JP2006042255A - Wireless communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication device capable of obtaining good antenna characteristics even when individual antennas constituting an antenna unit of the radio communication device are affected by a proximity substance.
SOLUTION: A first switch 108 and a second switch 109 are provided between a first monopole antenna 102, a second monopole antenna 103 and a branch conductor 104, and the first monopole antenna 102 and the second monopole antenna 103 are provided. When any one of the first and second switches 109 is affected by a nearby substance, the total impedance from the branch point 112 to the first termination impedance 106 or the second termination impedance 107 is changed to the affected antenna-side first switch 108 or second switch 109. By switching to the first termination impedance 106 or the second termination impedance 107 side that is set to be infinite, the power supplied to the antenna can be supplied to the antenna that is not affected by the proximity substance, Good characteristics of the antenna unit 101 can be maintained.
[Selection] Figure 1

Description

  The present invention relates to a wireless communication apparatus equipped with a plurality of antenna elements.

  Conventionally, a method has been proposed for improving a radiation gain during a call by mounting a plurality of antenna elements and operating them simultaneously in a wireless communication apparatus. One example is a wireless communication apparatus as shown in FIG. FIG. 6 is a diagram illustrating an example of a schematic configuration of a conventional wireless communication apparatus. As shown in FIG. 6, in this wireless communication apparatus, the first antenna element 602 and the second antenna element 603 constituting the antenna unit 601 are supplied with the first antenna element 602 and the second antenna element 603, respectively. The first conductor 605 and the second feeder 606 are connected to the branch conductor 604.

  Further, the branch conductor 604 is connected to a transmission circuit 609 and a reception circuit 610 that constitute a radio circuit unit 608 via a duplexer 607. By connecting the branch conductor 604 and the transmission circuit 609 via the duplexer 607 at the time of transmission, a transmission signal is distributed by the branch conductor 604 and then transmitted from the first antenna element 602 and the second antenna element 603. It is transmitted at the same time. Further, at the time of reception, by connecting the branch conductor 604 and the reception circuit 610 via the duplexer 607, signals received by the first antenna element 602 and the second antenna element 603 are transmitted by the branch conductor 604. The signals are combined and supplied to the receiving circuit 610.

  However, in the case of the wireless communication device, as shown in FIG. 7, when a part of a human body such as a hand or a finger 701, a metal or a dielectric substance is close to one of the antenna elements (601, 602), the input of the antenna unit 601 is performed. The impedance changes and mismatch loss occurs between the wireless circuit unit and the characteristics of the antenna unit are deteriorated.

Therefore, a method is disclosed in which a coaxial cable is used for the feeder line between the branch conductor and the antenna unit, and the electrical length from the branch conductor to the antenna is appropriately selected. FIG. 8 is a diagram illustrating another example of a schematic configuration of a conventional wireless communication apparatus. The apparatus shown in FIG. 8 eliminates the influence of adjacent substances by appropriately selecting the electrical length of the coaxial cable. As shown in FIG. 8, the second antenna element 803 affected by the proximity substance is a distributed constant circuit such as the second coaxial cable 806 determined so that the input impedance of the second antenna element 803 is infinite. In this method, the power supplied to the second antenna element 803 is reflected to reflect the power supplied to the second antenna element 803 to the unaffected first antenna element 802. is there.
JP 2001-308635 A

  However, in the method described in Patent Document 1, the input impedance of the antenna may not be infinite depending on the positional relationship between the second antenna element 803 and the adjacent substance, and the electric power supplied to the second antenna element 803 is reduced. There was a situation that the first antenna element 802 that was not affected could not be completely transferred.

  The present invention has been made in view of the above-described conventional circumstances, and it is possible to obtain good antenna characteristics even when individual antennas constituting the antenna unit of the wireless communication device are affected by a proximity substance. An object of the present invention is to provide a wireless communication device that can be used.

  The wireless communication device of the present invention has an antenna unit having a plurality of antenna elements, a wireless circuit unit that feeds power to the antenna unit, and a branch point that branches off the connection between the wireless circuit unit and the branch point from the branch point. A branch conductor connecting each of the plurality of antenna elements; a branch conductor of the branch conductor; and a branch point of the branch conductor and the antenna element, and feeding from the radio circuit unit to either the antenna element or the termination impedance Switching means for switching and connecting.

