JP2566295B2 - GPS receiving antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a Global Postion
g System (hereinafter abbreviated as GPS) Receiving antenna.

[Prior Art] Since the GPS receiving antenna is a self-supporting system that does not require any other position locating sensor, the GPS receiving antenna was provided independently on the roof top. However, if the GPS receiving antenna is used in an area with relatively poor visibility such as an urban area or a mountainous area, the signals from the three satellites required for positioning may not be received. As an auxiliary means in such a case, a geomagnetic sensor provided in the vehicle interior is used to measure the direction, and the moving distance is calculated from the number of rotations of the axle to know the relative movement amount, and the positioning result using the previous GPS satellite is calculated. There is a method of performing complementary positioning by using. When adopting such a method, since the GPS receiving antenna has a built-in circuit part attached to the antenna part such as a booster or a converter, a DC magnetic field is generated by the power supply, which causes an error of the geomagnetic sensor, Since the presence of the geomagnetic sensor may adversely affect the antenna characteristics, the geomagnetic sensor is used separately from the antenna section as described above.

[Problems to be Solved by the Invention] By the way, since the conventional GPS receiving antenna uses the antenna section and the geomagnetic sensor separately, the GPS receiving system and its complementary system system have a plurality of wiring lines. There was a problem that the reliability of the system was low.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a GPS receiving antenna capable of arranging a geomagnetic sensor and an antenna unit in proximity while reducing the influence on the antenna characteristics. The purpose of the present invention is also to provide a GPS receiving antenna in which the DC magnetic field generated from the circuit section attached to the antenna section does not affect the geomagnetic sensor. Also, the GPS receiving signal from the antenna section and the geomagnetic sensor are provided. It is an object of the present invention to provide a GPS receiving antenna in which the wiring for sending the detection signal to be output to the detection signal processing means and the wiring for sending the detection signal to the outside are suppressed to a necessary minimum.

[Means for Solving the Problem] The present invention is one in which an antenna unit is composed of a patch antenna, and a geomagnetic sensor is arranged between the radiator and the ground plate.

More specifically, a part of a housing for accommodating a circuit part attached to the antenna part constitutes a ground plate, and the case is composed of a magnetic plate to magnetically shield the circuit part.

Further, it is provided with means for converting the output signal of the detection signal processing means of the geomagnetic sensor into a high frequency signal and superimposing it on the output coaxial cable of the antenna section, and this superimposing means is the same casing as the circuit section attached to the antenna section. To store.

 Furthermore, the radiator is composed of a non-magnetic conductive plate.

[Operation] However, since the geomagnetic sensor is arranged between the patch portion and the ground plate, the geomagnetic sensor can be moved away from the peripheral opening of the patch antenna, which affects the radiation efficiency and radiation directivity of the antenna. It is possible to incorporate a geomagnetic sensor with less.

In addition, a part of the housing of the circuit accommodating part for accommodating the circuit part attached to the antenna part constitutes a ground plate, and the case is composed of a magnetic plate to magnetically shield the circuit part. The direct current magnetic field generated from is shielded to reduce the influence on the geomagnetic sensor.

Furthermore, a means for converting the output signal of the detection signal processing means of the geomagnetic sensor into a high frequency signal and superimposing it on the output coaxial cable of the antenna part is provided, and this superimposing means is the same housing as the circuit part attached to the antenna part. Since it is housed in the antenna, power can be supplied to the circuit part attached to the antenna part and the circuit of the geomagnetic sensor and the GPS reception signal and the detection signal of the geomagnetic sensor can be taken out by simply pulling out one coaxial cable from the case. .

Further, by constructing the antenna section with a non-magnetic conductive plate, it is possible to prevent the antenna section from affecting the geomagnetic sensor.

[Embodiment] FIGS. 1 (a) and 1 (b) show an embodiment of the present invention, in which a radome 1 is made of a magnetic material in which circuits such as a booster and a circuit attached to an antenna such as a converter are housed. The housing 2, the antenna portion having the ceiling surface of the housing 2 as a ground plate, and the geomagnetic sensor 3 are provided. The antenna part is a radiator 4 having a rectangular patch arranged above the ground plate.
A circularly polarized wave is received by connecting a power feed pin 5 on a diagonal line of the geomagnetic sensor 3. The geomagnetic sensor 3 is arranged between the ceiling surface of the housing 2 which is a ground plate and the radiator 4. To be done.
The housing 2 leads out the output coaxial cable 6 of the antenna part having a coaxial connector 7 at the tip.

