Low-cost long-distance direction backtracking system for moving target

Abstract

The invention discloses a low-cost long-distance direction backtracking system for a moving target, and the system comprises a transmitter which comprises a beacon signal receiving antenna, a four-channel phase conjugate circuit, and an energy transmitting antenna; the four-channel phase conjugate circuit comprises a low-noise amplifier in signal connection with the beacon signal receiving antenna, a frequency mixer in signal connection with the low-noise amplifier, and a local oscillator module and an energy transmitting antenna which are in signal connection with the frequency mixer; the receiver comprises a filtering module, a beacon signal transmitting antenna and a rectifying antenna, wherein the beacon signal transmitting antenna and the rectifying antenna are connected with the filtering module. According to the invention, phase compensation is carried out, so that the space between the energy transmitting antennas is reduced by half, the 3dB backtracking angle of the designed active device and antenna system can reach + / -30 degrees, and a direction backtracking system with low cost and wide backtracking angle is realized.

Description

Technical Field

[0001] The invention relates to the technical field of microwave wireless energy and information parallel transmission, and in particular to a low-cost long-distance direction tracing system for a mobile target. Background Art

[0002] Microwave Power Transmission (MPT) is a common long-distance energy transmission method. Energy is transmitted point-to-point from the transmitter to the receiver through free space. The energy transmitter converts DC into microwave energy and sends it to the energy receiver through the antenna. The rectenna receives the microwave energy and converts it into DC output. Currently, MPT technology is mainly used for wireless power supply to terminals. The direction tracing technology used in the MPT system is a beam adaptation technology based on phase conjugation. It can realize adaptive beam alignment through the beacon signal transmitted by the receiver without knowing the azimuth of the receiver. It has real-time directionality. The direction tracing technology can keep the beam and polarization direction of the antenna of the transmitting and receiving end aligned instantly, which can be regarded as the beam forming of the energy transmitting antenna array in the far field.

[0003] For directional MPT technology based on direction tracing, since the beacon signal and energy amplitudes differ greatly, once the energy leaks into the receiving channel of the beacon signal, the beacon signal cannot be recognized normally, and direction tracing is out of the question. Therefore, the beacon signal and energy need to have a very high degree of isolation. Directional tracing technology based on mixers mostly uses the method of transmitting and receiving frequency doubling. The system is completely composed of microwave devices. This method can essentially isolate the beacon signal and energy. However, the traditional direction tracing technology based on transmitting and receiving frequency doubling based on mixers has the following shortcomings:

[0004] (1) The energy transmitting antennas are spaced relatively large, which limits the backtracking angle. Since the frequency of the energy transmitting antenna is twice that of the beacon antenna, the electrical length spacing of the energy transmitting antenna subarray is twice that of the beacon antenna. According to antenna array theory, the larger the spacing between units, the smaller the beam scanning angle.

[0005] (2) Since part of the RF input signal will leak to the intermediate frequency end, this signal will interfere with the phase-conjugated signal and affect the system performance.

[0006] (3) The system is complex, which increases the number of mixers used and is costly. Summary of the invention

[0007] In view of the shortcomings existing in the prior art, the purpose of the present invention is to provide a low-cost long-distance direction tracing system for mobile targets. In the process of energy transmission, a new type of low-cost direction tracing technology with a wide tracing angle based on a mixer is used to supply energy to the mobile target. The energy transmission direction can be determined according to the beacon signal when the target position is uncertain, thereby realizing low-cost, wide-tracing-angle directional microwave energy transmission and reducing the system volume. By proposing a new type of direction tracing technology, phase conjugation and frequency doubling are realized on the same mixer, which can reduce the number of mixers in the traditional direction tracing system, thereby reducing the system cost. Then, phase compensation is performed through the layout of the energy transmitting antenna, so that the energy beam at the transmitting end of the system can be pointed to the receiving end in real time, thereby realizing energy transmission to the mobile target. In order to achieve the above-mentioned purpose and other advantages according to the present invention, a low-cost long-distance direction tracing system for mobile targets is provided, including:

[0008] A transmitter, the transmitter comprising a beacon signal receiving antenna, a four-channel phase conjugation circuit connected to the beacon signal receiving antenna signal, and an energy transmitting antenna;

[0009] The four-channel phase conjugation circuit includes a low noise amplifier connected to the beacon signal receiving antenna signal, a mixer connected to the low noise amplifier signal, and a local oscillator module connected to the mixer signal;

[0010] A receiver, the receiver comprising a filter module and a beacon signal transmitting antenna and a rectifying antenna connected to the filter module signal;

[0011] The beacon signal frequency at the beacon signal receiving antenna is a first frequency value;

[0012] The energy transmission frequency at the energy transmission antenna is the second frequency value, and the first frequency value is in a two-fold frequency relationship with the second frequency value. The beacon signal frequency is 5.6 GHz, and the energy frequency is 11.2 GHz. The beacon signal and the energy transmission frequency are in a two-fold frequency relationship, which has a certain degree of isolation, and the 11.2 GHz frequency rectifying antenna can take into account both miniaturization and high efficiency.

