Variable-frequency resonance matching low-frequency antenna and communication system

Abstract

According to the frequency conversion resonance matching low-frequency antenna and the communication system provided by the invention, frequency conversion modulation is performed on a low-frequency electric field signal capable of being propagated in seawater and a high-frequency modulation signal through up / down conversion of the modulation electrode, and high-efficiency and high-sensitivity signal receiving and transmitting can be realized by using a small antenna size. The high-Q-value quartz crystal resonator suppresses various harmonic components and noise through narrow-band filtering characteristics and improves the signal-to-noise ratio of the receiving antenna, meanwhile, the quartz crystal resonator is perceptual by controlling the working frequency, resonance matching is achieved between the quartz crystal resonator and a capacitive internal resistance underwater antenna, the sensitivity and the resolution ratio of a received electric field signal are greatly improved, and the receiving efficiency is improved. Therefore, the miniaturized transmit-receive antenna can realize long-distance underwater wireless communication. The antenna communication system can be flexibly applied to communication of a seabed sensor network, an underwater platform and an underwater vessel, a miniaturized underwater antenna array can be conveniently constructed, and sea-land-air multi-domain communication is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, in particular, to a variable frequency resonant matching low-frequency antenna and a communication system. BACKGROUND

[0002] Underwater wireless communication is one of the basic means of ocean information dissemination. However, due to the conductivity, turbidity and complex medium space of seawater transmission medium, the development of ocean underwater information exchange technology and the application of underwater wireless communication of various ocean instruments, equipment and ships are restricted.

[0003] Underwater electromagnetic wave communication has the advantages of high communication rate, strong anti-noise ability, low transmission delay, small interface and obstacle influence, no need for accurate alignment, simple structure, convenient power supply, low power consumption, high safety, small influence on aquatic organisms, etc. It can also be used for flexible networking transmission in sea-land-air cross-domain. However, high-frequency radio waves attenuate very seriously in seawater, and low-frequency waves require very long antennas. Currently, underwater antennas are mainly used for short-distance high-speed communication. If the problem of low-frequency small-size electromagnetic wave antenna transceiving efficiency in seawater can be solved, underwater electromagnetic wave communication can exhibit many technical advantages, which will have a profound impact on the application and development of ocean wireless communication.

[0004] The ocean communication receiving antenna is a traditional electric / magnetic small antenna, which receives weak special / ultra / extreme / low frequency signals through a super-high sensitive receiver. However, for special / ultra / extreme / low frequency transmitting antennas, super-long shore-based antennas (such as several kilometers to several hundred kilometers) are needed, and it is difficult to set up such a large size antenna on the ocean platform. Another mechanical antenna rotates / moves the permanent magnet or charged body driven by a motor to radiate electromagnetic waves, thereby reducing the size of the antenna. However, the mechanical rotating antenna has low efficiency. Therefore, in recent years, magneto-electric antennas and piezoelectric antennas have been proposed, which can realize low-frequency antennas with small size. However, the magneto-electric material of the magneto-electric antenna relies on the glue layer to transfer stress / strain, which has large loss, is easy to couple noise, and has low quality factor Q, which is not conducive to long-distance, high-speed and variable frequency wireless magnetic field transmission. The piezoelectric antenna needs to use bending resonance, and the Q value of the ultra-low frequency bending resonance piezoelectric antenna is low (Q<50), which has low receiving efficiency and sensitivity, and it is difficult to increase the transmission power and capture underwater weak electromagnetic wave signals.

[0005] To reduce the size of the antenna, the electromagnetic field frequency should be increased, however, the high frequency electromagnetic field has a very short propagation distance in seawater. If a small size antenna can be tuned to high frequency in seawater and frequency modulation is performed in seawater with low frequency signals, a small antenna can be used to transmit low frequency signals in seawater. The quartz crystal resonator has a very high quality factor, and through high Q value resonance matching, the antenna quality factor and efficiency can be greatly improved, and the influence of noise can be suppressed as much as possible. The technology can not only be used for seawater communication, but also be applied to air and lake water and other media. It can also be adapted to sea-land-air cross-domain communication and more extensive application fields. SUMMARY

[0006] In view of the defects in the prior art, the purpose of the present application is to provide a variable frequency resonant matching low frequency antenna and a communication system.

[0007] According to the variable frequency resonant matching low frequency antenna provided by the present application, the variable frequency resonant matching low frequency antenna comprises a modulation electrode, a transceiving antenna, a modulation switch, a resonant matching circuit, a computer and a transceiving circuit.

[0008] The transceiving antenna is connected with the resonant matching circuit, and the modulation electrode is arranged at the front end of the transceiving antenna.

