JPH0251083A - Antenna for gps reception - Google Patents

Abstract

PURPOSE:To enable assembling of an earth magnetism sensor by arranging the earth magnetism sensor between a radiation body at an antenna section composing a patch antenna and an earth plate to reduce effect on a radiation efficiency and radiation directivity of an antenna. CONSTITUTION:An antenna for GPS reception has an earth magnetism sensor 3 arranged between a patch near the center of a radiation body 4 and an earth plate as ceiling surface of a circuit housing section 2. In this case, the existence of the earth magnetism sensor 3 confines an adverse effect to an impedance characteristic of a patch antenna and reduces effect on radiation characteristic of the antenna substantially. This enables the assembling of the earth magnetism sensor with a reduction in effect on radiation efficiency and radiation directivity of the antenna.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a Global P
The present invention relates to a GPS receiving antenna.

[Prior Art] Since the GPS receiving antenna is a self-contained system that does not require any other positioning sensor, the GPS receiving antenna has been independently provided on the roof. However, in areas with relatively poor visibility such as urban areas and mountainous areas, GP
When using the S receiving antenna, the 3
In some cases, signals from individual satellites cannot be received. As an auxiliary means in such cases, a geomagnetic sensor installed inside the vehicle measures the direction, calculates the distance traveled from the rotation speed of the axle to determine the relative amount of travel, and then uses the previous positioning results using GPS satellites. There is a method of performing complementary positioning using When using such a method, the GPS receiving antenna has built-in circuitry attached to the antenna such as a booster or comparator, so a DC magnetic field may be generated by the power supply and cause errors in the geomagnetic sensor. Since the presence of the geomagnetic sensor may have an adverse effect on the antenna characteristics, the geomagnetic sensor has been used separately from the antenna section as described above.

[Problems to be Solved by the Invention] By the way, in the conventional GPS receiving antenna, the antenna part and the geomagnetic sensor are used separately, so the GPS receiving system and its complementary system have multiple wiring lines. The problem was that the reliability of the system was low.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a GPS receiving antenna that makes it possible to place a geomagnetic sensor and an antenna part close to each other while reducing the influence on antenna characteristics. The purpose of the present invention is to provide a GPS receiving antenna in which the direct current magnetic field generated from the circuit section attached to the antenna section does not affect the geomagnetic sensor. A GP that minimizes the wiring for sending the detection signal to the detection signal processing means and to the outside.
The purpose of this invention is to provide an S receiving antenna.

[Means for Solving the Problems] In the present invention, an antenna section is constructed from a patch antenna, and a geomagnetic sensor is arranged between the radiator and the ground plate.

More specifically, a part of the casing that houses the circuit section attached to the antenna section constitutes a grounding plate, and the casing is composed of a magnetic plate to magnetically shield the circuit section.

In addition, a part of the detection signal processing means of the geomagnetic sensor is housed in the same housing as the circuit section attached to the antenna section, and the output signal of the detection signal processing means is converted into a high frequency signal and a coaxial cable for outputting the antenna section. superimposed on

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

[Function] Since the geomagnetic sensor is placed between the patch part and the ground plate, the geomagnetic sensor can be moved away from the peripheral opening of the patch antenna, which has an effect on the radiation efficiency and radiation directivity of the antenna. This allows the geomagnetic sensor to be incorporated with less energy.

In addition, a part of the casing of the circuit storage section that stores the circuit section attached to the antenna section constitutes an air winter board, and the casing is composed of a magnetic material plate to provide magnetic shielding for the circuit section, so that the circuit section can be protected from the circuit section. This shields the generated DC magnetic field and reduces its influence on the geomagnetic sensor.

Further, a part of the detection signal processing means of the geomagnetic sensor is housed in the same housing as the circuit section attached to the antenna section, and the output signal of the detection signal processing means is converted into a high frequency signal and is connected to a coaxial cable for output from the antenna section. Because it overlaps with
Received signals and geomagnetic sensor detection signals can be extracted.

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

[Embodiment] Figures 1(a) and 1(b) show an embodiment of the present invention, in which a radome 1 is made of a magnetic material and houses circuits such as a booster, a converter, and other circuits attached to the antenna section. A casing 2, an antenna section using the ceiling surface of the casing 2 as a grounding plate, and a geomagnetic sensor 3 are arranged. The antenna part is a radiator 4 in the form of a rectangular batch placed above the ground plate.
The geomagnetic sensor 3 is arranged between the ceiling surface of the housing 2, which is a ground plate, and the radiator 4. Ru.

