JP4274904B2 - Antenna device and communication terminal - Google Patents

Description

The present invention relates to an antenna device applied to a mobile terminal device and the like and a communication terminal including the antenna device .

  An antenna mounted on a portable terminal such as a cellular phone or a portable information terminal is required to be small and light as the apparatus is miniaturized. However, when the antenna is miniaturized, degradation of antenna efficiency due to a decrease in radiation resistance becomes a problem. At the same time, since the Q value is increased, there is a problem that the specific bandwidth of the antenna is reduced, and there is a limit to downsizing the antenna element.

  In addition, many antennas mounted on mobile phones and the like use the electrical length λ / 4 system, and circuit boards are used as antenna ground conductors. For this reason, for example, in a two-fold cellular phone in which the circuit board is divided vertically, the antenna characteristics fluctuate depending on whether the cellular phone casing is closed or opened. Furthermore, when the antenna is built in the housing, the impedance changes because the user holds the mobile phone in his hand or the head or finger of the human body comes close to the antenna element during a call. As described above, in a small antenna built in a portable terminal such as a cellular phone, variation in antenna characteristics due to these factors is a problem.

  On the other hand, in recent years, development of portable terminals that support a plurality of frequency bands, such as dual mode, has been actively developed, and an antenna that can support a plurality of frequency bands is required. Therefore, the antenna device mounted on these portable terminals is required to have a function of switching the resonance frequency of the antenna.

  In addition, an amplifier (power amplifier) used in a transmission unit of an RF (Radio Frequency) circuit, which is an internal circuit of the antenna, has a problem that power consumption and distortion characteristics fluctuate depending on an output impedance to the antenna. . Therefore, in the past, an isolator was inserted between the antenna and the power amplifier to reduce the load fluctuation of the input impedance of the antenna. However, since the passing loss of the isolator is large, the maximum output of the power amplifier is not increased accordingly. There was a problem that it should not be. In recent years, in order to reduce the power consumption of power amplifiers in particular, it has been studied to apply parts and circuit configurations with less passage loss even if the amount of load fluctuation is somewhat large. Therefore, there is a demand for an antenna with less fluctuation in output impedance (that is, input impedance from the antenna).

  Conventionally, in order to cope with these problems and requirements, the circuit connected to the antenna is devised, the state of the mobile phone (opening / closing state, communication state, etc.) is detected by some method, and the resonance frequency of the antenna is arbitrarily switched. An antenna device provided with means is known.

  Patent Document 1 discloses a configuration in which a switch circuit that can vary impedance matching between an antenna and an antenna circuit is provided in series. FIG. 12 is a block diagram illustrating the configuration of a conventional antenna device. In the conventional antenna device, in order to perform impedance matching when transmitting and receiving, a matching circuit 22 connected to the antenna 21 is provided, a transmission line 23 is connected to the matching circuit 22, and a transmission system or reception system circuit not shown in the figure. It was set as the structure connected to the transmission / reception duplexer 28 connected to. That is, the matching circuit 22 and the transmission line 23 are connected in series between the antenna 21 and the transmission / reception duplexer 28 connected to the transmission system or the reception system circuit. Note that a switch 27 is provided between the transmission line 23 and the transmitter / receiver duplexer 28 for switching to an external RF output connector 26 used for inspection of RF (Radio Frequency) output.

  On the other hand, the configuration of the antenna device disclosed in Patent Document 1 is shown in FIG. In this example, with respect to the conventional antenna device shown in FIG. 12, a matching circuit 24 for adjusting fluctuations in impedance caused by the antenna approaching the human body and a matching circuit that maximizes transmission power are selected. The switch 25 for switching is provided, and these are connected in series between the antenna 21 and the duplexer 28.

Patent Document 2 discloses a configuration in which a changeover switch for making impedance variable is provided in parallel on an antenna feeding point and a line connected to an antenna element.
JP-A-11-145852 JP-A-6-224618

  However, in a configuration in which a switch capable of varying impedance matching is provided in series between the conventional antenna and the transmission system or the reception system circuit, a passage loss of the switch circuit occurs. For example, a general-purpose gallium arsenide switch, SP3T (one input system, three output switch), causes a passage loss of about 0.4 to 0.6 dB when used in a 50Ω system. Further, as shown in FIG. 13, since the switch 25 is directly connected to the antenna 21, when a small antenna having only a radiation resistance of about several Ω is applied, the passing loss of the switch becomes equivalently large. There is a concern that the antenna characteristics may deteriorate by about several dB.