[0009] The resonant matching circuit connects the computer through the transceiving circuit, and the computer and the modulation electrode are respectively grounded through the modulation switch.

[0010] When receiving signals, the computer controls the modulation electrode to send a modulation signal through the modulation switch, the modulation signal up-converts the low frequency electric field signal in the propagation medium, and the transceiving antenna sends the resonant matching circuit.

[0011] When transmitting signals, the computer controls the modulation electrode to send a modulation signal through the modulation switch, the modulation signal down-converts the output signal of the crystal resonator in the resonant matching circuit in the propagation medium, and the low frequency electric field signal is transmitted in the propagation medium.

[0012] Further, the modulation electrode and the transceiving antenna adopt a mesh, rod or spiral metal structure.

[0013] Further, the resonant element in the resonant matching circuit is a quartz resonator, a SAW device or an FBAR device.

[0014] Further, when receiving signals, the computer sends a modulation signal V k to the modulation switch, controls the modulation switch to be intermittently on and off at a frequency of f0-f a , so as to up-convert or down-convert.

[0015] Further, the modulation signal Vk a square wave signal with a frequency of f0-f a

[0016] Further, the transceiving circuit comprises a transceiving switch, a demodulation circuit, a signal conditioning circuit, a signal source, a modulation circuit and a power amplifier circuit.

[0017] The transceiving switch is connected to the resonant matching circuit, and the transceiving switch is connected to the computer in sequence through the demodulation circuit and the signal conditioning circuit, and the computer is connected to the transceiving switch in sequence through the modulation circuit and the power amplifier circuit, and the signal source is connected to the computer, the demodulation circuit and the modulation circuit respectively.

[0018] Further, when receiving a signal, the resonant matching circuit outputs a signal V3 through the transceiving switch, and the signal source outputs a signal V S The first multiplier of the demodulation circuit performs multiplication operation to obtain a signal V4 containing a frequency f a component, and the signal V5 obtained by filtering through the signal conditioning circuit is sent to the computer for signal detection and identification.

[0019] Further, when transmitting a signal, the computer outputs a signal V7, and the signal source outputs a signal V S The second multiplier of the modulation circuit performs multiplication operation to obtain a signal V1 containing a frequency f0 component, and the signal V2 obtained through the power amplifier is sent to the transceiving switch, and the signal containing the frequency f0 component is reserved through the filtering of the resonant matching circuit.

[0020] Further, the propagation medium comprises liquid and gas, and the liquid comprises seawater and freshwater.

[0021] According to the application, a communication system is provided, comprising the variable-frequency resonant matching low-frequency antenna.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] 1. The circuit of the application adopts a variable-frequency quartz resonant matching small-sized marine low-frequency antenna, has better electric field signal transceiving capability than a traditional small-sized seawater antenna, has higher sensitivity, signal-to-noise ratio and longer communication distance, and can be flexibly applied to a seabed sensor network, an underwater platform and underwater ship communication.

[0024] 2. The circuit of the application adopts seawater electric field variable frequency and quartz resonant matching, can work in a small-sized and strong-noise environment, and is particularly convenient for constructing an underwater antenna array.

[0025] ​3、The circuit of the present application adopts the variable frequency quartz resonant matching small marine low frequency antenna and communication system, which can be used for ocean underwater communication, river and lake freshwater underwater communication, and sea, land and air multi-domain communication, greatly expanding its application field and application occasion. BRIEF DESCRIPTION OF DRAWINGS

[0026] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments thereof, read in conjunction with the accompanying drawings:

[0027] Figure 1 A variable frequency quartz resonant matching small marine low frequency antenna and system overall block diagram is provided for the embodiments of the present application.

[0028] Figure 2 A variable frequency quartz resonant matching small marine low frequency antenna and system principle diagram is provided for the embodiments of the present application.

[0029] Figure 3 A crystal resonator amplitude-frequency characteristic diagram is provided for the embodiments of the present application.

[0030] Figure 4 A quartz resonator, SAW and FBAR equivalent circuit and impedance characteristic diagram is provided for the embodiments of the present application.

[0031] Figure 5a A receiving antenna communication system point waveform diagram is provided for the embodiments of the present application.

[0032] Figure 5b A receiving antenna communication system up-conversion amplitude-frequency characteristic diagram is provided for the embodiments of the present application.

[0033] Figure 6a A transmitting antenna communication system point waveform diagram is provided for the embodiments of the present application.

[0034] Figure 6b A transmitting antenna communication system down-conversion amplitude-frequency characteristic diagram is provided for the embodiments of the present application.