  As a result, the power supplied to the antenna element affected by the neighboring substance can be transferred to the antenna element not affected by the neighboring substance, so that the good characteristics of the antenna portion can be maintained. it can.

  In the wireless communication apparatus of the present invention, the termination impedance is set so that a total impedance from the branch point of the branch conductor to the termination impedance is infinite.

  As a result, the power supplied to the antenna element affected by the neighboring substance can be transferred to the antenna not affected by the neighboring substance as much as possible, so that the good characteristics of the antenna section are maintained. be able to.

  In the wireless communication device of the present invention, the switching unit includes a plurality of termination impedances that can be selected, and the switching unit selects a termination impedance to be connected according to a frequency band of communication performed through the antenna unit. .

  Thus, by using a plurality of terminal impedances for each frequency band in which the antenna element operates, the power supplied to the antenna element affected by the adjacent substance is influenced by the adjacent substance in the plurality of frequency bands. Since the antenna element can be switched to a non-antenna element, good characteristics of the antenna portion can be maintained.

  The wireless communication apparatus of the present invention further includes a switching control unit that switches the switching unit to acquire a received signal strength and controls the switching unit so as to select a switching state with the best received signal strength.

  As a result, the switching state with the best received electric field strength is selected, so that excellent antenna characteristics can be obtained even when individual antennas are affected by nearby substances.

  According to the present invention, it is possible to provide a wireless communication apparatus that can obtain good antenna characteristics even when individual antennas constituting the antenna unit of the wireless communication apparatus are affected by a proximity substance.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a wireless communication apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the wireless communication apparatus of the present embodiment includes an antenna unit 101 having a first monopole antenna 102 and a second monopole antenna 103, a first matching circuit 104, a second matching circuit 105, A first termination impedance 106, a second termination impedance 107, a first switch 108, a second switch 109, a branch conductor 112, a third matching circuit 115, a radio circuit 116, and a control circuit 117 are provided.

  The first monopole antenna 102 is connected to the first matching circuit 104. The first matching circuit 104 matches the input impedance of the first monopole antenna 102. Similarly, the second monopole antenna 103 is connected to the second matching circuit 105. The second matching circuit 105 matches the input impedance of the second monopole antenna 103. In the present embodiment, the input impedance of the first monopole antenna 102 and the second monopole antenna 103 is 50 [Ω].

  One of the first termination impedance 106 and the second termination impedance 107 is grounded to the ground of the circuit board or the like, and a predetermined impedance value is set. Details of the first termination impedance 106 and the second termination impedance 107 will be described later.

  The first switch 108 switches so as to select one of the first matching circuit 104 and the first termination impedance 106. Similarly, the second switch switches so as to select one of the second matching circuit 105 and the second termination impedance 107.

  The branch conductor 112 is connected to the first switch 108 via the first line 110 and to the second switch 109 via the second line 111. Further, it is connected to the third matching circuit 115 via the third line 114. The third line 114 is branched to the first line 110 and the second line 111 via the branch point 113.

  The third matching circuit 114 is connected to the branch conductor 112 and matches the input impedance of the entire branch conductor 112 side as viewed from the third matching circuit 114. The radio circuit 115 feeds power to the first monopole antenna 102 and the second monopole antenna 103 of the antenna unit 101. The control circuit 116 controls switching of each of the first switch 108 and the second switch 109.

  Next, the operation of the wireless communication apparatus of this embodiment will be described. In the wireless communication apparatus according to the present embodiment, both the first switch 108 and the second switch 109 are connected to the first matching circuit 104 and the second matching circuit 105 in the first monopole antenna 102 and the second monopole antenna 103, respectively. By doing so, it is possible to operate simultaneously.

  FIG. 2 is a diagram illustrating the antenna efficiency of the wireless communication apparatus according to the first embodiment. In FIG. 2, the characteristics shown on the left and center are the characteristics when both the first monopole antenna 102 and the second monopole antenna are operating at the same time. The antenna efficiency in the case of not receiving the antenna, and the center shows the antenna efficiency in the case where the first monopole antenna 102 or the second monopole antenna 103 of the antenna unit 101 is affected by the proximity substance. Here, the proximity substance is a metal, a dielectric substance, a hand, a finger, or the like that is close to the antenna unit 101.