  Further, in the configuration in which the changeover switch for making the impedance variable is provided in parallel, the loss due to the load of the switch is likely to be reduced as compared with the case where the switch is provided in series, but the resistance component of the switch is not sufficiently small. When a switch or the like is applied, the loss becomes even larger than when the switch is connected in series. In order to prevent this, there is a plan to use a PIN diode (Positive Intrinsic Negative Diode) having a small resistance component, but in that case, a phenomenon such as distortion or oscillation occurs due to the feedback current of the diode during transmission. Further, if the resistance component of the PIN diode is to be reduced to about 1 to 2Ω, which has a small influence on the antenna characteristics, the bias current needs to be about 1 to 2 mA. Considering the battery capacity of current mobile phones, the current consumption of milliampere order has a significant impact on power consumption, and it is not practical to use it especially when the circuit configuration with low power consumption is required. .

  As described above, the conventional portable terminal antenna apparatus has a problem of an increase in passage loss due to downsizing and deterioration of antenna characteristics due to the increase.

  It is an object of the present invention to reduce the resonance frequency of an antenna without sacrificing the conventional antenna characteristics in a configuration that can support a transmission / reception antenna without greatly changing the conventional antenna device and circuit configuration and that has low power consumption. It is to realize an antenna device that can be switched.

In order to solve the above-described problems, the present invention provides a first matching circuit connected to an antenna, a transmission line connected to the first matching circuit and one end and functioning as phase means for adjusting the phase, and other transmission lines . A second matching circuit for switching the frequency that connects one end to the end, and selects either the other end of the transmission line or the other end of the second matching circuit as a transmission system / reception system circuit. e Bei a changeover switch which connects, in a first matching circuit and said transmission line, and configured to adjust the phase so as to draw a locus of impedance characteristics on the equal resistance line.

  As a result, it is not necessary to increase the number of switches in the antenna circuit, and switching of the resonance frequency of the antenna can be realized without sacrificing the antenna performance.

  Moreover, antenna performance can be improved by switching according to surrounding environment and conditions by arbitrary switch control.

  In addition, since fluctuations in the impedance characteristics of the antenna can be reduced, load fluctuations in the output impedance from the power amplifier of the antenna circuit can be reduced.

  According to the present invention, it is possible to realize a circuit that adds a switch for switching the resonance frequency of an antenna with a simple configuration and without greatly changing the conventional antenna and circuit configuration. Further, the antenna performance can be improved and the size can be reduced.

  In addition, by reducing fluctuations in the impedance characteristics of the antenna, load fluctuations in the output impedance from the power amplifier of the antenna circuit can be reduced, making parts such as an isolator between the antenna and the power amplifier simpler and less lossy. As a result, the antenna circuit can be reduced in size and power consumption.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 shows a configuration example of a communication terminal in which the antenna device according to the first embodiment of the present invention is built. FIG. 1 shows an example in which an antenna device is configured on a circuit board 11. The antenna 1 is formed in a planar shape on the circuit board 11, and the first matching circuit 2 is connected to the feeder line 12 connected to the antenna 1. A transmission line 3 is connected to the first matching circuit 2. The transmission line 3 branches into two at a branch point 13 in the middle, and one of the branched lines is a second matching circuit 5 for switching the resonance frequency. Connect to. The other end of the second matching circuit 5 is connected to the first fixed contact 14 of the switch 7, and the other line branched at the branch point 13 is directly connected to the second fixed contact 15 of the switch 7. The switch 7 is also provided with a third fixed contact 16 connected to the external RF output connector 6 so that connection to an external antenna and inspection of the RF output can be performed. On the other hand, the movable contact 17 of the switch 7 is connected to one end of the transmission / reception duplexer 8. The other end of the transmission / reception duplexer 8 is configured to connect a transmission system circuit and a reception system circuit, and a power amplifier 10 is connected to the transmission system circuit. Although not shown in the circuit of the receiving system, an LNA (Low Noise Amplifier) is connected.

  In this way, the switch 7 has a configuration having one movable contact 17 and three fixed contacts 14 to 16, and selectively switches between the movable contact 17 and the fixed contacts 14 to 16 connected to the transmission system or the reception system circuit. Can do. The switch 7 is connected to a switch control circuit 9 for controlling the switching. The switch control circuit 9 switches the resonance frequency according to the surrounding environmental state and conditions.

