A multi-mode circularly polarized radio frequency transceiver with radar and communication functions

Abstract

The invention discloses a multi-mode circularly polarized radio frequency transceiver with radar and communication functions, comprising a 90-degree coupler for separating left and right circularly polarized signals, a local oscillator module and two transceiver modules; the local oscillator module is used to perform phase shifting, frequency multiplication, amplification and I / Q splitting on an input reference frequency signal, and send the generated orthogonal local oscillator signal to the two transceiver modules; each transceiver module comprises a transmitting part and a receiving part; each transceiver module can switch between a transmitting mode and a receiving mode, and the local oscillator module simultaneously sends the local oscillator signal to the transmitting part and the receiving part of the two transceiver modules; the 90-degree coupler comprises two output ports and two input ports; one transceiver module is connected to an output port of a 90-degree coupler.

Description

Technical Field

[0001] The invention belongs to the field of communication technology, and in particular relates to a multi-mode circularly polarized radio frequency transceiver with radar and communication functions. Background Art

[0002] Radar detection and wireless communication are the two main uses of RF transceiver chips. Both RF transceiver chips have two major functions: one is to receive and the other is to transmit. The transmission function is to generate electromagnetic signals required for radar or communication within a given frequency range and transmit them to free space via the antenna. The reception function is to amplify, frequency-convert, phase-shift and other operations on the electromagnetic signals received by the antenna, and convert them into low-frequency baseband analog signals, which are then sent to the analog-to-digital converter for sampling as digital signals.

[0003] Radar detection and wireless communication transceivers have many different performance requirements: For radar transceivers, receiving and transmitting must be turned on at the same time. The power of the transmitted electromagnetic signal is often about 80dB (100 million times) higher than the received signal. Therefore, the interference of the transmitted signal on the received signal is the biggest challenge faced by radar transceivers. In radar transceivers, in order to solve this problem, there are mainly two solutions:

[0004] 1. Dual antenna solution

[0005] As the name implies, the dual-antenna solution is to separate the transmitting and receiving parts of the transceiver in physical space, and use two isolated antennas for transmission and reception respectively. Although this solution has good isolation performance, compared with the single-antenna solution that integrates transmission and reception, considering that the two antennas need to maintain a certain distance, the antenna area required is more than twice that of the single-antenna solution.

[0006] The disadvantages of the dual-antenna solution are more prominent in phased array radars. Usually, a single radar transceiver can only measure the distance to the target and the speed at which the target moves away from or approaches itself. In order to determine the direction of the target, the radar transceiver often adopts a phased array working mode, that is, multiple radar transceivers are arranged at a certain distance on a one-dimensional straight line, or arranged in a grid on a two-dimensional plane. Phased array radar can measure the direction information of the target by the different times at which the same signal arrives at different radar transceivers in the array. The detection accuracy of the target direction is often related to the area covered by the radar transceiver array antenna (or called the aperture). The larger the aperture, the more accurate the direction measurement of the target. When a dual-antenna solution is used to form a phased array radar, its transmitting antenna and receiving antenna can only occupy a part of the entire antenna aperture. Compared with a single-antenna radar transceiver phased array with the same aperture, but each antenna has receiving and transmitting functions, its direction detection capability is worse. Under a given antenna aperture, the dual-antenna solution cannot give full play to its due direction detection capability.

[0007] 2. Electrically balanced duplexer

[0008] The basic principle of the electrical balanced duplexer (van Liempd, Barend, Benjamin Hershberg, Saneaki Ariumi, Kuba Raczkowski, Karl-Frederik Bink, Udo Karthaus, and others, 'A+70-DBm IIP3 Electrical-Balance Duplexer for Highly Integrated Tunable Front-Ends', IEEE Transactions on Microwave Theory and Techniques, 64.12 (2016), 4274–86) is to split the transmitted radar signal into two parts, one part flows into the balanced end resistor and is dissipated, and the other part flows into the antenna and is transmitted, and the antenna end and the balanced end are kept symmetrical; the radar signal transmitted by the antenna hits the detected object and is reflected back, and this radar echo is received by the antenna again. Obviously, the balanced end will not receive the radar echo, so the antenna end and the balanced end have an asymmetric difference due to the antenna's received signal. In the receiving part of the radar, the difference signal between the antenna and the balanced end is taken out through the induction coil and other devices on the chip to obtain the radar receiving signal. In this process, the transmission signal does not produce a difference because the antenna and the balanced end maintain symmetry, so it will not flow into the radar receiving part to cause interference.

[0009] The disadvantages of the electric balancer are obvious. In the transmitting part, it first wastes half of the power at the balanced end. In the receiving part, the difference method adopted can only get half of the received power. This is because the difference is actually to sense the part of the antenna end that is higher than the average power at both ends, and half of the received signal is actually used to push up the average power at both ends. The part of the antenna end that is higher than the average power is only the other half of the received signal. From the above analysis, it can be seen that in the entire process of radar detection, the electric balanced duplexer achieves isolation between the transmitting signal and the receiving signal at the cost of losing half of the power twice (i.e. -6dB loss).

[0010] Compared with radar detection, the RF transceiver used for wireless communication does not necessarily need to receive and transmit communication signals at the same time. At present, the mainstream communication transceiver working modes are time division duplex (TDD) and frequency division duplex (FDD). In addition, there is a full-duplex (FD) working mode that transmits and receives information at the same time, which is similar to the working mode of radar. In the full-duplex mode, the interference of high-power transmission signals on weak reception signals is still the main difficulty.

[0011] Time division duplex is a mode of operation in which the transmission function and the reception function are enabled at different times. The antenna is only responsible for transmitting or receiving communication signals at the same time, thus avoiding interference between the transmission signal and the reception signal. However, this communication mode is obviously not applicable to scenarios requiring real-time two-way communication. Moreover, its average two-way communication rate within a certain period of time is about half lower than that of the communication mode in which transmission and reception work at the same time.

