JPH0946125A - Radio wave receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently match a ground side potential of an MSA and a potential of a ground electrode of a printed circuit board with a simple configuration. SOLUTION: This radio wave receiver 1 is provided with a printed circuit board 5 on both sides of which electronic components 3 are arranged and a ground plate 7 covering the electronic components 3 is arranged on the one side. The ground plate 7 is fixed to the printed circuit board 5 at four corners by machine screws 9 and the plate 7 is in continuity with the ground electrode of the printed circuit board 5 at the fixed parts. An MSA 11 is provided to an upper side of the ground plate 7 and a shield case 13 is provided in the middle of the upper side of the printed circuit board 5 in opposition to the MSA 11. The shield case 13 is in continuity with the ground plate 7 via a conductive sheet 15 and the impedance of the ground plate 7 is reduced through the conduction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave receiver for receiving a radio wave via a microstrip antenna (hereinafter, also referred to as MSA) and processing the radio wave.

[0002]

2. Description of the Related Art Conventionally, a printed circuit board having an MSA, a plate-shaped member disposed on the ground side of the MSA and stabilizing the characteristics of the MSA, and a ground electrode electrically connected to the plate-shaped member. There is known a radio wave receiving device including an electronic component that is disposed on the printed circuit board and that processes the radio wave received by the MSA. An example of the radio wave receiving device having such a configuration is used in a vehicle navigation device, and a GPS (Global Posi
There is a method of calculating the current position of the vehicle by receiving the radio waves transmitted from the satellite for the tioning System) and processing the radio waves transmitted by electronic parts.

Further, in this type of apparatus, it is considered that the printed board and the plate-shaped member are arranged with a space therebetween, and electronic components are mounted on both surfaces of the printed board (so-called double-sided mounting). When electronic parts are mounted on both sides, the printed circuit board can be downsized, and the entire device can be downsized.

[0004]

However, when the printed circuit board and the plate-shaped member are arranged with a space therebetween, the ground electrode of the printed circuit board and the plate-shaped member are electrically connected at their peripheral portions. Will be. Then, a potential difference is generated between the center of the plate member and the ground electrode of the printed board, and
In some cases, the ground potential of the MSA and the ground electrode of the printed circuit board do not match. Further, the plate-shaped member has a significant impedance, and the impedance near the center of the plate-shaped member becomes high. In this case, the characteristics of MSA cannot be fully brought out.

Therefore, the MSA and the printed circuit board are connected via a coaxial cable, the electric wave received by the MSA is input to the printed circuit board by the inner conductor, and the outer conductor is connected to the ground side of the MSA and the ground electrode of the printed circuit board. It is considered to connect with. However, in this case, a complicated mechanism such as a connector must be provided on the MSA and the printed circuit board, which complicates the configuration of the device and increases the manufacturing cost.

Therefore, the present invention has a simple structure,
The present invention has been made for the purpose of providing a radio wave receiving device capable of appropriately lowering the impedance of a plate-shaped member arranged on the ground side of SA.

[0007]

In order to achieve the above object, the invention according to claim 1 is provided with a microstrip antenna and a grounding side of the microstrip antenna to stabilize the characteristics of the microstrip antenna. A plate-shaped member made of a conductor, a printed circuit board having a ground electrode electrically connected to the plate-shaped member, and an electron disposed on the printed circuit board for processing the radio wave received by the microstrip antenna In a radio wave receiver including a component and a shield case that covers at least a part of the electronic component and is electrically connected to a ground electrode of the printed circuit board, the plate-shaped member includes the shield of the printed circuit board. It is arranged on the side where the case is provided and is in contact with the shield case directly or with a conductive member sandwiched therebetween. It is summarized as receiving device.

The invention according to claim 2 is characterized in that the shield case is provided so as to surround a power feeding means for supplying the radio wave received by the microstrip antenna to the electronic component. The subject is the radio wave receiving device of.