Circular polarized wave reception is possible even if a circular patch or a patch having another shape is used as the patch of the radiator 4. Here, the radiation efficiency of the patch antenna is governed by the conductivity of the radiator 4 and the ground plate facing the radiator 4, and particularly the high frequency loss due to the dielectric or magnetic substance existing near the opening around the radiator 4. . In addition, the radiation directivity of the patch antenna is also easily affected by the magnetic material, dielectric material, and conductor existing near the opening around the patch.

The geomagnetic sensor 3 uses a fluxgate type sensor as shown in FIG. 2, in which the geomagnetic sense output windings 9 and 10 are wound around the annular core 8 made of a magnetic material such as permalloy so as to be orthogonal to each other. It is constructed by winding the wire 11. The terminals 12 and 13 are output terminals, and the terminal 14 is an excitation input terminal.

The geomagnetic sensor 3 operates according to the following principle. That is, when an excitation signal of frequency F is applied to the excitation winding 11 and the signal level is adjusted so that the annular core 8 is saturated near the peak value of the excitation signal, the distortion including the frequency 2F component in the annular core 8 is generated. Magnetic flux is generated. This distortion component is generated more as the non-linearity near the saturation portion of the saturation characteristic curve of the magnetic material is larger, and a minute change in the magnetic flux in the annular core 8 when a DC magnetic field due to the earth's magnetism or the like is applied from the outside. Changes to higher sensitivity. Therefore, if only the signal of the frequency 2F component is taken out from the output windings 9 and 10 wound orthogonally, it can be used as a highly sensitive geomagnetic sensor. That is, if the output winding 9 is used as the north-south direction sense winding and the output winding 10 is used as the east-west direction sense winding, the east-west direction sense is generated when there is a geomagnetism that intersects with the winding direction of the output winding 10 at an angle θ. The output of the output winding 10, which is the winding, is proportional to sin θ, and the output of the output winding 9, which is the north-south direction sense winding, is proportional to cos θ. It is possible to know the direction of the external magnetic field. This type of geomagnetic sensor has a large error if there is an electric circuit that generates a DC magnetic field in the surroundings. Therefore, it is necessary to devise to minimize the influence of the circuit section attached to the antenna section arranged below the patch antenna.

In the present invention, the geomagnetic sensor 3 does not adversely affect the radiation efficiency and radiation directivity of the patch antenna as described above.
As shown in the figure, the geomagnetic sensor 3 is arranged between the patch near the center of the radiator 4 and the ground plate which is the ceiling surface of the circuit housing 2. In this case, the presence of the geomagnetic sensor 3 only adversely affects the impedance characteristic of the patch antenna, and has little influence on the radiation characteristic of the antenna.

On the other hand, in order to prevent the patch antenna and the circuit section from adversely affecting the characteristics of the geomagnetic sensor 3, the circuit section is housed in a housing 2 formed of a magnetic material plate, magnetically shielded, and the radiator 4 is provided. Is composed of a non-magnetic plate. In this case, it is necessary that the magnetic material plate constituting the housing 2 has good conductivity as an earth plate, and therefore a magnetic material plate such as a tin-plated steel plate which has been subjected to conductive plating is used. Further, as the non-magnetic material plate forming the radiator 4, a copper plate, an aluminum plate or the like having good conductivity is used in order to improve the patch antenna characteristics.

FIG. 3 shows a circuit in the case where the geomagnetic sensor 3 is incorporated in the GPS receiving antenna with the above configuration, and the excitation winding 11 of the geomagnetic sensor 3 outputs the signal from the excitation signal oscillator 15.
The 40 KHz sine wave amplified by the excitation signal amplifier 16 is applied.

Further, since the double frequency component (for example, 80 KHz) signal generated as a result of the annular core 8 being excited to the saturation level by the excitation signal is detected by the orthogonal output windings 9 and 10 while being influenced by the geomagnetism, the band pass filter is detected. It is designed to be selected by 17,18.

The signals passed through the band pass filters 17 and 18 are amplifiers 19 and 20.
Respectively, are detected by the amplitude detectors 21 and 22, and are DC-amplified by the DC amplifiers 23 and 24.

From the DC-amplified signal component including the influence of the geomagnetism, the interlocking angle of the geomagnetic flux with the output windings 9 and 10 is obtained by the inverse calculation circuit 25. For example, the level of the excitation signal is set to the annular core 8
Is set to a level immediately before the saturation level, and the annular core 8 is saturated by the static magnetic field of the earth's magnetism. When the interlinkage angle between the earth's magnetism and one of the output windings 9 or 10 is θ, one output winding is The double distortion wave detection level from line 9 or 10 is proportional to sin θ, and the double distortion detection level from the other output winding 10 or 9 is proportional to COS θ, so the output from each output winding 9 and 10 If the ratio is calculated and the arctangent is calculated, the interlinkage angle θ can be detected. Such an inverse operation circuit 25 can be easily constructed by using a diode and an operational amplifier.