  FIGS. 3A and 3B are diagrams showing the characteristics of the antenna portion when not affected by the proximity substance, where FIG. 3A shows the input impedance characteristics and FIG. 3B shows the VSWR characteristics. FIGS. 4A and 4B are diagrams showing the characteristics of the antenna section when affected by a proximity substance, where FIG. 4A shows the input impedance characteristics and FIG. 4B shows the VSWR characteristics.

  Comparing FIG. 3 and FIG. 4, when a metal or dielectric material is close to the first monopole antenna 102 or the second monopole antenna 103, mismatch occurs in the input impedance of the antenna unit 101, and VSWR (Voltage Standing Wave) It can be seen that the ratio (voltage standing wave ratio) has deteriorated. As a result, as shown in FIG. 2, the antenna efficiency is reduced from −1.0 [dB] to −3.0 [dB] and 2 [dB] due to the proximity substance.

  Therefore, the wireless communication device according to the present embodiment is affected by the influence of a monolithic antenna 102 or a second monopole antenna 103 when a metal or a dielectric substance is close to the antenna and the antenna characteristics deteriorate. By switching from the pole antenna to the terminal impedance, a decrease in antenna efficiency is prevented. Here, the termination impedance (the first termination impedance 106 and the second termination impedance 107) is set so that the total impedance from the branch point 113 to the termination impedance is infinite, that is, VSWR is infinite.

  For example, when a proximity substance exists in the second monopole antenna 103, the second switch 109 is switched to the second termination impedance 107. As a result, the total impedance from the branch point 113 to the second termination impedance 107 is infinite, that is, VSWR is infinite.

  As a result, the power supplied to the second monopole antenna 103 is completely reflected, so that the power supplied to the second monopole antenna 103 is supplied to the first monopole antenna 102. Therefore, the antenna efficiency is −0.9 [dB] as shown on the right in FIG. 2, which is equivalent to the case where the antenna is not affected by the adjacent substance. The same applies when a proximity substance exists in the first monopole antenna 102.

  Next, switching between the first switch 108 and the second switch 109 will be described. As a switching pattern of the first switch 108 and the second switch 109, when the first switch 108 is ON on the first monopole antenna 102 side and the second switch 109 is ON on the second monopole antenna 103 side, the first switch 108 When 108 is ON on the first monopole antenna 102 side and the second switch 109 is ON on the second termination impedance 107 side, the first switch 108 is ON on the first termination impedance 106 side and the second switch 109 is the second monopole. There are three types when the pole antenna 103 is ON.

  The control circuit 117 switches the first switch 108 and the second switch 109 in the above pattern, receives the value of RSSI (Received Signal Strength Indicator) in the pattern from the radio circuit unit 105, and most A pattern indicating a good RSSI value is selected, and switching of the first switch 108 and the second switch 109 is determined. Further, since the pattern selection is always performed, the antenna unit 101 can maintain good characteristics.

  According to the first embodiment of the present invention as described above, in a wireless communication apparatus including an antenna unit having a plurality of antenna elements, when at least one of them is affected by a proximity substance, the power is fed to the antenna element. By switching from the terminal impedance to the terminal impedance, it is possible to maintain good characteristics of the antenna unit.

(Second Embodiment)
FIG. 5 is a diagram showing a schematic configuration of a wireless communication apparatus according to the second embodiment of the present invention. As shown in FIG. 5, the wireless communication apparatus according to the present embodiment includes an antenna unit 201 having a first helical antenna 202 and a second helical antenna 203, a first matching circuit 204, a second matching circuit 205, and a first matching circuit. Termination impedance 206, second termination impedance 207, third termination impedance 208, fourth termination impedance 209, first switch 210, second switch 211, branch conductor 214, third matching circuit 217, wireless A circuit 218 and a control circuit 219 are provided.

