JPH01195729A - Method for relaying broadcast wave in tunnel or the like - Google Patents

Abstract

PURPOSE:To reduce facility expenses and a cost by sharing a transmission path combining a leakage coaxial cable with a fly-back line in the relay of both broadcast waves. CONSTITUTION:When an ultrashort broadcast wave f1 received at an ultrashort wave reception antenna Ant1 is added on the leakage coaxial cable LCX as an input current I1, an output wave I3 being reduced by the transmission loss of the cable LCX flows on the termination side of the cable LCX, and the electromagnetic wave of the ultrashort broadcast wave f1 is radiated in the periphery of the leakage coaxial cable LCX. Also, a medium broadcast wave f2 received at a medium wave reception antenna Ant2 is added on the outer conductor 1 of the leakage coaxial cable LCX and the transmission path consisting of the fly-back line GW as an input current I2, an output current I4 reduced by the transmission loss of the transmission path flows on the termination side of the transmission path, and the inductive magnetic field of the medium broadcast wave f2 is generated in the periphery of the leakage coaxial cable LCX and the fly-back line GW. Thus, by sharing the outer conductor 1 of the leakage coaxial cable LCX with the transmission path of the medium broadcast wave, it is possible to reduce the facility expenses and the cost.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention increases the electric field strength of medium wave and very high frequency broadcast waves in places where the electric field strength is significantly reduced, such as inside a tunnel, and allows the broadcast waves to pass through the tunnel. The present invention relates to a broadcast wave relay method that allows a train, a car, or the like (hereinafter referred to as a mobile object) to easily receive the broadcast waves.

(Prior Art) Conventionally, as a method of relaying broadcast waves in Chendao, as shown in Fig. 4, a leaky coaxial cable LCXI for very short waves is used to relay the very short waves r1, and a medium wave broadcast wave f? A medium wave leaky coaxial cable LCX2 was used separately for each relay.

(Problems with the conventional technology) In the conventional relay method, the leaky coaxial cables for very high frequency broadcast waves and medium wave broadcast waves were installed separately, with a distance between them, which resulted in the problem of increased construction costs. there were.

Furthermore, since leaky coaxial cables are expensive, there is also the problem of high costs.

(Objective of the Invention) The object of the present invention is to use a transmission line that combines a 1g4 leaky coaxial cable and a return line in a method of relaying medium wave and very high frequency broadcast waves within a limited road, etc., for relaying both transmission waves. The purpose is to provide a relay method with low equipment costs and low costs.

(Means for Solving the Problems) As shown in FIG. 1, the broadcast wave relay method of the present invention connects the medium wave wave f1 and very short wave broadcast wave F2
In addition, guided waves of medium wave broadcast waves and electromagnetic waves of very high frequency broadcast waves are radiated from the composite transmission path into a dark road, etc.

(effect) The relay method of the present invention operates as follows.

The ultra-high-frequency broadcast wave f1 received by the ultra-high-frequency receiving antenna Anti shown in Fig. 2 is amplified by the amplifier FA, and as shown in Fig. 1, the ultra-high frequency broadcast wave f1 is input to the input fri, and the leakage coaxial cable LCX as stream ■1.
, an output current 1 reduced due to the transmission loss of the cable LCX flows on the terminal side of the same cable LCX, and an extremely short wave broadcasting wave f1 is generated around the leaky coaxial cable LCX.
electromagnetic waves are emitted.

Also, the medium wave broadcast wave f2 received by the medium wave receiving antenna Ant2 in FIG. 2 is amplified by the amplifier MA, and as shown in FIG.
When added to the transmission line formed by the external conductor 1 of CX and the return line GW, the output current I4, which is reduced due to the transmission loss of the transmission line, flows at the end of the transmission line, and the output current I4 flows around the leaky coaxial cable LCX and the return line GW. An induced magnetic field of the medium wave broadcast wave f2 is generated. This guided wave and the electromagnetic wave are received by a receiving antenna Ant3 mounted on the roof of the moving body M in FIG.

(Example) FIGS. 1 to 3 show an example of the present invention. In these figures, LCX is a leaky coaxial cable, 1 is the outer conductor of the cable, and GW is a return wire.

Zl is a termination impedance, which is connected to the end of the leaky coaxial cable LCX, and its impedance is equivalent to the characteristic impedance of the leaky coaxial cable LCX.

Z2 is a terminal impedance, which is connected to the end of the transmission line formed by the outer conductor 1 of the leaky coaxial cable LCX and the return wire GW, and its impedance is equivalent to the characteristic impedance of the transmission line.

Anti in Fig. 2 is a very short wave receiving antenna;
2 is a medium wave receiving antenna. Both antennas Anti
, Ant2 is installed outside the tunnel T in Figure i3 and in a place where radio waves can be received well.

In Figure 3, T is a narrow road, M is a moving object such as a train or car, and LC
X is a leaky coaxial cable, GW is a return wire, and S is an insulating support. The support S is attached to the inner wall surface of the tunnel T,
Supports leaky coaxial cable LCX and return line GW.

(Effects of the Invention) The relay method of the present invention, like the conventional relay method, can effectively relay very short wave and medium wave broadcast waves into the tunnel T, and can also connect the outer conductor 1 of the leaky coaxial cable LCX to the medium wave. Since it is shared as a broadcast wave transmission path, medium wave cables can be saved, installation costs can be reduced, and economic effects can be increased.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is an explanatory diagram of the relay method of the present invention, Fig. 3 is an explanatory diagram showing the cable installation situation in the barrier road and the broadcast wave radiation situation, and Fig. 4 is an explanatory diagram of the conventional method. FIG. 2 is an explanatory diagram of a relay method. 1 is the outer conductor of the leaky coaxial cable for very short waves LCX is the leaky coaxial cable for very short waves GW is the return wire Zl, Z2 is the terminal impedance T is the tunnel M is the mobile object fl is the very short wave broadcast wave f2 is the medium wave broadcast wave Antl is the very short wave reception Antenna Ant2 is a medium wave receiving antenna Ant3 is a mobile receiving antenna FA is a very short wave broadcast wave MA is a medium wave amplifier S is a leaky coaxial cable support

Claims (1)

[Claims] A medium wave broadcast wave and a very short wave broadcast wave are added to a composite transmission line consisting of a leaky coaxial cable LCX for ultra high frequency waves and a return line GW, and guided waves of the medium wave broadcast wave are transmitted from the composite transmission line into a tunnel etc. and a method for relaying broadcast waves in a tunnel or the like, characterized in that electromagnetic waves of very high frequency broadcast waves are radiated.