[0012] Frequency division duplex is a mode of operation in which communication signals are transmitted and received simultaneously, but the operating frequency bands of the two are staggered. The antenna is electrically connected to the transmitting module and the receiving module respectively using radio frequency filters. The two radio frequency filters only allow the communication signals of the transmitting and receiving frequency bands to pass through. Therefore, the transmitting signal is isolated from the receiving module by the filter, and the receiving signal received by the antenna will not enter the transmitting module to cause loss. The disadvantage of frequency division duplex is that it requires two different operating frequency bands. In order to achieve sufficient isolation between transmission and reception, a certain frequency interval needs to be maintained between the two operating frequency bands. Therefore, the frequency range required by the entire transceiver system is more than twice that of other working modes. In reality, the frequency band of free space is a very valuable resource, and most civilian frequency bands require a high licensing fee to use. Therefore, the communication mode of frequency division duplex has low spectrum efficiency and economic benefits.

[0013] Compared with time division duplex and frequency division duplex, full-duplex communication is similar to the radar working mode, that is, receiving and sending signals in the same frequency band at the same time. Therefore, full-duplex communication has the advantages of low latency, fast two-way communication rate, and high spectrum efficiency compared with the aforementioned time division duplex and frequency division duplex. The difficulties faced by full-duplex communication transceivers are the same as those faced by the aforementioned radar transceivers, and both need to solve the strong interference of the transmitted signal to the receiving module in the same frequency band. Therefore, the dual antenna scheme and the electrically balanced duplexer scheme used in radar can both be used in full-duplex working mode. The disadvantages of both are the same as those of radar use, which have been described in the previous article. In addition to the two full-duplex schemes described in the previous article, there is also a linear polarization diversity full-duplex communication scheme that is only applicable to full-duplex communication.

[0014] Plane electromagnetic waves propagating in free space can be divided into horizontal polarization and vertical polarization according to linear polarization. The difference between the two lies in whether the electric field in the electromagnetic wave oscillates in the horizontal direction or in the vertical direction. Whether the antenna transmits horizontally polarized or vertically polarized electromagnetic signals depends on whether the two poles of the antenna are placed horizontally or vertically. Configuring the transmitting and receiving modules in two linear polarization directions and using antennas compactly placed in the two polarization directions is a full-duplex communication solution using linear polarization diversity.

[0015] Full-duplex communication with linear polarization diversity (T.Dinc, A.Chakrabarti, and H.Krishnaswamy, "A 60GHz CMOS Full-Duplex Transceiver and Link with Polarization-Based Antenna and RF Cancellation," IEEE Journal of Solid-State Circuits, vol.51, no.5, pp.1125–1140, May 2016, doi:10.1109 / JSSC.2015.2507367.) The transmitting and receiving antennas are arranged closely together. According to the different feeder positions, the two antennas transmit or receive electromagnetic signals in two perpendicular polarization directions, so the interference between them is greatly reduced. However, when two identical transceivers communicate face to face (T.Chi, J.S. Park, S.Li, and H.Wang, “A Millimeter-Wave Polarization-Division-Duplex Transceiver Front-End With an On-Chip Multifeed Self-Interference-Canceling Antenna and an All-Passive Reconfigurable Canceller,” IEEE Journal of Solid-State Circuits, vol.53, no.12, pp.3628–3639, Dec.2018, doi:10.1109 / JSSC.2018.2878823.), the angle between the two transceivers must be strictly 90 degrees. This ensures that the transmitting antenna of one transceiver and the receiving antenna of another transceiver are in the same direction, and the linearly polarized communication signal emitted by the transmitting antenna can be smoothly received by the receiving antenna. This greatly restricts the actual scenario of this solution. On the other hand, when most objects are irradiated by plane electromagnetic waves, the reflected electromagnetic waves do not change their linear polarization direction, and the receiving antenna in another linear polarization direction cannot receive the electromagnetic signal reflected by the object. Therefore, the linear polarization scheme cannot be used for radar purposes.

[0016] In summary, for radar transceivers and communication transceivers, there is currently no integrated RF transceiver chip solution that does not increase additional losses, significantly reduces the strong interference of the transmitted signal to the receiving module, and can simultaneously transmit and receive two-way communications and have both radar and communication functions. Summary of the invention

[0017] The present invention provides a multi-mode circularly polarized radio frequency transceiver with radar and communication functions, the purpose of which is to be used for radar detection and full-duplex or time-division duplex communication without introducing additional power loss and requiring independent antennas for receiving and transmitting.

[0018] The present invention is achieved by at least one of the following technical solutions.

[0019] A multi-mode circularly polarized radio frequency transceiver with radar and communication functions, comprising a first 90-degree coupler, a local oscillator module and two transceiver modules; the local oscillator module is used to phase shift, frequency multiplication, amplification and I / Q splitting of an input reference frequency signal, and send the generated orthogonal local oscillator signal to the two transceiver modules;

[0020] Each transceiver module includes a transmitting part and a receiving part; each transceiver module switches between a transmitting mode and a receiving mode, and the local oscillator module simultaneously sends a local oscillator signal to the transmitting part and the receiving part of the two transceiver modules;

[0021] The first 90-degree coupler includes two output ports and two input ports, and the two transceiver modules are respectively connected to the output ports of the first 90-degree coupler.

[0022] Furthermore, the local oscillator module includes a first power amplifier, a first quadruple frequency multiplier connected to the first power amplifier, and two amplification routes connected to the first quadruple frequency multiplier.

[0023] Furthermore, the two amplification routes each include a phase shifter, a second power amplifier, a second quadrupler, and a third power amplifier connected in sequence; the output end of the first quadrupler is respectively connected to the phase shifter of each amplification route, and the third power amplifier of each amplification route is respectively connected to the second 90-degree coupler of the respective amplification line.

