patch antenna elements in one housing. In addition to the first and second antenna elements, first and second filter means are provided. The first filter means is connected to the first frequency antenna element, and the second filter means is also connected to the second frequency antenna element. The first filter means passes a signal of the first frequency but blocks a signal of the second frequency. The second filter means allows the signal of the second frequency to pass through but blocks the signal of the first frequency. For example, assuming that the first frequency is lower than the second frequency,
A low-pass filter having a cutoff frequency between the first and second frequencies is used as the first filter means, and a high-pass filter having a cutoff frequency between the first and second frequencies is used as the second filter means. can do. Further, a bandpass filter including the first frequency in the passband may be used as the first filter means, and a bandpass filter including the second frequency in the passband may be used as the second filter means. Then, a band elimination filter that does not include the first frequency in the stop band is used as the first filter means, and a band elimination filter that does not include the second frequency in the stop band is used as the second filter means. You can also Matching means is provided between the first and second filter means and the external connection terminal. Furthermore, the first
Also, the second filter means and the matching means are formed on the same substrate. In addition to the antenna elements for the first and second frequencies, antenna elements for other frequencies can be provided. In this case, it is desirable to provide a filter means for passing signals of other frequencies and blocking signals of the first and second frequencies, and to connect the antenna element for other frequencies to the matching means via the filter means.

When receiving the radio waves of the first and second frequencies by using the multi-frequency antenna thus constructed,
The signal of the first frequency received by the antenna for the first frequency is supplied to the external connection terminal through the first filter means and the matching means, and the signal of the second frequency received by the antenna for the second frequency is received. The signal is supplied to the external connection terminal via the second filter means and the matching means. At this time, the first filter means passes the signal of the first frequency but cuts off the signal of the second frequency, so that the second frequency signal is transmitted from the matching means to the antenna for the first frequency. There is no. Similarly, the second filter means passes the signal of the second frequency but blocks the signal of the first frequency,
The first frequency signal is not transmitted from the matching means to the second frequency antenna. Therefore, it is possible to satisfactorily receive the signals of the first and second frequencies without providing the antenna switching device. Since the antenna element has reversibility, the signals of the first and second frequencies can be satisfactorily transmitted as long as the signals of the first and second frequencies can be satisfactorily received. In this multi-frequency antenna, the first and second filter means and the matching means are formed on the same substrate, so that this multi-frequency antenna can be downsized, and at the same time both frequencies can be used. Can be sent and received.

A plurality of antenna elements can be provided as the first frequency antenna element. In this case, the first selection means for connecting the selected one of the plurality of antenna elements to the first filter means is provided.

According to this structure, each antenna element for the first frequency selected by the first selecting means can be changed. For example, radio waves having different polarization planes at the first frequency can be changed. It can either transmit or receive, or it can implement antenna diversity.

Further, the first selecting means may be provided on the substrate. With this structure, the structure can be further simplified.

Alternatively, the first selecting means is configured to select one of the plurality of antenna elements as the first frequency antenna element based on the control signal supplied to the external connection terminal. You can also The first selection means can be switched by using, for example, a DC voltage as the control signal and changing the value of the DC voltage or supplying or stopping the DC voltage. With this configuration, remote control becomes easy.

Alternatively, a plurality of antenna elements can be provided as the second frequency antenna element. Second selecting means is provided for connecting a selected one of the antenna elements for the second frequency to the one port of the second filter means. With this configuration, it is possible to switch the polarization plane and achieve antenna diversity at each of the first and second frequencies.

Further, the first and second selecting means may be provided on the substrate. According to this structure, in addition to the first and second filter means and the matching means, the first and second selecting means are also formed on the same substrate, so that the multi-frequency antenna can be miniaturized. can do.

Alternatively, the second selecting means may select one of the plurality of antenna elements as the second frequency antenna element based on the control signal. As the control signal, for example, two kinds of control signals, that is, a control signal for selecting one of the first and second switching means and a control signal for actually selecting the antenna element in the selected switching means. Can be used. With this configuration, the antenna elements for the two frequencies can be remotely controlled according to desired conditions.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A multi-frequency antenna 12 according to a first embodiment of the present invention is, for example, a transmission / reception antenna for a wireless LAN as shown in FIG. It is connected to 16.

The multi-frequency antenna 12 has an antenna section 18. The antenna unit 18 includes an antenna element 20 for a first frequency, for example, 2.4 GHz, and a second antenna element 20.
Antenna element 22 for the frequency of, for example, 5.2 GHz. These antenna elements 20 and 22 are configured by patch antenna elements, for example. These antenna elements 20 and 22 cooperate with the ground plane, and the ground plane is provided in one housing, and the antenna element 20 is provided above one main surface of the ground plane at a predetermined distance from the main plane.
22 is provided. A substrate 17 is provided on the other main surface side of the base plate. Although there is no difference in that it is provided in one housing, it is also possible to use a part of the substrate 17 as a base plate without providing the base plate as described above.

