JPS5970003A - Antenna cover for ultra-short distance lader - Google Patents

Abstract

PURPOSE:To reduce the weight of the titled antenna cover and to prevent the antenna cover from giving radio faults to the external and receiving influences from the external by forming spaces on the 1st and 2nd layer trough like coating bodies respectively and connecting the spaces with resistors. CONSTITUTION:Plural metallic semi-circular cylinders 2 with semi-circular sections are arranged so as to cover a dipole antenna 1. These semicircular cylinders 2 are arranged to form a space 3, the space 3 is charged with a resistor to connect these cylinders 2 and these semi-circular cylinders are united to constitute the 1st layer trough-like coating body 2. Subsequently, the external surface of the coating body 2 is covered with the 2nd layer trough-like coating body 4 consisting of semi-circular cylinders 4 having a redius slightly larger than that of the coating body 2, a side plate 4' and a space 5 and having the same structure as the coating body 2. These coating bodies 2, 4 are arranged so that the positions of these spaces 3, 5 do not coincide with each other. In order to absorb radio waves effectively and shield the antenna moreover, the periphery of hese coating bodies 2, 4 are covered with the 3rd layer trough-like coating body 6 provided with plural spaces 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cover for absorbing and shielding harmful radio waves in an ultra-short range radar antenna.

The present applicant previously proposed an ultra-short-range radar antenna in which the wideband antenna other than the front opening was covered with a bowl-shaped shielding member having a layer of radio wave absorber on the inner surface (Utility Application No. 54-47619). However, at present, this is less effective if the radio wave absorber layer is made thinner, so a considerably thicker absorber layer is required.
For this reason, the weight is heavy, and portable antennas that move on the surface of the earth like underground object detectors have the disadvantage of being difficult to carry.

The present invention is intended to eliminate these drawbacks and will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view (partially omitted) of an embodiment of the present invention.
1 is a dipole antenna, 2 is a plurality of semicircular metal cylinders with semicircular cross sections arranged to cover this antenna,
This can be done by arranging them with gaps 3 as shown in Figure 2, and filling these gaps with an electrically resistive material such as ceramic or resin.
Alternatively, a plurality of fixed resistors are connected between 2 and 2, and these are integrated to form the first layer trough-like cover 2. Note that 2′
is the side plate of this end.

Next, 4 is a semi-cylindrical cylinder 4 having a slightly larger radius than 2 above.
．． This is a second layer gutter-like cover having the same structure as 7 above, which includes a side plate 4' and a gap 5.

As shown in FIG. 1, this second layer trough-like cover 2 covers the outer surface of the first layer trough-like cover 2, but in this case, it is arranged so that the positions of these gaps 3 and 5 do not match. 2 and 4 are fixed at a predetermined distance by a suitable means (not shown) such as providing an intervening member.

Note that the lengths of the metal semi-cylinders 2 and 4 in the first and second layers are all the same, but in the second layer, because the gaps are not made to match as described above, only the length of the semi-cylinders at both ends is 1/2. becomes.

In normal cases, such a combination of the first layer and the second layer gutter-like cover 2, 4 is sufficient, but in order to achieve even better radio wave absorption and shielding, the outer periphery of these layers should be covered with a third layer. Cover with a gutter-like cover. As shown in Fig. 3, this stand has a plurality of gaps 7 in the length direction of the peripheral end of a semi-cylindrical cylinder, and 6'
is the side plate.

In the present invention having the above configuration, the first and second
Since the gaps between the layered trough-like coverings are connected by resistors, the current induced here is limited, and the third layer trough-like cover is connected to two to three layers by the gaps in the length direction. Since the antenna cover is covered, harmful reflected radio waves are not generated by the antenna cover, and radio waves from the antenna that pass through the cover do not cause radio interference to the outside. Since it is not affected by radio waves from the outside, nearby buildings, telephone poles, workers, etc., it is extremely easy to use it for underground object detectors and measure echoes from objects to be detected.

Furthermore, the weight is significantly reduced compared to those provided with a layer of radio wave absorber such as ferrite or semiconductor, making it ideal for this type of portable antenna.

[Brief explanation of drawings]

The figure is a perspective view of one embodiment of the present invention, FIG. 1 is a partially omitted view showing the overall configuration, and FIGS.
FIG. 3 is a partial view of the layers and the third layer trough-like covering. 1... dipole antenna, 2, 4... metal semi-cylinder,
3.5.7... Gap, 2. i, Dan... 1st. Second and third layer trough coverings.

Claims (1)

[Scope of Claims] 1. On the outer periphery of a first layer gutter-like cover, which is formed by arranging a plurality of metal semi-cylinders with gaps so as to cover the dipole antenna, and connecting and integrating a resistor to the gaps. , an antenna cover for an ultra-short-range radar in which a second layer gutter-shaped receptacle having a similar structure with a larger radius is provided so that the gaps between the two do not match. 2. A superstructure in which the outer periphery of the antenna cover according to claim 1 is further covered with a third layer gutter-like cover in which a plurality of gaps are provided in the length direction of the peripheral end of the semi-cylindrical shape. Antenna cover for short-range radar.