[0035] Figure 7 A mesh, rod, spiral-shaped transceiving antenna and modulation electrode structure diagram is provided for the embodiments of the present application.

[0036] Figure 8 A plurality of crystal resonators in parallel structure diagram and amplitude-frequency characteristic diagram are provided for the embodiments of the present application. DETAILED DESCRIPTION

[0037] The application will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the application. These are within the scope of the application.

[0038] As shown in Figure 1 A variable frequency resonant matching low frequency antenna includes a modulation electrode, a transceiving antenna, a modulation switch, a resonant matching circuit, a computer and a transceiving circuit. In this embodiment, the transceiving antenna is two: the first transceiving antenna and the second transceiving antenna. In other embodiments, the transceiving antenna can also be one or more. The transceiving antenna is connected to the resonant matching circuit, and the modulation electrode is arranged at the front end of the transceiving antenna. The resonant matching circuit is connected to the computer through the transceiving circuit, and the computer and the modulation electrode are respectively connected to the ground through the modulation switch. When receiving a signal, the computer controls the modulation electrode to send a modulation signal through the modulation switch, and the modulation signal up-converts the low frequency electric field signal in the propagation medium, and sends it into the resonant matching circuit through the transceiving antenna. When transmitting a signal, the computer controls the modulation electrode to send a modulation signal through the modulation switch, and the modulation signal down-converts the output signal of the crystal resonator in the resonant matching circuit in the propagation medium, and obtains a low frequency electric field signal that can be transmitted over a long distance. Since the frequency of the signal received on the first transceiving antenna and the second transceiving antenna is very high, the size of the transceiving antenna is greatly reduced, and the weak signal receiving ability and signal transmission ability of the small size transceiving antenna are also improved. The propagation medium includes liquid and gas, and the liquid includes seawater and freshwater.

[0039] As shown in Figure 1 The transceiving circuit includes a transceiving switch, a demodulation circuit, a signal conditioning circuit, a signal source, a modulation circuit and a power amplification circuit. The transceiving switch is connected to the resonant matching circuit, and the transceiving switch is connected to the computer through the demodulation circuit and the signal conditioning circuit in sequence. The computer is connected to the transceiving switch through the modulation circuit and the power amplification circuit in sequence, and the signal source is connected to the computer, the demodulation circuit and the modulation circuit respectively.

[0040] The variable frequency signal can improve the sensitivity of the small size antenna, and the high Q value resonant matching can reduce the harmonic component and greatly improve the signal output amplitude at the resonant point. In receiving a signal, the quartz resonant matching circuit can greatly improve the output amplitude of the first transceiving antenna and the second transceiving antenna, and improve the weak seawater electric field resolution capability. In transmitting a signal, it can efficiently send high frequency transmission signals on the small size first transceiving antenna and the second transceiving antenna, reduce the power consumption of driving the small size antenna, send larger power electric field signals with the small size antenna, improve the transceiving distance of the small size antenna, improve the communication ability of the variable frequency quartz resonant matching small size marine low frequency antenna, and expand the application occasions of the antenna in the field of seawater wireless communication.

[0041] Embodiment one

[0042] A variable frequency quartz resonant matching ocean underwater antenna, which realizes a small ocean low frequency antenna with high sensitivity, high signal-to-noise ratio, and long distance communication. The modulation electrode, the first transceiving antenna and the second transceiving antenna use metal mesh, and the modulation switch is a MOS device. The opening and closing of the modulation switch is controlled by the computer output signal V k Control, such as Figure 2 When the modulation switch is intermittently turned on and off at a frequency (f0-f a ), the modulation electrode converts the low frequency (frequency f a ) seawater electric field E a into a seawater electric field E u containing a frequency f0 component. The first transceiving antenna and the second transceiving antenna receive the upconverted signal V u , and the amplitude-frequency characteristic of the quartz resonator is as shown in Figure 3 , and a very narrow band (about 1 Hz bandwidth) output can be obtained. The quartz resonator can also be replaced by SAW or FBAR. The quartz resonator has a very high quality factor, and the corresponding bandwidth is very narrow. If the frequency f0 component of the upconverted signal V u just falls within the frequency band of the crystal, the signal can be transmitted to the output through the crystal device, while the harmonic components, noise and interference signals outside the frequency band of the crystal are greatly attenuated and suppressed, forming a filter with very narrow band filtering function, greatly improving the signal-to-noise ratio of the received signal. The equivalent circuit and impedance characteristics of the quartz resonator, SAW and FBAR are shown in Figure 4 . It can be seen that the crystal is inductive between the series resonance frequency f S and the parallel resonance frequency f P , and is purely resistive at the series resonance frequency f S , and is capacitive at other frequency points. Therefore, by utilizing the inductive characteristic of the quartz resonator, the transceiving antenna with capacitive internal resistance in seawater is resonantly matched, which can maximize the output power of the transceiving antenna and improve the sensitivity of the received signal and the resolution of weak signals. The time domain waveforms of each point in the receiving antenna communication system and the upconverted amplitude-frequency characteristic are shown in Figure 5. The low frequency electric field signal E a is a sinusoidal signal with frequency f a , and the modulation signal V k is a square wave signal with frequency (f0-f a ). Through the modulation electrode, the seawater upconverted electric field E u contains a frequency f0 component. The quartz resonator filters out the upconverted harmonic components and interference signals, and at its output, only the useful signal containing the f0 component is obtained. From Figure 5a , the waveform diagram of each point of the upconversion can be seen, and the upconversion amplitude-frequency characteristic is as followsFigure 5b The quartz resonator output signal is sent to the communication system. Figure 2 When the receiving path above is connected, the output signal V3 of the quartz resonator through the transceiver switch is connected to the signal source output V S (Frequency is (f0-f a )) performs multiplication in the first multiplier to obtain a low frequency (frequency f a ) component signal V4 is filtered out by an active low-pass filter to remove many other frequency components generated by the first multiplier, and a high signal-to-noise ratio signal V5 is obtained, which is finally sent to a computer for detection and identification of seawater electric field signals.