[0024] Furthermore, the 90-degree coupler includes two metals and four ports; the two metals are parallel at a set interval and form a coupling line at a distance of a quarter wavelength, and the middle of the coupling line crosses to exchange the routing directions; the magnetic field and the electric field of the coupling line are coupled to each other;

[0025] Two metals are arranged in parallel at a set interval of a quarter wavelength to form a coupling line, and cross in the middle of the coupling line to exchange the routing directions; the magnetic field and electric field of the coupling line are coupled to each other.

[0026] Further, when the signal enters the first port of the 90-degree coupler, the signal will be output from the second port and the third port of the 90-degree coupler, the second port and the third port output signal amplitudes are the same, the third port output signal lags 90 degrees compared with the second port, and the fourth port has no signal output;

[0027] When the second port and the third port are connected to two sets of feed lines of the circularly polarized antenna, the signal input to the first port will pass through the second port and the third port and make the circularly polarized antenna radiate left-handed polarized electromagnetic waves;

[0028] When the signal is input into the coupler from the fourth port of the 90-degree coupler, the signal is output from the second port and the third port with equal amplitude. At this time, the phase of the second port lags 90 degrees compared with the third port, and there is no signal output at the first port. After connecting to the circularly polarized antenna, the electromagnetic wave radiated will be right-handed polarized.

[0029] Furthermore, the transmitting part includes an up-converter and a radio frequency power amplifier; the receiving part includes a low noise amplifier and a down-converter; the local oscillator module multiplies the input reference frequency signal by 16 times, shifts the phase, amplifies, and splits the input reference frequency signal into two paths of I / Q, and outputs the local oscillator or radar signal to the two transceiver modules respectively;

[0030] When the transceiver module is in the radar transmission mode, the radar signal received from the local oscillator module is output to the corresponding first 90-degree coupler port through the RF power amplifier; when the transceiver module is in the communication transmission mode, the local oscillator signal received from the local oscillator module is mixed with the input I and Q two-way differential input data signals through the up-converter to form a RF communication signal, which is then output to the corresponding first 90-degree coupler port through the RF power amplifier;

[0031] When the transceiver module is in radar or communication reception, the RF receiving signal received from the corresponding first 90-degree coupler port is amplified by the low-noise amplifier and sent to the down-converter, and mixed with the local oscillator or radar signal received from the local oscillator module to form I and Q baseband output signals.

[0032] Furthermore, it can be switched to two radar modes, two full-duplex communication modes and two time-division duplex communication modes according to the usage.

[0033] Furthermore, radar mode 1: a low-frequency reference radar frequency sweep signal is input to the local oscillator module, and the signal is formed into a radar transmission signal through frequency multiplication and amplification of the local oscillator module; the baseband signal input of the two transceiver modules is turned off, and the first transceiver module connected to the first port of the first 90-degree coupler is switched to the transmission mode, and the second transceiver module connected to the fourth port is switched to the receiving mode; the radar frequency sweep signal sent by the local oscillator module to the first transceiver module connected to the first port is amplified by the RF power amplifier through the up-converter and output to the first port of the first 90-degree coupler; the frequency sweep radar signal passes through the first port of the first 90-degree coupler to drive the antenna to transmit a left-handed polarized frequency sweep radar signal; after encountering an external detection target, the electromagnetic signal is reflected and becomes a right-handed polarized signal;

[0034] At the same time, the second transceiver module connected to the fourth port is switched to the receiving mode. After the right-hand polarized signal irradiated to the antenna is received by the antenna, the signal is finally gathered at the fourth port. The signal is amplified by the low-noise amplifier of the second transceiver module and mixed by the down-converter, and finally forms the I and Q two-way baseband differential signals as the output of the radar mode of the whole system, which can be connected to the external digital-to-analog converter for sampling to obtain the digital signal;

[0035] Radar mode 2: Input a low-frequency reference radar sweep signal to the local oscillator module, which forms a radar transmission signal through frequency multiplication and amplification of the local oscillator module; turn off the calculation signal input of the two transceiver modules, and switch the second transceiver module connected to the fourth port of the first 90-degree coupler to the transmission mode. The radar sweep signal provided by the local oscillator module to the second transceiver module passes through the up-converter and the RF power amplifier to the fourth port of the first 90-degree coupler. The transmitted radar sweep signal passes through the first 90-degree coupler and the antenna and is transmitted to the free space in the form of right-hand polarization; the left-hand polarization signal generated by the target reflection is received by the antenna and converged to the first port by the first 90-degree coupler. The first transceiver module connected to the first port switches to the receiving mode, and the signal is amplified by the low-noise amplifier of the first transceiver module and mixed with the radar transmission signal from the local oscillator module in the down-converter to form I and Q baseband differential output signals. The output signal can be sampled by an external digital-to-analog converter to obtain a digital signal.

[0036] Furthermore, full-duplex communication mode 1: a fixed-frequency low-frequency reference signal is input to the reference frequency end of the local oscillator module, the first transceiver module connected to the first port is switched to the transmission mode, the reference frequency end of the local oscillator module inputs a fixed-frequency signal as a communication local oscillator, the first transceiver module connected to the fourth port is switched to the transmission mode, and the I and Q two-way communication baseband signals to be sent are input to the transceiver module, the communication baseband signal is mixed with the local oscillator signal output by the local oscillator module in the up-converter of the first transceiver module, thereby forming a communication RF signal, which is then transmitted to the first port of the first 90-degree coupler through the RF power amplifier of the transceiver module, and the communication signal is converted into a left-handed polarized electromagnetic wave communication signal for external transmission;

[0037] At the same time, the second transceiver module connected to the fourth port is switched to the receiving mode. After the right-handed polarized communication signal irradiated to the antenna is received by the antenna, the signal converges at the fourth port of the first 90-degree coupler, and is transmitted to the second transceiver module connected to the fourth port through the fourth port. The signal is amplified and down-converted by the second transceiver module into I and Q baseband signal differential outputs. The output signal can be sampled and calculated by the digital-to-analog converter to obtain the communication signal modulated in the right-handed polarized electromagnetic wave received;

[0038] Full-duplex communication mode 2: A fixed-frequency signal is input to the reference frequency end of the local oscillator module as the communication local oscillator. The second transceiver module connected to the fourth port is switched to the transmitting mode, and the I and Q baseband communication signals to be transmitted are input to the transceiver module. After modulation and amplification by the up-converter and the RF power amplifier, the transmitting communication signal is transmitted into the free space by the antenna with right-hand polarization. At the same time, the transceiver module connected to the first port is switched to the receiving mode, and the left-hand polarized communication signal received by the antenna is amplified and down-converted into I and Q baseband signal outputs by the receiving mode of the second transceiver module through the first port.

