JP2008283626A - Circularly polarized plane switching type gps antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a global positioning system (GPS) antenna capable of enhancing a reception property between both in expanded and in folded states of a foldable portable radio. <P>SOLUTION: When transmitting and receiving a right-turning polarized wave upward from a paper surface, in order to use a radiation conductor 3, a matching circuit changeover switch 7 is connected to the side of a matching circuit 5, and the matching circuit 5 and a power feeding section 8 are connected. Therefore, a GPS antenna is enabled to transmit and receive the right-turning polarized wave by operating the radiation conductor 3 and a helical antenna 2 as antennas. When transmitting and receiving a left-turning polarized wave, on the other hand, the matching circuit changeover switch 7 is connected to the side of a matching circuit 6, and the power feeding section 8 and the matching circuit 6 are connected. Accordingly, the GPS antenna is enabled to transmit and receive the left-turning polarized wave upward from the paper surface by operating a radiation conductor 4 and the helical antenna 2 as antennas. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a portable wireless device, and more particularly to a GPS antenna used in a folding portable wireless device.

  In recent years, portable wireless devices have been equipped with various functions such as a television reception function and a music playback function. One of the functions is GPS (global positioning system). With this function and the map, a navigation system is possible even in a portable wireless device. The GPS system receives radio waves from a plurality of satellites and determines the current position from the time difference between signals. Since the radio wave from the satellite is circularly polarized, the receiving antenna is preferably a circularly polarized antenna. GPS antennas mounted on automobiles, etc. are arranged on the dashboard and always face the zenith direction, and because of the circular polarization, the plane of polarization is the same regardless of the direction of the automobile, Good reception characteristics can be obtained. On the other hand, the GPS antenna mounted on the portable wireless device cannot be mounted with a circularly polarized antenna such as a patch antenna because the portable wireless device is downsized, and uses a linearly polarized wave element. However, the linearly polarized wave element actually radiates a circularly polarized wave component, although the axial ratio is greatly deteriorated, and the communication depends on whether or not the polarization rotation direction can be matched with the polarized wave of the opposing antenna. The performance is determined.

  A conventional GPS antenna for a portable radio is shown in FIG. The conventional GPS antenna includes a helical antenna 2, a radiating conductor 3, a matching circuit 5, a power feeding unit 8, a GPS circuit 23, a control circuit 24, a circuit board 25, and the like. Here, when considering the polarization of the GPS antenna, the conventional GPS antenna uses a linearly polarized antenna, but when the helical antenna 2 and the radiation conductor 3 are arranged as shown in FIG. A right-handed circularly polarized wave can be emitted in the front direction. On the other hand, if it arrange | positions like FIG.11 (b), a left-handed circularly polarized wave can be emitted in a front direction. FIG. 12 shows the polarization planes on the front and back of the circuit board 25 in the arrangement of FIG. As described above, a right-handed circularly polarized wave can be emitted in the front direction. However, in the rear direction, the same mounting as that in FIG.

  Here, a GPS antenna mounted on an actual portable wireless device will be described with reference to FIG. The portable wireless device shown in FIG. 13 is a foldable portable wireless device, which includes a helical antenna 2, a radiation conductor 3, a power feeding unit 8, a circuit board 25, a display unit 26, and a key input unit 27. The GPS antenna 1 is mounted on the display unit 26 side. The key input side housing is mounted with a portable radio circuit, a battery, and a key input unit 27. FIG. 13A shows the polarization plane of the GPS antenna in the deployed state. FIG. 13B shows a polarization plane at the time of folding. As described above, when the antenna is designed so as to emit a right-handed circularly polarized wave when deployed in FIG. 13A, it can be seen that the left-handed circularly polarized wave is obtained when folded. Considering the actual use state of the portable radio device, the GPS use state is the browser mode, and therefore, good characteristics can be obtained by matching the polarization plane in the developed state of FIG. However, even in the folded state, because there is an inquiry about position information from other users, the GPS function may be used. If the polarization plane is matched in the unfolded state, the polarization plane does not match in the folded state. The characteristics have deteriorated significantly.