A third aspect of the present invention is based on the radio wave receiving device according to the first or second aspect, wherein the shield case is arranged so as to face the microstrip antenna with the plate member interposed therebetween. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 thus constructed has a shield case which covers at least a part of an electronic component and is electrically connected to a ground electrode of a printed circuit board. I have it. The shield case is, for example, a conductive case that covers an LNA (low noise amplifier) or the like to prevent noise from being superimposed on a processed signal of the LNA or the like, and is commonly used in radio wave receiving devices of this type. ing. In the present invention, the plate member is disposed on the side of the printed circuit board where the shield case is provided, and is in contact with the shield case directly or with the conductive member sandwiched therebetween. Therefore, the plate-shaped member is electrically connected to the ground electrode of the printed circuit board even through the shield case, and the impedance of the plate-shaped member with respect to high frequencies can be favorably lowered. Therefore, the characteristics of MSA can be sufficiently obtained. Moreover, in the present invention, since a commonly used shield case is used, it is not necessary to provide a new structure, and the structure of the device is not complicated. Therefore, the manufacturing cost of the device can be kept low.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the shield case is provided so as to surround the power feeding means for supplying the electric wave received by the MSA to the electronic component. Therefore, when the radio wave received by the MSA is supplied to the electronic component, the radiation noise from the peripheral circuits (especially the digital system circuit) can be prevented from being superposed by the shield case. Therefore, claim 1
In addition to the effects of the described invention, the effect that the radio wave received by the MSA can be processed more accurately is produced.

The invention according to claim 3 is the invention according to claim 1 or 2.
In addition to the configuration described above, the shield case is characterized in that it is arranged so as to face the MSA with the plate-shaped member interposed therebetween. Therefore, the ground side of the MSA and the ground electrode of the printed circuit board can be short-circuited in an extremely short distance. Therefore, the impedance of the portion of the plate-shaped member arranged on the ground side of the MSA can be further lowered. Therefore, in addition to the effect of the invention described in claim 1 or 2, there is an effect that the characteristics of the MSA can be more effectively brought out.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 2 is a perspective view showing the configuration of the radio wave receiving apparatus 1 according to the first embodiment, and FIG. 1 is a sectional view taken along the line AA. The radio wave receiving apparatus 1 of the present embodiment is a so-called GPS radio wave receiving apparatus that receives a transmission radio wave from a GPS satellite and calculates the current vehicle position based on the radio wave.

As shown in FIG. 1, the radio wave receiving apparatus 1 of this embodiment includes a printed circuit board 5 on which electronic parts 3 such as an amplifier and an IC are arranged on both sides, and one side of the printed circuit board 5 is provided. A base plate 7 having a shape covering the electronic component 3 arranged on the surface is arranged. The base plate 7 is formed by subjecting a plate material of a good conductor to drawing or bending, and is formed in a substantially square shape having a thickness of 0.5 to 1.6 mm and a side of about 80 mm. The base plate 7 is fixed to the printed circuit board 5 by screws 9 at the four corners, and the printed circuit board 5 is fixed at these fixed portions.
Of the ground electrode (not shown).

A discharge electrode 11a, a dielectric substrate 11b made of a ceramic material (both of which are shown in FIG. 2), and a ground electrode (not shown) are sequentially laminated on the upper surface of the base plate 7 (the side opposite to the printed board 5). A microstrip antenna (MSA) 11 is provided, and its ground electrode is soldered to the ground plane 7. An electronic component 3 including an LNA (low noise amplifier) 3a and the like is arranged near the center of the upper surface of the printed circuit board 5, and the periphery thereof is covered with a shield case 13. The shield case 13 is a metal housing connected to the ground electrode of the printed circuit board 5, and prevents noise and the like from coming to the electronic components 3 and the like disposed inside from the outside.