[0039] Furthermore, in the time division duplex transmission mode: a fixed-frequency communication local oscillator signal is input into the reference frequency port of the local oscillator module, and both transceiver modules are switched to the transmission mode, and different baseband data signals are input into each of the two transceiver modules. The two transceiver modules will up-convert their respective baseband data signals and amplify them through the RF power amplifier to become two different RF signals, and output them through the first port and the fourth port respectively. The RF signals of the first port and the fourth port will be converted into left-hand polarized and right-hand polarized electromagnetic signals respectively and transmitted;

[0040] Time division duplex receiving mode: The reference frequency port of the local oscillator module inputs the fixed-frequency communication local oscillator signal, and the two transceiver modules are switched to the receiving mode. The antenna simultaneously receives left-hand polarization and right-hand polarization electromagnetic signals, and outputs the two circularly polarized signals at the first port and the fourth port of the first 90-degree coupler respectively; the two transceiver modules connected to the first port and the fourth port are both in the receiving mode, and the received signals are amplified, down-converted to baseband signals and output.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The present invention has a compact structure and realizes signal transmission and reception on a pair of circularly polarized antennas at the same time. When multiple RF transceiver chips are arranged in an array for operation, all antennas are used simultaneously for both transmission and reception. Compared with a traditional RF transceiver array with the same antenna area but with the transmitting antenna and the receiving antenna placed separately, the angular resolution of the present invention is finer when used for radar purposes; when used for communication purposes, the beam focusing capability of the present invention is stronger and the communication distance is longer at the same power.

[0043] (2) When the present invention works in radar or full-duplex communication mode, compared with the radio frequency transceiver based on the electric balancer principle, it does not introduce power loss at the balanced end during the receiving and transmitting process. This makes the present invention have lower energy consumption when transmitting radio frequency signals, greater gain when receiving radio frequency signals, and longer radar detection or wireless communication distance.

[0044] (3) Compared with the traditional communication RF transceiver using frequency division duplex, the present invention uses the same frequency band for reception and transmission, and has a higher spectrum utilization rate, which is more economical in the context of having to pay frequency band authorization fees.

[0045] (4) Compared with the RF transceiver using linear polarization separation, the present invention uses circular polarization as the carrier of the radar or communication signal, so it can use the characteristic of reverse polarity when the circular polarization signal is reflected by the object to perform radar detection. This is different from the linear polarization full-duplex RF transceiver which requires the orientation of the two transceivers to strictly maintain a 90-degree angle. When performing full-duplex wireless communication, the present invention only needs the antennas of the two transceivers to face each other, and the orientation of the two transceivers does not affect the reception and transmission of circular polarization signals.

[0046] (5) Compared with the traditional time-division duplex communication transceiver, the present invention can fully utilize two circularly polarized carrier signals in the time-division communication mode to simultaneously transmit two data signals, so its information transmission rate is twice that of the traditional time-division duplex communication system. It is more suitable for one-way high-speed wireless communication scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and other objects, features and advantages of the present invention will become more apparent by describing in detail the embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0048] Figure 1 It is a structural block diagram of the radio frequency transceiver described in the present invention;

[0049] Figure 2 This is a schematic diagram of the structure of a 90-degree coupler according to an embodiment of the present invention;

[0050] Figure 3 A schematic diagram of the structure of a local oscillator module according to an embodiment of the present invention;

[0051] Figure 4 The figure is a schematic diagram of the structure of a radio frequency transceiver module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0053] like Figure 1 As shown, a multi-mode circularly polarized radio frequency transceiver with radar and communication functions of this embodiment includes a first 90-degree coupler for separating left and right circularly polarized signals, a local oscillator module, and two identical transceiver modules (a first transceiver module 1 and a second transceiver module 2). Each transceiver module includes a transmitting part and a receiving part. The transmitting part includes a radio frequency power amplifier and an up-converter, and the receiving part includes a low noise amplifier and a down-converter.

[0054] As one of the preferred embodiments, Figure 2 The chip layout of the 90-degree coupler shown in the figure has 11 layers of metal interconnects from the substrate to the chip surface. The metal layer closest to the substrate is called M1. From M1, the metal interconnect layer closer to the chip surface is called M2, and the layers are called M3 to M11 in sequence. Among them, M11 is closest to the top surface of the chip and is the outermost metal interconnect layer of the chip. Each metal interconnect layer can be designed with a metal pattern of a certain shape, and the upper and lower adjacent metal interconnects can be connected to each other through through holes. Therefore, metal interconnects of specific shapes can form different passive RF devices.

[0055] exist Figure 2 In the schematic diagram of the 90-degree coupler layout. Patterns M1 to M10 indicate that a total of ten layers of metal interconnects in the area M1, M2... to M10 are interconnected through through holes to form a metal wall for shielding. Patterns M1 to M2 indicate that the two layers of metal M1 and M2 are connected to each other, covering most of the area of ​​the 90-degree coupler to form a ground plane for the 90-degree coupling line. M10 represents a single layer of M10 metal. M11 represents a single layer of M11 metal. In the 90-degree coupler, M10 metal wires are used as electrical connections for four ports. Two M10 metal wires are parallel in the middle of the 90-degree coupler. In the middle of the parallel connection, the M10 metal wire connecting the first port 1 passes through another M10 metal wire through M11 and directly passes through the third port 3: the M10 metal wire connecting the fourth port 4 is directly exchanged to the other side and connected to the second port 2. At the same time, the metal ground planes at the bottom of the two lines are hollowed out. The spacing between the two metal wires, the spacing between the hollowed-out ground planes, and the overall length dimensions have been determined by Figure 2 By adjusting the parallel spacing between the metal lines and the width of the ground plane hollowing, proper coupling between the two metal lines can be achieved.

