JPH0354418Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a helical antenna for space use in which a conductor is spirally wound around a support.

[Conventional technology]

FIG. 4 is a cross-sectional view showing a conventional antenna.
In the figure, 1 is a cylindrical support made of an insulating material such as glass epoxy, and 2 is a wire or foil conductor that is tightly wound around the outer surface of the support 1 in a spiral shape.

The conventional antenna is constructed as described above, and when one end of the conductor 2 is excited with a high frequency, a traveling wave proceeds in a spiral shape, and a circularly polarized radio wave is radiated from the other end of the conductor 2.

[Problem that the invention attempts to solve]

In the conventional antenna described above, the support 1, which is an insulator, is exposed to space, so it cannot be charged to a high potential (several + kV) due to the radiation trapping zone around the earth or the injection of electrons from the solar wind. Are known.

When charging occurs and reaches several + kV, a creeping arc discharge occurs on the outer surface of the support 1 and a large current (several 100 A,
A pulse width of several 100 ns) momentarily flows toward the conductor 2. At this time, electromagnetic interference occurs over a wide frequency band from several KHz to several GHz and is input to the receiver via the conductor 2, which may cause damage to the preamplifier or malfunction. As an example of a foreign satellite, there are reports of receivers being destroyed in orbit due to this type of electrostatic discharge.

To prevent such electrostatic discharge, in the case of thermal control materials, conductive coatings are applied to the surface of the material to allow the electrical charge to leak to the satellite ground. However, in the case of a spiral antenna, if a conductive coating is applied to the surface of the support 1, the conductors 2 will be short-circuited and the antenna will lose its function. It has been installed on satellites without any.

The reason for this was that it was thought that conductor 2 could leak the surface charge to the satellite structure, so it would not be a big problem, but it was impossible to leak the entire surface charge with conductor 2. is self-evident, and the current situation is that great expectations must be placed on noise removal filters in receivers and the like. By the way, the strength of the radio waves caused by the above electrostatic discharge is 14KHz.
It is extremely large, reaching 180dBμV/m (1000V/m) at ~10MHz, and affects other electronic devices, and even if it does not easily destroy the receiver, it adds stress and degrades performance after a long time. There was a problem.

This invention was made in order to solve this problem, and the purpose is to obtain an antenna that is not charged by ensuring that the charges accumulated in the support are leaked.

[Means for solving problems]

In the antenna according to this invention, a conductive film is formed on the inner surface of a support, and this conductive coating film can be bonded with a flange.

[Effect]

In this invention, the conductive film collects charges and leaks them to the ground, thereby suppressing charging.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of this invention, and numerals 1 and 2 are exactly the same as the above-mentioned conventional antenna. Reference numeral 3 denotes a conductive film formed in close contact with the inner surface of the support 1 and the surface of the flange 4, and is formed by coating a metal oxide such as ITO. 4 is a flange attached to the end face of the support 1.

In the antenna configured as described above, when space radiation is injected into the outer surface of the support 1, the amount of electrons is one order of magnitude larger than the amount of protons, so that the support 1 becomes negatively charged. At this time, as shown in FIG. 3, if there is no conductive film 3, no leakage current flows, so surface charges are accumulated and discharged, and the surface potential changes in a sawtooth pattern. On the other hand, when there is a conductive film 3, leakage current can be ensured by connecting the flange 4 to the ground of the satellite, as shown in Figure 2.
The surface potential saturates immediately and stabilizes without discharge.

Further, since the conductive film 3 is formed inside the support 1, the conductor 2 will not be short-circuited, so that the function of the antenna will not be adversely affected.

Therefore, charging and discharging of the antenna in space can be prevented.

By the way, in the above explanation, the conductor was explained as a linear one, but it is also possible to use a foil-shaped conductor.
It goes without saying that the conductive film can produce similar effects not only by coating, but also by applying conductive paint, adhering metal foil, etc.

[Effect of idea]

As explained above, this device has a simple structure in which a conductive film is attached to the inside of the support, which prevents electrostatic discharge due to space charge without increasing weight, and is effective in preventing stress and malfunction of satellite electronic equipment. There is.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention, Figure 2 is a charging characteristic diagram with a conductive film, Figure 3 is a charging characteristic diagram without a conductive film, and Figure 4 is a cross section of a conventional antenna. It is a diagram. In the figure, 1 is a support, 2 is a conductor, 3 is a conductive film, and 4 is a flange. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A support made of a cylindrical insulator; a wire or foil conductor attached in a spiral shape in close contact with the outer surface of the support; a flange attached to one end of the support; An antenna comprising: a conductive film provided in close contact with the inner surface of the support and the surface of the flange.