The housing 2 leads out an output coaxial cable 6 of an antenna section, which has a coaxial connector 7 at its tip.

It is also possible to receive circularly polarized waves by using circular patches or patches of other shapes as the patches of the radiator 4. Here, the radiation efficiency of the patch antenna is controlled by the conductivity of the radiator 4 and the ground plate facing the radiator 4, and especially by the high frequency loss due to the dielectric or magnetic material present near the opening around the radiator 4. .

Furthermore, the radiation directivity of the patch antenna is likely to be shadowed by magnetic materials, dielectric materials, and conductive materials that exist near the opening around the patch.

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

This geomagnetic sensor 3 operates on the following principle.

In other words, applying an excitation signal of frequency F to the excitation winding 11,
When the signal level is adjusted so that the annular core 8 is saturated near the peak value of the excitation signal, a distorted magnetic flux containing a frequency 2F component is generated in the annular core 8. This distortion component occurs more often as the nonlinearity near the saturation point of the saturation characteristic curve of the magnetic material increases, and it also occurs due to minute changes in the magnetic flux in the annular core 8 when a DC magnetic field is applied from the outside due to terrestrial magnetism. The sensitivity also changes to higher. Therefore, by extracting only the signal of the frequency 2F component from the output windings 9 and 10 wound orthogonally, it can be used as a highly sensitive geomagnetic sensor. In other words, if the output winding 9 is used as a north-south sense winding and the output winding 10 is used as an east-west sense winding, when there is a geomagnetic field interlinking with the winding direction of the output winding 10 at an angle θ, the east-west sense will be detected. The output of the output winding 10, which is a winding, is proportional to sinθ, and the output of the output winding 9, which is a north-south direction sense winding, is proportional to eO8θ. Therefore, by inversely calculating from the respective output windings 9 and 10, the earth's magnetic field is calculated. It is possible to know the direction of an external magnetic field. This type of geomagnetic sensor has a large error when there is an electric circuit around it that generates a DC magnetic field. Therefore, it is necessary to take measures to minimize the influence of the circuit section attached to the antenna section disposed below the patch antenna.

In the present invention, in order to prevent the geomagnetic sensor 3 from having an adverse effect on the radiation efficiency and radiation directivity of the patch antenna as described above, as shown in FIG. A geomagnetic sensor 3 is disposed between it and a certain ground plate. In this case, the presence of the geomagnetic sensor 3 only has an adverse effect on the impedance characteristics of the patch antenna, and has little effect on the radiation characteristics of the antenna.

On the other hand, in order to prevent the patch antenna and the circuit section from having an adverse effect on the characteristics of the geomagnetic sensor 3, the circuit section is housed in a casing 2 made of a magnetic plate and magnetically shielded. 4 is composed of a non-magnetic plate. In this case, since the magnetic plate constituting the housing 2 needs to have good electrical conductivity as a ground plate, a magnetic plate subjected to conductive plating such as a tin-plated steel plate is used. Further, the non-magnetic plate forming the radiator 4 is made of a copper plate, an aluminum plate, etc. having good conductivity in order to improve the patch antenna characteristics.

FIG. 3 shows a circuit when the geomagnetic sensor 3 is incorporated into the GPS receiving antenna with the above configuration. A 40 KHz sine wave amplified by

In addition, since the double frequency component (e.g. 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 1o while being affected by the earth's magnetism, the band pass filter is used. 17.18
It is possible to select according to

The signal passed through the bandpass filters 17 and 18 is sent to the amplifier 1.
They are each amplified at 9.20, further detected by amplitude detectors 21.22, and DC amplified by DC amplifiers 23.24.

