JPH06188604A - Coaxial rotation coupler - Google Patents

Abstract

PURPOSE:To provide a small sized coaxial rotation coupler whose structure is simple and whose characteristic is stable. CONSTITUTION:A 1st outer circumferential conductor 22 and a 2nd outer circumferential conductor 24 are overlapped by the 1/4 wavelength around a center conductor 21 to make the 1st outer circumferential conductor 22 and the 2nd outer circumferential conductor 24 conductive in terms of high frequencies and the 1st outer circumferential conductor and the 2nd outer circumferential conductor are physically separated, then the coupler is able to be used even under the circumstance attended with the rotation motion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial type rotary coupler which satisfies physical separation and high frequency conduction.

[0002]

2. Description of the Related Art Generally, a coaxial line is used for transmitting a high frequency signal. However, this coaxial line could not be used because of the problem of stiffness under the conditions of use involving rotational movement.

Therefore, when the high-frequency signal is transmitted under a condition involving a rotary motion, it is necessary to make the rotary motion compatible with the high-frequency transmission, so that the transmission line is physically separated. And it must be conducting at high frequency.

As a transmission line which satisfies this condition, a transformer type rotary coupler has been conventionally used as shown in FIG. FIG. 7 (A) is a sectional view taken along the center conductor of the transformer type rotary coupler, and FIG. 7 (B) is a view showing a spiral pattern arranged on a printed circuit board.

In FIG. 7A, a shield case 11 is provided.
Printed boards 12a and 12b are provided inside the printed circuit board, and microstrip lines 13 having a spiral pattern as shown in FIG. 7B are provided on the surfaces of the printed boards 12a and 12b facing each other. ing. Then, the coaxial lines 1 are respectively provided on the microstrip lines 13 arranged on the printed boards 12a and 12b.
Central conductors 15a and 15b of 4a and 14b are connected.

According to the above configuration, the coaxial lines 14a and 14
It is physically separated from b, and the microstrip line 13 having a spiral pattern functions as a transformer, so that the coaxial lines 14a and 14b are electrically connected at high frequency.

[0007]

However, since the conventional transformer type rotary coupler uses the shield case 11 and the printed boards 12a and 12b, the structure is complicated and the size of the coupler is large. There was a problem that

Further, it is necessary to adjust the distance between the printed board 12a and the printed board 12b and the central axes of the central conductors 15a and 15b, which is troublesome to adjust. If the central axes of the central conductors 15a and 15b are not properly adjusted, the coaxial line 14a or 1
When 4b rotates, the microstrip line 13
There is a problem that the characteristics of the transmission signal fluctuate because the high-frequency coupling state fluctuates. The present invention has been made in view of the above points, and an object thereof is to provide a coaxial type rotary coupler having a simple structure, a small size, and stable characteristics.

[0009]

SUMMARY OF THE INVENTION A coaxial rotary coupler according to the present invention comprises a center conductor, a first outer peripheral conductor centered on the center conductor and having an open end, and an end centered on the center conductor. Part is opened in the opposite direction to the first outer conductor,
Of the outer conductor has a larger inner diameter than the outer periphery of the outer conductor and has a second outer conductor which overlaps with the first outer conductor in a quarter wavelength section. The center conductor on the second outer conductor side is a probe. It has a structure, and the second outer conductor is rotatable about the central axis.

[0010]

Since the first outer conductor and the second outer conductor are overlapped with each other by ¼ wavelength, the first outer conductor and the second outer conductor are electrically connected to each other at a high frequency, and moreover, the first outer conductor and the second outer conductor are electrically connected to each other. Since the outer peripheral conductor and the second outer conductor are physically separated from each other, they can be used even in a situation involving a rotational movement.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A coaxial rotary coupler according to an embodiment of the present invention will be described below with reference to the drawings. 1 is a perspective view of a coaxial rotary coupler 20, FIG. 2A is a principle diagram of an open-ended line, FIG. 2B is a diagram showing the relationship between Zo and L, and FIG. 3 is a high frequency wave of this coupler. It is sectional drawing which shows the flow of a signal.

In FIG. 1, reference numeral 21 is a central conductor. A first outer peripheral conductor is provided with the center conductor 21 as the center, and a Teflon 23 is filled between the center conductor 21 and the first outer conductor 22. This first outer conductor 22 and L =
The second outer peripheral conductor 24 is provided so as to overlap by λ / 4, and the open end of the second outer peripheral conductor 24 has the first outer peripheral conductor 22.
The open ends of the two are facing away from each other. The inner circumference of the second outer conductor 24 is set to be slightly larger than the outer circumference of the first outer conductor 22 described above. Further, the Teflon 23 is formed in a columnar shape with a diameter substantially the same as the inner circumference of the first outer peripheral conductor 22 in the section where the first outer peripheral conductor 22 and the second outer peripheral conductor 23 exist.

