JP2017098885A - Coaxial arrester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coaxial arrester that suppresses momentary surge voltage on coaxial cable in wireless communication to low voltage instantaneously, and is easily made smaller in an overall configuration while securing insulation between an inner conductor and an outer conductor for supplying power supply voltage.SOLUTION: A coaxial arrester has three-branch-type coaxial connector structure in a coaxial cable system to supply low-voltage power supply voltage in a wireless device including an electronic circuit. A branch side coaxial line is a quarter-wavelength coaxial line with short-circuit structure at one side, and uses a transient voltage suppression diode 21 as an internal conductor 14 of the branch side coaxial line.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coaxial lightning arrester having a lightning protection function that protects a wireless device including an electronic circuit from a lightning surge in a coaxial cable system that performs power supply in a receiving system in wireless communication.

  For example, as for an antenna and a wireless device in wireless communication, conventionally, it is common to install an antenna in an upper part of a tower body and install a wireless device including an electronic circuit in a lower part of the tower body.

  However, because of the recent miniaturization of radio equipment and the increase in operating frequency, a preamplifier such as a low noise amplifier is installed immediately below the antenna, and a radio controller is installed at a location separated from the preamplifier. The power supply voltage is supplied from the wireless controller to the preamplifier through a coaxial cable that connects the preamplifier and the wireless controller.

  For this reason, the risk of lightning surges entering the coaxial cable is increased, and thus a lightning arrester for the coaxial cable is required. In this case, the power supply voltage supplied to the preamplifier is low and the allowable voltage of the preamplifier is also low. For this reason, a lightning arrester having characteristics that can cope with a low voltage is required.

  On the other hand, a 1/4 wavelength short-circuit type coaxial arrester is used as a arrester for coaxial cables. This coaxial lightning arrester adds a coaxial line having a length of ¼ wavelength with one end short-circuited, and since it is short-circuited in a direct current, it has a configuration capable of withstanding overcurrent caused by lightning surge. It is valid. However, since it has a structure in which the outer conductor and the inner conductor are short-circuited, it cannot be used when it is necessary to supply a power supply voltage with a coaxial cable.

  On the other hand, a coaxial lightning arrester having a coaxial connector structure in which a discharge gap type lightning protection element is incorporated has been proposed (for example, see Patent Document 1). This coaxial lightning arrester is insulative between the two conductors until the inner conductor and the outer conductor are in a discharged state, and can be used when it is necessary to supply a power supply voltage with a coaxial cable.

JP 2002-25745 A

  By the way, in the conventional coaxial arrester disclosed in Patent Document 1, since a discharge gap type lightning protection element is used, there is a time delay until the start of discharge in the discharge gap type lightning protection element as a voltage limiting characteristic. High voltage is reached. Therefore, it is difficult to suppress an instantaneous surge voltage for a wireless device including an electronic circuit that is driven by a low power supply voltage of about several volts.

  In the coaxial lightning arrester of Patent Document 1, the length of the 1/4 wavelength short-circuited coaxial line is set to 1/4 wavelength in order to suppress the influence on the main coaxial line in the 1/4 wavelength short-circuited coaxial line. In order to supply voltage, it is necessary to insulate between the inner conductor and the outer conductor of the coaxial cable. Therefore, in this coaxial lightning arrester, the outer conductor in the 1/4 wavelength short-circuited coaxial line has a three-layer insulation structure.

  This structure is an effective means for suppressing the influence on the main coaxial line in the 1/4 wavelength short-circuited coaxial line. However, in the manufacturing side of the coaxial arrester having the coaxial connector structure, high-precision processing and insulation are required. A complicated process for ensuring insulation, such as mounting of objects, is required. Therefore, it is difficult to reduce the cost in manufacturing the coaxial arrester. Moreover, since the structure which provides a discharge gap type lightning protection element in the outer side of a 1/4 wavelength short circuit coaxial line is employ | adopted, the whole structure of a coaxial lightning arrester will be complicated and will enlarge.

  Therefore, the present invention has been proposed in view of the above-described problems, and the object of the present invention is to quickly suppress an instantaneous surge voltage and to simplify an insulating structure for supplying a power supply voltage. Another object of the present invention is to provide a coaxial lightning arrester that can easily realize downsizing of the entire configuration.

  As a technical means for achieving the above-mentioned object, the present invention has a three-branch coaxial connector structure in a coaxial cable system for supplying a low power supply voltage in a wireless device including an electronic circuit. The side coaxial line is a quarter wavelength coaxial line having a short circuit at one end, and a transient voltage suppression diode is used as an internal conductor of the branch side coaxial line.