[0056] When the RF signal enters the 90-degree coupler from the first port 1, the signal will be output from the second port 2 and the third port 3. The output signal amplitudes of the second port 2 and the third port 3 are the same, but the output signal of the third port 3 lags 90 degrees compared with the second port 2. There is almost no signal output from the fourth port 4. Therefore, when the second port 2 and the third port 3 are connected to the two sets of feed lines of the circularly polarized antenna, the signal input to the first port 1 of the coupling line will pass through the second port 2 and the third port 3 and make the circularly polarized antenna radiate left-handed polarized electromagnetic waves; when the signal is input to the coupler from the fourth port 4, the signal is also output from the second port 2 and the third port 3 with equal amplitude. At this time, the phase is that the second port 2 lags 90 degrees compared with the third port 3, and there is almost no signal output at the first port 1, and the electromagnetic wave radiated after connecting to the circularly polarized antenna will be right-handed polarized electromagnetic waves.

[0057] Since the passive electromagnetic structure composed of the antenna and the 90-degree coupler has reciprocity, when receiving a signal, the signal will propagate in the reverse direction along the above-mentioned transmission path. When the antenna receives a left-handed polarized signal, the signal will eventually be output at the first port, and there will be no signal at the fourth port 4. When the antenna receives a right-handed polarized signal, the signal will eventually be output at the fourth port 4, and there will be no signal at the first port 1. Therefore, the 90-degree coupler can realize the separation function of the two circular polarizations.

[0058] like Figure 3 As shown, the local oscillator module includes a phase shifter, a first frequency multiplier, a second frequency multiplier, a first power amplifier, a second power amplifier, a third power amplifier and a second 90-degree coupler. All of the above structures can be produced using semiconductor technology and integrated into a chip.

[0059] As another preferred embodiment, the local oscillator module multiplies the input reference frequency signal by 16 times, phase shifts, amplifies, and splits it into two I / Q paths. After the reference frequency signal input from the outside is amplified by the first power amplifier and multiplied by the first quadrupler, it is divided into two paths and enters the phase shifter to obtain independent phases. After being amplified by the second power amplifier, multiplied by the second quadrupler, and amplified by the third power amplifier, a 16-times-of-the-input reference signal with phase shift is obtained. The two paths of the signal pass through the respective second 90-degree couplers mentioned above, and are each split into I and Q orthogonal local oscillator signals with the same power and a phase difference of 90 degrees, and are respectively input into the first transceiver module 1 and the second transceiver module 2.

[0060] When the RF transceiver is used for radar purposes, the input reference frequency signal should be a radar sweep frequency signal; when it is used for communication purposes, the reference frequency signal should be a fixed frequency signal.

[0061] Each transceiver module is a radio frequency transceiver module without a radio frequency switch. Figure 4 As shown, each transceiver module includes a transmitting part and a receiving part. The transmitting part includes an up-converter and a radio frequency power amplifier; the receiving part includes a low noise amplifier and a down-converter. When in use, the two transceiver modules of the radio frequency transceiver switch between the transmitting mode and the receiving mode respectively.

[0062] In the transmitting mode, the transmitting part is turned on, the upconverter and RF power amplifier bias voltage of the transceiver module are adjusted to the preset value, and the receiving part is turned off. At this time, the transceiver module can amplify and output the differential input I and Q communication signals or swept frequency radar signals through the RF power amplifier; in the receiving mode of the transceiver module, the bias voltage of each circuit of the transmitting part is adjusted to 0, so that the transmitting part is turned off. The bias voltage of the receiving part is adjusted to the preset value. The receiving part works normally, and the weak electromagnetic signal input from the RF port is amplified and restored to the differential output of the I and Q baseband signals by the downconverter. The output signal can be sampled by the analog / digital converter to become a digital signal.

[0063] The first port 1 and the fourth port 4 of the 90-degree coupler are respectively connected to the RF ports of the two transceiver modules (see Figure 4 ), the second port 2 and the third port 3 are connected to two feeders of the circularly polarized antenna. Each transceiver module can switch between the transmission mode and the reception mode. At the same time, the local oscillator module provides the local oscillator signal to the up-converter and down-converter of the two transceiver modules at the same time.

[0064] The RF receiver can be switched to two radar modes, two full-duplex communication modes and two time-division duplex communication modes according to the application. Radar use only requires a single RF transceiver; full-duplex or time-division duplex communication modes require two RF transceivers to communicate wirelessly with each other.

[0065] Radar Mode 1:

[0066] In this mode, a frequency sweep radar signal is input to the reference frequency end of the local oscillator module, the baseband signal input of the two transceiver modules is turned off, and the transceiver module connected to the first port 1 of the first 90-degree coupler is switched to the transmitting mode, and the transceiver module connected to the fourth port 4 is switched to the receiving mode. The radar frequency sweep signal provided by the local oscillator module to the first transceiver module 1 connected to the first port 1 is output to the first port 1 of the first 90-degree coupler after being amplified by the up-converter and the RF power amplifier. According to the principle of the first 90-degree coupler, the frequency sweep radar signal will be converted by the first 90-degree coupler into two radar signals with equal power and a phase difference of 90 degrees, which are output through the second port 2 and the third port 3, driving the antenna to transmit the left-hand polarized frequency sweep radar signal; after encountering the external detection target, the electromagnetic signal is reflected and becomes a right-hand polarized signal.

