JPH11205206A - Radio equipment and antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deterioration in the characteristic of radio equipment due to interference between diversity antennas and to make the equipment small in size. SOLUTION: This equipment is provided with a reception circuit 13 built in a case, 1st and 2nd antennas 11, 12, a feeder line 14, a 1st switch 15 turning on/off the connection between the 1st antenna and the feeder line, a 2nd switch 16 connecting either one of the 2nd antenna or the feeder line to the reception circuit 13 and a control circuit that switches and controls the 1st and 2nd switches in response to the strength of a radio wave received by the 1st and 2nd antennas. Then, in the case that one antenna connects to the reception circuit in response to the strength of the received radio wave, the other antenna is opened independently of the feeder or a matching circuit to execute the termination. Furthermore, in the case of an antenna so as to include a matching element in itself, a switch is provided to a part of the antenna to execute the open-termination independently of the feeder of the matching circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antenna switching type radio apparatus and an antenna.

[0002]

2. Description of the Related Art In general, in a wireless device such as a portable wireless device, different antennas are mounted on a housing in combination in order to realize a diversity receiving system, and an antenna is selected according to the strength of a radio wave to be received. Switching methods are known. However, in recent wireless devices, since the housing is relatively small, the distance between the antennas is short, and interference may occur between the antennas, thereby deteriorating the antenna characteristics.

Therefore, in order to suppress the interference between the antennas, it is common practice to open the ends of the antennas not selected. By opening the antenna end, the antenna element has a high impedance value, and interference is suppressed. However, in a wireless device such as a portable wireless device, the antenna and the receiving circuit are connected via a feed line, so that the length of the feed line is limited due to the condition of opening the end of the unselected antenna. Due to the lack of flexibility and possibly long lengths, there have been problems with implementation and transmission losses. Hereinafter, problems occurring in the related art will be described with reference to the drawings.

[0004] According to a radio apparatus such as a portable radio apparatus that realizes a generally used diversity antenna system, a feed line 104 is connected to an antenna 101 as shown in FIG. The receiving circuit 103 is connected to the receiving circuit 103. The antenna 102 is the switch 10
5 is connected to the receiving circuit 103. Switch 10
Reference numeral 5 denotes a receiving circuit 103 including a feed line 104 and an antenna 102
Antenna 10 which is received by the receiving circuit 103 when the controller 106 is in the test mode.
The switching of the switch 105 is controlled such that the magnitudes of the received radio wave intensities of the antennas 1 and 102 are compared and the antenna having the higher radio wave intensity is connected to the receiving circuit 103. When the switch 105 connects the receiving circuit 103 to the feed line 104, the antenna 102 is open-ended. Conversely, the switch 105 connects the receiving circuit 103 to the antenna 102
, The antenna 101 is terminated via a feed line whose end is open. The feed line 104 whose end is opened functions as a reactance element, and the length of the feed line 104 is set to an integral multiple of a half wavelength,
The antenna 101 can be open-ended. Therefore, regardless of which antenna is used for reception, the end of the antenna can be opened, and wireless communication can be performed without deteriorating the radiation characteristics of the antenna.

However, the power supply line 104 is halved.
In order to set the length to an integral multiple of the wavelength, it is necessary to route the power supply line 104 on the board of the wireless device. As a result, particularly in a small-sized radio, a problem arises in that routing of the power supply line 104 hinders mounting of an electronic circuit on a substrate.

Further, when the length of the feed line 104 is increased, the controller 106 selects the antenna 101 and controls the switch 105 so as to connect the receiver 103 to the feed line 104. Problems such as an increase in transmission loss occur. A similar problem occurs when the feed line 104 includes a matching circuit for adjusting the antenna impedance. At this time, even if the length of the feed line 104 is appropriately selected, there is a problem that the end of the antenna is not opened due to the matching circuit.

On the other hand, there is an antenna in which a matching circuit is included in the antenna 101. An example of such an antenna is an inverted-F antenna. The inverted F antenna is an antenna element often used as a built-in antenna of a wireless device such as a portable wireless device, and has a problem of interference between antennas in an antenna switching diversity system.