Note that Patent Document 1 describes that a left-handed circularly polarized wave and a right-handed circularly-polarized wave can be transmitted and received by a single planar antenna by switching the horizontal feeding conductor and the vertical feeding conductor (paragraphs 0016 and 0017). ).
Japanese Patent Laid-Open No. 11-266120

  As described above, in the folding portable wireless device, when the GPS antenna is mounted on the LCD display side, the polarization plane is reversed by the unfolding, and the communication characteristics are significantly changed by unfolding. There was a problem. In the folded state, the portable wireless device is carried in a bag or pocket, so the posture of the portable wireless device is not constant with respect to the zenith direction and the plane of polarization is matched. There was a problem that it was even more difficult.

  Accordingly, an object of the present invention is to provide a GPS antenna that can improve reception characteristics in both the deployment and folding states of a foldable portable wireless device.

  According to the first aspect of the present invention, a GPS antenna includes an antenna element, two radiating conductors connected to the antenna element at one end and corresponding to the direction of rotation of received circularly polarized waves, and each of the radiating conductors. Each of which is connected to the other end of the antenna and selectively feeds the radiation conductor and the antenna element. , One is switched on and the other is switched off.

  According to the second aspect of the present invention, a GPS antenna includes an antenna element, two radiating conductors connected to the antenna element at one end and corresponding to the direction of rotation of received circularly polarized waves, and the antenna element and the radiating conductor. And two GND connection portions that are connected to the other end of each radiating conductor and selectively connect the radiating element to GND, and both GND connection portions receive circularly polarized waves that are received. Depending on the rotation direction, one is switched on and the other is switched off by the switching signal.

  According to the third aspect of the present invention, the GPS antenna is connected to the antenna element including the two radiation conductors according to the direction of rotation of the received circularly polarized wave and the power supply terminal, and the power supply terminal. One of the power supply unit that supplies power, two GND connection units that selectively connect each radiation conductor to GND, and both GND connection units are turned on by a switching signal according to the rotational direction of the circularly polarized wave that is received. The other is switched off.

  The present invention provides two radiation conductors corresponding to the rotational direction of the circularly polarized wave to be received, feeds the radiation conductor according to the rotational direction of the circularly polarized wave to be received, and reverses the rotational direction of the circularly polarized wave. Thus, the reception characteristics of GPS are improved in both the deployment state and the folding state of the folding portable wireless device.

  According to the present invention, by providing two radiation conductors corresponding to the rotational direction of the circularly polarized wave to be received and feeding one of these radiation conductors, it becomes possible to emit left and right circularly polarized waves. It is possible to realize an antenna capable of optimizing the GPS reception characteristics in both the expanded state and the folded state of the tatami type portable wireless device.

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

[First Embodiment]
FIG. 1 is a block diagram of a polarization-switching GPS antenna according to a first embodiment of the present invention. The polarization-switching GPS antenna of this embodiment includes a helical antenna 2, radiation conductors 3 and 4, matching circuits 5 and 6, a matching circuit switch 7, and a power feeding unit 8. Here, the radiating conductors 3 and 4 are formed of a conductor pattern formed on a substrate. In addition, when transmitting and receiving a right-handed polarized wave upward from the paper surface, the radiating conductor 3 is used, and when transmitting and receiving a left-handed circularly polarized wave upward from the paper surface, the radiating conductor 4 is used.

  The operation of this embodiment will be described. First, when transmitting and receiving right-hand polarized waves upward from the page, the matching circuit switch 7 is connected to the matching circuit 5 side by the polarization switching signal 10, and the matching circuit 5 and the power feeding unit 8 are connected. Therefore, in this GPS antenna, the radiation conductor 3 and the helical antenna 2 operate as antennas and can transmit and receive right-hand polarized waves. On the other hand, when transmitting and receiving a left-handed polarized wave, the matching circuit switch 7 is connected to the matching circuit 6 side by the polarization switching signal 10, and the power feeding unit 8 and the matching circuit 6 are connected. Therefore, in this GPS antenna, since the radiation conductor 4 and the helical antenna 2 operate as antennas, it becomes possible to transmit and receive left-handed circularly polarized waves upward from the paper surface. In addition, when transmitting and receiving a right-handed circularly polarized wave upward from the plane of the paper, when transmitting and receiving a left-handed circularly polarized wave downward from the plane of the paper, and when transmitting and receiving a left-handed circularly polarized wave upward from the page, A right-handed circularly polarized wave can be transmitted and received in the downward direction of the drawing.

