JP2757604B2 - Planar antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna having an intended frequency characteristic at all times, and more particularly to a planar antenna capable of adjusting a deviation of the frequency characteristic and preventing a change in the characteristic.

[0002]

2. Description of the Related Art A planar antenna of this kind is expected to be small in size and good in appearance, which is suitable for use in mobile communications such as automobile telephones. Mode Ring Patch Antenna and Its Feeding Method "(IEICE, 1987, VOL.5)
3, p. 21-24). As shown in FIGS. 15 and 16, a patch 2 as an antenna element is disposed with a gap provided from a ground plane 1 of a conductor, and a feeding shaft 3 is connected to a central portion of the patch 2 to be a feeding point Q. ing. The ground plate 1 and the patch 2 are electrically connected by the short pins 4 provided around the power supply shaft.

[0003]

However, in such a conventional planar antenna, FIG. 17 shows the relationship between the distance r between the feeding point Q and the short pin 4 and the frequency band.
As can be seen from the graph, the frequency band is narrow, and the characteristics are deteriorated even if the distance is slightly changed. In the figure, λ is the wavelength at the frequency f, and h is the depth of the concave portion from the surface of the vehicle body panel to the ground plane when the antenna is installed in the concave portion of the vehicle body and measured. For this reason, for example, when mass-produced for a mobile phone, there is a risk that the antenna will deviate from the target frequency band to be used and will not actually function as an antenna, depending on the management level of the antenna parts and the accuracy of assembling the antenna. Here, the deviation can be adjusted by changing the thickness of the short pin, but it is not practical to prepare short pins of various sizes for adjustment in consideration of mass production.

Furthermore, even if the target characteristics are adjusted during assembly, if rain or snow adheres to the surroundings, the characteristics of the antenna will change and the sensitivity will deteriorate. FIG. 18 shows the antenna return loss characteristics when a resin plate is placed on the upper part of the patch and there is no snow and when snow is piled on the resin plate. Those that resonated sharply without snow almost do not resonate due to the adhesion of snow.

When this was further examined, there was no problem even if an antenna for a vehicle obstructed the emission of radio waves such as rain and snow in the upper part of the patch, and the effect of snow accumulation in the side direction was great. .

This is determined for the following reasons. An antenna using a patch has different directivity characteristics depending on its resonance mode. When resonating in the TM11 mode shown in FIG. 19, the antenna has a directivity characteristic in which a main beam is radiated in the upper surface direction of the patch (θ = 0 degree direction). This is because an electromagnetic field is generated when power is supplied to the antenna as shown in FIG. For this reason, if there is moisture such as rain or snow in the upper surface direction of the patch, the characteristics of the antenna will deteriorate.

However, the TM01 mode is used for automobiles, and the directional characteristics in this case are oblique as shown in FIG. This is because an electromagnetic field is generated and radio waves are radiated from the gap between the ground plate and the patch as shown in FIG. Therefore, if water such as rain or snow exists outside the side wall corresponding to the gap or the periphery of the patch, reflection of radio waves occurs, which adversely affects characteristics.

[0008] Accordingly, the present invention is directed to the above-mentioned conventional problems.
In view of the above, it is an object of the present invention to provide a planar antenna that can be easily adjusted to a required frequency characteristic at the time of assembling the antenna or after starting use, and further, the adjusted antenna characteristic is affected by environmental changes such as weather. It is an object of the present invention to provide a planar antenna that is prevented from receiving.

[0009]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a base plate of a conductor, a patch of a conductor which is disposed opposite to the base plate with a gap therebetween, and is fed as an antenna element, and short pin for conducting a Bei <br/> planar antenna Ru give a, together with the patch and the ground plane
Provide matching long holes, patches and short pins and ground plane
And short pins are screwed through the long holes, respectively.
So that
Adjustable short pin position with respect to patch feed point
Adjustment means. Furthermore, the above
Assemble the assembly consisting of the main plate, patches and short pins.
Install the antenna element inside the antenna case
Power as well as a heating element in the antenna case.
Can be connected to a power supply to generate heat.

