JPH0411375Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention relates to a radar antenna that detects an extremely short distance of several meters.

[Conventional technology]

Radar used for the purpose of detecting buried objects located within several meters underground from the ground surface.
Ultra-short-range radar uses isolated pulse waves with a pulse width of several nanoseconds as the transmission wave, so
An antenna with wideband frequency characteristics is required.

As an antenna device of this kind, in order to widen the band using a folded die hole of a plate-shaped fan-shaped dipole and to dampen it by intervening a resistor, resistors are arranged symmetrically in a semicircular or diamond shape from both ends of the fan-shaped die hole. A broadband antenna with a resistive short-circuited body consisting of a continuous body or a series connection of a resistive body and a conductive plate was developed in 1983, which reduced transient phenomena caused by isolated pulses.
44916 and others.

On the other hand, among such antennas, a radio wave absorber shielded dipole antenna was put into production in 1972, in which a shielding cover made of a bowl-shaped radio wave absorber was applied to the back side of the dipole antenna in order to shield unnecessary radiation in directions other than the desired direction. -157307 and others.

[The problem that the idea attempts to solve]

The above-mentioned ultra-short-range radar antenna using a dipole antenna with a semicircular or diamond-shaped resistance short-circuiting body is installed in a steep structure, for example, in a part very close to the wall of a building, or buried underground in a narrow trench. If there is an object, it is limited by the size of the antenna body and cannot be detected.

Furthermore, in the case where a shielding cover made of a bowl-shaped radio wave absorber is provided as described above, the shielding cover becomes larger, which makes detection even more difficult in a narrow place.

Furthermore, when receiving reflected waves from a nearby object to be detected, the radiated waves from the resistive short-circuit part interfere with the radiated waves from the fan-shaped dipole part in a complex manner, resulting in wave reception operation. There are also disadvantages such as instability.

Therefore, there is a problem in that it is desired to provide something that can eliminate these inconveniences even to a small extent.

[Means to solve the problem]

This idea connects a resistor short-circuit body, which is a resistor and a conductor plate connected in series alternately, between both ends of the plate-shaped, fan-shaped dipole as described above to form an antenna body. An ultra-short-range radar antenna device in which a bowl-shaped shielding cover is applied to a fan-shaped dipole, the shielding cover having a shape that covers the fan-shaped dipole and whose opposing sides are horizontally rectangular vertical surfaces, and each conductor plate. The above-mentioned problem can be solved by providing a resistor short-circuiting body whose surface is arranged along the outer surface of the vertical surface.

〔Example〕

Examples will be described below with reference to figures.

First, let me explain about the antenna body.
In FIG. 1, a wideband antenna 1 is formed by arranging two isosceles triangular plate-shaped antenna elements so that their vertices face each other, as shown in the figure. It is formed by a sector-shaped dipole to which electric wires 5 are connected and power is supplied with transmission pulse waves.

As shown in the figure, the resistor short circuit parts 11 and 11' are formed in a straight line, and specifically, a plurality of resistors and conductor plates are connected alternately in series.

That is, the folded elements formed by the conductor plates 9, 10 and 9', 10' are arranged in a straight line between the outer ends of the broadband antenna 1, and the resistors 6, 8 and 6', 8' The fan-shaped dipole element of the broadband antenna 1 and the conductor plates 9, 10 and 9',
10′, and
Resistors 7 and 7' are connected to conductor plates 9, 10 and 9',
10', and these resistors dissipate heat from the electromagnetic waves.

Therefore, the structure of the antenna portion is such that a linearly formed resistance short-circuit body is arranged between both outer ends of each fan-shaped dipole.

Next, to explain the structure in which the antenna body is covered with a shielding cover of a radio wave absorber, in FIG. 2, the parts indicated by the same numbers and symbols as in FIG. As shown in the figure, the wideband antenna 1 has a plate-shaped surface other than the front opening 3, that is, the back side and the surrounding area are covered with a bowl-shaped shielding cover 2.

As shown in the figure, the bowl-shaped shielding cover 2 is formed of a metal plate with opposing sides having horizontally long rectangular vertical surfaces and a radio wave absorber 4 pasted on the inner surface. The surfaces of the conductor plates 9, 10 and 9', 10' of the resistance short-circuiting bodies 11, 11' are aligned along the outer surface of the shielding cover 2 such that the surfaces are perpendicular to the plate-like surfaces of the fan-shaped dipoles. It is arranged as follows.

That is, holes 12 and 13 are provided on the side surface of the bowl-shaped shielding cover 2, and as shown in the figure, the connecting wires of the resistors 6 and 8 constituting the resistor short-circuiting body 11 are inserted through the holes 12 and 13, which are placed on the outer surface of the shielding cover. It is connected to both ends of the series connection body of the conductor plate 9, the resistor 7, and the conductor plate 10, and, although not shown, the resistor short-circuit body 11' is similarly arranged on the opposite side. .

[Effect of idea]

According to this invention, as described above, the bowl-shaped shielding cover 2 is configured such that at least the opposing sides thereof are horizontally elongated rectangular vertical surfaces, and the resistive short-circuiting body 11 is formed on this vertical surface.
Since the conductor plates 9, 10 and 9', 10' of 11' are arranged, the width of the antenna body in both side directions, that is, the dimension in the x direction in Fig. 2, is narrower than that of the conventional one. This allows the antenna device to be placed extremely close to the wall of a steep building or placed in an extremely narrow trench to detect the object to be detected. Accordingly, the amount of expensive radio wave absorbers used in the bowl-shaped shielding cover can be reduced, thereby making the device compact and inexpensive.

Furthermore, according to this invention, since the conductor plate of the resistance short circuit is attached to the outer surface of the bowl-shaped shielding cover, the electromagnetic waves radiated from the conductor plate are blocked by the bowl-shaped shielding cover. Therefore, since there is no interference with the electromagnetic waves radiated from the antenna, for example, the electromagnetic waves radiated downward from the antenna are irradiated onto an object to be detected that is located directly below the antenna at a close distance. Even when electromagnetic waves reflected from the antenna reach the antenna in a very short period of time, the wave receiving operation is extremely stable.

[Brief explanation of drawings]

The drawings show an embodiment, and FIG. 1 is a plan view showing the shape of the antenna body, and FIG. 2 is a cutaway perspective view of the main part with a shielding cover applied. 1... Broadband antenna, 2... Bowl-shaped shielding cover, 3
...Antenna opening, 4...Radio wave absorber, 5...
Power supply line, 6, 7, 8, 6', 7', 8...resistor,
9, 10, 9', 10'...conductor plate, 11, 11'
...Resistance short circuit, 12, 13 ... Hole, x, y, z
...coordinate axis.

Claims (1)

[Claims for Utility Model Registration] An antenna body is formed by connecting a resistor short-circuit body in which a resistor and a conductor plate are alternately connected in series between both ends of a plate-shaped and fan-shaped dipole, and a fan of the antenna body. An antenna device for an ultra-short range radar in which a bowl-shaped shielding cover is applied to a dipole-shaped dipole, the shielding cover having a shape that covers the fan-shaped dipole and whose opposing sides are horizontally rectangular vertical surfaces; An antenna device comprising: a resistive short-circuit body in which the surface of each conductor plate is arranged along the outer surface of each of the vertical surfaces.