A conductive sheet 15 is provided in the gap between the bottom surface of the main plate 7 and the top surface of the shield case 13. The conductive sheet 15 is configured by covering the entire circumference of the cushion material with a wire mesh, and one surface thereof is fixed to the upper surface of the shield case 13 with an adhesive. The other surface of the conductive sheet 15 is pressed against the lower surface of the main plate 7 by tightening the screws 9. In addition, a hole having a small diameter is formed in the center of the main plate 7, the shield case 13, and the conductive sheet 15, and the power feeding pin 17 is disposed through the hole. The power supply pin 17 includes the MSA 11,
The base plate 7, the conductive sheet 15, the shield case 13, and the printed circuit board 5 are penetrated and fitted into the jack 19 provided on the lower surface of the printed circuit board 5. The radio waves received by the MSA 11 are input to the LNA 3a on the printed circuit board 5. To do. The power supply pin 17 is made of a good conductor such as brass and is soldered to the discharge electrode 11a of the MSA 11. The inner surface of the jack 19 is tapered so that the power supply pin 17 can be attached and detached with one touch. Then, the radio wave received by the MSA 11 is input to the LNA 3a via the power feeding pin 17 and the jack 19.

In the radio wave receiving apparatus 1 of the present embodiment configured as described above, the radio wave received by the MSA 11 is transmitted to the LNA 3a.
It is possible to calculate the latitude and the longitude according to the current position of the vehicle by amplifying and demodulating by using other electronic components. Then, the latitude and longitude calculated by the electronic component 3 are transmitted to a CPU (not shown) for a navigation device that drives a CRT, LCD or the like provided in the driver's seat of the vehicle.

Further, in this embodiment, the main plate 7 is the MSA 11
However, it has a sufficiently large area and is made of a good conductor. Therefore, it is possible to prevent the lines of electric force from wrapping around the lower surface of the MSA 11 and stabilize the characteristics of the MSA 11. However, since the ground plane 7 is large, the distance L between adjacent screws 9 (FIG. 1) cannot be ignored for the wavelength (λ = 19 cm) of the radio wave used in GPS. Therefore, temporarily, the shield case 13 and the main plate 7
If and are not conducted through the conductive sheet 15, the following problems occur. That is, the ground plane 7 has an inherent impedance. Ideally, the impedance of the ground plane 7 is 0, but it has a significant impedance,
The impedance near the center of the ground plane 7 becomes high. That is, the ground electrode of the MSA 11 and the ground electrode of the printed circuit board 5 are not equipotential. Then, the characteristics of the MSA 11 cannot be fully brought out.

On the other hand, in this embodiment, the base plate 7 is electrically connected to the shield case 13 via the conductive sheet 15. Moreover, the shield case 13 faces the ground electrode of the MSA 11 with the base plate 7 and the conductive sheet 15 interposed therebetween. Therefore, the ground electrode of the MSA 11 and the printed circuit board 5
Can be short-circuited to the ground electrode of the. Therefore, both ground electrodes can be held at substantially the same potential, and the characteristics of the MSA 11 can be sufficiently brought out. Below, an example of an experiment showing this situation will be introduced.

FIG. 3 shows a radio wave receiving apparatus 1 of this embodiment, a conductive sheet 15 and a shield case 1 of this embodiment.
3 is a comparison of the elevation angle-gain characteristics of the MSA 11 with a radio wave receiving device of a comparative example in which 3 is omitted. As illustrated in FIG. 3, in this embodiment, a better gain is obtained over all elevation angles than in the comparative example. If the shield case 13 is not provided, noise (noise) superimposed on the input / output signal of the LNA 3a or the like also increases, but the elevation angle-gain characteristic is MSA11.
It is a characteristic related only to the performance of. Therefore, even when the shield case 13 is provided but the shield case 13 is not electrically connected to the ground plane 7, the same characteristic curve as that of the comparative example of FIG. 3 is obtained. This situation also applies to the Smith chart and frequency-reflection coefficient characteristics described below.

FIG. 4 is an explanatory diagram showing loci on the Smith chart corresponding to various frequencies of the MSA 11 of this embodiment. As illustrated in FIG. 4, at 1.575 GHz, which is the frequency band used by GPS, the light passes through almost the center of the Smith chart as indicated by arrow B. FIG. 5 is an explanatory diagram showing the frequency-reflection coefficient characteristic of the MSA 11 of this embodiment. As illustrated in FIG. 5, it can be seen that the reflection coefficient is close to 0 in the GPS frequency band (1.575 GHz). These experimental results show that the impedance of the ground plane 7 is almost 0 for the above frequency band and that the MSA1
It has been proved that the ground electrode of No. 1 and the ground electrode of the printed circuit board 5 are held at substantially the same potential.

