JP2002025717A - Coaxial power injecting and extracting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate limitations of parts selection and current-carrying capacity, due to frequency rise and self resonant frequency of an inductor in an antenna facility or the like for mobile radio communication, adopting a power superimposing method using internal and external conductors of a coaxial cable performing radio signal transmission for power supply to a radio apparatus installed in a top part of a construction, such as a steel tower and a method using serial inductance and a bypass capacitor for power injection and extraction circuits. SOLUTION: A power-superimposing function to main coaxial lines is realized by connecting a center contact 612 of a power terminal 607 with the outer wall of a shorting plate 611 of an inner side coaxial line, forming a quarter- wavelength shorting coaxial circuit for triple coaxial lines 603 and 604 which are divergently provided in the main coaxial lines 601 and 602, and is realized not by a method of blocking an outflow of a high frequency signal to a power terminal side using a lumped inductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving or relaying device provided at the top of a steel tower or the like by utilizing an inner conductor and an outer conductor of a coaxial feed line used in various radio communication fields such as mobile radio communication. The present invention relates to a coaxial power injection / extraction device used when supplying or extracting power to an electronic device.

[0002]

2. Description of the Related Art A conventional power injection circuit using a series inductance and a bypass capacitor built into a receiving device such as a mobile radio communication or fixed radio communication relay base station or a relay transmission / reception device or a device / component. The power is supplied to the feed line by the power supply.

The principle circuit configuration will be described with reference to FIG. This figure shows that the internal conductor 1 of the coaxial line constituted by the internal conductor 1 and the external conductor 2 surrounding the internal conductor 1 and the center contact 61 of the power injection / extraction terminal 6 are connected via an inductor (inductance element). To the power supply side, and power supply or power supply extraction while preventing an increase in the voltage standing wave ratio VSWR and loss of the coaxial line. A bypass capacitor 4 is connected between the power supply terminal side of the inductor and the power injection / extraction terminal outer conductor to prevent the leakage of the high-frequency signal component to the power supply terminal 6 side. Is).

[0004]

The main problems of the injection / extraction circuit for power supply superimposition are the self-resonance frequency of the series inductance and the distribution of static electricity between the metal shields surrounding the coil as the transmission frequency of the coaxial feed line increases. The frequency of use is limited by the capacity, and in the case of using a chip inductor, the current capacity of the element wire or the ferrite element is limited. In particular, the small zone system has become mainstream due to the reform of mobile radio communication systems. For this reason, a receiving device or a relay device is often installed on the top of a tower or a building, and the number of installed devices is also increasing. For this reason, there is a growing demand for an increase in the supply current capacity in the power supply superimposition method, and the development of a coaxial component capable of coping with this is desired.

[0005] Table 1 summarizes the results of investigations on the inductance value, self-resonance frequency, and DC current capacity of available inductors (coil inductors and chip inductors) including overseas products.

[0006]

[Table 1]

[0007] An inductor used in the 900 MHz band of the current mobile communication is about 100 nH, and an inductor used in the 2 GHz band, which is expected to start service soon, is about 47 nH. . As shown in Table 1, the DC current capacity is 1 A or less, and those exceeding 1 A have a self-resonant frequency of 700 MHz.
z or less.

[0008]

The solution proposed in the present invention is not a method of using a inductor to prevent a high-frequency signal from flowing out to the power supply terminal side.
1, 602, the inner coaxial lines 603, 604 of the triple coaxial line formed by 603, 604, 605 divergently provided.
(To form a 1/4 wavelength short circuit coaxial circuit) short plate 611
By connecting the center wall 612 of the power supply terminal 607 to the outer wall of the power supply terminal 607, a function of superimposing the power supply on the main coaxial line is realized. According to the present invention, the T-shaped branch point 60 of the inner conductor 601 is provided.
The input impedance when looking at the power supply terminal side from 8 is 603
And 604, which are extremely large due to the high impedance characteristic inherent in the 1/4 wavelength short-circuited coaxial line, so that the outflow of the high-frequency signal to the power supply terminal side can be completely prevented. In this case, the outer conductor 604 of the short-circuited coaxial line and the outer conductor 605 surrounding the outer conductor 604 are insulated and separated.
The input impedance as viewed from the power supply terminal side between the input end 609 of the four-wavelength short-circuited coaxial line and the branch point 610 of the outer conductor of the main coaxial line is constituted by the low impedance characteristic peculiar to the quarter-wavelength open line, and 604 and 605. By designing the characteristic impedance of the coaxial line to be several ohms or less, the input impedance is further reduced, and a state where 609 and 610 can be regarded as being short-circuited at high frequencies is established. In this way, the power supply can be superimposed by isolating the quarter-wave short-circuit coaxial circuit in a DC manner.
According to the present invention, unlike the general-purpose system of FIG. 2 in which a lumped inductance element (inductor) is connected to the inner conductor of the main coaxial line, a distributed constant line is used, so that there is no restriction on the frequency rise in principle (the cutoff frequency of the coaxial line). Excluding restrictions). Although the leakage of high-frequency components to the power supply side is small in principle, the bypass capacitor 606 is inserted for the purpose of blocking signal components outside the operating frequency band, and a capacitor component is added by a through-type capacitor or internal component design.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partially cutaway side view showing an example of the structure of a coaxial power injection / extraction converter according to one embodiment of the present invention. This converter has a flange structure at both ends, and an insulator (insulator). The inner conductor of the main coaxial line and the inner conductor 400 of the 1/4 wavelength short-circuited coaxial circuit are directly connected to substantially the center of the inner conductor 101 held by the support plate 102. External conductor 4 of 1/4 wavelength short circuit coaxial circuit
03 and the outer conductor 504 surrounding it form a 1/4 wavelength open line by high-frequency coupling with the outer conductor 403 of the 1/4 wavelength terminated short-circuit coaxial line. Therefore, the impedance between the outer conductor branch portion 104 of the main coaxial line and the distal end of the outer conductor 403 exhibits an operation equivalent to a short-circuited state at high frequencies due to the low impedance characteristic peculiar to the 1/4 wavelength open line. Therefore, the quarter-wavelength short-circuited coaxial circuit exhibits the same high impedance characteristics as a normal quarter-wavelength short-circuited coaxial line in terms of high frequency even though it is insulated from the main coaxial line in DC. A power terminal internal contact 502 is connected to an outer wall 406 of the outer conductor 403 by a through capacitor 503. Insulators 404 and 405 serve to properly hold outer conductors 403 and 504 coaxially.