[0008] The inverted F antenna will be described below. FIG. 8 shows the structure of a linear inverted-F antenna. The linear inverted-F antenna is composed of linear elements, that is, it can be composed of a combination of the L-shaped antennas 111 and 112 and the matching element 113.

The power supply position is between the antenna 111 and the ground 11
5, and the feeding point is indicated as 114. Matching element 113 is short-circuited to L-shaped antennas 111 and 112 and ground 115. Actually, the matching element 113 is used for input impedance matching of the L-shaped antennas 111 and 112.

If the inverted F antenna is not selected when performing the antenna switching diversity, the feeding point of the inverted F antenna is generally terminated at the open end. At this time, the L-shaped antennas 111 and 112
3 causes a problem that the termination is not actually opened.

[0011] The present inventors have studied the interference between antennas with respect to the degradation of the radiation characteristic due to the interference between the monopole antenna and the inverted F antenna in the antenna switching diversity combining the monopole antenna and the inverted F antenna. Experimented. The model used in this experiment has the structure shown in FIG. 6, in which a monopole antenna 122 and an inverted-F antenna 123 are attached to the upper end of a conductor plate 121 simulating a substrate of a wireless device. The length of the conductor plate 121 is about one-third wavelength, and
The length of the antenna 2 was approximately one-fourth of the transmitting wavelength, and the height of the inverted F antenna was about one-seventh the wavelength. Further, a reactance element 125 is connected to the feeding point of the inverted F antenna, and the feeding point 124 of the monopole antenna 122 and the feeding point 126 of the inverted F antenna are arranged at a position close to the upper end of the conductor plate 121.

An experimental method using a wireless device model having such a structure is one in which power is supplied to the monopole antenna 122 and radiation efficiency (radiation power / input power) is measured while changing the termination condition of the inverted F antenna 123. The termination conditions were changed by connecting capacitors or coils of various values as the reactance element 125 at the feeding point 126.

The result of the change in antenna characteristics obtained by this experiment is as shown in the graph of FIG. 7. In this model, the radiation efficiency may be degraded at most by about 12 dB depending on the termination condition of the inverted F antenna. Do you get it. Further, it can be seen that the termination condition at which the maximum value of the radiation efficiency is obtained is not the open condition. That is, in the inverted F antenna, the matching element 11
It was found that even if the input end was opened due to the existence of the antenna 3, the inverted F antenna as a whole was not terminated at the open end but caused interference between antennas. The matching circuit included in the antenna is when the antenna is not selected.
When the antenna input terminal is opened, the matching circuit functions as a reactance element, and the input terminal of the antenna does not open.

[0014]

As described above,
In a wireless device such as a portable wireless device having a conventional antenna switching diversity, an end of an unselected antenna is opened in order to suppress interference between antennas. If a desired length is to be obtained, there is a problem that the degree of freedom of design is hindered and miniaturization cannot be achieved.

Further, in an antenna in which a matching circuit is included in the antenna itself, even if the terminal is opened at the antenna input end, the antenna does not actually have an open end due to the existence of the matching circuit. was there.

The present invention has been made in view of such a conventional problem, and can prevent deterioration of radiation characteristics occurring in an antenna, and can maintain a degree of freedom in designing a feed line. It is an object of the present invention to provide a wireless device and an antenna that can be downsized.

[0017]

SUMMARY OF THE INVENTION The present invention provides a housing, a receiving circuit built in the housing, first and second antennas installed in the housing, a feed line, and the first antenna. 1 to turn on / off the connection between the power supply line
A second switch for connecting one of the second antenna and the feed line to the receiving circuit, and a second switch for connecting one of the second antenna and the feeder line to the receiving circuit. A wireless device includes a control circuit that performs switching control between a first switch and a second switch.

In the wireless device of the present invention, when one antenna is connected to the receiving circuit in correspondence with the received radio wave, the other antenna is separated from the feed line immediately below the antenna feed point and performs open termination. Irrespective of the feed line or the matching element, it is possible to prevent radiation characteristics from deteriorating by setting the terminating condition of the antenna not connected to the receiving circuit to the open terminating condition.