[0010]

[Function] The resonance frequency and the directional characteristics change depending on the position of the short pin for conducting the ground plate and the patch. By adjusting these positions, the deviation of the characteristics due to the manufacturing variation such as the accuracy of the parts at the time of mass production is absorbed. The intended desired antenna characteristics can be obtained. And position adjustment
The rest is fixed by screw tightening, so it was adjusted
The characteristics are easily destroyed by, for example, vibration
There is no. In addition, readjustment is possible if necessary.

Further, when the above-mentioned assembly of the patch and the base plate is housed in an antenna case and a heating element is provided in the case, rain and snow adhering to the case are removed even if the weather changes, and There is no accumulation of reflectors affecting transmission and reception, and the desired antenna characteristics and sensitivity are maintained without deterioration.

[0012]

1 and 2 show an embodiment of the present invention.
A flat patch 1 made of a conductor such as iron or copper is provided in parallel with a gap above the conductor ground plate 11 forming the ground side.
2 are arranged opposite to each other to form an antenna element, and a central portion of the patch 12 is connected to a feed shaft 13 to serve as a feed point Q. The ground plate 11 and the patch 12 are formed by four sets of short pins 14 provided so as to surround the feeding point Q at the center.
Are conducted.

An opening 15 is provided at the center of the base plate 11, and the power supply shaft 13 extends from the power supply connector 23 attached to the lower surface of the base plate to the patch through the opening 15 and is connected to the lower surface of the patch. .

For attaching the short pin, the main plate 11
And the patch 12 have elongated holes 1 extending from the center to
6 and 17 are provided. The short pin 14 is formed of a conductor in a hollow pipe shape, and a bolt 20 is inserted into the elongated hole 17 from the upper surface side of the patch 12, passes through the short pin 14, passes through the elongated hole 16 of the ground plate 11, and passes through the lower surface of the ground plate 11. The patch 12 and the base plate 11 are joined together by tightening with the nut 21 on the side. At this time, the gap between the patch 12 and the base plate 11 is defined by the length of the short pin. On the upper surface of the patch 12, as shown in FIG.
A graduation 18 is displayed along the scale. A scale can also be displayed on the main plate.

The assembly of the patch 12 and the base plate 11 is housed in an antenna case 30. A boss 33 is provided on the base 31 of the antenna case 30, and the base plate 11 is fixed to the boss portion with screws 25. Base 31
A wiring hole 34 is provided at a central portion of the power supply connector to avoid the power supply connector 23 attached to the base plate 11 and to pass the power supply cable 24 connected to the connector. A cover 32 is put on the base 31 so as to cover the assembly of the patch 12 and the base plate 11, and is joined at a peripheral portion.

A cover 32 of the assembly housed in the antenna case 30 corresponding to the gap between the patch 12 and the base plate 11
A plurality of ring-shaped heating wires 36 are arranged on the outer peripheral surface of the side wall as heating elements along the circumferential direction thereof. As shown in FIG. 4, each end of the heating wire 36 is connected to a bus bar 37, 38, from which a power supply wire 39 and a ground wire 40 are drawn out of the wiring hole 34 through the inside of the antenna case and shown in FIG. A circuit is formed and connected to a vehicle battery or the like to be driven. The heating wire and the bus bar may be embedded in the cover 32 or may be formed by printing.