<Other Embodiments> The present invention is not limited to the above embodiments, but includes various other embodiments. That is, in the above embodiment, the inner conductor 400 and the inner outer conductor 403 of the short-circuited coaxial line are
Although the short-circuit coaxial circuit is formed by independent components, the length of the 1/4 wavelength short-circuit coaxial line becomes shorter as the operating frequency increases. Therefore, the insulating plate 401 is omitted and the 400 and 403 are integrated. It may be an integrated processing structure.

Further, in the above embodiment, the short-circuited coaxial line and the open line have an air insulation structure. However, solid insulation using polyethylene, polystyrene, polyfluoroethylene, ceramics or the like having a small dielectric loss, or a composite including an air layer is provided. An insulating structure may be used. According to these structures, there is an advantage that the physical length of the short-circuited coaxial line is shortened.

Further, in the above embodiment, the short-circuit coaxial line and the open coaxial line have a rigid structure. -An extractor may be manufactured. In particular, the former semi-rigid coaxial cable is an effective means for producing a small and simple power injection / extractor. In the case of the latter flexible coaxial cable, it can be a practical structure for producing a power injection / extractor for a relatively low operating frequency. Further, the cross-sectional shape of the coaxial line is not limited to a circular shape, but is also applicable to a rectangular coaxial line.

[0013]

[Calculation Example 1 of VSWR Characteristics] In order to explain the principle effectiveness of the present invention, the characteristic impedance of the main coaxial line is set to 50.
Table 1 shows the calculation results in the 810 to 970 MHz band when Ω, the characteristic impedance of the short-circuited coaxial line is 72Ω, and the characteristic impedance of the triple coaxial line is 6 ohms.

[0014]

[Table 2]

[0015]

[Calculation Example 2 of VSWR Characteristics] Table 3 shows the calculation results under the same conditions as in Calculation Example 1 above, with the operating frequency band being 1.9 to 2.1 GHz.

[0016]

[Table 3]

[0017]

As described above, according to the power injection / extraction device according to the first aspect of the present invention, the power injection / extraction point is the outer surface of the 1/4 wavelength short-circuit coaxial line having no high-frequency potential. Therefore, there are few restrictions on the design of the power supply terminal, and there are no many restrictions such as a self-resonant frequency and a current capacity in selecting an inductor, and the present invention can be applied to a frequency of 2 GHz band or more expected in the future. In addition, the voltage standing wave ratio VSWR and the insertion loss with respect to the high-frequency signal can have the same low VSWR and low-loss high-frequency characteristics as those of the 1/4 wavelength short-circuit arrester.

[0018]

[Brief description of the drawings]

FIG. 1 is a half sectional view showing an example of a coaxial power injection / extraction device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of a conventional power injection method.

FIG. 3 is a diagram illustrating the principle of a power injection / extraction system according to the present invention.

FIG. 4 shows a one-end flange, one-end N according to an embodiment of the present invention.
It is an external view which shows an example of a mold plug type.

FIG. 5 is a half sectional view showing an example of an L-type coaxial power injection / extraction device according to an embodiment of the present invention.

[Explanation of symbols]

 301 Connection hardware 302 Round flange 303 Body 304 Gasket 401 Insulator 407 Nut 500 Body 501 Insulator 505 Gasket

Claims (1)

[Claims] 1. An outer surface of an outer conductor end of an inner coaxial line which forms a short-circuited coaxial line having an odd-numbered electrical length of a quarter wavelength of a triaxial line provided in the middle of a main coaxial line and a triaxial line. A coaxial power injection / extraction device for supplying power between an inner conductor and an outer conductor of a main coaxial line by using a connector for connecting an inner conductor of a power injection / extraction coaxial connector provided on an outer conductor forming the above.