  The first helical antenna 202 is connected to the first matching circuit 204. The first matching circuit 204 matches the input impedance of the first helical antenna 202. Similarly, the second helical antenna 203 is connected to the second matching circuit 205. The second matching circuit 205 matches the input impedance of the second helical antenna 203. Here, the first helical antenna and the second helical antenna 202 operate in two frequency bands, a first frequency band and a second frequency band.

  One of the first termination impedance 206 and the second termination impedance 207 is grounded to the ground of the circuit board or the like, and a predetermined impedance value is set. The first switch 210 switches so as to select one of the first matching circuit 204, the first termination impedance 206, and the third termination impedance 208. Similarly, the second switch switches to select one of the second matching circuit 205, the second termination impedance 207, and the fourth termination impedance 209.

  The branch conductor 214 is connected to the first switch 210 via the first line 212 and to the second switch 211 via the second line 213. Further, it is connected to the third matching circuit 217 via the third line 216. The third line 216 is branched to the first line 212 and the second line 213 via the branch point 215.

  The third matching circuit 217 is connected to the branch conductor 214 and matches the input impedance of the entire branch conductor 214 side as viewed from the third matching circuit 217. The radio circuit 218 supplies power to the first helical antenna 202 and the second helical antenna 203 of the antenna unit 201. The control circuit 218 controls switching of each of the first switch 210 and the second switch 211.

  Here, the first termination impedance 206 is set so that the total impedance from the branch point 215 to the first termination impedance 206 is infinite when communication is performed in the first frequency band. The third termination impedance 208 is set such that the total impedance from the branch point 215 to the third termination impedance 208 becomes infinite when communication is performed in the second frequency band.

  Similarly, the second termination impedance 207 is set so that the total impedance from the branch point 215 to the second termination impedance 207 is infinite when communication is performed in the first frequency band. The fourth termination impedance 209 is set such that the total impedance from the branch point 215 to the fourth termination impedance 209 is infinite when communication is performed in the second frequency band.

  Then, the wireless communication device of the present embodiment, when a metal or a dielectric material or the like approaches the first helical antenna 202 or the second helical antenna 203 that can operate in a plurality of frequency bands, the antenna characteristics deteriorate. Depending on the frequency band being used, switching from the affected monopole antenna to the termination impedance prevents a decrease in antenna efficiency.

  For example, when the second helical antenna 203 is affected by a proximity substance when the wireless communication device is used in the first frequency band, the second switch 211 is moved from the second helical antenna 203 side to the second terminal impedance 207 side. In addition, if the second switch 211 is switched from the second helical antenna 203 side to the fourth terminal impedance 209 side when it is affected by a proximity substance when used in the second frequency band, the second helical The electric power supplied to the antenna 203 is completely reflected, and the electric power supplied to the second antenna element 203 is supplied to the first helical antenna 202. Therefore, good characteristics of the antenna unit 301 can be maintained regardless of which frequency band is the first used frequency band or the second frequency band.

  Next, switching between the first switch 210 and the second switch 211 will be described. As a switching pattern of the first switch 210 and the second switch 211 in the first frequency band, when the first switch 210 is ON on the first helical antenna 202 side and the second switch 211 is ON on the second helical antenna 203 side, When the first switch 210 is ON on the first helical antenna 202 side and the second switch 211 is ON on the second termination impedance 207 side, the first switch 210 is ON on the first termination impedance 206 side and the second switch 211 is the second There are three types when the 2-helical antenna 203 is ON.

  In addition, as a switching pattern of the first switch 210 and the second switch 211 in the second frequency band, the first switch 210 is ON on the first helical antenna 202 side, and the second switch 211 is ON on the second helical antenna 203 side. In this case, when the first switch 210 is ON on the first helical antenna 202 side and the second switch 211 is ON on the fourth terminal impedance 209 side, the first switch 210 is ON on the third terminal impedance 208 side, and the second switch 211 There are three types when ON is on the second helical antenna 203 side.