Since this embodiment is configured as described above, the position of the short pin 14 can be adjusted by sliding. FIG. 6 shows the antenna characteristics when the distance ρ between the short pins facing each other across the feeding point is extended in units of 5 mm from 108 mm using the assembly of the patch and the base plate having a diameter of 147 mm as shown in FIG. Since the resonance frequency and its return loss change according to the change in the distance ρ, the position of the short pin 14 can be adjusted at the time of assembling the antenna or after assembling, thereby absorbing the deviation of the frequency characteristics due to manufacturing variations. In particular, in the case of an antenna for a car telephone or the like, the position of the short pin 14 is adjusted with reference to the scale 18 provided along the long hole 17 of the patch 12 so that the directional characteristics are directed sideways and the radio wave is not directed upward. Perform Once the position of the short pin is determined, bolt 2
The position is fixed by tightening the nut 0 and the nut 21.

Since the heat wire is provided on the side surface of the antenna case 30, when the snow which hinders the emission of radio waves accumulates or gets wet with rain, the antenna is degraded by energizing to melt them or evaporating water. Good transmission / reception of radio waves is possible.

FIGS. 8 and 9 show another embodiment of the present invention. The patch 52 has a rhombic shape and is further downsized so that it can be mounted in a limited space such as an automobile. I have. Cross holes 56 and 57 are provided in the base plate 51 and the patch 52, respectively, for mounting four sets of short pins 54 provided so as to surround the feeding point Q at the center. The cross hole has a shape obtained by combining a long hole extending in the radial direction similar to the previous embodiment and a long hole extending at right angles or in the circumferential direction.

As in the previous embodiment, the short pin 54 is formed of a conductor in the shape of a hollow pipe, and the bolt 20 is connected to the patch 5.
2 is inserted into the cross hole 57 from the upper surface side, penetrates the short pin 54, passes through the cross hole 56 of the main plate 51,
And the nut 52 on the lower surface side of the
And the main plate 51 are connected. At this time, if the diameter of the bolt nut or the short pin 54 is small,
Since the contact portion between the patch 52 and the ground plate 51 becomes narrow in the vicinity of the center of 6, 57, the large-diameter washer 60 may be inserted between the patch and the ground plate as shown in FIG.

In this embodiment, the central portion of the patch 52 is formed in a conical cone 59 shape facing the main plate 51 side. From the power supply connector 23 attached to the lower surface of the main plate 51, the power supply shaft 13 penetrates through the opening 55 at the center of the main plate, and connects to the tip of the conical cone 59 of the patch to become the power supply point Q. FIG.
Although not shown, the base plate 51 is attached to the base of the antenna case by the screw 25 and is housed in the antenna case.

With the above configuration, in this embodiment, the position of the short pin 54 can be slid to adjust not only the distance between the short pins sandwiching the feeding point Q but also the angle. 10 and 11 show the antenna characteristics according to the change of the vertical and horizontal distances x and y between the short pins 54 by using the assembly of the diamond-shaped patch and the ground plate having a length of 224 mm and a length of 112 mm as shown in FIG. . Especially FIG.
Changes the distance between the short pins facing each other across the feeding point, and FIG. 11 shows the distances x and y so as to change the angle between the two sets of straight lines connecting the short pins.
Is changed. The position of the short pin 54 is adjusted on the basis of the change in the resonance frequency and the return loss obtained thereby.

In the above two embodiments, the elongated holes 16 and
If the area of 17 or the cross holes 56 and 57 is about 0.0006 or less when divided by the square of the wavelength λ, the characteristics are the same as those provided with the smallest hole capable of fixing the short pin. In the case where a hole having a larger area is provided, the influence can be easily avoided by closing the remaining hole portion with a conductive tape or the like after completing the position adjustment of the short pin. .