  FIG. 2 is a circuit diagram of the matching circuit change-over switch 7 composed of a PIN diode. PIN diodes X1 and X2 are inserted in series between the matching circuits 5 and 6 and the power feeding unit 8, respectively. The matching circuit 5 or 6 is connected to the power feeding unit 8 by turning on the PIN diodes X1 and X2. When the matching circuit 5 side is selected, the control signal 10 becomes a high level. Here, the resistor R1 is a current control resistor and is used for adjusting a current flowing through the PIN diode X1. L2 and C2 are circuits that adjust the control signal line to high impedance so that the control signal line does not affect the high frequency band. Further, C1 and C3 are capacitors for preventing direct current resistance from flowing to the antenna and GPS circuit side, and L1 is a coil for allowing direct current to flow. On the contrary, when the matching circuit 6 side is selected, the control signal 11 becomes high level and the PIN diode X2 is turned on. Also in this case, the use of the resistor R2, the capacitor, and the coil is the same as described above, and is omitted.

  Although the matching circuit selector switch 7 using a PIN diode is shown here, it is also possible to use a GaAs switch or a mechanical switch. Further, although a helical antenna is used as an antenna element of the GPS antenna, a plate-shaped radiating element 12, a linear antenna 13, a meander antenna 14, and a chip antenna 15 loaded with a dielectric as shown in FIGS. The same effect can be obtained even if such as is used. Here, the radiation conductors 3 and 4 are also formed in a plane by a pattern on the substrate, but can also be configured three-dimensionally using sheet metal.

  As the control signals 10 and 11, a signal for detecting opening / closing of the folding cellular phone may be used, and the polarization plane may be switched between unfolding and folding, or the reception level detected by a GPS circuit (not shown). And may be switched so as to select a higher reception level.

[Second Embodiment]
FIG. 7 is a block diagram of a polarization-switching GPS antenna according to the second embodiment of the present invention. The polarization switching antenna according to this embodiment includes an open-end feed type chip antenna 16, radiation conductors 3 and 4, a matching circuit 5, a feed unit 8, and GND connection switches 17 and 18. Here, a chip element of a type that feeds power from the open end side is used as the antenna element. When transmitting and receiving right-handed circularly polarized waves upward from the page, the polarization switching signal 10 becomes high level, the GND connection switch 17 is connected to GND, and the radiation conductor 3 and the chip antenna 16 operate. On the other hand, when transmitting and receiving left-handed circularly polarized waves upward from the page, the polarization switching signal 11 becomes high level, the GND connection switch 18 is connected to GND, and the radiation conductor 4 and the chip antenna 16 operate. Again, on the opposite side of the page, circular polarization opposite to the upper direction is transmitted and received.

  FIG. 8 is a circuit diagram of the GND connection switches 17 and 18 formed of PIN diodes. In order to transmit and receive right-handed polarized waves, the control signal 10 becomes high level, and the PIN diode X1 is turned on. As a result, the radiation conductor 3 is connected to GND, and the radiation conductor 3 and the chip antenna 16 operate as an antenna. Here, the resistor R1 is a current control resistor and is used for adjusting a current flowing through the PIN diode. L2 and C2 are circuits for adjusting the control signal line to be open at high frequencies. Further, C1 is a capacitor for preventing a direct current from flowing to the antenna and GPS circuit side. On the other hand, when operating as a left-handed circularly polarized antenna, the control signal 11 becomes high level, the PIN diode X2 is turned on, and the radiation conductor 4 is connected to GND. The peripheral circuit is the same as described above, and is omitted here.

[Third Embodiment]
FIG. 9 is a block diagram of a polarization-switching GPS antenna according to the third embodiment of the present invention. The polarization switching antenna according to this embodiment includes an inverted F antenna 19 having GND connection terminals 21 and 22 and a power supply terminal 20, a matching circuit 5, a power supply unit 8, and GND connection switches 17 and 18. Here, an inverted F antenna 19 is used as an antenna element. Further, the arms at both ends of the three arms protruding from the inverted F antenna 19 serve as a radiation conductor.

  When transmitting and receiving right-handed circularly polarized waves upward from the page, the polarization switching signal 10 is at a high level, the GND connection switch 17 is connected to GND, and the GND connection terminal 21 and the power supply terminal 20 are inverted F antennas. Operate. On the other hand, when transmitting and receiving a left-handed circularly polarized wave upward from the page, the polarization switching signal 11 is at a high level, the GND connection switch 18 is connected to GND, and the GND connection terminal 22 and the power supply terminal 20 are inverted F antennas. Works as. Again, circular polarization opposite to the upper direction is transmitted and received on the opposite side of the page.