[0013] The beacon signal is a 5.6GHz left-hand circularly polarized wave, and the energy transmission is a 11.2GHz right-hand circularly polarized wave. The polarization directions of the two are orthogonal, which can further improve the isolation, and the circularly polarized rectenna does not require polarization alignment.

[0014] The beam scanning angle of the energy transmitting antenna is the tracing angle of the direction tracing MPT system. In order to be able to traverse within ±30°, the beam scanning angle of the energy transmitting antenna should be greater than ±30°.

[0015] The 5.6GHz beacon signal receiving antenna is a 1×4 array, and the 4 channels are fed in phase through a 1-to-4 power divider. The antenna is composed of two layers of dielectric plates and one layer of air layer. The top layer is a radiation patch, and the bottom layer is a feed line, which is coupled and fed through an I-shaped gap. Using the perturbation method, the two symmetrical corners of the radiation patch are cut off to achieve circular polarization characteristics, and the four-channel consistency of the direction tracing system is guaranteed through the antenna array.

[0016] The 11.2GHz energy transmitting antenna is a 4×4 array antenna composed of two layers of dielectric plates, both of which are 0.8mm thick. The top layer is a radiation patch, the bottom layer is a feeding network, and the middle is a ground plate, which is fed by slot coupling. The antenna array consists of 4 1×4 linear arrays, each of which is composed of 4 circularly polarized microstrip antenna units fed in series, and the spacing between antenna units is 0.68λ0. The circular polarization characteristics are achieved by cutting the angle on the radiation patch for micro-perturbation, and the open branches in the feeding network are used to adjust the matching characteristics.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The beacon signal and the energy signal of the present invention have a frequency doubling relationship, which can essentially isolate the two and improve the isolation degree.

[0019] By applying antenna arrays with different polarizations, the polarization directions of the beacon signal and the energy signal are made orthogonal, thereby further improving the isolation, and the circularly polarized rectenna does not require polarization alignment.

[0020] Through the new direction tracing system, the spacing between the energy transmitting antenna elements is reduced, and a wider tracing angle can be achieved. The system beam scanning angle is greater than ±30°, and the large-angle scanning provides more stable energy for mobile targets.

[0021] The phase conjugation circuit in the direction tracing system uses the same mixer to realize phase conjugation and frequency conversion, so that the leakage signal generated by the poor isolation of the mixer is different from the frequency of the phase conjugated signal, avoiding the interference of the leakage signal on the phase conjugated signal, avoiding the addition of equipment to improve isolation, and reducing system complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of single-channel energy transmission of a low-cost long-distance direction tracing system for a mobile target according to the present invention;

[0023] Figure 2 A diagram of a beacon signal receiving antenna for a low-cost long-distance direction tracing system for a mobile target according to the present invention;

[0024] Figure 3The energy transmitting array antenna diagram of the low-cost long-distance direction tracing system for mobile targets according to the present invention;

[0025] Figure 4 It is a working principle diagram of a phase conjugation circuit of a low-cost long-distance direction tracing system for a mobile target according to the present invention;

[0026] Figure 5 A flowchart of the transmitting end of a long-distance direction tracing system is provided for an embodiment of the low-cost long-distance direction tracing system for a mobile target according to the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Reference Figure 1 , a low-cost long-distance direction tracing system for mobile targets. When the receiving end needs to be powered, the beacon signal is sent to the transmitting end through the beacon antenna. After the beacon antenna at the transmitting end receives the beacon signal, it is input into the phase conjugation circuit for mixing and phase conjugation. The local oscillator module is then used to provide the mixer with the same phase local oscillator signal, and the electromagnetic wave with the opposite phase to the input end is output and the energy is traced back to the receiving end through the energy transmitting antenna. The rectifying antenna at the receiving end captures and rectifies it, and finally DC energy can be obtained for power supply. Specifically including:

[0029] A transmitter, the transmitter comprising a beacon signal receiving antenna, a four-channel phase conjugation circuit connected to the beacon signal receiving antenna signal, and an energy transmitting antenna;

[0030] The four-channel phase conjugation circuit includes a low noise amplifier connected to the beacon signal receiving antenna signal, a mixer connected to the low noise amplifier signal, and a local oscillator module connected to the mixer signal;