These antenna elements 20 and 22 are formed on the substrate 1.
7 is connected to the demultiplexing / mixing unit 24 provided on the upper part 7.
The demultiplexing / mixing unit 24 includes two filter means, for example, filters 26 and 28, and a matching means, for example, a matching unit 30. The filter 26 has two ports 26a and 2
6b and one port 26a has an antenna element 20
, And the other port 26b is connected to the matching section 30. Similarly, the filter 28 has two ports 28.
a and 28 b, one port 28 a is connected to the antenna element 22, and the other port 28 b is connected to the matching section 30.

The filter 26 passes a signal of 2.4 GHz and cuts off a signal of 5.2 GHz. For example, the filter 26 is a low-pass filter whose cutoff frequency is selected between 2.4 GHz and 5.2 GHz. It is configured. Alternatively, a band pass filter including 2.4 GHz in the pass band or a band elimination filter not including 2.4 GHz in the stop band can be used. The filter 28 is
It passes a signal of 5.2 GHz and cuts off a signal of 2.4 GHz. For example, it is configured as a high-pass filter whose cutoff frequency is selected to be a frequency between 2.4 GHz and 5.2 GHz. Alternatively, a band pass filter including 5.2 GHz in the pass band or 5.2 in the stop band.
It is also possible to use a band elimination filter that does not include GHz.

The matching section 30 is for impedance matching with the external connection terminal 32 provided on the substrate 17 to connect the filters 26 and 28.

In practice, the demultiplexing / mixing unit 24 is constituted by a microstrip line as shown in FIG. That is, the matching unit 30 has the characteristic impedance Z0,
For example, it is connected to the external connection terminal 32 via a matching line 34 of 50 ohms. The matching section 30 has a line width of a value obtained by dividing the characteristic impedance Z0 by the square root of 2, for example, about 35 ohms, and further has first and second frequencies, 2.4 GHz and 5.2 GHz in this embodiment. It has an optimized line length of about 1/4 wavelength of the frequency between and. The matching section 30 is divided into two parts 30a and 30b having a line width of characteristic impedance. The tip of the portion 30a is connected to the antenna element 20,
The tip of 0b is connected to the antenna element 22.

At the portions 30a and 30b, the matching portion 30
Filters 26 and 28 are provided at positions equidistant from. In FIG. 2, the filter 26 is formed as a trap filter that blocks a signal of 5.2 GHz, and the filter 28
Is formed in a trap filter that blocks a 2.4 GHz signal.

Therefore, if the signal from the external connection terminal 32 is a 2.4 GHz signal, it is transmitted to the antenna element 20 in the 2.4 GHz band and is a 5.2 GHz signal.
It is transmitted to the antenna element 22 in the 5.2 GHz band. On the contrary, the signal received by the antenna element 20 does not flow to the opposite antenna element 22 side, and the signal received at the antenna element 22 does not flow to the antenna element 20 side, but to the external connection terminal 32. Only transmitted.

The circuits other than the antenna elements 20 and 22 and the external connection terminal 32 can be formed on the substrate 17 only by an operation such as etching, and no special parts are required. Therefore, a simple structure and low loss characteristics can be obtained.

The multi-frequency antenna 1 of the second embodiment
2a is shown in FIGS. 3, 4 and 5. The multi-frequency antenna of this embodiment is provided with a plurality of, for example, two 2.4 GHz antenna elements, which are first frequency antennas. That is, the antenna unit 18a includes two 2.4G units.
It has antenna elements 20a and 20b of Hz. These antenna elements 20a and 20b are patch antenna elements like the antenna element 20 in the multi-frequency antenna 12 of the first embodiment. The antenna element 20a is for vertical polarization, and the antenna element 20b is for horizontal polarization.

The antenna elements 20a and 20b are provided with a filter 26 via a first selecting means, for example, a polarization switching circuit 34.
Connected to the port 26a. This polarization switching circuit 3
4 is also provided on the substrate 17. Since other configurations are the same as those of the multi-frequency antenna 12 of the first embodiment,
The same parts are designated by the same reference numerals and the description thereof will be omitted.

The polarization switching circuit 34 filters one of the antenna elements 20a and 20b depending on whether or not a control signal, for example, a DC voltage is supplied to the external connection terminal 32.
Port 26a.

FIG. 4 shows a circuit diagram of the polarization switching circuit 34. When a DC voltage is externally supplied to the external connection terminal 32, this DC voltage is applied to the matching section 30 and the filter 26.
Through the strip line 38 of the polarization switching circuit 34.