  In this example, the transmission / reception duplexer 8 is connected to a transmission system circuit and a reception system circuit, and has a function of demultiplexing the transmission / reception radio waves. A switch having a circuit switching function may be used. In addition, the circuit connected to the transmitter / receiver demultiplexer 8 may be configured as a plurality of circuits that perform transmission / reception of different communication methods, in which case the transmitter / receiver demultiplexer 8 has a function of a communication method changeover switch. You may comprise as. If the communication terminal has only one of the transmission system and the reception system, the transmitter / receiver demultiplexer 8 may be omitted and connected directly to the transmission system or the reception system.

  In this example, the second matching circuit is configured using a capacitor (C) and an inductor (L). As for the configuration of the matching circuit, an appropriate circuit may be assembled in accordance with a desired resonance frequency of the antenna device, usage conditions, and the like.

  FIG. 2 is a block diagram showing a configuration example of an apparatus according to the first embodiment of the present invention. The operation of this example will be described with reference to FIG. In this apparatus, by switching operation of the switch 7, the first path a connected to the circuit via only the first matching circuit 2, and the circuit via the first matching circuit 2 and the second matching circuit 5 are connected. Three paths can be realized: a second path b to be connected and a third path c to connect the external RF output connector and the circuit. The first matching circuit 2 is adjusted in advance so as to resonate in a certain frequency band in the first path a, and the first matching circuit is resonated in another frequency band in the second path b. 2 and the second matching circuit 5 are adjusted in advance.

  First, a case where radio waves are received using this apparatus will be described. As an initial state, the switching state of the switch 7 is a state in which the second fixed contact 15 and the movable contact 17 are connected, and the first path a is configured. The radio wave received by the antenna 1 first matches the impedance through the first matching circuit 2. Next, the signal passes through the transmission line 3 connected to the first matching circuit 2, is input to the second fixed contact 15 of the switch 7, is transmitted from the movable contact 17 to the transmission / reception duplexer 8, and is input to the circuit of the reception system To do. Thus, first, radio waves are received without passing through the second matching circuit 5. Next, the switch control circuit 9 detects the radio wave reception state, determines whether or not to switch the switch according to the state, and performs switching control on the switch 7 if necessary. For example, when the power of the line input to the transmitter / receiver demultiplexer 8 is measured and the value is decreased by a certain value or more from the value necessary for maintaining the designed frequency characteristics, the switch 7 is switched and the first The fixed contact 14 and the movable contact 17 are connected, and the connection is changed to the second path b. By switching in this way, radio waves are transmitted to the circuit of the reception system via the second matching circuit 5, so that impedance matching can be achieved and the resonance frequency can be switched.

  As antenna characteristics when the first route a is set and when the second route b is set, for example, when the communication device of this example is a so-called foldable mobile phone terminal that can be folded in two. The first path a has an antenna characteristic suitable for a folded state, and the second path b has an antenna characteristic suitable for an open state.

  In this case, as described above, the change-over switch 7 may be switched based on the determination of the reception state of the radio wave. However, when the terminal is in the folded state, control is performed so that the first path a is established, and the terminal opens. It may be controlled so as to be the second path b in the state.

  In the above description, the first path a is set as the switching state of the switch 7 in the initial state, but other paths may be set depending on the use conditions of the antenna device.

  In the case of transmitting a radio wave, the radio wave is transmitted from the transmitting antenna circuit through the power amplifier 10 and input to the movable contact 17 of the switch 7 via the transmitter / receiver demultiplexer 8. The switch 7 connects the movable contact 17 and the first fixed contact 14 or the second fixed contact 15 and transmits radio waves from the antenna 1 through the first path a or the second path b. The switch control circuit 9 measures, for example, the transmission power of the antenna and switches to a path with higher transmission power based on the value.

  In this way, even when the circuit is switched for switching the resonance frequency, only one switch 7 is always present on the circuit from the antenna 1 to the transmitter / receiver demultiplexer 8, so that the load of the switch Does not increase the passage loss. Further, since the transmission line 3 from the antenna 1 to the switch 7 can be used as a phase shifter as a part of the matching circuit, the loss from the antenna 1 to the transmission / reception duplexer 8 can be considered in total. . Conventionally, there is a problem that the phase changes due to the presence of the transmission line and the desired frequency cannot be switched. However, since the transmission line is used as a phase shifter to make it easy to switch the resonance frequency of the antenna, the resonance frequency Can be easily switched. Further, since this transmission line is also used in a conventional antenna device, the loss does not change even when used as a phase shifter.