[0031] A receiver, the receiver comprising a filter module and a beacon signal transmitting antenna and a rectifying antenna connected to the filter module signal;

[0032] The beacon signal frequency at the beacon signal receiving antenna is a first frequency value; the energy transmitting frequency at the energy transmitting antenna is a second frequency value, and the first frequency value and the second frequency value are in a double frequency relationship. The specific beacon signal receiving antenna is used to receive f0 = 5.6G beacon signals, and the phase conjugation circuit realizes phase conjugation and mixing functions on a mixer, wherein the low noise amplifier is used to amplify the beacon signal, and the mixer is used to realize double frequency and phase conjugation. The power divider in the local oscillator module is used to divide the f2 = 16.8GHz local oscillator signal into 4 channels, so that the voltage-controlled oscillator with an oscillation frequency of 16.8GHz provides the same-phase local oscillator signal for the mixers of the 4 channels, and the energy transmitting antenna transmits the f3 = 11.2GHz high-frequency signal to the receiving antenna in the form of electromagnetic waves. In the receiver: the beacon signal transmitting device sends the f0 = 5.6GHz beacon signal to the transmitting end, and the rectifying antenna array receives the high-frequency signal transmitted from the transmitting antenna to the receiver, captures the f3 = 11.2GHz electromagnetic wave and rectifies it to obtain DC energy.

[0033] The technical principle of the present invention is: in the direction tracing system for mobile targets, a new type of mixer-based wide tracing angle low-cost direction tracing technology is proposed in the transmitter part, which can be used for the same-direction energy transmission of mobile targets, and in the process of realizing the direction tracing of a single channel in this system, phase conjugation and double frequency are realized on the same mixer, and then phase compensation is performed through the layout of the energy transmitting antenna. Compared with the traditional direction tracing technology, the use of the mixer is reduced, and the cost is reduced. The phase conjugation circuit is optimized, and the array element spacing of the energy transmitting antenna is reduced, so a wider tracing angle can be achieved. In addition, since phase conjugation and frequency conversion are realized on the same mixer, the leakage signal generated due to the poor isolation of the mixer is different from the signal frequency of the phase conjugation, and the leakage signal will not interfere with the phase of the phase conjugation signal, and no additional isolation reduction is required, which indirectly reduces the cost.

[0034] The phase conjugation circuit, the phase conjugation circuit of a single channel is composed of a low noise amplifier (Low Noise Amplifier, LNA), a mixer (Mixer) and a local oscillator module. The low noise amplifier is used to amplify the beacon signal, and the mixer is used to achieve double frequency and phase conjugation. The beacon signal f0 (5.6GHz) is input into the low noise amplifier, and after amplification, it is input into the mixer. At the same time, the VCO with an oscillation frequency of 16.8GHz in the local oscillator module is used to divide the 16.8GHz local oscillator signal into 4 channels through a 1-to-4 power divider to provide a local oscillator signal for a mixer of 4 channels. After mixing and phase conjugation, a 2f0 (11.2GHz) signal is output to achieve frequency doubling between signals. The direction tracing system requires two RF sources, one is the transmitting source of the beacon signal at the receiving end, with a frequency of 5.6GHz, and the other is the local oscillator signal source of the mixer at the transmitting end, with a frequency of 16.8GHz. Since the performance of this system has high requirements on the phase, a high-phase-stable coaxial cable and a connector with high consistency are required for the connection between the components.

[0035] Reference Figure 4 , the circuit structure and working principle of the application embodiment of the present invention are further described.

[0036] like Figure 4 As shown in the figure, in the long-distance directional tracing system, if the beacon signal is incident at an angle of θ, assuming that the frequency of the beacon antenna is f0 and the spacing is d, the phases of the beacon signals received by the antenna units of the two beacon signals are 0 and Then the phase difference of the beacon signal is: The signal frequency provided by the local oscillator module is 3f0, and the beacon signal frequency after the mixer is 2f0, and the phases are 0, At this time, the phase difference between the two signals is: The frequency of the energy transmitting antenna is 2f0, and the spacing is d / 2, which is the same as the electrical length of the beacon antenna unit spacing. The spatial phase difference of the energy transmitting antenna at angle θ is At this time, the sum of the spatial phase difference of the energy transmitting antenna and the feeding phase difference is 0, that is, the energy beam points to the incident direction of the beacon signal. The rectenna array is used to receive electromagnetic waves in the corresponding direction to complete directional energy transmission, thus completing the direction tracing of the moving target. Since the direction of the electromagnetic wave received by the rectenna is determined by the incoming wave direction of the beacon signal, the position of the beacon signal transmitting antenna is consistent with the rectenna array.