  The radio circuit 218 notifies the control circuit 219 which frequency band is used for radio communication. The control circuit 219 switches the first switch 210 and the second switch 211 in the above pattern based on the information on the used frequency band notified from the wireless circuit 218. Then, the radio circuit 218 notifies the control circuit 219 of the RSSI value in each of the above patterns, and the control circuit 219 selects the pattern indicating the best RSSI value, and the first switch 108 and the second switch 109 are selected. Determine the switch. Further, since the pattern selection is always performed, the antenna unit 201 can maintain good characteristics.

  According to the second embodiment of the present invention, in the wireless communication apparatus including the antenna unit having the plurality of antenna elements each capable of communication using the plurality of frequency bands, at least one of them is a proximity substance In the case of being influenced by the above, by switching the power feeding from the antenna element to the terminal impedance according to the operating frequency band, it is possible to maintain good characteristics of the antenna unit.

  In the first and second embodiments, two antenna elements are used, but the same effect can be obtained even with three or more antenna elements. Further, the present invention is not limited to a monopole antenna or a helical antenna, and the same effect can be obtained even when a linear antenna or a planar antenna other than the monopole antenna is used.

  Moreover, although the same antenna is used for all antenna elements constituting the antenna unit, the same effect can be obtained even if different antennas are used.

  In the above embodiment, the switching of each switch is determined by the RSSI value notified from the radio circuit unit to the control circuit. However, the present invention is not limited to this. Alternatively, the switch may be switched by detection means for detecting contact. For example, a control circuit is configured to switch a switch based on a detection result using a non-contact type substance detection unit such as a photoelectric sensor or an infrared sensor, or a contact type detection unit that detects contact of a human body such as a temperature sensor. May be.

  The wireless communication device of the present invention has an effect of obtaining good antenna characteristics even when individual antennas constituting the antenna unit of the wireless communication device are affected by a proximity substance, such as a mobile phone device Useful for.

The figure which shows schematic structure of the radio | wireless communication apparatus which concerns on the 1st Embodiment of this invention. The figure which shows the antenna efficiency of the radio | wireless communication apparatus which concerns on 1st Embodiment The figure which shows the input impedance and VSWR characteristic of an antenna part when not receiving the influence of a proximity substance The figure which shows the input impedance and VSWR characteristic of an antenna part when it receives to the influence of a proximity substance The figure which shows schematic structure of the radio | wireless communication apparatus which concerns on the 2nd Embodiment of this invention. The figure which shows an example of schematic structure of the conventional radio | wireless communication apparatus. It is a figure which shows an example of schematic structure of the conventional radio | wireless communication apparatus, Comprising: The figure which shows the state which the finger | toe touched one of the antenna elements The figure which shows the other example of schematic structure of the conventional radio | wireless communication apparatus.

Explanation of symbols

101, 201 Antenna portion 102 First monopole antenna 103 Second monopole antenna 104, 204 First matching circuit 105, 205 Second matching circuit 106, 207 First termination impedance 107, 208 Second termination impedance 108, 209 First Switch 109, 211 Second switch 110, 212 First line 111, 213 Second line 112, 214 Branch conductor 113, 215 Branch point 114, 216 Third line 115, 217 Third matching circuit 116, 218 Radio circuit 117, 219 Control circuit 202 First helical antenna 203 Second helical antenna 208 Third terminal impedance 209 Fourth terminal impedance

Claims (4)

An antenna unit having a plurality of antenna elements;
A radio circuit unit for supplying power to the antenna unit;
A branch point that branches the connection with the wireless circuit unit, and a branch conductor that connects each of the plurality of antenna elements from the branch point;
Switching means provided between a branch point of the branch conductor and the antenna element, and switching the power supply from the radio circuit unit to either the antenna element or a terminal impedance;
A wireless communication device comprising: The wireless communication device according to claim 1,
The terminal impedance is a wireless communication device that is set so that a total impedance from a branch point of the branch conductor to the terminal impedance becomes infinite. The wireless communication device according to claim 1 or 2,
A wireless communication apparatus comprising a plurality of termination impedances selectable by the switching means, wherein the switching means selects a termination impedance to be connected according to a frequency band of communication performed via the antenna unit. A wireless communication device according to any one of claims 1 to 3,
A wireless communication apparatus further comprising: a switching control unit that switches the switching unit to acquire a received signal strength and controls the switching unit so as to select a switching state with the best received signal strength.

Images