The inverse calculation circuit 2 calculates the interlinkage angle of the geomagnetic flux with the output windings 9 and 10 from the DC amplified signal component including the influence of the geomagnetism.
It is found in 5. For example, if the level of the excitation signal is set to a level just before the saturation level of the annular core 8, and the annular core 8 is saturated by the static magnetic field of the earth's magnetism, the earth's magnetism and
When the interlinkage angle with one output winding 9 or 10 is θ,
The double distorted wave detection level from one output winding 9 or 10 is proportional to sin θ, and the double distortion wave detection level from the other output winding 10 or 9 is proportional to sin θ.
Since the double distortion detection level is proportional to CO8θ, each output winding 9
．． By taking the ratio of the outputs from 10 and finding the arctangent, the interlinkage angle θ can be detected. Such an inverse calculation circuit 25
can be easily configured using a diode and an operational amplifier 6 Earth's magnetism detected by the inverse calculation circuit 25 and the output winding 9,
The interlinkage angle signal No. 10 is converted into a high frequency signal (for example, a 100 KHz FM signal) via an FM modulator 26, and is further converted into a series resonant circuit (
In this case, the resonant frequency is 100KHz) and the coaxial cable 6
is supplied to

On the other hand, 1°5 GHz received by GPS receiving antenna A
The band signal is supplied to the coaxial cable 6 via two band pass filters, a high quality width filter 30, and a coupling capacitor 31.

The left side section of the coaxial cable 6 marked by a dashed line is a part of a signal processing circuit (not shown) mounted inside the moving body, and DC power is supplied from a terminal 32 via a high frequency choke coil 33. A high-frequency choke coil 34 separates a DC component from the antenna section of the coaxial cable 6 (the part to the right of the dotted chain line in the figure), and DC power for the antenna section is obtained from a terminal 35.

Note that the capacitor 36 is a coupling capacitor, and the terminal 37 is a GPS
The received signal extraction terminal, coil 38, and capacitor 39 are a series resonant circuit (resonant frequency in this case is 100 KHz)
Terminal 40 is a terminal for taking out a geomagnetic angle signal.

In addition to the 1.5 GHz band GPS reception signal, the coaxial cable 6 carries an angle detection signal (100 KHz in this embodiment).
and DC power are superimposed, the actance of the capacitors 31 and 36 should be sufficiently large for the angle detection signal frequency, and the coil 28, which constitutes the series resonant circuit,
The impedances of the capacitor 27, coil 38, and capacitor 39 are selected to be sufficiently large with respect to the GPS reception signal frequency. Furthermore, a high frequency choke coil 34.
The reactance of 33 is selected so as 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 arranges the geomagnetic sensor between the radiator and the ground plate, the geomagnetic sensor can be moved away from the opening of the patch antenna, which improves the radiation efficiency and radiation direction of the antenna. This has the effect that a geomagnetic sensor can be incorporated with less influence on the magnetic field.

In addition, a part of the casing that houses the circuit section attached to the antenna section constitutes a grounding plate, and the casing is composed of a magnetic plate to provide magnetic shielding for the circuit section. The influence of the generated DC magnetic field can be reduced.

Further, a part of the detection signal processing means of the geomagnetic sensor is housed in the same housing as the circuit section attached to the antenna section, and the output signal of the detection signal processing means is converted into a high frequency signal and superimposed on the antenna section output coaxial cable. This allows you to supply power to the circuit section of the geomagnetic sensor in the circuit section and take out the GPS reception signal and the detection signal of the geomagnetic sensor by simply leading one coaxial cable to the outside, and as a result, the number of wires can be reduced. This has the effect of increasing the reliability of the system.

Furthermore, by configuring the radiator with a non-magnetic conductive plate, there is an effect that the influence of the antenna section on the geomagnetic sensor can be reduced.

[Brief explanation of the drawing]

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

Claims (4)

[Claims] (1) A GPS receiving antenna characterized in that a geomagnetic sensor is disposed between a radiator of an antenna part constituting a patch antenna and a ground plate. (2) A part of the casing that houses the circuit section attached to the antenna section constitutes a grounding plate, and the casing is composed of a magnetic plate to magnetically shield the circuit section. The GPS receiving antenna according to claim 1. (3) Part of the detection signal processing means of the geomagnetic sensor is housed in the same housing as the circuit section attached to the antenna section, and the output signal of the detection signal processing means is converted into a high frequency signal for output from the antenna section. 3. The GPS receiving antenna according to claim 2, wherein the antenna is superimposed on a coaxial cable. (4) The S receiving antenna according to claim 1, wherein the radiator is formed of a non-magnetic conductive plate.