  Next, FIG. 3 shows a block diagram showing a configuration example of an apparatus according to the second embodiment of the present invention. In this example, the first matching circuit 2 is connected to the antenna 1, and the spare phase shifter 4 is connected to the transmission line 3 connected to the first matching circuit 2. A branch point 13 is arranged after the spare phase shifter 4 and branches into two. One branched line is configured to be connected to the first fixed contact 14 of the switch 7 via the second matching circuit 5 for switching the resonance frequency, and the other branched line is connected to the second line of the switch 7. It is configured to connect directly to the fixed contact 15. The switch 7 is provided with a third fixed contact 16 connected to the external RF output connector 6. On the other hand, the movable contact 17 of the switch 7 is connected to one end of the transmission / reception duplexer 8. The other end of the transmission / reception duplexer 8 is configured to connect a transmission system circuit and a reception system circuit, and a power amplifier 10 is connected to the transmission system circuit. Thus, the switch 7 can selectively switch between the movable contact 17 and the fixed contacts 14 to 16 connected to the transmission system or the reception system circuit, and is connected to the switch control circuit 9 for controlling the switching. It is.

  As described above, in this example, after the spare phase shifter 4 is connected to the transmission line 3, the line is branched, and the second matching circuit 5 is arranged in series on one of the branched lines and connected to the switch 7. It is configured to do.

  FIG. 4 is an explanatory diagram showing an application example of the apparatus according to the second embodiment of the present invention. A planar antenna 1 is formed on the circuit board 11, and power is fed from a feeding point 18 located at the end of the antenna 1. The transmission line 3 is connected from the feeding point 18, and the switch 7 is connected to the other end of the transmission line 3. The transmission line 3 functions as a phase shifter, and is configured using, for example, a coaxial cable having an impedance of 50Ω and a length of 25 mm. Smith charts showing the impedance characteristics of the antenna in such a configuration are shown in FIGS.

  FIG. 5 shows a locus representing the impedance characteristics of the antenna when viewed from the feeding point 18 side. Ordinary small antennas have almost the same trajectory. Next, FIG. 6 shows a locus representing the impedance characteristics of the antenna when viewed from the switch 7 side. In this example, since the transmission line 3 functions as a phase shifter together with the first matching circuit 2, the locus can be adjusted to rotate clockwise and draw the locus of the impedance characteristic on the equal resistance line. The auxiliary phase shifter 4 shown in FIG. 3 has the adjustment function. The spare phase shifter 4 adjusts so that the locus of the impedance characteristic changed by the first matching circuit 2 and the transmission line 3 is drawn on the equal resistance line. It is assumed that the resonance frequency at this time is 934 MHz. FIG. 7 shows a Smith chart showing the locus of the impedance characteristic viewed from the switch 7 side when the second matching circuit 5 shown in FIG. 3 is connected in this state. In this example, the impedance characteristics are almost the same, and only the resonance frequency can be changed to 975 MHz.

  Thus, according to the present embodiment, the first matching circuit, the phase shifter that also serves as the transmission line, and the spare phase shifter can be adjusted so that the locus of the impedance characteristic is on an equal resistance, Accordingly, the resonant frequency can be easily switched by inserting elements in series as the second matching circuit. Since the matching circuit can be configured with only series elements, adjustment is easy and the passage loss can be reduced.

  Next, FIG. 8 is a block diagram showing the configuration of an apparatus according to the third embodiment of the present invention. In the present embodiment, the transmission line is branched into three. In this example, the transmission line 3 is first branched at a branch point 13, and one branched line is directly connected to the fixed contact 15 of the switch 7 'without going through a matching circuit. The other branched line is further branched at a branch point 13 ′ and connected to the fixed contacts 19 and 14 of the switch 7 ′ through different second matching circuit 51 and third matching circuit 52, respectively. Constitute. The branch point 13 and the branch point 13 ′ may be combined into one branch point.

  The second matching circuit 51 and the third matching circuit 52 are designed and adjusted to have different resonance frequencies, and are switched by the switch control circuit 9 so that the resonance frequency of the antenna becomes three. It is possible to switch. In this way, by increasing the number of branches of the transmission line and increasing the number of switching contacts of the switch, by switching according to the environment where the mobile terminal is placed or the case of the folding mobile phone terminal is folded or opened The antenna characteristics can be further optimized.

  FIG. 9 is a block diagram showing the configuration of an apparatus according to the fourth embodiment of the present invention. In this example, the first matching circuit 2 ′ and the second matching circuit 5 ′ are configured with series inductances.