  In the coaxial lightning arrester of the present invention, since the transient voltage suppression diode is an inner conductor of the branch wavelength coaxial line having a quarter wavelength, the transient voltage suppression diode performs a voltage limiting function as a lightning protection element. An instantaneous surge voltage can be quickly suppressed for a wireless device including an electronic circuit driven by a power supply voltage.

  Further, since the above-described transient voltage suppression diode becomes an insulator as a coaxial cable system that supplies a low-voltage power supply voltage in a wireless device including an electronic circuit, the insulation structure can be simplified.

  Furthermore, by using a transient voltage suppression diode for the inner conductor of the 1/4 wavelength branch side coaxial line, the coaxial length of the branch side inner conductor can be reduced by the wavelength shortening effect of the resin jacket of the transient voltage suppression diode. Since it can be shortened, the overall configuration can be reduced in size.

  According to the present invention, the transient voltage suppression diode is used as the inner conductor of the quarter wavelength branching coaxial line, so that an instantaneous surge voltage is applied to a wireless device including an electronic circuit driven by a low-voltage power supply voltage. Can be quickly suppressed. In addition, it is possible to simplify the insulating structure for supplying a low power supply voltage in a wireless device including an electronic circuit. Further, the length of the branch side coaxial line can be shortened by the wavelength shortening effect by the resin sheath of the transient voltage suppression diode, and the overall configuration can be downsized.

  As a result, it is possible to provide a coaxial lightning arrester that is excellent in lightning resistance performance, has a simple insulating structure, and has a reduced overall size and simplification.

In embodiment of this invention, it is sectional drawing which shows schematic structure of a coaxial lightning arrester. It is a block diagram which shows the use condition of the coaxial lightning arrester of FIG. It is a characteristic view which shows the relationship between a branch side coaxial length and a passage center frequency. It is a characteristic view which shows the loss characteristic of a coaxial lightning arrester.

  An embodiment of a coaxial lightning arrester according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of the structure of the coaxial arrester in this embodiment, and FIG. 2 shows an example of use of the coaxial arrester of FIG.

  For example, in wireless communication, as shown in FIG. 2, a preamplifier 2 such as a low noise amplifier is installed immediately below the antenna 1, and a radio controller 3 is installed at a location separated from the preamplifier 2, A low power supply voltage is supplied from the wireless controller 3 to the preamplifier 2 via a coaxial cable 4 connecting the preamplifier 2 and the wireless controller 3. The coaxial lightning arrester 11 of the embodiment is inserted in the coaxial cable 4 between the preamplifier 2 and the radio controller 3. The preamplifier 2 and the radio controller 3 constitute a radio apparatus.

  The coaxial lightning arrester 11 of this embodiment has a three-branch coaxial connector structure as shown in FIG. 1 and supplies a low-voltage power source from the wireless controller 3 to the preamplifier 2 (see FIG. 2). Is transmitted to the wireless controller 3. The coaxial lightning arrester 11 includes a passage-side outer conductor 13 that coaxially accommodates a passage-side inner conductor 12 and a branch-side outer conductor 15 that coaxially accommodates a quarter-wave branch-side inner conductor 14. Yes. The passage-side inner conductor 12 and the passage-side outer conductor 13 constitute a passage-side coaxial line. The branch side inner conductor 14 and the branch side outer conductor 15 constitute a branch side coaxial line.

  The branch-side outer conductor 15 is integrally formed so as to extend in a direction perpendicular to the passage-side outer conductor 13 at the center of the passage-side outer conductor 13. One end of the branch-side inner conductor 14 is electrically and mechanically connected to the central portion of the passage-side inner conductor 12, and the other end is electrically connected to the short-circuit conductor 16 provided at the tip of the branch-side outer conductor 15. Connected mechanically and mechanically.

  Male thread portions 17 and 18 are formed on the outer peripheral surface of the end portion of the passing-side outer conductor 13. A preamplifier is formed by screwing a female screw part 19 formed on the inner peripheral surface of the end of the coaxial cable 4 extending from the preamplifier 2 (see FIG. 2) into a male screw part 17 at one end of the passing-side outer conductor 13. 2 are electrically connected. Further, the wireless controller 3 is electrically connected to the external threaded portion 18 formed on the inner peripheral surface of the end of the coaxial cable 4 extending from the wireless controller 3 (see FIG. 2) with the male threaded portion 18 at the other end. Connected.