[0043] The transmission and reception of low frequency electric field signals are exactly opposite. Computer controlled signal source V S (Frequency is (f0-f a )) and signal V7 (frequency f a ) is multiplied in the second multiplier to obtain a signal component containing frequency f0. This component signal is passed through the power amplifier to obtain signal V2. The transceiver switch contacts are placed at the bottom ( Figure 2 ), narrowband filtering characteristics of quartz resonator ( Figure 3 ) filters out other frequency components and retains the signal component of frequency f0. At the same time, the inductive characteristics of the quartz resonator ( Figure 4 ), and also realize the resonant matching between the first transceiver antenna and the power amplifier, ensuring that the power amplifier efficiently outputs power to the first transceiver antenna. a ) When intermittently switched on and off, the high-frequency seawater electric field E a ' is down-converted to a low frequency (frequency f) through the modulation electrode a )Seawater electric field E a , and there are many high-frequency electric field components. The waveforms of each point in the transmitting antenna communication system and the amplitude-frequency characteristics of the down-conversion, such as Figure 6a 、 Figure 6b As shown. Since seawater has a huge attenuation on high-frequency components, only the low-frequency electric field signal E a It can be transmitted over long distances, thus realizing long-distance transmission of low-frequency electric fields.

[0044] Through up / down conversion modulation, antenna size is significantly reduced, and the sensitivity of small antennas is improved. The resonant matching of high-Q quartz maximizes signal response. At the same time, its narrowband filtering characteristics effectively suppress interference and noise from other components, improving the signal-to-noise ratio and signal resolution, while reducing driving power consumption and improving transmission efficiency. This enhances the communication capabilities of small transceiver antennas in seawater and expands their application in marine wireless communications.

[0045] The application can modulate the low frequency electric field signal which can be propagated in seawater and the high frequency modulated signal by up / down conversion of the electrode, can realize high efficiency and high sensitivity signal receiving and transmitting with small antenna size. The high Q quartz crystal resonator can suppress various harmonic components and noise through narrow band filtering characteristics, improve the signal to noise ratio of the receiving antenna, at the same time, by controlling the working frequency, the quartz crystal resonator presents inductive, and the capacitive internal resistance underwater antenna realizes resonance matching, greatly improves the sensitivity and resolution of the received electric field signal, so that the miniaturized transceiving antenna can realize long distance underwater wireless communication. The antenna communication system can be flexibly applied to seabed sensor network, underwater platform and underwater ship communication, and can also be conveniently constructed into a small underwater antenna array, and realize sea-land-air multi-domain communication.

[0046] Embodiment two

[0047] The first transceiving antenna, the second transceiving antenna and the modulation electrode in embodiment one are all net-shaped metal structures, similar to the antenna in the air, other structure antennas can also realize underwater wireless communication well, and the rod-shaped, spiral-shaped transceiving antenna and modulation antenna structure can also communicate with linear and elliptical polarization electric field respectively. They can maximize the realization of long distance wireless communication by using limited size, and the structure is as shown in Figure 7 .