[0037] For the above-mentioned long-distance direction tracing system, Figure 5 It is a schematic diagram of the signal transmission process applicable to the long-distance direction tracing system of the present invention.

[0038] (1) The beacon signal transmitting antenna at the receiving end generates a signal f0 with a frequency of 5.6 GHz;

[0039] (2) Signal f0 is received by the 1×4 beacon antenna and enters the four channels of the phase conjugation circuit. The power is increased by the noise amplifier. The high-power signal f1 remains unchanged in frequency and is input to port 1 of the mixer. The f2 input by the local oscillator module is input to port 2 of the mixer.

[0040] (3) The two signals pass through the mixer to achieve phase conjugation and frequency conversion, and the output frequency is 11.2 GHz signal f3;

[0041] (4) The high-power signal f3 is transmitted to the energy transmitting antenna, which transmits the signal in the form of electromagnetic waves;

[0042] The receiving end rectifier antenna array receives the high-frequency signal transmitted in the corresponding direction, captures the 11.2GHz electromagnetic wave and rectifies it to obtain DC energy. The direction of the signal received by the rectifier antenna is consistent with the direction of the beacon signal transmission, which can realize long-distance directional tracing for mobile targets.

[0043] The number of devices and processing scales described here are used to simplify the description of the present invention, and the application, modification and variation of the present invention will be obvious to those skilled in the art.

[0044] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A low-cost long-distance direction tracing system for mobile targets, characterized in that: include: A transmitter, the transmitter comprising a beacon signal receiving antenna, a four-channel phase conjugation circuit signal-connected to the beacon signal receiving antenna, and an energy transmitting antenna signal-connected to the phase conjugation circuit; The four-channel phase conjugation circuit includes a low noise amplifier connected to the beacon signal receiving antenna signal, a mixer connected to the low noise amplifier signal, and a local oscillator module connected to the mixer signal; A receiver, the receiver comprising a filter module and a beacon signal transmitting antenna and a rectifying antenna connected to the filter module signal; The beacon signal frequency at the beacon signal receiving antenna is a first frequency value; The energy transmission frequency at the energy transmission antenna is a second frequency value, and the first frequency value and the second frequency value are in a double frequency relationship.

2. A low-cost long-distance direction tracing system for a mobile target as claimed in claim 1, characterized in that: The beacon signal receiving antenna is a 1×4 right-hand circularly polarized antenna array that receives 5.6GHz signals and feeds four channels in phase through a 1-to-4 power splitter.

3. A low-cost long-distance direction tracing system for a mobile target as claimed in claim 1, characterized in that: The energy transmitting antenna is a 4×4 array left-hand circularly polarized antenna, and the energy transmitting antenna is an 11.2 GHz energy transmitting antenna.

4. A low-cost long-distance direction tracing system for a mobile target as claimed in claim 3, characterized in that: The left-hand circularly polarized antenna is composed of four 1×4 linear arrays, each of which is composed of four circularly polarized microstrip antenna units fed in series, and the spacing between the antenna units is 0.68λ0.

5. A low-cost long-distance direction tracing system for a mobile target as claimed in claim 1, characterized in that: The local oscillator module includes a power divider and a voltage-controlled oscillator, and a VCO with an oscillation frequency of 16.8 GHz provides local oscillator signals of the same phase to mixers of four channels through a 1-to-4 power divider.

6. A low-cost long-distance direction tracing method for a mobile target as described in any one of claims 1 to 5, characterized in that: The following steps are involved: A signal f0 with a frequency of 5.6 GHz is generated by a beacon signal transmitting antenna; The beacon signal transmitting antenna receives the signal f0, which enters the four channels of the phase conjugation circuit, and is increased in power by the noise amplifier. The high-power signal f1 remains at the same frequency and is input to the first port of the mixer. The f2 input by the local oscillator module is input to the second port of the mixer. The high power signal f1 and the local oscillator module input f2 are passed through the mixer to achieve phase conjugation and frequency conversion, and then the output frequency is 11.2GHz signal f3; The high-power signal f3 is transmitted to the energy transmitting antenna, which transmits the signal in the form of electromagnetic waves; The rectenna receives high-frequency signals transmitted in the corresponding direction, captures the 11.2GHz electromagnetic wave, rectifies it and filters it to obtain DC energy. The direction of the signal received by the rectenna is consistent with the direction of the beacon signal transmission. The long-distance direction alignment for mobile targets is achieved according to the beacon signal transmitted by the receiving end of the receiver.

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