FIG. 13 shows another example of power supply to the heating element, in which a power supply line for supplying DC power to the heating element and a power supply cable for supplying power to the antenna are shared. That is, the antenna case 130 in which the assembly of the patch 12 and the base plate 11 is housed is provided with a plurality of heating wires 136 on the peripheral side wall, and each end of the heating wire is connected to the bus bars 137 and 138 vertically arranged on the side wall. . The electrical connection will be described.
5 is connected, and the ground plate 11 is
26 is connected, the core wire 125 and the bus bar 13 are connected.
7 is connected by a power supply line 139 via a choke coil 143, and the shield 126 and the bus bar 138 are connected by a ground line 140 via a chiyoke coil 144. At the end of the power supply cable 124 on the transceiver 150 side, the core wire 1
25 is connected to the transceiver 150 via the capacitor 146, and this core wire 125 is connected to a DC 12V power supply. The shield 126 is grounded. In addition,
The base plate 11 and the patch 12 are clearly shown in FIGS.
As described above, the first embodiment has the long holes 16 and 17.
Short pin between them can be adjusted as well
It is assembled by tightening with bolts and nuts
However, they are not shown in FIG.

According to this, the heating wire 136 is connected to the power supply line 139 through the core wire 125 of the power supply cable and the shield 12.
Power is supplied from a DC power supply by a ground line 140 through 6. Since this DC current does not flow to the transceiver 150 due to the presence of the capacitor 146, it does not adversely affect the input / output unit of the transceiver. In addition, antenna and heating wire 1
36 is separated at high frequencies by choke coils 143 and 144 provided on the power supply line and the ground line, so that there is no influence of noise or the like on each other. Further, since the high-frequency signal transmitted and received by the antenna passes through the capacitor 146 and is transmitted to the transceiver 150, no problem occurs in the operation as the antenna.

In FIGS. 1 and 9, the antenna is first assembled as an assembly of the antenna patch and the ground plate, and then attached to the antenna case by using a special screw, so that the number of parts is large. There is a tendency to become. FIG. 14 shows an example in which the configuration is simplified based on the configuration shown in FIG.

The base plate 211 of FIG.
An elongated hole 216 extending in four directions from the center is provided similarly to 2. The base 231 of the antenna case is provided with a boss 233 having a receiving wall 235 on which the ground plate 211 is placed. The boss 233 is formed at a position corresponding to the short pin 14, and has an elongate hole 236 that is aligned with the elongate hole 216 for attaching the short pin of the base plate 211 on its receiving wall 235.
Are formed.

A bolt 20 is inserted into the elongated hole 17 from the upper surface side of the patch 12, penetrates the short pin 14, and
11 and the boss 2 on which the main plate 211 is placed.
The nuts 21 are tightened from the lower surface side of the receiving wall through the elongated holes 236 of the receiving wall 235. As a result, the assembly of the patch 12 and the base plate 211 and the fixing of the assembly to the base 231 are simultaneously performed at the boss 233 portion. For this reason, there is no need to use a separate screw to provide a separate hole on the main plate to attach the case,
The structure is simple and the number of parts is small. In addition, assembling of the antenna body and attachment to the case are completed at the same time.

[0029]

As described above, according to the present invention, the present invention provides a planar antenna Ru comprising a base plate and a patch and the short pins, patches
And the base plate are provided with long holes that match each other,
Pin and ground plate and short pin each
And tighten it with a screw.
Adjust the position of the short pin with respect to the feed point of the patch.
Adjustment means that can be adjusted,
Slide adjustment of the position of the short pin for conducting the patch
To secure target frequency characteristics by absorbing deviations in antenna characteristics due to component precision and other manufacturing variations.
And fix the state by screw tightening
Can vibrate when mounted on a vehicle, etc.
Therefore, there is no fear that the adjustment position is shifted. I
Therefore, it is suitable for mass production.
Also has the advantage that it can be adjusted as needed
You.

Further, when the assembly of the patch and the base plate is housed in an antenna case and a heating element is provided in the case, rain and snow adhering to the case are removed even in a bad weather environment, and the desired antenna is adjusted. It can be maintained without lowering the characteristics and sensitivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a plan view of a portion AA in FIG. 1;

FIG. 3 is an enlarged view of a portion B in FIG. 2;

FIG. 4 is an external perspective view of an antenna case.

FIG. 5 is a hot wire circuit diagram.

FIG. 6 is an antenna characteristic diagram.