The present invention also relates to a base plate, a first linear element extending in a direction perpendicular to the base plate and connected to a feeding point, and a tip of the first linear element and the base plate. Provided is an antenna constituted by a second linear element to be connected, and a third linear element which is connected to the tip of the first linear element via a switch and is open-terminated.

In the antenna of the present invention, when one of the antennas is connected to the receiving circuit in correspondence with the received radio wave, the antenna of the present invention is separated from the feeder line at a part of the antenna element and performs open termination. Irrespective of the feed line or the matching element, it is possible to prevent radiation characteristics from deteriorating by setting the terminating condition of the antenna not connected to the receiving circuit to the open terminating condition.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

According to the wireless device of the first embodiment shown in FIG. 1, the antenna 11 is directly connected to one end of the switch 15, and the switch 15, the feed line 14, and the switch 1
6 to a receiving circuit 13. The antenna 12 is connected to the receiving circuit 13 via the switch 16. The switch 16 has a contact for selectively connecting the receiving circuit 13 to the feed line 14 and the antenna 2. The switch 15 sets the connection between the antenna 11 and the feed line 14 to 0.
It has a contact for N / OFF.

The control circuit, that is, the controller 17, turns on the switch 15 when the switch 16 connects the receiving circuit 13 to the power supply line 14, and the switch 16 turns on the receiving circuit 1
When switch 3 is connected to antenna 12, switch 15 is turned off.
The control of two switches to be F is performed. Further, the controller 17 receives the received signal from the receiving circuit 13 in the test mode, compares the received signal strengths of the antennas 11 and 12 received by the receiving circuit 13 with each other, and determines the antenna having the larger signal strength. The switching of these switches 15 and 16 is controlled so as to connect to the receiving circuit 13.

The wireless device having the above configuration is a housing (not shown).
The controller 17 compares the received radio wave intensities of the antennas 11 and 12 at high speed, connects the antenna having the stronger radio wave intensity to the receiving circuit 13, and opens the other antenna at the open condition. The switching of the switches is controlled so that

Normally, in the portable telephone, the transmission / reception mode is switched at a high speed in a cycle of 20 ms, and the controller 17 sets the switching timing to several tenths to several hundredths, for example, one tenth to one hundredth. During the time of, the received radio waves of both antennas are simultaneously integrated respectively, and the one with the larger integrated value is selected as the one with the higher received radio wave intensity,
The switching of the switches 15 and 16 is controlled.

The switch 16 connects the receiving circuit 13 to the feed line 1
4 and the switch 15 is connected to the antenna 11 and the feed line 1
When the connection of No. 4 is turned on, the antenna 12 becomes an open end. Conversely, the switch 16 connects the receiving circuit 13 to the antenna 12, and when the switch 15 turns off the connection between the antenna 1 and the feed line 14, the antenna 11 is open-ended. Therefore, regardless of which antenna is used for receiving, the end of the antenna can be opened regardless of the feed line 14, and wireless communication can be performed without lowering the radiation characteristics of the antenna.

Here, the switches 15 and 16 can be easily constituted by components using a PIN diode or the like which is currently on the market. Note that the present invention is not limited to the above-described embodiment.
Circuit element for input bead matching. Also in this case, since the terminal of the antenna 11 becomes an open terminal by turning off the switch 15,
Regardless of which antenna is used, wireless communication can be performed without reducing the radiation characteristics of the antenna, regardless of the feed line 14 including the matching circuit.

Further, the present invention is not limited to the above embodiment, and can be applied to a case where a feed line is connected to both the antenna 11 and the antenna 2.

A wireless device according to a second embodiment of the present invention will be described with reference to FIG. According to this wireless device, the antenna 21 is directly connected to one end of the switch 26, and is connected to the receiving circuit via the switch 26, the power supply line 24, and the switch 28. Antenna 22 is switch 2
7 is connected directly to one end of the receiving circuit 23 via the switch 27, the feed line 25, and the switch 28.
Connected to.