[0067] At the same time, the second transceiver module 2 connected to the fourth port 4 is switched to a receiving module. After the right-hand polarized signal irradiated to the antenna is received by the antenna, the signal is finally converged at the fourth port 4 according to the principle of the first 90-degree coupler. The signal is amplified by the low-noise amplifier of the second transceiver module 2, and the down-converter is mixed to become the I and Q baseband signals, which are differentially output to the external digital-to-analog converter. The distance information and speed information of the target are obtained after sampling and calculation by the external digital-to-analog converter. Thus, the radar function is realized.

[0068] Radar Mode 2:

[0069] This mode is opposite to the polarity of radar mode 1, and the RF transceiver transmits a right-hand polarized radar sweep signal and receives a left-hand polarized target reflection signal.

[0070] In radar mode 2, the radar sweep signal is still input to the reference frequency end of the local oscillator module, and the calculation signal input of the two transceiver modules is turned off. The difference is that the second transceiver module 2 connected to the fourth port 4 is switched to the transmission mode, and the radar sweep signal provided by the local oscillator module to the second transceiver module 2 is amplified and output through the up-converter and the RF power amplifier, and the radar sweep signal transmitted by it passes through the first 90-degree coupler and the antenna and is transmitted to the free space in the form of right-hand polarization. The left-hand polarized signal generated by the reflection of the object waiting for radar detection is received by the antenna and then converged to the first port 1 by the first 90-degree coupler. The transceiver module 1 connected to the first port 1 switches to the receiving mode, and the signal is also output to the external digital-to-analog converter as the I and Q baseband signals. The distance information and speed information of the target are obtained after sampling and calculation by the external digital-to-analog converter. Thereby realizing the radar function.

[0071] Since the polarity of the circularly polarized electromagnetic signals transmitted and received in the two modes is different, if two RF transceivers in the same environment perform radar detection at the same time, as long as the two work in different radar modes, the radar signals between them will not interfere with each other. They can work independently at the same time.

[0072] Full-duplex communication mode 1:

[0073] In full-duplex communication mode 1, a fixed frequency signal is input to the reference frequency end of the local oscillator module as a communication local oscillator. The first transceiver module 1 connected to the first port 1 is switched to the transmission mode, and the I and Q baseband communication signals generated by the external digital-to-analog converter are input to the up-converter of the transceiver module 1. After being modulated to the RF frequency by the up-converter, the two baseband signals pass through the RF power amplifier and enter the first 90-degree coupler from the first port 1. According to the principle of the aforementioned first 90-degree coupler, the communication signal is converted into a left-handed polarized communication signal for external transmission.

[0074] At the same time, the second transceiver module 2 connected to the fourth port 4 is switched to a receiving module. After the right-handed polarized communication signal irradiated to the antenna is received by the antenna, the signal is finally converged at the fourth port 4 according to the principle of the first 90-degree coupler mentioned above, and the signal is amplified and down-converted by the receiving module into I and Q two-way baseband signal differential output. The communication signal modulated in the received right-handed polarized electromagnetic wave is obtained after sampling and calculation by an external digital-to-analog converter.

[0075] In addition to being used for radar purposes, the radio frequency transceiver can also realize full-duplex wireless communication and time-division duplex wireless communication functions.

[0076] Full-duplex communication mode 2:

[0077] This mode is opposite to the full-duplex communication mode 1 polarity type. The radio frequency transceiver modulates the communication information to be sent into a right-handed polarized electromagnetic signal and simultaneously receives a left-handed polarized communication signal.

[0078] In full-duplex communication mode 2, a fixed-frequency signal is still input to the reference frequency end of the local oscillator module as a communication local oscillator. The difference is that the second transceiver module 2 connected to the fourth port 4 is switched to the transmission mode, and the I and Q two-way communication baseband signals to be sent are input to the transceiver module. Similarly, after being modulated by the up-converter and amplified by the RF power amplifier, the communication signal to be transmitted is transmitted to the free space by the antenna in right-handed polarization. At the same time, the first transceiver module 1 connected to the first port 1 is switched to the receiving mode, and the left-handed polarized communication signal received by the antenna is amplified and down-converted through the first port 1 to be output as I and Q two-way baseband signals.

[0079] When the two RF transceivers work in the above two full-duplex communication modes respectively, real-time full-duplex wireless communication between each other can be realized. One of them works in full-duplex communication mode 1, and the other works in full-duplex communication mode 2. The left-handed polarized signal transmitted by the transceiver in full-duplex communication mode 1 can be received by the transceiver in full-duplex communication mode 2, and conversely, the right-handed polarized wireless communication signal transmitted by it can also be received by the RF transceiver in full-duplex communication mode 1. The real-time full-duplex wireless communication function can be used in wireless communication scenarios where the two-way delay requirements are stringent and two-way data transmission is required.

[0080] In addition to radar applications and full-duplex communication applications, the RF transceiver can also be used for time-division duplex communication applications, in which case the RF transceiver can operate in a transmission mode and a reception mode.

[0081] Time division duplex transmission mode:

[0082] In this mode, a fixed-frequency communication local oscillator signal is input to the reference frequency port of the transceiver local oscillator module, and both transceiver modules are switched to the transmission mode. At this time, different baseband data signals can be input to each of the two transceiver modules. The two transceiver modules will up-convert and power-amplify their respective baseband data signals into two different RF signals, and output them through the first port 1 and the fourth port 4, respectively. As mentioned above, the RF signals of the first port 1 and the fourth port 4 will be converted into left-hand polarized and right-hand polarized electromagnetic signals, respectively, and transmitted. In this mode, the transceiver has twice the communication information transmission rate and no longer receives signals.

