An on-train shortwave antenna for electrified railway environment

Abstract

The present invention discloses an on-train short-wave antenna for the electrified railway environment. The antenna as a whole is set as a circular closed loop and arranged inside the "electromagnetic space" formed by the metal car body, the high-voltage catenary and the rail, overcoming the risk of electric shock to personnel and equipment caused by the high-voltage electric field environment of the electrified railway catenary to short-wave electromagnetic emission, breaking through the interference of the magnetic field characteristics of the electrified railway electromagnetic environment to short-wave communication, greatly improving the gain performance of the short-wave antenna, and finally realizing the deployment of short-wave communication on the train in the electrified railway environment, enriching the technical means of railway vehicle-ground communication.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and relates to the electric field safety prevention and magnetic field effectiveness control of short-wave communication in the environment of electrified railways. Background Art

[0002] The standard for regulating the traction power supply construction of domestic electrified railways issued by the National Railway Administration is: "TB10009-2016 Code for Design of Railway Electric Traction Power Supply J452-2016". Section 5.1.5 of this standard stipulates the height of the catenary from the rail surface. The lowest height requirement is: the line with only EMUs in operation should not be less than 5150mm. Table 5.3.2 in Section 5.3.2 of this standard stipulates the air insulation gap value. The regulation related to the roof where the antenna needs to be installed is: the gap between the 25kv live conductor and the rolling stock or the loaded goods should not be less than 350mm. The above two regulations have clearly defined height restrictions on the antenna installed on the roof. And due to the influence of the car body and the rail on the antenna, it is not feasible for traditional short-wave antennas to communicate in this environment. Summary of the Invention

[0003] The present invention provides a train-mounted short-wave antenna for the environment of electrified railways to solve the problem that short-wave antennas cannot be installed on trains in the environment of electrified railways in the prior art.

[0004] The present invention provides a train-mounted short-wave antenna for the environment of electrified railways. The whole antenna is designed as a circular closed loop. The antenna is fixed to the roof through a support mechanism. Its long side is parallel to the train car body, and the antenna loop is perpendicular to the roof.

[0005] The antenna is arranged inside the "electromagnetic space" composed of the metal car body, the high-voltage catenary and the rail, overcoming the risk of electric shock to personnel and equipment caused by the high-voltage electric field environment of the electrified railway catenary to short-wave electromagnetic emission, breaking through the interference of the magnetic field characteristics of the electromagnetic environment of electrified railways to short-wave communication, and greatly improving the gain performance of the short-wave antenna.

[0006] Among them, the installation parameters of the antenna on the car body top are:

[0007] The vertical distance from the whole antenna to the catenary ≥ 466mm;

[0008] The horizontal distance from the whole antenna to the catenary ≥ 1000mm;

[0009] And the lowest point of the antenna body is ≥ 325mm from the roof.

[0010] The size parameters of the antenna are:

[0011] The length of the long side of the loop antenna is 9000 mm, the width is 200 mm, and the height is 300 mm (excluding the fixed bracket). It should be noted that this is only a dimensional parameter given by the present invention. Those skilled in the art can also adjust the specific antenna dimensional parameters according to actual needs with the fundamental setting idea of finally realizing the antenna performance.

[0012] The antenna is a high-performance low-profile narrowband antenna, which consists of an antenna body + a vector antenna tuner and mainly has the following characteristics: When the antenna is tuned, the vector automatic antenna tuning method is adopted. The antenna feed system does not take the minimum system standing wave ratio as the priority tuning target, but takes obtaining the maximum high-frequency resonant current as the target, so as to obtain the maximum antenna radiation efficiency.

[0013] The antenna is a closed-loop circuit. The grounding resistance between any point of the antenna and the metal contact point on the top of the train is < 0.01 Ω. It is connected to the grounding end of the antenna tuner through an impedance matching network, and the whole antenna body is in a grounded short-circuit state. When the antenna body senses a large low-frequency (50 Hz) current, it can flow directly into the ground through the train body and the railway track, eliminating the safety threat of the high-voltage low-frequency signal of the electrified railway catenary to the antenna feed system.

[0014] The high-frequency (HF) current of the antenna overcomes the influence of the antenna body's conduction to the ground and can oscillate, transmit and radiate in the "space" between the catenary, the train body and the railway track.

[0015] The antenna is balanced-fed via an impedance matching network at the feeding end to further reduce the influence of the imbalance of the grounding wire on the high-frequency resonant current.

[0016] The 3 dB radiation pattern in the vertical plane of the antenna is controlled within 12° to 168°, achieving the goal of long-distance communication of 2000 km for a 400 W short-wave radio station.