The output of the receiving circuit 23 is connected to a control circuit, that is, a controller 29. The controller 29 turns ON and OFF the switches 26 and 27 according to the output of the receiving circuit 23.
The switching of the FF and the switch 28 is controlled.

In the wireless device shown in FIG. 2, when the antenna 21 is selected, the switch 27 is turned off, and when the antenna 22 is selected, the switch 26 is turned off. Thus, whichever antenna is selected, the other antenna that is not selected can perform open termination regardless of the feed line or the matching circuit. Therefore,
Wireless communication can be performed without lowering the radiation characteristics of the antenna.

Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

According to the wireless device of the third embodiment shown in FIG. 3, the antenna 31a is directly connected to one end of the switch 35a, and is connected to the receiving circuit 32 via the contact A of the switch 35a, the feed line 34a, and the switch 35b. Connected.
The antenna 31b is directly connected to a common terminal of the changeover switch 35c, and the switch 35c, the feed line 34b,
It is connected to the receiving circuit 32 via the contact B of the switch 35b, connected to the transmitting circuit 33 via the feed line 34c, and further connected to the high resistance element 37 via the switch 35c. That is, the changeover switch 35c has three changeover contacts C, D, and E, and the antenna 31b is selectively connected to the reception circuit 32, the transmission circuit 33, and the high-resistance element 37 via these terminals.

The controller 36b controls switching between the transmission mode and the reception mode, and sends a transmission mode / reception mode switching signal to the reception circuit 32, the transmission circuit 33, and the controller 36a.

In the transmission mode, the controller 36a connects the switch 35c to the feed line 34c,
a and the power supply line 34a is turned off. In the receiving mode, when the switch 35b connects the receiving circuit 32 to the feed line 34a, the controller 36a switches the switch 35b.
a is turned on, and the switch 35c is switched so that the antenna 31b is connected to the high-resistance element 37.
The switch 35a is turned off when the receiving circuit 32 is connected to the feed line 34b, and the switches 35a and 35c are controlled so as to switch the switch 35c so as to connect the antenna 31b to the feed line 34b. That is, the controller 36a compares the magnitudes of the received radio waves of the antennas 31a and 31b received by the receiving circuit 32 in the test mode, and connects these antennas to the receiving circuit 32 so as to connect the antenna having the larger radio field strength. Suisochi 35a, 35
The switching control between b and 35c is performed.

In the radio apparatus having the above-described configuration, the transmission mode and the reception mode are alternately switched. In both the transmission mode and the reception mode, the switch is set so that the end of the unselected antenna is in the open condition. Switching control is being performed. Normally, 20 m
The transmission / reception mode is alternately switched in the cycle of s. At that timing, the controller 36b switches between the transmission mode and the reception mode. In addition, the controller 36a simultaneously integrates the received radio waves of both antennas within the time period of 1/10 to 1/100 at the switching timing, and selects the one with the larger integrated value as the one with the higher received radio wave intensity. , Switches 35a, 35
The switching control between b and 35c is performed.

In the transmission mode, the switch 35c connects the antenna 31b to the feed line 34c and turns off the switch 35a, so that the antenna 31a is terminated at the open end. Note that in a wireless device such as a portable wireless device, antenna switching diversity is not performed at the time of transmission, and thus the antenna 31a is always open-ended. The switch 35b switches connection of the receiving circuit 32, and thus does not perform control in the transmission mode. However, even in the transmission mode, the switch 35b is actually set to the contact A
Or, the switch 35a is connected to B
Since the FF is provided and the antenna 31b is connected to the receiving circuit 33 by the switch 35c, the antenna characteristics do not deteriorate.

In the receiving mode, the switch 35b connects the receiving circuit 32 to the feed line 34a, the switch 35a connects the antenna 31a to the feed line 34a,
When 5c connects the antenna 31b to the high resistance element, the antenna 31b is an open termination. Conversely, when the switch 35b connects the receiving circuit 32 to the feed line 34b, the switch 35a turns off the connection between the antenna 31a and the feed line 34a, and the switch 35c connects the antenna 31b to the feed line 34b, the antenna 31a Open termination. Therefore, at both the time of transmission and the time of reception, the termination of the antenna element that is not selected can be opened without being related to the feed line.
Wireless communication can be performed without deteriorating the radiation characteristics of the antenna.