  In addition, in this embodiment, although the external thread parts 17 and 18 are formed in the edge part of the passage side outer conductor 13, and the female thread parts 19 and 20 are formed in the edge part of the coaxial cable 4, the connection form is illustrated. Conversely, a connection form in which a female thread portion is formed at the end of the passing-side outer conductor 13 and a male thread portion is formed at the end of the coaxial cable 4 may be employed.

  In this embodiment, a transient voltage suppression diode 21 [TVS (Transient Voltage Suppressor) diode] that limits the surge voltage is used as the branch-side inner conductor 14. The transient voltage suppression diode 21 is a current limiting element having a non-linear current-voltage characteristic indicating a low resistance against a surge voltage and a high resistance against a normal power supply voltage. In addition, the transient voltage suppression diode 21 functions as a ¼ wavelength short-circuit conductor in terms of radio frequency.

  The outer diameter of the transient voltage suppression diode 21 used in this embodiment is 9 mmφ or less. On the other hand, since the outer diameter of the general branch side outer conductor 15 is about 10 mmφ, the transient voltage suppression diode 21 can be accommodated in the branch side outer conductor 15.

  This transient voltage suppression diode 21 is normally high resistance and insulated from the branch-side outer conductor 15. However, when an abnormal voltage is generated due to lightning surge or switching surge, it becomes low resistance and is instantly grounded. For example, a high voltage is not applied to the wireless device. When the abnormal voltage disappears, the resistance becomes high and the short circuit state with respect to the power supply voltage is interrupted. This valve action protects the wireless device from abnormal voltages caused by lightning surges and switching surges.

  Since the transient voltage suppression diode 21 constituting the branch side inner conductor 14 of the coaxial lightning arrester 11 has an impedance determined by the ratio between the outer diameter of the branch side outer conductor 15 and the outer diameter of the branch side inner conductor 14, In order to obtain an outer diameter corresponding to the impedance, a lead wire 22 having a thick outer diameter is used.

  In the coaxial lightning arrester 11 of this embodiment, the transient voltage suppression diode 21 that limits the surge voltage is the quarter-wave branch-side inner conductor 14, so that the transient voltage suppression diode 21 functions as a current limiting element. As a result, it is possible to quickly suppress an instantaneous surge voltage with respect to a wireless device that is driven with a power supply voltage as low as several volts. As a result, the wireless device can be reliably protected from the surge voltage.

  In addition, as the insulation structure for supplying the low-voltage power supply voltage to the wireless device, the transient voltage suppression diode 21 becomes a high insulation resistor at a normal voltage, so that the conventional three-layer insulation structure is unnecessary. The insulation structure can be simplified.

  Further, since the transient voltage suppression diode 21 is used for the quarter-wave branch-side inner conductor 14, the resin jacket portion of the transient voltage suppression diode 21 is between the branch-side inner conductor 14 and the branch-side outer conductor 15. Therefore, the transient voltage suppression diode 21 exhibits a wavelength shortening effect. Because of this wavelength shortening effect, the branch-side coaxial length can be shortened, so that the overall configuration of the coaxial arrester 11 can be reduced.

  FIG. 3 shows the relationship between the branch side coaxial length L (see FIG. 1) of the coaxial lightning arrester 11 and the passing center frequency in this embodiment. As shown in the figure, when the center frequency of passing is 1.5 GHz, if the wavelength is 1/4, it is 50 mm, whereas the branch side coaxial length L is 35 mm, and the coaxial length is 15 mm. Can be shortened. Here, the branch side coaxial length L means the dimension from the axis of the passage side inner conductor 12 to the end of the branch side outer conductor 15.

  FIG. 4 shows the loss characteristics of the coaxial lightning arrester 11. As shown in the figure, the pass frequency band of the coaxial lightning arrester 11 is in the range of 1.3 to 1.7 GHz, and the center frequency is 1.5 GHz. Thereby, the loss in the coaxial lightning arrester 11 can be made small. When the passing center frequency is away from the above range, the length of the branch side outer conductor 15 and the like may be adjusted to the frequency to be used.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

4 Coaxial cable 11 Coaxial lightning arrester 14 Inner conductor of branch side coaxial line 21 Transient voltage suppression diode

Claims (1)

  In a coaxial cable system that supplies a low-voltage power supply voltage in a wireless device including an electronic circuit, it has a three-branch coaxial connector structure, and the branch-side coaxial line is a quarter-wavelength coaxial line with one end short-circuited. A coaxial lightning arrester comprising a transient voltage suppression diode as an inner conductor of the branch side coaxial line.

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