[0017] The antenna has good omnidirectional communication performance. In any azimuth within the 360° range of the horizontal plane pattern, the change in the relative gain of each frequency point compared to the average value is less than ±1.5 dB.

[0018] The overall frequency band tuning success rate of the antenna in the electrified railway environment is ≤ 5% of the number of channels, where the number of channels of the radio station is divided at 200 KHz frequency intervals.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention solves the problem that a short-wave antenna cannot be installed on a train in the electrified railway environment, and finally realizes the deployment of short-wave communication on the train in the electrified railway environment, enriching the technical means of railway vehicle-ground communication.

[0021] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. In order to make the above and other objects, features and advantages of the present invention more obvious and understandable, the following specific embodiments of the present invention are given. Description of the Drawings

[0022] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0023] Figure 1 a is the vertical plane pattern of the antenna at 3 MHz provided by the embodiment of the present invention;

[0024] Figure 1 b is the azimuth plane pattern of the antenna at 3 MHz provided by the embodiment of the present invention;

[0025] Figure 2 a is the vertical plane pattern of the antenna at 6 MHz provided by the embodiment of the present invention;

[0026] Figure 2 b is the azimuth plane pattern of the antenna at 6 MHz provided by the embodiment of the present invention;

[0027] Figure 3 a is the vertical plane pattern of the antenna at 9 MHz provided by the embodiment of the present invention;

[0028] Figure 3 b is the azimuth plane pattern of the antenna at 9 MHz provided by the embodiment of the present invention;

[0029] Figure 4 a is the vertical plane pattern of the antenna at 12 MHz provided by the embodiment of the present invention;

[0030] Figure 4 b is the azimuth plane pattern of the antenna at 12 MHz provided by the embodiment of the present invention;

[0031] Figure 5 a is the vertical plane pattern of the antenna at 18 MHz provided by the embodiment of the present invention;

[0032] Figure 5 b is the azimuth plane pattern of the antenna at 18 MHz provided by the embodiment of the present invention;

[0033] Figure 6 a is the vertical plane pattern of the antenna at 24 MHz provided by the embodiment of the present invention;

[0034] Figure 6b is the azimuth pattern of the antenna at 24 MHz provided by the embodiment of the present invention;

[0035] Figure 7 a is the vertical pattern of the antenna at 30 MHz provided by the embodiment of the present invention;

[0036] Figure 7 b is the azimuth pattern of the antenna at 30 MHz provided by the embodiment of the present invention;

[0037] Figure 8 is the electrical connection schematic diagram of the short-wave antenna provided by the embodiment of the present invention;

[0038] Figure 9 is the front view of the short-wave antenna entity provided by the embodiment of the present invention;

[0039] Figure 10 is the side view of the short-wave antenna entity provided by the embodiment of the present invention;

[0040] Figure 11 is the top view of the short-wave antenna entity provided by the embodiment of the present invention;

[0041] Figure 12 is the actual installation picture of the short-wave antenna on the train roof provided by the embodiment of the present invention. Detailed implementation manners

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention.

[0043] The embodiment of the present invention provides a train-mounted short-wave antenna for an electrified railway environment. Refer to Figure 8 、 Figure 9 、 Figure 10 、 Figure 11 and Figure 12 .

[0044] The antenna of the present invention is designed as an overall annular closed loop. The antenna is fixed to the train roof through a support mechanism, with its long side parallel to the train body and the antenna loop perpendicular to the train roof;

[0045] The antenna is arranged inside the "electromagnetic space" formed by the metal train body, the high-voltage catenary and the railway track. By setting the installation parameters of the antenna on the train roof and the size parameters of the antenna, the risk of electric shock to personnel and equipment caused by the electric field environment of the electrified railway catenary to short-wave electromagnetic emission is overcome, the interference of the magnetic field characteristics of the electrified railway electromagnetic environment to short-wave communication is broken through, and at the same time, the gain performance of the wave antenna is improved;

[0046] Among them, the installation parameters of the antenna on the train roof are:

[0047] The overall vertical distance between the antenna and the catenary is ≥ 466 mm;

[0048] The overall horizontal distance between the antenna and the catenary is ≥ 1000 mm;

[0049] And the lowest point of the antenna body is ≥ 325 mm away from the roof of the train.

[0050] The size parameters of the antenna are as follows: the length of the long side of the loop antenna is 9000 mm, the width is 200 mm, and the height is 300 mm.

[0051] In specific implementation, when tuning the antenna according to the embodiments of the present invention, the vector automatic antenna tuner method is adopted, and the antenna-feeding system aims to obtain the maximum high-frequency resonance current, and finally obtains the maximum antenna radiation efficiency.

[0052] The antenna is a closed-loop circuit. The grounding resistance between any point of the antenna and the metal contact point on the top of the train is < 0.01 Ω, and it is connected to the grounding end of the antenna tuner through an impedance matching network. The entire antenna body is in a grounded short-circuit state. When the antenna body senses the low-frequency current of the electrified railway catenary, where the low frequency is the industrial frequency of 50 Hz, the sensed low-frequency current directly flows into the ground through the train body and the rails, so as to eliminate the safety threat of the high-voltage low-frequency signal of the electrified railway catenary to the antenna-feeding system.

[0053] Further, in the embodiments of the present invention, the high-frequency current of the antenna overcomes the influence of the conduction of the antenna body to the ground, and can oscillate, transmit and radiate in the "space" between the catenary, the train body and the rails, where the high frequency is the HF band and above.

[0054] The antenna is balanced-fed through an impedance matching network at the feeding end to further reduce the influence of the unbalance of the grounding wire on the high-frequency resonance current.

[0055] Specifically, in the embodiments of the present invention, the 3 dB radiation pattern in the vertical plane of the antenna is controlled within 12° to 168° to achieve the goal of long-distance communication of 2000 km for a 400 W short-wave radio.

[0056] In the embodiments of the present invention, the antenna has an omnidirectional communication performance. In any azimuth within the 360° range of the horizontal plane pattern, the change of the relative gain of each frequency point compared with the average value is less than ±1.5 dB.

[0057] In specific implementation, in the embodiments of the present invention, the success rate of full-band tuning of the antenna in the electrified railway environment is ≤ 5% of the number of channels, and tuning is performed in steps of 200 KHz.

[0058] Of course, the above is only an example of the present invention. In specific implementation, those skilled in the art can set the sizes of antennas with other values according to actual needs, and the present invention does not make detailed limitations thereto.

[0059] Practical applications show that the antenna body of the embodiment of the present invention can work in a bad environment where there is an electrified railway catenary above, a large-area metal car body and an extremely long railway track below, and can adapt to the adverse communication environment with complex electromagnetic fields of electrified railways for work;

[0060] As can be seen from the figure, the antenna of the embodiment of the present invention is in a closed loop, is integrally grounded through an impedance matching network, allows low-frequency large current to enter the ground, and high-frequency energy can be transmitted and radiated, effectively solving the safety impact of the electrified railway catenary on the antenna; in the embodiment of the present invention, the antenna is arranged inside the "electromagnetic space" composed of a metal car body, a high-voltage catenary and a railway track. Through comprehensive design, good gain performance of the antenna body is effectively achieved, and it can reach more than 2000 kilometers through a 400W radio;

[0061] Actual measurements show that the elevation angle range of the vertical plane beam of the antenna of the present invention can reach up to 9° to 171° at most, with a large elevation angle range; the pattern in the azimuth plane (the maximum radiation direction) has good omnidirectional performance, and the coverage range in the azimuth plane is wide.

[0062] According to the Figure 1 - appendix Figure 7 vertical plane pattern and azimuth plane pattern, it can be seen that the present invention can effectively achieve various antenna performance indicators in each frequency band.

[0063] Specifically, in terms of design, the present invention selects a high-performance low-profile loop antenna as the basis for adaptive design. Although this type of antenna is a narrowband antenna, the antenna gain has no obvious decrease (less than 1 dBi decrease) compared with the case without a car body and a catenary, and can maintain a high gain characteristic.

[0064] The calculation of the insulation distance in the embodiment of the present invention specifically includes: it is known that the breakdown voltage of dry air is 12 kV / cm, and it drops to about 1.2 kV / cm when it is wet. A spacing of 350 mm can ensure that the voltage below 42 kV is not broken down. Therefore, when the antenna erection height is lower than 4800 mm, it can theoretically ensure that there is no sparking with the high-voltage catenary wire. In addition, the designed antennas are all installed in the interval more than 50 mm above the car roof and less than 50 mm below the 4800 mm limit height. For the 400W antenna on this platform, an insulation distance of 50 mm can meet the safety requirements. In addition, an insulating protective material can be installed on the outside of the antenna body to further reduce the risk of sparking with the high-voltage catenary wire.

[0065] The radiation elevation angle of the antenna of the present invention: According to the height of the reflection point, the antenna radiation elevation angles corresponding to different great circle distances (50 km to 2000 km) in the receiving area are shown in Table 1 as follows:

[0066] Table 1 Distribution of communication distance and corresponding radiation elevation angle

[0067]

[0068] As can be seen from the above table, for short-wave communication within 2000 km, whether it is the 1-hop or 2-hop mode of the F2 layer or the Es layer, the antenna is required to have a relatively large vertical plane radiation elevation angle range.

[0069] Furthermore, for the gain, elevation angle, and azimuth plane beam width of the antenna, the elevation angle of the antenna designed by the present invention is shown in Table 2 as follows.

[0070] Table 2 Elevation angle table of the antenna designed by the present invention

[0071]

[0072] Generally speaking, in the implementation case of the present invention, the antenna is integrally set as a circular closed loop and arranged inside the "electromagnetic space" composed of a metal vehicle body, a high-voltage catenary, and a railway track, overcoming the risk of electric shock to personnel and equipment caused by the high-voltage electric field environment of the electrified railway catenary to short-wave electromagnetic emission, breaking through the interference of the magnetic field characteristics of the electromagnetic environment of the electrified railway to short-wave communication, and greatly improving the gain performance of the short-wave antenna.

[0073] Although the preferred implementation cases of the present invention have been disclosed for illustrative purposes, those skilled in the art will realize that various improvements, additions, and substitutions are also possible. Therefore, the scope of the present invention should not be limited to the above implementation cases.

Claims

1. An on-vehicle short-wave antenna for an electric railway environment train, characterized in that, Including: The overall antenna is designed as a circular closed loop. The antenna is fixed to the roof of the train through a support mechanism. Its long side is parallel to the train body, and the antenna loop is perpendicular to the roof. The antenna is arranged inside the "electromagnetic space" formed by the metal train body, the overhead catenary, and the railway track. By setting the installation parameters of the antenna on the train body and the size parameters of the antenna, the risk of electric shock to personnel and equipment caused by the electric field environment of the electrified railway catenary to short-wave electromagnetic emission is overcome, the interference of the magnetic field characteristics of the electromagnetic environment of the electrified railway to short-wave communication is broken through, and at the same time, the antenna gain performance is improved. Among them, the installation parameters of the antenna on the train body are: The vertical distance from the overall antenna to the catenary ≥ 466 mm; The horizontal distance from the overall antenna to the catenary ≥ 1000 mm; And the lowest point of the antenna body is ≥ 325 mm from the roof; The size parameters of the antenna are: the length of the long side of the circular antenna is 9000 mm, the width is 200 mm, and the height is 300 mm; When the antenna is tuned, the vector automatic antenna tuner method is adopted. The antenna feeding system aims to obtain the maximum high-frequency resonance current, and finally obtains the maximum antenna radiation efficiency. The antenna is a closed-loop circuit. The grounding resistance of any point of the antenna to the metal contact point on the top of the train: <0.01 Ω, and it is connected to the grounding end of the antenna tuner through an impedance matching network. The entire antenna body is in a grounded short-circuit state. When the antenna body senses the low-frequency current of the electrified railway catenary, where the low frequency is the industrial frequency of 50 Hz, the sensed low-frequency current flows directly into the ground through the train body and the railway track, so as to eliminate the safety threat of the high-voltage low-frequency signal of the electrified railway catenary to the antenna feeding system.

2. The on-vehicle short-wave antenna for an electric railway environment train according to claim 1, characterized in that, The high-frequency current of the antenna overcomes the influence of the antenna body's conduction to the ground and can oscillate, transmit, and radiate in the "space" between the catenary, the train body, and the railway track. Among them, the high frequency is the HF band and above. The antenna is balanced-fed via an impedance matching network at the feeding end to further reduce the influence of the imbalance of the grounding wire on the high-frequency resonance current.

3. The on-vehicle short-wave antenna for an electric railway environment train according to claim 2, characterized in that, The 3 dB radiation pattern in the vertical plane of the antenna is controlled within 12° - 168° to achieve the goal of long-distance communication of 2000 km for a 400 W short-wave radio station.

4. The on-vehicle short-wave antenna for an electric railway environment train according to claim 2, characterized in that, The antenna has an omnidirectional communication performance. In any azimuth within the 360° range of the horizontal plane pattern, the change in the relative gain of each frequency point compared to the average value is less than ±1.5 dB.

5. The on-vehicle short-wave antenna for an electric railway environment train according to claim 2, characterized in that, The success rate of full-band tuning of the antenna in the electrified railway environment: ≤ 5% of the number of channels, where the number of channels of the radio station is divided at a frequency interval of 200 KHz.

Images