JPS582051Y2 - Coaxial capacitor for high frequency and high voltage - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a coaxial capacitor for coupling an external conductor in a coaxial line.

Conventionally, this type of coaxial capacitor has been used, as shown in FIG. 1, in which a cylindrical hole for coaxial is provided in the center of a dielectric material.

That is, in FIG. 1, 1' is a dielectric, 2' is a counter electrode provided on the dielectric 1', and 3' is the electrode 2'.
This is a terminal for connecting the external conductor (not shown) of the coaxial line.

Therefore, when using this coaxial capacitor, the inner conductor of the coaxial line is passed through the hole penetrating the dielectric 1',
The outer conductor is coupled by the terminal 3'.

By the way, in order to guarantee the transmission characteristics in the high frequency band,
The diameter l' of the dielectric hole is usually determined based on the diameter of the internal conductor of the coaxial line in accordance with the characteristic impedance of the coaxial line.

However, in such a structure, if the thickness of the dielectric 1' is made thick for high voltage use, the electromagnetic energy 1 trapped in the coaxial line will be dissipated using the dielectric as a window, resulting in poor transmission in the high frequency band. There was a drawback that the characteristics deteriorated.

The present invention was proposed in order to improve the above-mentioned drawbacks, and the terminal has a structure in which the outer conductor of the coaxial line reaches deep into the hole penetrating the dielectric so as to confine the electromagnetic energy within the coaxial line. By providing this, the purpose is to improve the transmission characteristics of the coaxial condenser in the high frequency band.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which 1 is a dielectric having a circular hole in the center, 2 a and 2 b are counter electrodes provided on both sides of the dielectric 1, and 4 and 5 are terminals connected to the counter electrode 1, which form the outer conductor of the coaxial line.

This terminal 4 is located outside the dielectric 1 and is coupled to an external conductor, and its tip end is connected to a tube 4a of good conductor inserted deep into a circular hole bored in the center of the dielectric 1 and a counter electrode 2a.
and a disk-shaped portion 4b connected to the disk-shaped portion 4b.

Therefore, the terminal 4 is equipped with such a tube 4a of good conductor.
This shields the window in the dielectric thickness direction, allowing electromagnetic waves to be transmitted without leakage loss.

The inner diameter of the good conductor tube 4a is determined from the inner conductor diameter so as to match the characteristic impedance of the coaxial line, and the good conductor tube 4a inserted into the circular hole of the dielectric 1
The optimal insertion length of a is the same as the thickness of the dielectric 1, but even if it is less than that, it is effective in improving the transmission characteristics.

The diameter 12 of the circular hole in the dielectric 1 is determined so that there is a distance between the opposing electrodes 2a, 2b connected to the dielectric 1 and the tube 4a of a good conductor of the terminal 4 so that dielectric breakdown does not occur. It is not determined from the characteristic impedance of the coaxial line.

Since 5 is a terminal opposite to the terminal 4, it has a tapered portion 5a so as to be insulated from the tube 4a of good conductor inserted deep into the circular hole of the dielectric 1.

It is better for the length of the tapered portion 5a to be short in terms of transmission characteristics, but
It is necessary to take a distance between the terminal 4 and the terminal 4 in consideration of dielectric breakdown.

In order to improve the withstand voltage, it is also effective to fill the space 6 defined by the inner peripheral surface of the circular hole of the dielectric 1, the tube 4a of good conductor, and the tapered portion 5a with a high withstand voltage resin, such as silicone resin. It is also possible to shorten the length of the tapered portion 5a by filling with resin.

Figure 3 shows the frequency characteristics of the mismatched attenuation of a capacitor, where curve A represents the mismatched attenuation of a conventional coaxial capacitor having the structure shown in Figure 1, and curve B represents the mismatched attenuation of the conventional coaxial capacitor with the structure shown in Figure 1. 2 shows the amount of mismatch attenuation of a capacitor having a structure in which the outer conductor of a coaxial line is introduced into a circular hole penetrating a dielectric 1.

As is clear from the figure, the amount of mismatch attenuation in the high frequency band of the capacitor of the present invention shown by curve B is small, demonstrating the effectiveness of the present invention.

As explained above, the capacitor according to the present invention has the effect of having excellent high frequency transmission characteristics without leakage loss of electromagnetic waves even when the dielectric material is made thick for high voltage use.

Therefore, a capacitor having the structure of the present invention is particularly suitable for a high-voltage capacitor used in a filter circuit that separates a high-voltage direct current and a minute high-frequency signal current, such as a PSF circuit in a coaxial transmission system.

[Brief explanation of the drawing]

Figure 1 is a side cross-sectional view of the main parts showing the structure of a conventional high-voltage coaxial capacitor, Figure 2 is a side cross-sectional view of the main parts of an embodiment of the present invention, and Figure 3 is a cross-sectional view of the main parts of the conventional product and the present invention. This shows the frequency dependence of the mismatch attenuation of a capacitor. 1... Dielectric ceramic, 2a, 2b... Counter electrode, 3... Terminal, 4, 4 a, 4 b.
...Terminal, 5...Terminal, 5a...
...Taper part, 6...Space, 7...
Filled resin.

Claims (2)

[Scope of utility model registration request] (1) In a parallel plate coaxial capacitor for coupling an external conductor of a coaxial line, opposing electrodes 2a and 2b are provided on both sides of a dielectric 1 having a circular hole in the center, and one of the opposing electrodes 2a is The tip is connected to a terminal 4 having a tube 4a inserted into a circular hole provided in the dielectric 1,
The other opposing electrode 2b is connected to a terminal 5 having a tapered portion 5a whose inner diameter gradually increases from the cylindrical portion toward the opposing electrode 2b of the dielectric 1 to prevent leakage loss of electromagnetic waves. A coaxial capacitor for high frequency and high voltage use. (2) High-frequency high-voltage according to claim 1, in which a resin 7 is filled in a space 6 defined by the inner circumferential surface of a circular hole in the dielectric 1, the tube 4a of good conductor, and the tapered portion 5a. coaxial capacitor.