JP3352480B2 - Biconical planar antenna for mobile objects - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biconical planar antenna mounted on a vehicle. In particular, the present invention relates to achieving a small shape in a low frequency region and securing a wide band.

[0002]

2. Description of the Related Art Heretofore, there has been the following one of such technical fields. FIG. 7 is a diagram showing a conventional biconical planar antenna for a mobile object. The mobile biconical planar antenna shown in the figure has a triangular shape, a so-called planar conical shape, and two metal flat plates 10 whose vertices face each other.
It consists of 0 and 101. This can be approximated to a self-complementary antenna, and to some extent (actually, f = c / 2a (c: speed of light, a: length of facing triangle sides)) At frequencies equal to or higher than 3c / 2a) or more, the input impedance is substantially constant, and broadband characteristics are obtained. This frequency is defined as a working frequency. This mobile biconical planar antenna is:
Generally, the band is wider than that of a dipole antenna, and it is suitable for receiving broadcasts having a predetermined frequency band such as FM and TV. Since the biconical planar antenna is housed inside the body of the vehicle, the appearance is improved, and there is an advantage that the wind noise and damage are reduced as compared with the rod antenna, but it has not been used in the vehicle yet. It is described as a known antenna in literature and the like.

[0003]

By the way, in the conventional biconical planar antenna for a mobile object, since the used frequency is determined by the length of the triangular sides of the two flat metal plates facing each other, it is necessary to reduce the used frequency. It is necessary to increase the length of the sides of the triangle. However, increasing the length of the sides of the triangle is good when the vehicle is large, but when the vehicle is small, there is a limit in the planar space, so that the use of the biconical planar antenna for mobile objects is limited. There's a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a biconical planar antenna for a mobile object which can be used even in a low frequency range and has a wide band.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a biconical planar antenna for a moving object having a conical shape and two flat metal plates whose vertices face each other and have the same shape. A first metal plate, a second metal plate, and a linear conductor are provided. The first metal plate divides each of the two metal flat plates into two, and one of the divided portions forms an isosceles triangle including the vertices and having the same shape.

[0006] The second metal plate is configured so that the other of the divided two parts forms a trapezoid having the same shape as each other. The linear conductor has a folded shape provided between the first metal plate and the second metal plate. Further, the first metal plate divides each of the two metal flat plates into two, one of which is a scalene triangle including the vertices and having the same shape as each other, and wherein the second metal plate is The other of the divided parts may have a shape close to a triangle.

Further, the two biconical planar antennas for a moving object are arranged orthogonally to a resin roof of a vehicle.

[0008]

According to the biconical planar antenna for a mobile object of the present invention, the linear conductors are respectively provided between the first metal plate and the second metal plate and formed in a folded shape, so that the sides of the apparently upwardly facing triangle are formed. Becomes longer, and the low frequency region can be expanded without increasing the shape of the entire metal plate. The high-frequency signal is cut off to the second metal plate by the return of the linear conductor,
High frequency characteristics are ensured by the first metal plate.

In addition, the first metal plate is changed from an isosceles triangle to a non-equilateral triangle, the length of one side of the first metal plate is increased, and at the same time, the shape of the second metal plate is changed from a trapezoid to a triangle. Become. Further, by arranging the two biconical planar antennas for a mobile object so as to be orthogonal to the resin roof of the vehicle, low frequency characteristics can be secured in a small space, and at the same time omnidirectionality can be secured.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a biconical planar antenna for a mobile object according to a first embodiment of the present invention. This figure (a)
The biconical planar antenna for a mobile object shown in FIG. 1 is composed of elements 200 and 201, and the elements 200 and 201 have a triangular shape. One of the first metal plates 1 and 4 including one of the vertices and forming an isosceles triangle having the same shape, and the other of the divided second metal plates 2 and 5 forming a trapezoid having the same shape. And folded linear conductors 3 and 6 provided between the first metal plates 1 and 4 and the second metal plates 2 and 5, respectively. This figure (b) shows an enlargement of the linear conductor 3 or 6, and the length of the folded conductor is L. The function of the linear conductor 3 or 6 has the function of lowering the operating frequency in the low frequency region. That is, in the low-frequency region, the length of two opposing triangular sides formed by the first metal plates 1 and 4, the linear conductors 3 and 6, and the second metal plates 2 and 5 is defined as a.
Then, the use frequency is f = c / (a + p · 2L)
Becomes Here, p <1.0. That is, the linear conductor 3
And 6 have the function of apparently increasing the length a of the triangular side whose vertices face each other. Therefore, the working frequency can be reduced without substantially increasing the triangular shape. However, in the high frequency region, the linear conductors 3 and 6 function as coils and flow between the first metal plate 1 and the second metal plate 2 and between the first metal plate 4 and the second metal plate 5. The current is interrupted. In this case, the first metal plates 1 and 4 have reception sensitivity as a high frequency region, and in this case, if the length of the sides of the first metal plates 1 and 4 whose vertices face each other is b, the use frequency is f = C / b.

Next, the points to be improved in the first embodiment will be described. In FIG. 1, since the second metal plates 2 and 5 have a trapezoidal shape and are not a triangular so-called planar conical shape, this shape causes deterioration of the wide band as an antenna. Since the first metal plates 1 and 4 have short sides,
This shape degrades the receiving sensitivity and degrades the broadband characteristics. The deterioration of these frequency characteristics will be described.