[0083] Time division duplex receiving mode:

[0084] The fixed-frequency communication local oscillator signal is still input to the reference frequency port of the transceiver local oscillator module. The time division duplex receiving mode is opposite to the time division duplex transmitting mode. The two transceiver modules of the RF transceiver are switched to the receiving mode. The antenna can simultaneously receive both left-handed polarized and right-handed polarized electromagnetic signals, and output the two circularly polarized signals at the first port 1 and the fourth port 4 of the first 90-degree coupler, respectively. The two transceiver modules connected to the first port 1 and the fourth port 4 are both in the receiving mode, amplifying the received signal, down-converting it to a baseband signal and outputting it. The output data can also be sampled by an external analog-to-digital converter to become a digital signal. In this mode, the transceiver has twice the communication information receiving rate and no longer sends a signal.

[0085] The two RF transceivers can achieve time division duplex use through the above-mentioned transmission and reception modes, one of which works in time division duplex transmission mode and the other works in time division duplex reception mode, so that two baseband communication signals can be transmitted simultaneously in two circular polarization directions.

[0086] The RF transceiver does not need to adjust the configuration hardware, and only needs to change the bias voltage of the internal circuit and the signal input type to switch between the above-mentioned 6 modes to complete the three different purposes of radar detection, full-duplex communication and time division communication.

[0087] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A multi-mode circularly polarized radio frequency transceiver with radar and communication functions, characterized in that: It includes a first 90-degree coupler, a local oscillator module, a first transceiver module and a second transceiver module; the local oscillator module is used to phase shift, frequency multiplication, amplification and I / Q splitting of the input reference frequency signal, and send the generated orthogonal local oscillator signal to the two transceiver modules; Each transceiver module includes a transmitting part and a receiving part; each transceiver module switches between a transmitting mode and a receiving mode, and the local oscillator module simultaneously sends a local oscillator signal to the transmitting part and the receiving part of the two transceiver modules; The first 90-degree coupler includes two output ports and two input ports, and the two transceiver modules are respectively connected to the output ports of the first 90-degree coupler; The 90-degree coupler includes two metals and four ports; the first port and the fourth port of the 90-degree coupler are respectively connected to the radio frequency ports of the two transceiver modules, and the second port and the third port are connected to the two feeders of the circularly polarized antenna; each transceiver module switches between the transmission mode and the reception mode; and the local oscillator module provides the local oscillator signal to the up-converter and down-converter of the two transceiver modules at the same time; When a signal enters the first port of a 90-degree coupler, the signal will be output from the second and third ports of the 90-degree coupler. The output signal amplitudes of the second and third ports are the same, and the output signal of the third port lags 90 degrees behind the second port. There is no signal output from the fourth port. When the second port and the third port are connected to two sets of feed lines of the circularly polarized antenna, the signal input to the first port will pass through the second port and the third port and make the circularly polarized antenna radiate left-handed polarized electromagnetic waves; When the signal is input into the coupler from the fourth port of the 90-degree coupler, the signal is output from the second port and the third port with equal amplitude. At this time, the phase of the second port lags 90 degrees compared with the third port, and there is no signal output at the first port. After connecting to the circularly polarized antenna, the radiation will be right-handed polarized electromagnetic waves. When the antenna receives a left-hand polarized signal, the signal will eventually be output at the first port, and there will be no signal at the fourth port. When the antenna receives a right-hand polarized signal, the signal will eventually be output at the fourth port, and there will be no signal at the first port. The 90-degree coupler realizes the separation function of the two circular polarizations. The local oscillator module includes a phase shifter, a first frequency multiplier, a second frequency multiplier, a first power amplifier, a second power amplifier, a third power amplifier and a second 90-degree coupler, all of which are produced using semiconductor technology and integrated into a chip; The local oscillator module performs 16-fold frequency multiplication, phase shifting, amplification, and I / Q two-way splitting on the input reference frequency signal. After the external input reference frequency signal is amplified by the first power amplifier and frequency multiplied by the first quadruple frequency multiplier, it is divided into two ways and enters the phase shifter to obtain independent phases. After being amplified by the second power amplifier, frequency multiplied by the second quadruple frequency multiplier, and amplified by the third power amplifier, a 16-fold frequency-shifted signal of the input reference signal is obtained. The two ways of the signal pass through the respective second 90-degree couplers mentioned above, and are each split into I and Q orthogonal local oscillator signals with the same power and a phase difference of 90 degrees, and are respectively input into the first transceiver module and the second transceiver module; When the RF transceiver is used for radar purposes, the input reference frequency signal should be a radar sweep frequency signal; when it is used for communication purposes, the reference frequency signal should be a fixed frequency signal; Each transceiver module is a radio frequency transceiver module without a radio frequency switch, and each transceiver module includes a transmitting part and a receiving part; the transmitting part includes an up-converter and a radio frequency power amplifier; the receiving part includes a low noise amplifier and a down-converter; when in use, the two transceiver modules of the radio frequency transceiver are switched between the transmitting mode and the receiving mode respectively; In the transmitting mode, the transmitting part is turned on, the upconverter and RF power amplifier bias voltage of the transceiver module are adjusted to the preset value, and the receiving part is turned off. At this time, the transceiver module amplifies and outputs the differential input I and Q communication signals or swept-frequency radar signals through the RF power amplifier; in the receiving mode of the transceiver module, the bias voltage of each circuit of the transmitting part is adjusted to 0, so that the transmitting part is turned off, and the bias voltage of the receiving part is adjusted to the preset value; the receiving part works normally, and the weak electromagnetic signal input from the RF port is amplified and restored to the differential output of the I and Q baseband signals by the downconverter. The output signal can be sampled by the analog / digital converter to become a digital signal.

2. The multi-mode circularly polarized radio frequency transceiver with radar and communication functions according to claim 1, characterized in that: The 90-degree coupler includes two metals and four ports; the two metals are parallel at a set interval and form a coupling line at a distance of one quarter wavelength, and the middle of the coupling line crosses to exchange the routing directions; the magnetic field and electric field of the coupling line are coupled to each other; Two metals are arranged in parallel at a set interval of a quarter wavelength to form a coupling line, and cross in the middle of the coupling line to exchange the routing directions; the magnetic field and electric field of the coupling line are coupled to each other.