FIG. 6 is an explanatory diagram showing a locus on the Smith chart of the MSA 11 of the comparative example, and FIG. 7 is an explanatory diagram showing its frequency-reflection coefficient characteristic. As illustrated in FIG. 6, in the comparative example, the points on the Smith chart for any frequency band are located relatively far from the center of the circle. In FIG. 6, a point on the Smith chart corresponding to the frequency band used by GPS is indicated by an arrow C. FIG.
In the comparative example, the reflection coefficient for any frequency band is relatively high, and it can be seen that the difference from the present example is large particularly in the vicinity of the GPS use frequency band (1.5754 GHz).

From the above measurement results, in this embodiment, the impedance of the ground plane 7 is dramatically reduced by connecting the ground plane 7 to the ground electrode of the printed circuit board 5 through the conductive sheet 15 and the shield case 13. MSA11
It is understood that the characteristics of can be fully brought out. In particular, a dramatic improvement in performance is seen in the frequency band used by GPS. Moreover, in this embodiment, since the impedance of the ground plane 7 is reduced by using the general shield case 13 which has been used conventionally, it is not necessary to provide a new configuration, and the configuration of the device becomes complicated. Nor. Therefore, the manufacturing cost of the device can be kept low.

Further, in this embodiment, the shield case 13 is used.
The conductive sheet 15 surrounds the power supply pin 17. Therefore, it is possible to prevent noise from being superposed when the radio wave received by the MSA 11 is supplied to the electronic component 3. Therefore, the radio wave received by the MSA 11 can be processed more accurately.

In the above embodiment, the ceramic material is used as the derivative substrate 11b of the MSA 11, but other materials having a dielectric constant substantially equal to that of the ceramic material may be used. In the above embodiment, the base plate 7 is a plate-shaped member,
The conductive sheet 15 corresponds to a conductive member, and the power feeding pin 17 corresponds to a power feeding member. Further, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the scope of the present invention. For example,
The conduction between the ground plane 7 and the shield case 13 is determined by the conductive sheet 1.
The conductive sheet 15 may not be provided if it can be sufficiently secured without providing 5.

FIG. 8 is a perspective view showing the structure of the shield case 31 of the radio wave receiving apparatus of the second embodiment. The radio wave receiving apparatus of this embodiment has the same structure as that of the first embodiment except for the shield case 13 and the conductive sheet 15. The shield case 31 is made of metal and has a rectangular parallelepiped shape with an open lower surface, and the projections 3 connected to the ground electrode (not shown) of the printed circuit board 5 are provided on four sides of the open surface.
5 are formed. Further, on the upper surface of the shield case 31, there are formed projecting pieces 37 that are hollowed out along three sides of the rectangle and project in a leaf spring shape. A hole 39 is formed in the center of the upper surface of the shield case 31 to allow the power supply pin 17 to pass therethrough.

In the shield case 31 of the second embodiment constructed as described above, when the base plate 7 is fixed to the printed circuit board 5 by the screw 9 after being mounted on the printed circuit board 5,
The protruding piece 37 presses against the main plate 7 by its own elastic force. Therefore, even if the conductive sheet 15 is not used, the characteristics of the MSA 11 can be sufficiently obtained as in the first embodiment. Further, since the conductive sheet 15 is unnecessary, the number of parts can be reduced and the manufacturing cost can be further reduced. However, in order to prevent noise from being superimposed on the signal transmitted through the power feeding pin 17, it is desirable that the circumference of the power feeding pin 17 be completely surrounded by the conductive sheet 15 as in the first embodiment described above. .