Based on the voltage of the strip line 38, switching means such as a PIN diode 40,
A current flows through the inductance 42 and the resistor 44, and the PIN
The diode 40 becomes conductive. As a result, the antenna element 2
0a is connected to the strip line 38 via the capacitor 48, and the vertically polarized signal from the antenna element 20a is transmitted to the strip line 4a.
6, the capacitor 48, and the strip line 38 to supply the filter 26.

The voltage on the stripline 38 causes a current to flow through the resistor 50, the stripline 52, the switching means, eg the PIN diode 54. As a result, the PIN diode 54 becomes conductive and the antenna element 20
The strip line 58 connected to b is the capacitor 6
0, grounded via a PIN diode 54. As a result, the horizontally polarized signal from the antenna element 20b is not transmitted to the strip lines 52 and 38, and thus is not transmitted to the filter 26. That is, only the vertically polarized signal from the antenna element 20a is transmitted to the filter 26. When a 2.4 GHz signal is supplied to the external connection terminal 32, this signal is similarly transmitted only to the antenna element 20a.

On the other hand, when no DC voltage is supplied to the external connection terminal 32, the two PIN diodes 40, 54
Are both non-conductive. Therefore, stripline 4
6 and 38 are not connected, and the vertically polarized signal from the antenna element 20a is not transmitted to the strip line 38. However, the strip line 58 is
Is connected to a strip line 52 by means of a capacitor 62 and the strip line 3
8 is connected to the strip line 58 and the capacitor 6 from the antenna element 20b.
0, the strip line 52, the capacitor 62, and the strip line 38, and is supplied to the filter 26. That is,
When the DC voltage is not supplied to the external connection terminal 32, only the horizontally polarized signal from the antenna element 20b is supplied to the filter 26. 2.4G on the external connection terminal 32
Even when a Hz signal is supplied, it is similarly transmitted only to the antenna element 20b. In FIG. 4, reference numeral 64 is a bypass capacitor.

FIG. 5 shows a pattern diagram of the polarization switching circuit 34. In this pattern diagram, reference numerals 66, 68,
70 is the ground potential surface. Stripline 38
And the strip line 52 are formed between the ground potential surfaces 66 and 68. The strip line 46 is formed between the ground potential surfaces 66 and 70. A pad 42 a of the inductance 42 is formed between the strip line 46 and the strip line 38. Also, the ground potential surface 68,
A strip line 58 is formed between 70.

A capacitor 48 is connected between the pad 42a and the strip line 46, and a PIN diode 40 is connected between the pad 42a and the strip line 38. A parallel circuit of a resistor 44 and a capacitor 64 is connected between the tip portion 42b of the inductance 42 and the ground potential surface 70. A parallel circuit of a resistor 50 and a capacitor 62 is connected between the strip lines 38 and 52, a PIN diode 54 is connected between the strip line 52 and the ground potential surface 68, and a capacitor is provided between the strip lines 52 and 58. 60 is connected.

In the multi-frequency antenna 12a, one of the antenna elements 20a and 20b for desired polarization can be selected and connected to the filter 26. In this polarization switching circuit 34, the diode 40 is connected in series between the strip lines 46 and 38, and the strip lines 58 and 5 are connected.
2 is connected, a diode 54 is connected between the connection point and the ground potential, and the PIN diodes 40 and 54 are simultaneously turned on or off, and the strip line 46 is connected.
Or the antenna element 20a or 20 transmitted through 58
One of the signals of b is transmitted to the strip line 38.

P is also connected in series between the strip lines 58 and 52.
A configuration in which the IN diode 54 is connected is also possible. However, in this configuration, a comparator circuit or the like that changes the value of the DC voltage supplied to the external connection terminal 32 depending on which of the PIN diodes 40 and 54 is conducted and determines which voltage is supplied is required. Therefore, the circuit configuration becomes complicated.

Multifrequency antenna 1 of the third embodiment
2b is shown in FIG. In this multi-frequency antenna 12b, not only the antenna for the first frequency but also a plurality of antennas for the second frequency, for example, two are provided. That is, the antenna portion 18b also has two 2.4 GHz antenna elements 22a and 22b. These antenna elements 22a and 22b are patch antenna elements, like the antenna element 22 in the multi-frequency antenna 12 of the first embodiment. The antenna element 22a is for vertical polarization, and the antenna element 22b is for horizontal polarization. The antenna elements 20a and 20b are the same as the antenna elements 20a and 20b of the second embodiment.

These antenna elements 22a and 22b are connected to the filter 26 via the second selecting means, for example, the polarization switching circuit 34b. The polarization switching circuit 34b, together with the first selection means connecting the antenna elements 20a and 20b to the filter 24, for example, the polarization switching circuit 34a,
It has the same configuration as the polarization switching circuit 34 in the multi-frequency antenna 12a of the second embodiment. The polarization switching circuits 34a and 34b are provided on the substrate 17.