3. A multi-mode circularly polarized radio frequency transceiver with radar and communication functions according to any one of claims 1 to 2, characterized in that: Depending on the application, it can be switched to two radar modes, two full-duplex communication modes, and two time-division duplex communication modes.

4. The multi-mode circularly polarized radio frequency transceiver with radar and communication functions according to claim 3, characterized in that: Radar mode 1: Input a low-frequency reference radar sweep signal to the local oscillator module, which is multiplied and amplified by the local oscillator module to form a radar transmit signal; turn off the baseband signal input of the two transceiver modules, switch the first transceiver module connected to the first port of the first 90-degree coupler to the transmit mode, and switch the second transceiver module connected to the fourth port to the receive mode; The radar frequency sweep signal sent by the local oscillator module to the first transceiver module connected to the first port is amplified by the RF power amplifier through the up-converter and then output to the first port of the first 90-degree coupler; the frequency sweep radar signal passes through the first port of the first 90-degree coupler to drive the antenna to transmit the left-hand polarized frequency sweep radar signal; After encountering an external detection target, the electromagnetic signal is reflected and becomes a right-hand polarized signal; At the same time, the second transceiver module connected to the fourth port is switched to the receiving mode. After the right-hand polarized signal irradiated to the antenna is received by the antenna, the signal is finally gathered at the fourth port. The signal is amplified by the low-noise amplifier of the second transceiver module and mixed by the down-converter, and finally forms the I and Q two-way baseband differential signals as the output of the radar mode of the whole system, which can be connected to the external digital-to-analog converter for sampling to obtain the digital signal; Radar mode 2: input a low-frequency reference radar frequency sweep signal to the local oscillator module, and the signal is multiplied and amplified by the local oscillator module to form a radar transmission signal; close the calculation signal input of the two transceiver modules, and switch the second transceiver module connected to the fourth port of the first 90-degree coupler to the transmission mode. The radar frequency sweep signal provided by the local oscillator module to the second transceiver module is output to the fourth port of the first 90-degree coupler through the up-converter and the RF power amplifier. The transmitted radar frequency sweep signal is transmitted to the free space in the form of right-handed polarization through the first 90-degree coupler and the antenna; the left-handed polarized signal generated by the target reflection is received by the antenna and then converged to the first port by the first 90-degree coupler. The first transceiver module connected to the first port switches to the receiving mode, and the signal is amplified by the low-noise amplifier of the first transceiver module and mixed with the radar transmission signal from the local oscillator module in the down-converter to form I and Q baseband differential output signals. The output signal can be connected to an external digital-to-analog converter for sampling to obtain a digital signal.

5. The multi-mode circularly polarized radio frequency transceiver with radar and communication functions according to claim 4, characterized in that: Full-duplex communication mode 1: a fixed-frequency low-frequency reference signal is input to the reference frequency end of the local oscillator module, the first transceiver module connected to the first port is switched to the transmission mode, the reference frequency end of the local oscillator module inputs a fixed-frequency signal as the communication local oscillator, the first transceiver module connected to the fourth port is switched to the transmission mode, and the I and Q two-way communication baseband signals to be sent are input to the transceiver module, the communication baseband signal is mixed with the local oscillator signal output by the local oscillator module in the up-converter of the first transceiver module, thereby forming a communication RF signal, which is then transmitted to the first port of the first 90-degree coupler through the RF power amplifier of the transceiver module, and the communication signal is converted into a left-handed polarized electromagnetic wave communication signal for external transmission; At the same time, the second transceiver module connected to the fourth port is switched to the receiving mode. After the right-handed polarized communication signal irradiated to the antenna is received by the antenna, the signal converges at the fourth port of the first 90-degree coupler, and is transmitted to the second transceiver module connected to the fourth port through the fourth port. The signal is amplified and down-converted by the second transceiver module into I and Q baseband signal differential outputs. The output signal can be sampled and calculated by the digital-to-analog converter to obtain the communication signal modulated in the right-handed polarized electromagnetic wave received; Full-duplex communication mode 2: A fixed-frequency signal is input to the reference frequency end of the local oscillator module as the communication local oscillator. The second transceiver module connected to the fourth port is switched to the transmitting mode, and the I and Q baseband communication signals to be transmitted are input to the transceiver module. After modulation and amplification by the up-converter and the RF power amplifier, the transmitting communication signal is transmitted into the free space by the antenna with right-hand polarization. At the same time, the transceiver module connected to the first port is switched to the receiving mode, and the left-hand polarized communication signal received by the antenna is amplified and down-converted into I and Q baseband signal outputs by the receiving mode of the second transceiver module through the first port.

6. The multi-mode circularly polarized radio frequency transceiver with radar and communication functions according to claim 5, characterized in that: Time division duplex transmission mode: the reference frequency port of the local oscillator module inputs the fixed-frequency communication local oscillator signal, the two transceiver modules are switched to the transmission mode, and different baseband data signals are input to each of the two transceiver modules. The two transceiver modules will up-convert their respective baseband data signals and amplify them through the RF power amplifier to become two different RF signals, which will be output through the first port and the fourth port respectively. The RF signals of the first port and the fourth port will be converted into left-hand polarization and right-hand polarization electromagnetic signals respectively and transmitted; Time division duplex receiving mode: The reference frequency port of the local oscillator module inputs the fixed frequency communication local oscillator signal, and both transceiver modules switch to the receiving mode. The antenna simultaneously receives left-hand polarization and right-hand polarization electromagnetic signals, and outputs the two circularly polarized signals at the first port and the fourth port of the first 90-degree coupler respectively; The two transceiver modules connected to the first port and the fourth port are both in the receiving mode, amplifying the received signal, down-converting it to a baseband signal and outputting it.

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