Geomagnetism detected by the inverse operation circuit 25 and output winding 9,10
The interlinking angle signal of is converted into a high frequency signal (for example, an FM signal of 100 KHz) via the FM modulator 26, and further, a capacitor 27,
Series resonance circuit consisting of coil 28 (resonance frequency in this case)
It is supplied to the coaxial cable 6 at 100 KHz.

On the other hand, the 1.5 GHz band signal received by the GPS receiving antenna A is a band pass filter 29, a high quality amplifier 30, a coupling capacitor.
It is supplied to the coaxial cable 6 via 31.

The left-hand side section of the coaxial cable 6 sectioned by the alternate long and short dash line is a part of a signal processing circuit (not shown) mounted inside the moving body, and DC power is supplied from the terminal 32 through the high frequency choke coil 33. The DC component is separated by the high frequency choke coil 34 on the side of the antenna portion of the coaxial cable 6 (the portion on the right side of the alternate long and short dash line in the figure), and a DC power source for the antenna portion is obtained from the terminal 35.

The capacitor 36 is a coupling capacitor, the terminal 37 is a GPS reception signal extraction terminal, the coil 38 and the capacitor 39 are a series resonance circuit (resonance frequency in this case is 100 KHz), and the terminal 40
Is a geomagnetic angle signal extraction terminal.

In addition to the GPS reception signal in the 1.5 GHz band, the coaxial cable 6 is superposed with the angle detection signal (100 KHz in this embodiment) and the DC power source, so that the reactances of the capacitors 31 and 36 with respect to the angle detection signal frequency. Is sufficiently large, and the impedances of the coil 28, the capacitor 27 and the coil 38, and the capacitor 39 which form the series resonance circuit are selected to be sufficiently large with respect to the GPS reception signal frequency. Further, the reactances of the high frequency choke coils 34 and 33 are selected to be sufficiently large for both the angle detection signal frequency and the GPS reception signal frequency.

EFFECTS OF THE INVENTION Since the present invention has the geomagnetic sensor arranged between the radiator and the ground plate, the geomagnetic sensor can be moved away from the opening of the patch antenna, and therefore the radiation efficiency and radiation directivity of the antenna can be increased. There is an effect that a geomagnetic sensor can be incorporated with less influence on the sex.

Further, the earth plate is formed by a part of the housing for accommodating the circuit part attached to the antenna part, and the housing is made of a magnetic material plate to magnetically shield the circuit part. The influence of the DC magnetic field generated from the part can be reduced.

Furthermore, a means for converting the output signal of the detection signal processing means of the geomagnetic sensor into a high frequency signal and superimposing it on the output coaxial cable of the antenna section is provided, and this superimposing means is the same casing as the circuit section attached to the antenna section. Since it is housed in the housing, power can be supplied to the circuit part of the geomagnetic sensor of the circuit part and the GPS reception signal and the detection signal of the geomagnetic sensor can be taken out only by pulling out one coaxial cable from the housing. There is an effect that the reliability of the system can be improved by reducing the number of problems.

Furthermore, by constructing the radiator with a non-magnetic conductive plate, the effect of the antenna section on the geomagnetic sensor can be reduced.

[Brief description of drawings]

FIG. 1 (a) is a sectional view of an embodiment of the present invention, and FIG. 1 (b).
Is a partially cutaway top view of the above, FIG. 2 is an enlarged perspective view of the geomagnetic sensor of the above, and FIG. 3 is a circuit diagram of the same. Reference numeral 2 is a housing, 3 is a geomagnetic sensor, 4 is a radiator, and 6 is a coaxial cable.

Claims (4)

(57) [Claims] 1. A GPS receiving antenna characterized in that a geomagnetic sensor is arranged between a radiator and a grounding body of an antenna section constituting a patch antenna. 2. A grounding plate is formed by a part of a housing for accommodating a circuit part attached to the antenna part, and the housing is made of a magnetic material plate so that the circuit part is magnetically shielded. The GPS receiving antenna according to claim 1, wherein: 3. A means for converting the output signal of the detection signal processing means of the geomagnetic sensor into a high frequency signal and superimposing it on the output coaxial cable of the antenna section, and a circuit section attached to the antenna section. The GPS receiving antenna according to claim 2, wherein the GPS receiving antenna is housed in the same housing. 4. The GPS receiving antenna according to claim 1, wherein the radiator is composed of a non-magnetic conductive plate.