Therefore, when a DC voltage is supplied to the external connection terminal 32, the antenna element 20a moves to the polarization switching circuit 34.
The antenna element 22a is selected by a and connected to the filter 26, and the antenna element 22a is selected by the polarization switching circuit 34b and connected to the filter 28. When the DC voltage is not supplied to the external connection terminal 32, the antenna element 20b is selected by the polarization switching circuit 34a, and the filter 26
And the antenna element 22b is selected by the polarization switching circuit 34b and supplied to the filter 28. That is, the antenna elements 20a and 22a are selected in conjunction with each other, and the antenna elements 20b and 22b are selected in conjunction with each other. Therefore, a signal from a desired one of the antenna elements 20a and 20b and a signal from a desired one of the antenna elements 22a and 22b can be simultaneously transmitted.

For example, if a voltage comparison circuit and a pulse detection circuit are provided on the substrate 17 and a control signal composed of a combination of a DC voltage and a pulse signal is supplied to the external connection terminal 32, each antenna element 20a, 20b, It is also possible to select a desired one of 22a and 22b. For example, when the direct current voltage value is 3V and the pulse signal is not superposed on the direct current voltage, the antenna element 20a is configured to be selected, and when the direct current voltage value is 6V and the pulse signal is not superposed on the direct current voltage value. , The antenna element 20b is selected, the DC voltage value is 3V, and when the pulse signal is superimposed on the antenna element 22a, the antenna element 22a is selected, and the DC voltage value is 6V. Then, when the pulse signal is superposed on this, the antenna element 22b can be selected.

In each of the above embodiments, the antenna element used for transmitting and receiving the radio wave in the 2.4 GHz band and the 5.2 GHz band is used. However, the present invention is not limited to this, and the antenna element of another frequency band is used. You may use the thing for transmitting / receiving an electric wave. Furthermore, in each of the above embodiments, two antenna elements for different frequencies are provided, but more antenna elements for different frequencies can be provided.
In addition, in the second and third embodiments, the polarization switching circuit 3
Although 4, 34a and 34b are provided on the substrate 17, they may be provided on the antenna element side.

[0039]

As described above, according to the present invention, it is possible to transmit and receive signals of a plurality of frequencies with an antenna device in which a plurality of antenna elements are housed in one housing, and to provide main components on one substrate. Therefore, the configuration is simple.

[Brief description of drawings]

FIG. 1 is a block diagram of a multi-frequency antenna according to a first embodiment of the present invention.

FIG. 2 is a pattern diagram of a demultiplexing / mixing unit of the multi-frequency antenna of FIG.

FIG. 3 is a block diagram of a multi-frequency antenna according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a polarization switching circuit of the multi-frequency antenna of FIG.

5 is a pattern diagram of the polarization switching circuit of FIG.

FIG. 6 is a block diagram of a multi-frequency antenna according to a third embodiment of the present invention.

FIG. 7 is a block diagram of a conventional multi-frequency antenna.

[Explanation of symbols]

17 board 20 Antenna element (first frequency antenna element) 22 Antenna element (second frequency antenna element) 26 filter (first filter means) 28 filter (second filter means) 30 Matching unit (matching means) 34 Polarization switching circuit (first selecting means) 34a Polarization switching circuit (first selecting means) 34b Polarization switching circuit (second selecting means)

Claims (7)

[Claims] 1. An antenna element for a first frequency, an antenna element for a second frequency different from the first frequency, and an antenna element for the first frequency, which are connected to pass a signal of the first frequency. A first filter means for blocking a signal of the second frequency and a second frequency antenna element for passing a signal of the second frequency but blocking a signal of the first frequency; Filter means and matching means provided between the first and second filter means and the external connection terminal, and the first and second filter means and the matching means are the same. Multi-frequency antenna formed on the substrate. 2. The multi-frequency antenna according to claim 1, wherein a plurality of antenna elements are provided as the first frequency antenna element, and a selected one of them is connected to the first filter means. Multi-frequency antenna provided with the selection means of. 3. The multi-frequency antenna according to claim 2, wherein the first selecting means is provided on the substrate. 4. The multi-frequency antenna according to claim 2, wherein the first selecting means selects among the plurality of antenna elements as the first frequency antenna based on the control signal supplied to the external connection terminal. A multi-frequency antenna that selects one. 5. The multi-frequency antenna according to claim 2, wherein a plurality of antenna elements are provided as the second frequency antenna element, and a selected one of these is connected to the second filter means. Multi-frequency antenna provided with the selection means of. 6. The multifrequency antenna according to claim 5, wherein the first and second selecting means are provided on the substrate. 7. The multi-frequency antenna according to claim 5, wherein the second selecting means is configured to perform the second selection based on the control signal.
A multi-frequency antenna that selects one of a plurality of antenna elements as the frequency antenna.