In the region where the first outer conductor 22 and the second outer conductor 24 overlap, the end of the first outer conductor 22 is opened and the end of the second outer conductor 24 is opened. There is. Incidentally, λ is the wavelength of the high frequency signal to be transmitted.

By configuring the coaxial rotary coupler 20 as described above, the first outer conductor 22 and the second outer conductor 2 are formed.
4 and 4 can be physically separated and can be conducted at high frequency.

First, the reason for high frequency conduction will be described. Here, the principle of the open-ended line will be described. FIG. 2A is an explanatory diagram for explaining the principle. Each parameter in the figure represents Zin ... input impedance Zo ... characteristic impedance L ... line length. Then, a relational expression of Zin = -jZo cotβL ... (1) is established between these parameters. Figure 2 is a graphical representation of equation (1).
As shown in (B).

Since the gap between the two outer conductors 22 and 24 is an open termination line, the equation (1) can be applied. Assuming that the characteristic impedance of the gap between the outer peripheral conductors 22 and 24 is Zo = constant and the line length is l = λ / 4, Zin = 0 from FIG. 2 (B).
Becomes This means that the inside of the gap is short-circuited at high frequencies. Therefore, the leaky wave becomes zero. In this way, the two outer peripheral conductors 22 and 24 can be conducted at high frequencies.

Next, referring to FIG. 3, the coaxial type rotary coupler 2 will be described.
The flow of high frequency in 0 will be described. The high frequency input to the coupler 20 is divided into a leaky wave, a reflected wave, and an output wave. In FIG. 3, the center conductor 21 is connected to the high frequency conduction path of the printed board 31. Since the gap between the two outer conductors 22 and 23 is an open termination line, the formula (1) can be applied. If the characteristic impedance of the gap between the outer peripheral conductors 22 and 23 is Zo = constant and the line length L = λ / 4, then FIG.
From (B), Zin = 0. This means that the inside of the gap is short-circuited at high frequencies. Therefore, the leaky wave becomes zero.

Here, the leakage wave becomes zero due to the principle of the open termination line described above regarding the leakage wave. Regarding the reflected wave, by reducing the difference in diameter between the two outer conductors 22 and 24, the difference in characteristic impedance due to the difference in diameter is reduced, and good return loss is obtained. By doing so, the reflected wave at the coupler 20 becomes substantially zero. In this way, the high frequency wave input to the coupler 20 is divided into a leak wave, a reflected wave, and an output wave, but the leak wave and the reflected wave are reduced to reduce the passage loss.

As described above, the coaxial rotary coupler 20 is composed of two peripheral conductors which are physically separated from each other and which are electrically connected at high frequency, so that the radial waveguide helical planar antenna (FIG. 4), Even when the waveguide slot antenna (FIG. 5) and the waveguide-fed microstrip antenna (FIG. 6) are used in a situation involving rotational movement, it is possible to prevent the coaxial line from being jammed.

In FIG. 4, 41 is a helical element, 42 is a radial waveguide, and 51 in FIG.
Is a slot, 52 is a waveguide, and in FIG.
Is an antenna cover, and 62 is a microstrip pattern.
Reference numeral 63 indicates a waveguide.

[0021]

As described in detail above, according to the present invention, it is possible to provide a coaxial rotary coupler having a simple structure, a small size, and stable characteristics.

[Brief description of drawings]

FIG. 1 is a perspective view of a coaxial rotary coupler according to an embodiment of the present invention.

2A and 2B are diagrams for explaining characteristics of an open-ended line, FIG. 2A is a principle diagram of the open-ended line, and FIG. 2B is a diagram showing a relationship between Zo and L.

FIG. 3 is a cross-sectional view showing the flow of a high frequency signal in the present coupler.

FIG. 4 is a sectional view of a radial waveguide helical planar antenna incorporating the present coupler.

FIG. 5 is a sectional view of a waveguide slot antenna incorporating the present coupler.

FIG. 6 is a cross-sectional view of a waveguide-fed microstrip antenna incorporating the present coupler.

FIG. 7 shows a conventional transformer type rotary coupler, FIG. 7 (A) is a cross-sectional view taken along the center conductor of the transformer type rotary coupler, and FIG. 7 (B) is arranged on a printed circuit board. The figure which shows a spiral pattern.

[Explanation of symbols]

21 ... Central conductor, 22 ... 1st outer peripheral conductor, 23 ... Teflon, 24 ... 2nd outer peripheral conductor.

Claims (1)

[Claims] 1. A central conductor, a first outer peripheral conductor centered on this central conductor and having an end open, and an end centered on the central conductor and open in an opposite direction to the first outer conductor, The first outer conductor has an inner diameter larger than that of the outer circumference, and further includes a second outer conductor that overlaps the first outer conductor in a quarter wavelength section, and the center conductor on the second outer conductor side is a professional conductor. A coaxial rotary coupler, which has a tubular structure and in which the second outer conductor is rotatable about the central axis.