  When the antenna element is reduced in size, in many cases, a series inductor is added to the matching circuit in order to increase the resonance length of the antenna. However, a series inductor has a problem that the passage loss increases as the inductance value used increases, and the antenna efficiency deteriorates. On the other hand, if the inductance value is small, a sufficient resonance length cannot be obtained, and a phenomenon occurs in which the antenna resonates at a frequency higher than the design value. Therefore, in this example, when the resonance frequency is switched by the switch 7, the inductor is adjusted to be large when the resonance frequency is low, and the inductor is adjusted to be small when the resonance frequency is high.

  In this example, the first path connected to the transmission system or the reception system circuit only through the first matching circuit 2 ′, the first matching circuit 2 ′, and the second matching circuit by the switching operation of the switch 7 Two paths of the second path connected to the transmission system or the reception system circuit via 5 'are used for switching the resonance frequency. Here, when the first path connected to the fixed contact 15 of the switch only through the first matching circuit 2 'is assigned to the higher resonance frequency, the inductor value in the first matching circuit 2' is small. Therefore, the antenna efficiency can be improved.

  As described above, in the antenna device that switches the resonance frequency between high and low, the loss of the matching circuit particularly when used at a high resonance frequency can be reduced, and the antenna efficiency can be improved.

  FIG. 10 is a block diagram showing a configuration of an apparatus according to the fifth embodiment of the present invention. In the present embodiment, the first matching circuit 2 is connected to the antenna 1, and the transmission line 3 is connected to the first matching circuit 2. The transmission line 3 is branched into two at a branch point 13 on the way, one of the branched lines is connected to the second matching circuit 5 for switching the resonance frequency, and the other end of the second matching circuit 5 is connected to the switch 30. Connect to the first fixed contact 14. The other line branched at the branch point 13 is configured to be directly connected to the second fixed contact 15 of the switch 30. On the other hand, the first movable contact 31 of the switch 30 is connected to the power amplifier 10, and the other end of the power amplifier 10 is connected to a transmission system circuit. Further, the second movable contact 32 of the switch 30 is configured to be connected to a reception system circuit. The switch 30 can selectively switch between the fixed contacts 14 and 15 and the movable contacts 31 and 32, and the switch control circuit 9 connected to the switch 30 controls the switching.

  With this configuration, the switch 30 has a switching function for switching between a transmission system and a reception system, and can also perform frequency switching by switching the matching circuit at the same time.

  Next, FIG. 11 is a block diagram showing a configuration of an apparatus according to the sixth embodiment of the present invention. In the present embodiment, the switch 30 described in FIG. 10 is further provided with a third fixed contact 16 connected to the external RF output connector 6. With this configuration, the switch 30 can selectively switch between the fixed contacts 14, 15, 16 and the movable contacts 31, 32.

  In each of the embodiments described above, the transmission line may be constituted by a strip line on a circuit board. Thereby, the electrical length can be easily adjusted at low cost.

  Moreover, you may comprise a transmission line with a coaxial cable. In that case, for example, in the case of a foldable mobile phone terminal, the embodiment described above can be applied even when an antenna and a transmission system or reception system circuit are mounted on different substrates.

  It is also possible to configure the characteristic impedance of the transmission line in a non-50Ω system. By configuring with a non-50Ω system, it is possible to improve the design freedom of the input impedance characteristics when the antenna side is viewed from the front of the switch. Further, depending on the design, the first matching circuit can be eliminated, and the circuit can be reduced in size and cost.

  In each of the embodiments described above, the switch for switching the resonance frequency of the antenna can be constituted by a gallium arsenide switch or a micromachine switch. When a gallium arsenide switch is used, it can be used for both transmission and reception, and a high-speed switching response is possible and low power consumption. When a micromachine switch is used, it is possible to construct a switch with very little passage loss and high isolation, and it is possible to apply a multistage changeover switch.

  Further, among the contact points of the switch connected to the antenna, a configuration using a switch characterized in that the input impedance of the switch viewed from the antenna side when not selected is adjusted to open is also possible. This eliminates the need to adjust the antenna characteristics by the impedance characteristics on the non-selected side of the switch.

  Further, the configuration according to the embodiment described above can be formed into a chip. In the case of chip formation, a series circuit portion from a feeding point connected to an antenna element to a changeover switch can be configured as one circuit element. Thereby, it is possible to further reduce the size of the apparatus.