FIG. 7 is a specification diagram of an antenna whose characteristics in FIG. 6 are measured.

FIG. 8 is a diagram showing another embodiment.

FIG. 9 is a plan view of a portion CC in FIG. 8;

FIG. 10 is an antenna characteristic diagram.

FIG. 11 is an antenna characteristic diagram.

FIG. 12 is a specification diagram of an antenna measuring the characteristics of FIGS. 10 and 11;

FIG. 13 is a view showing still another embodiment.

FIG. 14 is a view showing still another embodiment.

FIG. 15 is a sectional view showing a conventional example.

FIG. 16 is a plan view of a conventional example.

FIG. 17 is a diagram showing a frequency band.

FIG. 18 is a diagram showing changes in antenna characteristics due to snow.

FIG. 19 is a diagram illustrating directivity characteristics of a planar antenna having TM11 mode resonance.

FIG. 20 is a diagram illustrating the principle of operation of a planar antenna having TM11 mode resonance.

FIG. 21 is a diagram illustrating directivity characteristics of a planar antenna having TM01 mode resonance.

FIG. 22 is a diagram illustrating the operation principle of a planar antenna having TM01 mode resonance.

[Explanation of symbols]

 11, 51 Base plate 12, 52 Patch 13 Power supply shaft 14, 54 Short pin 15, 55 Opening 16, 17 Elongated hole 18 Scale 20 Bolt 21 Nut 23 Power supply connector 24 Power supply cable 25 Screw 30 Antenna case 31 Base 32 Cover 33 Boss 36 Hot wire 37,38 Bus bar 39 Power line 40 Ground line 56,57 Cross hole 59 Conical cone 60 Washer 211 Main plate 216 Long hole 231 Base 233 Boss 235 Receiving wall 236 Long hole

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichiro Kato 2 Nissan Motor Co., Ltd., Nissan Motor Co., Ltd. (72) Inventor Morita Ikuhiro 2 Takaracho, Kanagawa Ward, Yokohama City, Kanagawa Prefecture Nissan Motor Co., Ltd. (56) References JP-A-4-199903 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01Q 13/08

Claims (7)

(57) [Claims] 1. A conductor and the earth plate, and patches disposed opposite conductors fed as the antenna element provided with a gap above the該地plate, planar antenna Ru comprises a short pin for conducting a and patch the base plate a is provided with a long hole aligned with each other on the patch and the ground plane, patches
And short pin and ground plate and short pin respectively.
Secure by tightening the screw through the slot.
Along the slot to the feed point of the patch
A planar antenna having an adjusting means for adjusting a position of a port pin . 2. The short pin is formed in a hollow pipe shape.
And a bolt penetrating the short pin through the slot
Between the patch and the base plate with the short pin
2. The planar antenna according to claim 1, wherein the antenna is fixed . 3. The patch has a feed point in the center thereof,
There are four slots at opposite positions across the feeding point on the plane
Provided, each extending in the radial direction around the feeding point
3. The planar antenna according to claim 1 , wherein the planar antenna is formed. 4. The base plate, a patch and a short pin
Is assembled in the antenna case, and
The patch is fed as an antenna element and
In addition, a heating element is provided in the antenna case,
It is characterized by being connected and generating heat
The planar antenna according to claim 1, 2 or 3. 5. The heating element is connected to a power supply cable for a patch.
Be sure to connect to the power supply via the
The planar antenna according to claim 4, wherein: 6. The heating element corresponds to a gap between the patch and the ground plate.
Along the peripheral side wall of the corresponding antenna case.
The planar antenna according to claim 4 or 5, wherein 7. The antenna case has a receiving wall.
A boss is provided, and the receiving wall has the length of the patch and the main plate.
A slot matching the hole is formed, and the base plate is placed on the receiving wall.
To put the bolt through the slot in the wall
Thus, the assembly can be attached to the antenna case.
The planar antenna according to claim 4, 5 or 6, wherein: