Environmentally Adaptable Broadband Buried Methods

Abstract

This invention relates to an environmentally adaptable broadband buried method, comprising the following steps: S1, measuring the conductivity of the geological surface using a conductivity meter, and simultaneously recording the measured values ​​after different environmental changes; S2, setting a first power network and a second power network in the middle of the buried antenna, and after laying the buried antenna underground, selecting single-feed or center-feed as the main feeding method according to the conductivity of the geological surface; S3, designing and optimizing the first power network and the second power network in the main feeding mode to achieve the required impedance characteristics. The advantages of this invention are: the broadband buried device proposed in this invention is not only adaptable to environmental changes and has a simple structure, but also has versatility, thus providing conditions and possibilities for the promotion and application of underground communication.

Description

Technical Field

[0001] This invention relates to an environmentally adaptable broadband underground method, belonging to the fields of communication technology and electronics. Background Technology

[0002] The input impedance of a buried antenna is a crucial parameter in the antenna feed system. It determines how to achieve circuit matching between the antenna and the transmitter, ensuring efficient power delivery to the antenna. According to lossy transmission line theory, the input impedance Zin of a buried antenna can be expressed by the following formula:

[0003] (1)

[0004] (2)

[0005] In the formula Let be the terminal reflection coefficient of the antenna. This is the antenna termination load impedance. The antenna length is in meters (m). Zc is the transmission constant of the antenna, and Zc is the characteristic impedance of the antenna.

[0006] In medium and long wave communication, it is usually satisfied that >> , >> ( (where b is the skin depth of the conductor) and δ is the skin depth of the earth, and its propagation constant is...

[0007] (3)

[0008] Among them, skin depth , and For the 0th-order type 2 Hankel function and the 1st-order type 2 Hankel function, , Let be the attenuation constant of the buried antenna. Let be the phase shift constant of the buried antenna. The characteristic impedance of the antenna is the ratio of the traveling wave voltage U to the traveling wave current on the line Zc, i.e.

[0009] (4)

[0010] The dielectric constant of the medium filling the antenna cavity;

[0011] The relative permittivity of the medium filling the antenna cavity;

[0012] The wavelength of the buried antenna line;

[0013] a is the radius of the antenna conductor;

[0014] b is the radius of the antenna cavity;

[0015] From equations (1), (2), (3), and (4), it is known that, given a fixed antenna conductor diameter *a* and antenna burial cavity radius *b*, the input impedance of the buried antenna is affected by the burial environment. The impact is significant, therefore a new antenna feeder device is needed to adapt to different environmental requirements. Summary of the Invention

[0016] Buried antennas, including short-circuit and open-circuit antennas, are simple in structure, but their input impedance varies drastically with frequency, making it impossible to achieve efficient signal transmission and reception over a wide bandwidth. To change the impedance characteristics within the bandwidth, methods such as increasing the antenna diameter or reducing losses are often used, at the cost of high cost or low efficiency. Furthermore, the uncertainty of the buried environment affects the antenna's input impedance, resulting in a lack of low-cost, high-efficiency buried antenna feeders that can meet the needs of different environments.

[0017] To address the issue that buried antennas are easily affected by the surrounding environment, a buried antenna feeder device that adapts to environmental changes is proposed, solving problems such as low antenna feeder efficiency and difficulty in selection in buried communication systems.

[0018] To overcome the shortcomings of existing technologies, this invention provides an environmentally adaptable broadband underground burial method. The technical solution of this invention is as follows:

[0019] An environmentally adaptable broadband underground burial method includes the following steps:

[0020] S1. Measure the conductivity of the geology using a conductivity meter, and record the measured values ​​after different environmental changes.

[0021] S2. A first power network and a second power network are set in the middle of the buried antenna. After the buried antenna is laid under the ground, single-feed or mid-feed is selected as the main feeding method according to the conductivity of the soil.

[0022] S2. Design and optimize the first and second power networks in the main power supply mode to achieve the required impedance characteristics.

[0023] Step S1 specifically involves: using a pair of electrodes as transmitting electrodes, inserting them into the geological medium within a preset distance; simultaneously, using another pair of electrodes as receiving electrodes, also inserting them into the geological medium to form a four-electrode system; measuring the voltage on the receiving electrodes using the signal generated by the transmitting electrodes, and then calculating the conductivity of the medium. Since the conductivity is affected by soil type, soil physical and chemical properties, and changes before and after rain, 2-4 measurements are taken to determine the conductivity variation range.

[0024] The feeding method for the buried antenna is selected based on the measured conductivity; the parameters under geological conditions are as follows: in a wetland environment, In a terrestrial environment, In dry environments, In buried equipment, the conductivity is greater than 10. -2 The conductivity is on the order of high conductivity, less than 10. -3 For low conductivity environments, a single-pole feeding method is used; for low conductivity environments, a bipolar feeding structure in the intermediate feeding method is used.

[0025] In the single-pole feeding method, the antenna current distribution is changed by the lossless network in the first power network, and the broadband matching network is integrated to improve the energy transmission between the excitation source and the antenna body. In the low-frequency band of operation, the current on the antenna body passes through the low-frequency channel, which is composed of lossless capacitors and inductors. In the high-frequency band of operation, the current on the antenna body passes through the high-frequency channel, which is composed of lossless capacitors and inductors connected in series with the capacitors.

[0026] In the bipolar feeding method, a broadband matching network and an air-core multi-ratio balancer are added. In the buried environment with low conductivity, the real part of the input impedance varies from 100 ohms to 200 ohms. At this time, impedance transformation is performed on this impedance to meet the 50-ohm impedance requirement of the transmitter. The broadband matching network consists of a lossless capacitor and an inductor connected in series with the capacitor. The air-core multi-ratio balancer has impedance ratio functions of 2:1, 3:1 and 4:1.

[0027] Step S3 specifically involves adjusting the parameters of the first and second power networks. When operating in monopole-fed mode, the first power network is used to regulate the current distribution on the antenna body. Since the dipole antenna is a balanced device, a balanced-to-unbalanced converter is connected between the transmitter and the antenna. The balanced-to-unbalanced converter uses a hollow-wound balanced-to-unbalanced device with 2:1, 3:1, and 4:1 tap ratios. Based on the antenna's input impedance measured by a network analyzer, the parameters of the first and second power networks are designed using the real-frequency method.

[0028] The advantages of this invention are: the broadband buried device proposed in this invention is not only adaptable to environmental changes and has a simple structure, but also has versatility, thus providing conditions and possibilities for the promotion and application of underground communication. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the current distribution on the low-frequency antenna body in the single-fed configuration of the present invention.

[0030] Figure 2This is a schematic diagram of the current distribution on the high-frequency antenna body in the single-fed mode of the present invention.

[0031] Figure 3 This is a schematic diagram of the bipolar power supply structure and power network of the present invention.

[0032] Figure 4 This is a schematic diagram of the input impedance versus frequency curves for three geological conditions according to the present invention.

[0033] Figure 5 This is a schematic diagram of the buried antenna radiator of the present invention.

[0034] Figure 6 This is a schematic diagram of the intermediate power supply (two-port open circuit) of the present invention.

[0035] Figure 7 This is a schematic diagram of the single-port power supply of the present invention.

[0036] Figure 8 This is a schematic diagram of the hollow multiplier device of the present invention.

[0037] Figure 9 This is a schematic diagram of the broadband buried antenna feeder of the present invention. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0039] See Figures 1 to 9 This invention relates to an environmentally adaptable broadband underground burial method, comprising the following steps:

[0040] S1. Measure the conductivity of the geology using a conductivity meter, and record the measured values ​​after different environmental changes.

[0041] S2. A first power network and a second power network are set in the middle of the buried antenna. After the buried antenna is laid under the ground, single-feed or mid-feed is selected as the main feeding method according to the conductivity of the soil.

[0042] S2. Design and optimize the first and second power networks in the main power supply mode to achieve the required impedance characteristics.

[0043] The specific steps of S1 are as follows:

[0044] A pair of electrodes is used as transmitting electrodes and inserted into the geological medium within a preset distance. At the same time, another pair of electrodes is used as receiving electrodes and also inserted into the geological medium to form a four-electrode system. The voltage on the receiving electrodes is measured by the signal generated by the transmitting electrodes, and then the conductivity of the medium is calculated. Since the conductivity is affected by soil type (such as sand and gravel), soil physical and chemical properties (such as loose density, water content and salinity), and changes before and after rain, multiple measurements (2-4 times) are taken to determine the range of conductivity variation.

[0045] The aforementioned method for selecting the feed mode of the buried antenna is based on the measured conductivity. During the calculation process, parameters under several typical geological conditions can be selected as follows: In a wetland environment, In a terrestrial environment, In dry environments, However, in real-world environments, its conductivity varies with various factors and needs to be measured. Common buried media are shown in the table below:

[0046]

[0047] The table above shows that the conductivity of buried media is closely related to humidity. In buried equipment, a conductivity greater than 10 is preferred. -2 The conductivity is on the order of high conductivity, less than 10. -3 For low conductivity environments, a single-pole feeding method is used; for low conductivity environments, a bipolar feeding structure in the intermediate feeding method is used.

[0048] Different measures are adopted for different power supply methods; such as Figure 1 and Figure 2 As shown, in the single-pole feeding method, the antenna current distribution is changed by the lossless network in the first power network, and the broadband matching network is integrated to improve the energy transmission between the excitation source and the antenna body. In the low-frequency band of operation, the current on the antenna body passes through the low-frequency channel, which is composed of lossless capacitors and inductors. In the high-frequency band of operation, the current on the antenna body passes through the high-frequency channel, which is composed of lossless capacitors and inductors connected in series with the capacitors.

[0049] In the bipolar feeding method, a broadband matching network and a hollow-core multi-ratio balancer are added. In buried environments with low conductivity, the real part of the input impedance varies from 100 ohms to 200 ohms. Impedance transformation is then performed on this impedance to meet the transmitter's 50-ohm impedance requirement. Figure 3As shown, the power network consists of an air-core multi-ratio balancer, a grounding device, a switch, and a matching network. The matching network consists of a lossless capacitor and an inductor connected in series with the capacitor. The air-core multi-ratio balancer has impedance ratio functions of 2:1, 3:1, and 4:1. The switch can be connected to the air-core multi-ratio balancer with the corresponding ratio according to the input impedance of the antenna.

[0050] After multiple measurements of the soil environment, the network under various conditions (such as before and after rain) was confirmed. Various power supply methods and related circuits were selected by switching via vacuum relays. The table below is for reference.

[0051]

[0052] This invention applies the medium-long wave band, with a frequency range of 200kHz to 400kHz. The selected buried antenna structural parameters are: b=20mm, a=2mm, l=150m. During the calculation process, the parameters for several typical geological conditions are as follows: (wetland), (general land), and (dry land). For ease of calculation and analysis, a bipolar feeding method is selected for the antenna, such as... Figure 4 As shown in the curve, the input impedance varies drastically with frequency under different geological conditions, with the real part changing from 20Ω to 120Ω and the imaginary part changing from 11Ω to 60Ω, thus making it impossible for the transmitter to transmit effectively in a wide frequency band.

[0053] Due to variations in the site environment (different installation sites) and antenna selection requirements, the design exhibits varying degrees of adaptability, becoming more complex when the operating bandwidth is wide. Different antenna configurations show minor differences in efficiency and consist of two defined antenna types: single-pole open-circuit and double-pole open-circuit.

[0054] Considering feasibility and sustainability, the buried antenna adopts the form of an antenna, with an operating frequency of 200kHz~400kHz.

[0055] like Figure 5As shown, the lateral dimension of the antenna can be adjusted from 140 meters to 150 meters, mainly considering different geological variations. The first power network consists of a power inductor, a power ceramic capacitor, a vacuum relay, and an impedance transformer. The power inductor is wound with silver-plated wire, and its two ends are connected to the two ends of the power ceramic capacitor (i.e., one end of the power inductor is connected to one end of the power ceramic capacitor, and the other end of the power inductor is connected to the other end of the power ceramic capacitor). The two port networks between the power inductor and the power ceramic capacitor are respectively connected to the vacuum relays; the two vacuum relays are respectively connected to the antenna and the impedance transformer. The second power network consists of a power inductor, a power ceramic capacitor, a vacuum relay, and an impedance transformer. The second power network is a balanced network and is a mirror image of the first power network, with the same connection method. The antenna conductor uses copper tubing. The wall thickness of the fiberglass pipe is ≥ b / 10 (b is the radius of the fiberglass pipe).

[0056] Step S3 specifically involves adjusting the parameters of the first power network and the second power network. When operating in single-pole feeding mode, the first power network is used to regulate the current distribution on the antenna body. Since the bipolar antenna is a balanced device, a balanced to unbalanced converter is connected between the transmitter and the antenna. The balanced to unbalanced converter uses a hollow-wound balanced to unbalanced device with a ratio of 2:1, 3:1, and 4:1 taps.

[0057] Based on the input impedance of the antenna measured by the network analyzer, the first power network parameters and the second power network parameters are designed according to the real frequency method.

[0058] In this invention, considering the antenna's survivability and effective radiation, the antenna conductor can be made of copper tubing with anti-oxidation and anti-corrosion treatment. The antenna is reinforced with a high-strength insulated hollow tube. For survivability reinforcement, high-strength fiberglass reinforced plastic (FRP) material can be used, fabricated into a thick-walled cylindrical prefabricated component, with the antenna conductor placed at the center of the insulated tube. The wall thickness of the FRP tube is ≥b / 10 (where b is the radius of the FRP tube). To facilitate handling and construction, the antenna body should be manufactured in sections and assembled on-site, with each section being 3m in length.

[0059] 1) Geological conditions for installation: Following the installation and process requirements for buried antennas, the antenna was installed in the selected area. Multiple angle steel rods were buried in the middle (first power network location) and (second power network location) of the buried antenna, with the angle steel rods terminated by angle iron. A grounding resistance tester was used to measure the grounding resistance at the middle and one end of the antenna; the measured results were 2.87 ohms and 4.39 ohms, respectively.

[0060] 2) Measurement of Earth's Electrical Conductivity: Earth's electrical conductivity can be measured using instruments or calculated theoretically. The resistivity of the aforementioned installation site was measured using instruments, specifically the soil conductivity at a depth of 15 meters near the antenna. The results showed that the resistivity near the second power network location was 26.4 Ω·m, equivalent to a conductivity of 0.037 S / m. The resistivity near the first power network location was 19.6 Ω·m, equivalent to a conductivity of 0.051 S / m.

[0061] 3) Intermediate Feed Test: The intermediate feed method involves opening both ports of the antenna, such as... Figure 6 As shown;

[0062] The impedance measured is as follows:

[0063]

[0064] The test results show that the impedance of the open-ended center feed method varies drastically with frequency, which is detrimental to energy matching between the transmitter and antenna ports. Based on these results, simulations were performed using a multi-stage power network (including a 1:1 converter). The results show that even the added power network cannot meet the VSWR requirements within the 200kHz~400kHz bandwidth.

[0065] 4) Single-port power supply test: To change the input impedance of the intermediate power supply (open circuit at both ends), an experimental study was conducted on single-port power supply, i.e., one port is powered while the other port is open circuit, such as... Figure 7 As shown;

[0066] The impedance measured is as follows (without converter):

[0067]

[0068] The measurement results show that:

[0069] (1) Compared with bipolar feeding, single feeding can improve both radiation resistance in the frequency band and reactance characteristics;

[0070] (2) The unbalanced feeding method is adopted in the single feeder, which avoids the balance to unbalanced device of the intermediate feeder, and facilitates measurement and analysis.

[0071] (3) The measurement results show that although the Q value has been reduced, it is very difficult to achieve broadband matching in this frequency band.

[0072] 5) Determine the parameters of the first power network and the second power network:

[0073] Both open-ended center-fed and single-fed antennas have high radiation efficiency, but the added power networks cannot cover the required operating frequency. To meet the energy transfer conditions between the transmitter and antenna (such as a VSWR of less than 2), the parameters of the first and second power networks need to be adjusted simultaneously.

[0074] When operating in single-fed mode, the first power network functions to regulate the current distribution on the antenna body, improving the input impedance in the low-frequency band. The table shows the impedance after adding the first power network:

[0075]

[0076] The second power network was optimized and designed, and the measurement results were obtained.

[0077] The dipole antenna is a balanced device, therefore a balun (balanced to unbalanced) converter must be connected between the transmitter and the antenna. The dipole antenna has a large impedance variation range, making it difficult to match with conventional broadband networks; the network parameters and turns ratio cannot be confirmed and must be adjusted and debugged on-site. The balun uses a hollow-wound balun with turns ratios of 2:1, 3:1, and 4:1 taps. Its electrical schematic diagram is as follows. Figure 8 As shown below. Based on the above analysis, the schematic diagram of the environmentally adaptable broadband buried antenna feeder is as follows. Figure 9 As shown.

[0078] Underground communication is a form of radio communication in which all transmitting and receiving equipment and their antennas are located underground. Under certain conditions, it can be used to establish a communication network. Especially with the rapid development of modern weapons' precision guidance and destruction capabilities, as well as radio electronic reconnaissance and electronic jamming technologies, underground radio communication has shown new advantages in terms of resistance to destruction, electronic reconnaissance, and electronic countermeasures.

[0079] Buried antennas can be applied in various scenarios, including underground command centers, underground communication hubs, missile silos and their underground control centers, air-raid shelters, tunnels, railway tunnels, underground railways, and mines, but the terrain conditions of these application scenarios vary significantly. The broadband buried device proposed in this invention is not only adaptable to environmental changes and has a simple structure, but also possesses versatility, thus providing conditions and possibilities for the promotion and application of underground communication.

[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An environmentally adaptable broadband buried method, characterized by, Includes the following steps: S1. Measure the electrical conductivity of the geology using an electrical conductivity meter, and record the measured values ​​after different environmental changes. S2. A first power network and a second power network are set in the middle of the buried antenna. After the buried antenna is laid under the ground, the feeding method is selected according to the conductivity of the soil. S3. Design and optimize the first and second power networks in the power supply mode to achieve the required impedance characteristics; The specific steps of S1 are as follows: A pair of electrodes is used as transmitting electrodes and inserted into the geological medium within a preset distance. At the same time, another pair of electrodes is used as receiving electrodes and also inserted into the geological medium to form a four-electrode system. The voltage on the receiving electrodes is measured by the signal generated by the transmitting electrodes, and then the conductivity of the medium is calculated. According to the measured conductivity, the feeding mode of the buried antenna is selected; the geological conditions are as follows: in wet environment, ; in land environment, ; in dry environment, ; in the buried equipment, the conductivity is greater than 10 -2 order of magnitude, which is high conductivity, and less than 10 -3 is low conductivity; in the high conductivity environment, the single pole feeding mode is adopted; in the low conductivity environment, the bipolar feeding structure is adopted.

2. The environmentally adaptable broadband buried approach of claim 1, wherein, In the single-pole feeding method, the antenna current distribution is changed by the lossless network in the first power network, and the broadband matching network is integrated to improve the energy transmission between the excitation source and the antenna body. In the low-frequency band of operation, the current on the antenna body passes through the low-frequency channel, which is composed of lossless capacitors and inductors. In the high-frequency band of operation, the current on the antenna body passes through the high-frequency channel, which is composed of lossless capacitors and inductors connected in series with the capacitors.

3. The environmentally adaptable broadband buried method according to claim 1, characterized in that, In the bipolar feeding method, a broadband matching network and an air-core multi-ratio balancer are added. In the buried environment with low conductivity, the real part of the input impedance varies from 100 ohms to 200 ohms. At this time, impedance transformation is performed on this impedance to meet the 50-ohm impedance requirement of the transmitter. The broadband matching network consists of a lossless capacitor and an inductor connected in series with the capacitor. The air-core multi-ratio balancer has impedance ratio functions of 2:1, 3:1 and 4:

1.

4. The environmentally adaptable broadband buried approach of claim 1, wherein, Step S3 specifically involves: adjusting the parameters of the first power network and the second power network. When operating in single-pole feeding mode, the first power network is used to regulate the current distribution on the antenna body. Since the dipole antenna is a balanced device, a balanced-to-unbalanced converter is connected between the transmitter and the antenna. The balanced-to-unbalanced converter uses a hollow-wound balanced-to-unbalanced device with a tap ratio of 2:1, 3:1, and 4:

1. Based on the input impedance of the antenna measured by the network analyzer, the parameters of the first power network and the second power network are designed according to the real frequency method.

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