  In the above-described embodiment, the antenna characteristics change due to the path switching has been described as setting the characteristics when the folding terminal is folded and the characteristics when the terminal is opened. You may set the characteristic according to the change of the state of 2 states (or 3 states). For example, the first route a may be an antenna characteristic suitable for a state where a mobile phone terminal is not making a call, and the second route b may be an antenna characteristic suitable for a state during a call. Further, as described in the third embodiment, when switching to three stages, the terminal may be switched to three stages by combining a folded state, an open state, and a busy state.

It is a top view which shows the structural example of the antenna apparatus by the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the antenna apparatus by the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the antenna apparatus by the 2nd Embodiment of this invention. It is explanatory drawing which shows the example of application of the antenna device by the 2nd Embodiment of this invention. It is a Smith chart showing the locus | trajectory of the impedance characteristic seen from the feeding point side of the antenna device by the 2nd Embodiment of this invention. It is a Smith chart showing the locus | trajectory of the impedance characteristic seen from the switch side of the antenna device by the 2nd Embodiment of this invention. It is a Smith chart showing the locus | trajectory of the impedance characteristic seen from the switch side of the antenna device by the 2nd Embodiment of this invention. It is a block diagram which shows the structural example of the antenna apparatus by the 3rd Embodiment of this invention. It is a block diagram which shows the structural example of the antenna device by the 4th Embodiment of this invention. It is a block diagram which shows the structural example of the antenna apparatus by the 5th Embodiment of this invention. It is a block diagram which shows the structural example of the antenna device by the 6th Embodiment of this invention. It is a block diagram which shows the structural example of the conventional antenna apparatus. It is a block diagram which shows the structural example of the conventional antenna apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Antenna 2, 2 '... 1st matching circuit, 3 ... Transmission line, 4 ... Spare phase shifter, 5, 5' ... 2nd matching circuit, 6 ... External RF output connector, 7, 7 '... Switch, 8... Transmitter / receiver, 9. Switch control circuit, 10... Power amplifier, 11... Circuit board, 12 .. Feed line, 13, 13 ′ ... Branch point, 14, 15, 16. ... movable contact of switch, 18 ... feed point, 19 ... fixed contact of switch, 21 ... antenna, 22 ... matching circuit, 23 ... transmission line, 24 ... matching circuit, 25 ... switch, 26 ... external RF output connector, 27 ... Switch, 28... Transmitter and receiver duplexer, 30... Switch, 31, 32... Movable contact of switch, 51... Second matching circuit, 52.

Claims (8)

An antenna,
A first matching circuit which is connected to the antenna and one end and performs matching to a predetermined impedance characteristic;
A transmission line connected to the other end and one end of the first matching circuit and functioning as a phase adjusting means for adjusting the phase ;
A second matching circuit having one end connected to the other end of the transmission line;
A changeover switch for selecting one of the other end of the second matching circuit and a connection point between the transmission line and the second matching circuit and connecting the transmission system circuit and / or the reception system circuit; Prepared,
An antenna device that adjusts a phase so that a locus of an impedance characteristic is drawn on an equal resistance line between the first matching circuit and the transmission line . The antenna device according to claim 1, wherein
The transmission system circuit and the reception system circuit include a plurality of transmission system circuits and reception system circuits for different communication systems,
An antenna apparatus configured to switch the changeover switch according to the communication method . The antenna device according to claim 1 or 2 ,
The said transmission line is a transmission line comprised with the stripline on a board | substrate antenna apparatus. The antenna device according to claim 1 or 2 ,
The transmission line is a transmission line constituted by a coaxial cable. An antenna,
A first matching circuit which is connected to the antenna and one end and performs matching to a predetermined impedance characteristic;
A transmission line connected to the other end and one end of the first matching circuit and functioning as a phase adjusting means for adjusting the phase;
A second matching circuit having one end connected to the other end of the transmission line;
A changeover switch for selecting one of the other end of the second matching circuit and a connection point between the transmission line and the second matching circuit and connecting the transmission system circuit and / or the reception system circuit;
A transmission system circuit and a reception system circuit connected to the system selected by the changeover switch;
The phase is adjusted by the first matching circuit and the transmission line so that a locus of impedance characteristics is drawn on an equal resistance line.
Communication terminal. The communication terminal according to claim 5, wherein
The transmission system circuit and the reception system circuit include a plurality of transmission system circuits and reception system circuits for different communication systems,
According to the communication method, the changeover switch is switched.
Communication terminal. The communication terminal according to claim 5 or 6,
The transmission line is a transmission line composed of strip lines on a substrate.
Communication terminal . The communication terminal according to claim 5 or 6,
The transmission line is a transmission line constituted by a coaxial cable.
Communication terminal .

Images