FIG. 2 is a diagram showing frequency characteristics of a biconical planar antenna for a mobile object. In the figure, the curve a represents the conventional frequency characteristic, and the curve b represents the frequency characteristic of the first embodiment. In the first embodiment, the frequency characteristics are improved in the low frequency range and the same as the conventional one in the high frequency range. However, the degradation occurs in the intermediate range due to the above-mentioned reason, and the band is not wider than the conventional one. This improvement is described below.

FIG. 3 is a view showing a biconical planar antenna for a mobile object according to a second embodiment of the present invention, and FIG. 4 shows a comparison between the shapes of the metal plates of the first embodiment and the second embodiment. FIG. The second embodiment is different from the first embodiment in that
In the first embodiment, the linear conductors 3 and 6 are arranged in parallel to the sides opposite to the opposing vertices of the triangle. In the second embodiment, the linear conductors 13 and 16 in the elements 202 and 203 correspond to the opposing vertices of the triangle. The point is that it is arranged non-parallel to the opposite side. As shown in FIG. 4, the second metal plate 15 formed by the linear conductor 16 has a shape close to a triangle formed by a dotted line in the figure. As a result, the band becomes closer to a triangular shape, so that the band characteristics are improved and the band becomes wider. The first metal plate 1 formed by the linear conductor 16
Reference numeral 4 forms a scalene triangle, but maintains a conical shape and expands the length of the side, so that the band characteristic is improved and the band is widened.

In the above description, the case where the conical metal plate is divided into two parts has been described. However, the present invention is not limited to this, and the same operation and effect can be generally obtained even if the metal plate is divided into a plurality of parts. FIG. 5 is a diagram showing a biconical planar antenna for a mobile object when used in a vehicle, and FIG. 6 is an enlarged view of a power supply unit in FIG. As shown in FIG. 5, AM, F
FIG. 5A shows a biconical planar antenna for a mobile object used for receiving M and TV broadcasts. A biconical planar antenna according to a second embodiment of the present invention is provided on a resin roof (hatched portion) 300 of a passenger car shown in FIG. The antenna is embedded. FIG.
As shown in (b), the biconical planar antenna for a mobile object embedded in the resin roof 300 has two biconical planar antennas arranged in a direction orthogonal to each other. That is, the biconical planar antenna for a moving object has one antenna, the element 2 and the element 202A and 203A.
02B and 203B constitute one antenna. The orthogonality is provided in this way to ensure omnidirectionality when diversity reception is performed.

Next, as shown in FIG.
The antennas A and 203A are fed via a feeder line 401 using a matching unit 400, and the elements 202B and 203A are fed.
For the antenna B, the core wire 403 of the coaxial cable 402 is connected to the element 202B, and the outer conductor is connected to the element 203B, and the element 203B acts as a ground plate.
The power supply cable 401 (coaxial cable) passes through pillars and is connected to a diversity unit (not shown) and each tuner.

[0016]

As described above, according to the present invention, since the linear conductors are provided between the first metal plate and the second metal plate and formed in a folded shape, the shape of the entire metal plate is enlarged. The low-frequency region can be expanded without the need. The first metal plate is changed from an isosceles triangle to an inequilateral triangle, and the length of the side is enlarged. At the same time, the shape of the second metal plate is changed from a trapezoid to a triangle, so that a wide band can be improved. Further, since the two biconical planar antennas for the mobile object are arranged so as to be orthogonal to the resin roof of the vehicle, low-frequency characteristics can be secured in a small space, and at the same time omnidirectionality can be secured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a biconical planar antenna for a mobile object according to a first embodiment.

FIG. 2 is a diagram showing frequency characteristics of a biconical planar antenna for a mobile object.

FIG. 3 is a view showing a biconical planar antenna for a mobile object according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a comparison of metal plate shapes of the first and second embodiments.

FIG. 5 is a diagram showing a biconical plane for a mobile object when used in a vehicle.

FIG. 6 is an enlarged view of a power supply unit of FIG. 5;

FIG. 7 is a diagram showing a conventional biconical planar antenna for a mobile object.

[Explanation of symbols]

 1, 4, 11, 14 ... first metal plate 2, 5, 12, 15 ... second metal plate 3, 6, 13, 16 ... linear conductor 200, 201, 202, 203 ... element

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01Q 1/32 H01Q 11/04 H01Q 5/01

Claims (2)

(57) [Claims] 1. Two sheets having a triangular shape and vertices facing each other
Biconical Planar Antenna with Moving Metal Plate for Moving Object
A is, each said two metal plates were bisected, while divided each
Form a trapezoidal triangle containing the vertices and equal in shape
A first metal plate (11, 14) and a second metal plate, the other of which is divided into a triangular shape;
Metal plates (12, 15), the first metal plate (11, 14), and the second metal plate
Folded shapes provided between (12, 15)
(13, 16).
Biconical planar antenna for mobile objects. 2. The two moving object bicos according to claim 1.
The planar antenna is perpendicular to the resin roof of the vehicle.
Biconical flat for mobile objects, characterized in that
Plane antenna .