Table 1 shows the relationship between the operation of the switches 35a, 35b and 35c in the reception mode and the transmission mode, and the termination of the unselected antenna.

[0040]

[Table 1]

Switching of the switch is performed by the controller 36a.
Will do. The actual configuration of the switch can be formed by a commercially available switch using a pin diode, and can be controlled by the controller 36a.

The present invention is not limited to the third embodiment. In particular, the feed lines 34a, 34b and 34c can include input impedance matching circuit elements of the antennas 31a and 31b. In this case, antenna 3
The ends of 1a and 31b are open ends. Therefore, the end of the unselected antenna element can be opened regardless of the feed line at any time of transmission and reception. Therefore, wireless communication can be performed without deteriorating the radiation characteristics of the antenna.

Hereinafter, an antenna according to a fourth embodiment of the present invention will be described with reference to FIG. This embodiment is an antenna related to a case where a matching element is included in the antenna itself. An embodiment of such an antenna includes an inverted F
There is an antenna. The inverted F antenna is an antenna element that is often used as a built-in antenna of a wireless device such as a portable wireless device, and is used as one antenna in an antenna switching diversity system. In this case, interference between antennas is a problem.

In the embodiment shown in FIG. 4, a switch 46 is provided between the intersection of the linear element 41 and the matching element 43 and the linear element 42 to solve this problem. That is, according to this embodiment, the first linear element 41 extends in the direction perpendicular to the base plate 45 and is connected to the feeding point, and the second linear element 4
3 is provided so as to connect the tip of the linear element 41 and the ground plate 45. The switch 46 turns ON / OFF the connection between the intersection of the linear element 41 and the matching element 43 and the linear element 42.
It is provided so that.

When performing the antenna switching diversity, if the inverted F antenna is not selected, the controller 47 turns off the switch 46, and if the inverted F antenna is selected, the controller 47 turns on the switch 46.
To

The linear element 41 is the height of the inverted-F antenna. In the case of an inverted-F antenna built in a radio apparatus such as a portable radio, the linear element 41 is required to reduce the size and the attitude of the antenna.
The length of the linear element 41 is about 1/70 wavelength of the working frequency. However, since the length of the linear element 42 is about a quarter wavelength of the operating frequency, the linear element 41 is not open-ended by the switch 46, but is sufficiently shorter than the linear element 42. In addition, the influence on the interference between antennas is very small.

Therefore, the linear element 42 is open-ended irrespective of the termination of the matching element 43 and the inverted F antenna, thereby suppressing interference between antennas and performing wireless communication without deteriorating the radiation characteristics of the antenna. be able to.

FIG. 5 shows a fifth embodiment specifically showing the switch 46 shown in FIG. According to this, the intersection of the linear element 41 and the matching element 43 and the linear element 4
Between them, a diode 51 is provided. Capacitors 53a and 53b are inserted between the linear element 41 and the feeding point 44 and between the linear element 42 and the ground electrode, respectively, to pass a high-frequency signal and cut a direct current.
In addition, choke coils 54a and 54b are inserted between the linear element 42 and the capacitor 53b and between the controller 53b and the capacitor 52, respectively, to pass a direct current and cut a high-frequency signal.

The capacitance of the capacitors 53a and 53b and the inductance of the choke coils 54a and 54b are appropriately selected according to the frequency band used. For example, 1GH
In radio communication of a frequency band of about z, capacitors 53a,
If components of 100 pF are used for 53b and 47 nH are used for choke coils 54a and 54b, the capacitor becomes -j 1.6 ohm and the choke coil becomes about 10 j 300 ohm in high frequency, which is sufficient for DC blocking and high frequency blocking, respectively.

The operation of the circuit shown in FIG. 5 will now be described.
, A positive bias is applied to the diode 51, and the impedance of the diode 51 becomes almost close to O. Conversely, when the controller 52 applies a negative DC voltage to the diode 51, the diode 51 is negatively biased and the impedance of the diode 51 becomes very large.

Therefore, when the controller 52 applies a positive or negative DC voltage to the diode 51, the diode 51 functions as a short-circuit and open switch in high frequency. In addition, since the capacitors 53a and 53b and the choke coils 54a and 54b are inserted at appropriate locations, leakage of high-frequency signals to unnecessary locations and leakage of direct current to unnecessary locations are prevented.

[0052]

As described above, according to the present invention, when one antenna is connected to the receiving circuit in correspondence with the received radio wave, the other antenna is cut off from the feed line immediately below the antenna feed point and opened. By terminating the antenna, the termination condition of the antenna that is not connected to the receiving circuit can be set as open termination without depending on the feed line or the matching circuit. Since there is no need to route the feed line for a long time and the feed line does not need to be routed for a long time, transmission loss can be reduced, so that the degree of freedom of design is not limited and the size of the housing can be reduced. Further, even when a matching circuit is included in the non-selected antenna, the termination can be set to the open condition regardless of the feed line or the matching circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a wireless device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a wireless device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a wireless device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of an inverted-F antenna according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of an inverted-F antenna according to a fifth embodiment of the present invention.

FIG. 6 is a perspective view of a model radio used for measuring antenna radiation efficiency.

7 is a characteristic diagram of antenna radiation efficiency obtained by the model radio of FIG. 6;

FIG. 8 is a configuration diagram of a conventional inverted-F antenna.

FIG. 9 shows a conventional wireless device.

[Explanation of symbols]

11, 12, 21, 22, 31a, 31b Antenna 13, 23, 32 Receiving circuit 33 Transmitting circuit 14, 24, 25, 34a, 34b, 34c Feeding line 15, 16, 26, 28, 35a, 35b , 35c, 4
6 Switch 17, 29, 36a, 36b, 47, 52 Controller 37 High-resistance element 41, 42, 43 Linear element 44 Feeding point 45 Ground plate 51 Diode 53a, 53b Capacitor 54a, 54b Choke coil

Claims (5)

[Claims] A first switch for turning on / off a connection between the first antenna and the feed line; a second switch for turning on / off a connection between the first antenna and the feed line;
And a second switch for connecting one of the antenna and the feed line to the receiving circuit, and the first switch according to the intensity of radio waves received by each of the first and second antennas.
A control circuit that controls switching between the first switch and the second switch, and a housing that houses the receiving circuit, the first and second antennas, the first and second switches, and the control circuit. Wireless device. 2. A second power supply line connected between the second antenna and the second switch, and a third power supply line for turning on / off the connection between the second power supply line and the second antenna.
And the control circuit turns off the third switch when the first antenna is selected, and turns off the first switch 26 when the second antenna is selected. The wireless device according to claim 1, wherein: 3. A receiving circuit, a transmitting circuit, and first and second circuits.
, The first, second, and third power supply lines, and the connection between the first antenna and the first power supply line is turned ON / OFF.
A first switch that turns off, a second switch that switches the second antenna to one of the second feed line, the third feed line, and a high-resistance element;
A third switch for switching the receiving circuit to one of the feeder line and the second feeder line, and switching between a transmission mode and a reception mode to reduce the intensity of radio waves received by each of the first and second antennas. A control circuit that controls switching of the first, second, and third switches so as to connect one of the first and second antennas to the receiving circuit via a corresponding feed line in response thereto; A wireless device including a receiving circuit, the transmitting circuit, the first and second antennas, the first, second, and third power supply lines, and a housing that houses the control circuit. 4. The control circuit simultaneously integrates radio waves received by the first and second antennas within a time period of several tens to several hundredths of a switching cycle in which a transmission / reception mode is switched at a high speed. 4. The switching device according to claim 1, wherein the first, second, and third switches are switched by using a larger value as an antenna having a higher received signal strength. 5.
A wireless device according to claim 1. 5. A ground plane, a first linear element extending in a direction perpendicular to the ground plane and connected to a feeding point, and a second linear element connecting a tip of the first linear element and the ground plane. And an open-ended third linear element connected to the tip of the first linear element via a switch.