  In the second and third embodiments, since the planes of polarization are switched by providing the GND connections SW 17 and 18, the number of matching circuits can be reduced to one, and adjustment is facilitated.

It is a block diagram of the polarization switching GPS antenna by the 1st Embodiment of this invention. FIG. 2 is a circuit diagram of a matching circuit switching SW in FIG. 1. It is a block diagram of a polarization switching GPS antenna using a plate antenna as an antenna element. It is a block diagram of a polarization-switching GPS antenna using a rod-shaped antenna as an antenna element. It is a block diagram of a polarization switching GPS antenna using a meander antenna as an antenna element. It is a block diagram of a polarization switching GPS antenna using a chip antenna as an antenna element. It is a block diagram of the polarization switching GPS antenna by the 2nd Embodiment of this invention. It is a circuit diagram of GND connection SW of FIG. It is a block diagram of the polarization switching GPS antenna by the 3rd Embodiment of this invention. It is a GPS antenna block diagram of a prior art example. It is a figure which shows the relationship between a mounting position and circular polarization characteristics. It is a circular polarization characteristic figure of a mounting position and front and back. FIG. 10 is a mounting diagram of a conventional folding mobile phone.

Explanation of symbols

1 GPS antenna 2 Helical antenna 3, 4 Radiation conductor 5, 6 Matching circuit 7 Matching circuit switching SW
DESCRIPTION OF SYMBOLS 8 Feed part 10,11 Polarization switching signal 12 Plate antenna 13 Rod antenna 14 Meander antenna 15 Chip antenna 16 Open end feeding type chip antenna 17, 18 GND connection SW
19 Inverted F antenna 20 Power supply terminal 21, 22 GND connection terminal 23 GPS circuit 24 Control circuit 25 Circuit board 26 Display unit 27 Key input unit X1, X2 PIN diode C1-C6 Capacitance L1-L4 Inductance R1, R2 Current control resistor

Claims (14)

An antenna element;
Two radiation conductors corresponding to the rotational direction of the circularly polarized wave to be received, one end of which is connected to the antenna element;
Two feeding parts connected to the other end of each of the radiation conductors and selectively feeding the radiation conductor and the antenna element;
Have
The both power feeding units are switched on and off by the switching signal according to the rotational direction of the circularly polarized wave received.   The GPS antenna according to claim 1, wherein the GPS antenna is used in a foldable portable radio device, and an open / close signal of the foldable portable radio device is used as the switching signal.   The GPS antenna according to claim 1, wherein the GPS antenna is used in a foldable portable wireless device and uses a reception level as the switching signal.   The GPS antenna according to claim 1, wherein a helical antenna is used as the antenna element.   The GPS antenna according to claim 1, wherein a meander antenna is used as the antenna element.   The GPS antenna according to claim 1, wherein a plate-like antenna is used as the antenna element.   The GPS antenna according to claim 1, wherein a linear antenna is used as the antenna element.   The GPS antenna according to any one of claims 1 to 3, wherein a dielectric loaded antenna is used as the antenna element. An antenna element;
Two radiation conductors corresponding to the rotational direction of the circularly polarized wave to be received, one end of which is connected to the antenna element;
A power feeding unit that feeds power to the antenna element and the radiation conductor;
Two GND connections connected to the other end of each of the radiating conductors to selectively connect the radiating element to GND;
Have
One of the GND connection portions is switched on and the other is switched off by a switching signal according to the rotational direction of the circularly polarized wave received.   The GPS antenna according to claim 9, wherein the GPS antenna is used in a folding portable wireless device, and an opening / closing signal of the portable wireless device is used as the switching signal.   The GPS antenna according to claim 9, wherein the GPS antenna is used in a foldable portable wireless device and uses a reception level as the switching signal. An antenna element including two radiation conductors according to the direction of rotation of the circularly polarized wave to be received, and a feed terminal;
A power feeding unit that is connected to the power feeding terminal and feeds power to the antenna element;
Two GND connections for selectively connecting each radiating conductor to GND;
The both GND connection portions are switched to one on and the other off according to the direction of rotation of the circularly polarized wave received.   The GPS antenna according to claim 12, wherein the GPS antenna is used in a foldable portable radio device, and an open / close signal of the foldable portable radio device is used as the switching signal.   The GPS antenna according to claim 12, wherein the GPS antenna is used in a foldable portable radio device and uses a reception level as the switching signal.

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