FIG. 9 is a sectional view showing the structure of the radio wave receiving apparatus 51 of the third embodiment. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals as those used in FIG. 1 in FIG. 9, and detailed description of the components will be omitted. In the center of the lower surface of the main plate 57 of this embodiment, a tubular projecting portion 59 having a square cross section is formed. When the base plate 57 is fixed to the printed circuit board 5 and the tip of the projecting portion 59 is soldered to the ground electrode of the printed circuit board 5, the projecting portion 59 forms a shield case for covering the LNA 3a and the like. That is, in this embodiment, the shield case is integrated with the base plate 57. Therefore, the same operation and effect as those of the first embodiment described above can be obtained, and the number of parts can be reduced to simplify the structure of the device.

Further, in each of the above embodiments, the ground electrode of the MSA 11 is soldered to the ground planes 7, 57, but the ground electrode does not have to be in contact with the ground planes 7, 57.
By directly laminating the dielectric substrate and the discharge electrode on the base plates 7 and 57, the base plates 7 and 57 may be used as they are as the ground electrode of the MSA 11. In the latter case, the configuration is further simplified,
The manufacturing cost can be further reduced. Further, the material of each member used in each of the above-mentioned embodiments can be changed as necessary, and the portion soldered in each of the above-mentioned embodiments is replaced by another connecting method such as welding or fitting. You can also

Furthermore, in each of the above-described embodiments, the shield cases 13 and 31 or the protruding portion 59 are provided at a position surrounding the power supply pin 17 and facing the MSA 11.
The shield case may be provided at any place such as one corner of the main plate 7. In this case as well, the impedance of the ground plane 7 can be lowered by bringing the shield case and the ground plane 7 into contact with each other directly or with the conductive member interposed therebetween. However, in order to keep the ground electrode of the MSA 11 and the ground electrode of the printed circuit board 5 at the same potential, it is more effective to dispose the shield case so as to face the MSA 11 as described above, and superimpose noise on the power supply pin 17. To prevent this, it is more effective to surround the power supply pin 17 with the shield case as described above. Further, the present invention is G
It can be applied to radio wave receiving devices other than PS.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a radio wave receiving apparatus according to a first embodiment.

FIG. 2 is a perspective view showing a configuration of the radio wave receiving device.

FIG. 3 is an explanatory view showing the elevation angle-gain characteristics of the radio wave receiving device for comparison.

FIG. 4 is an explanatory diagram showing a locus on a Smith chart of an MSA of the radio wave receiving device.

FIG. 5 is an explanatory diagram showing frequency-reflection coefficient characteristics of the MSA.

FIG. 6 is an explanatory diagram showing a locus on a Smith chart of a MSA of a comparative example.

FIG. 7 is an explanatory diagram showing frequency-reflection coefficient characteristics of the MSA.

FIG. 8 is a perspective view showing a configuration of a shield case of the radio wave receiving apparatus according to the second embodiment.

FIG. 9 is a cross-sectional view showing a configuration of a radio wave receiving apparatus according to a third embodiment.

[Explanation of symbols]

1 ... Radio receiver 3 ... Electronic component 3
a ... LNA 5 ... printed circuit board 7 ... ground plane 1
1 ... MSA 13 ... Shield case 15 ... Conductive sheet 1
7 ... Power supply pin

Claims (3)

[Claims] 1. A microstrip antenna, a plate-shaped member that is disposed on the ground side of the microstrip antenna, and includes a conductor that stabilizes the characteristics of the microstrip antenna, and is electrically connected to the plate-shaped member. A printed circuit board having a ground electrode, an electronic component disposed on the printed circuit board, for processing radio waves received by the microstrip antenna, at least a part of the electronic component, and a ground electrode for the printed circuit board. And a shield case electrically connected to the shield case, wherein the plate-shaped member is disposed on the side of the printed circuit board on which the shield case is provided, and the shield case is directly or electrically sandwiched between the shield case and the shield case. A radio wave receiver characterized in that it is contacted with. 2. The radio wave receiving device according to claim 1, wherein the shield case is provided so as to surround a power feeding means for supplying the radio wave received by the microstrip antenna to the electronic component. 3. The radio wave receiving apparatus according to claim 1, wherein the shield case is arranged so as to face the microstrip antenna with the plate member interposed therebetween.