[0048] Embodiment three

[0049] The quartz resonator in embodiment one and embodiment two has very narrow frequency band and good filtering performance. However, the manufacturing deviation of the quartz crystal center frequency may cause small deviation of the center frequency of the two communication systems, resulting in the situation that the signal cannot be normally communicated. In order to avoid the problem that the signal cannot pass due to the resonance frequency difference of the two quartz crystals when transmitting and receiving signals, a plurality of crystal devices (quartz, SAW, FBAR resonators and filters) with slightly different frequencies can be connected in parallel, as shown in Figure 8 At this time, the center frequencies of each crystal are slightly different (such as f1, f2···f N ), and the frequency band is appropriately widened after parallel connection, but the Q value of the crystal is not affected, even if the transmitted signal is slightly changed, the received signal will also fall within the widened frequency band, solving the problem of frequency deviation of the quartz crystal during manufacturing, improving the adaptability of the antenna to the manufacturing deviation of the crystal, and realizing the antenna with high signal to noise ratio and high sensitivity.

[0050] The application also provides a communication system comprising the above-mentioned frequency conversion resonant matching low frequency antenna.

[0051] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like refer to the orientation or positional relationship shown in the drawings, and are only intended to facilitate the description of the present application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0052] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which do not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other without conflict, provided that the combinations do not conflict.

Claims

1. A variable frequency resonant matching low frequency antenna, characterized in that: include: Modulation electrode, transceiver antenna, modulation switch, resonant matching circuit, computer and transceiver circuit; The transceiver antenna is connected to the resonant matching circuit, and the modulation electrode is arranged at the front end of the transceiver antenna; The resonant matching circuit is connected to the computer via the transceiver circuit, and the computer and the modulation electrode are grounded via the modulation switch respectively; When receiving a signal, the computer controls the modulation electrode to emit a modulation signal through the modulation switch. The modulation signal up-converts the low-frequency electric field signal in the propagation medium and is sent to the resonant matching circuit through the transceiver antenna. When transmitting a signal, the computer controls the modulation electrode to emit a modulation signal through the modulation switch. The modulation signal down-converts the output signal of the crystal resonator in the resonant matching circuit in the propagation medium to obtain a low-frequency electric field signal for transmission in the propagation medium.

2. The variable frequency resonant matching low frequency antenna according to claim 1, characterized in that: The modulation electrode and the transceiver antenna adopt a mesh, rod or spiral metal structure.

3. The variable frequency resonant matching low frequency antenna according to claim 1, characterized in that: The resonant element in the resonant matching circuit is a quartz resonator, a SAW device or a FBAR device.

4. The variable frequency resonant matching low frequency antenna according to claim 1, characterized in that: When receiving a signal, the computer sends a modulated signal V k To the modulation switch, control the modulation switch to a frequency of f0-f a Intermittent switching to achieve up-conversion or down-conversion.

5. The variable frequency resonant matching low frequency antenna according to claim 4, characterized in that: The modulation signal V k The frequency is f0-f a square wave signal.

6. The variable frequency resonant matching low frequency antenna according to claim 1, characterized in that: The transceiver circuit includes: a transceiver switch, a demodulation circuit, a signal conditioning circuit, a signal source, a modulation circuit and a power amplifier circuit; The transceiver switch is connected to the resonant matching circuit, and the transceiver switch is connected to the computer via the demodulation circuit and the signal conditioning circuit in sequence. The computer is connected to the transceiver switch via the modulation circuit and the power amplifier circuit in sequence. The signal source is connected to the computer, the demodulation circuit, and the modulation circuit respectively.

7. The variable frequency resonant matching low frequency antenna according to claim 6, characterized in that: When receiving a signal, the resonant matching circuit matches the signal V3 sent by the transceiver switch with the signal V output by the signal source. S The first multiplier of the demodulation circuit performs a multiplication operation to obtain a signal containing the frequency f a The component signal V4 is filtered by the signal conditioning circuit to obtain a signal V5 which is sent to the computer for signal detection and identification.

8. The variable frequency resonant matching low frequency antenna according to claim 6, characterized in that: When transmitting the signal, the signal V7 output by the computer is the same as the signal V output by the signal source. S The second multiplier of the modulation circuit performs a multiplication operation to obtain a signal V1 containing a frequency f0 component, which is then passed through the power amplifier to obtain a signal V2, which is sent to the transceiver switch and filtered through the resonant matching circuit to retain the signal with frequency f0.

9. The variable frequency resonant matching low frequency antenna according to claim 1, characterized in that: The transmission medium includes: liquid and gas; the liquid includes sea water and fresh water.

10. A communication system, characterized in that: The invention comprises the variable frequency resonant matching low frequency antenna according to any one of claims 1 to 9.

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