Modular radio frequency system and method for unmanned aerial vehicles

Abstract

This invention discloses a modular radio frequency system and method for unmanned aerial vehicles (UAVs). The system includes a transmit chain, a receive chain, and a multi-level isolation unit. The transmit chain and the receive chain share the same antenna through the multi-level isolation unit, which is connected between the antenna interface, the transmit chain, and the receive chain. The multi-level isolation unit includes a first radio frequency switch, a second radio frequency switch, and an absorptive controllable attenuation unit. This application solves the problem of low isolation in the UAV's transmit and receive links, thereby significantly reducing signal leakage energy from the transmit chain to the receive chain under shared antenna conditions. This achieves the technical effect of protecting the front-end components of the receive chain from high-power signal impacts and improving the reliability of the system's transmit and receive isolation without increasing the number of antennas.

Description

Technical Field

[0001] This application relates to the field of communications, and more specifically, to a modular radio frequency system and method for unmanned aerial vehicles (UAVs). Background Technology

[0002] In wireless communication applications for unmanned aerial vehicles (UAVs), the radio frequency (RF) front-end system must maintain stable operation under conditions of high vibration, strong electromagnetic interference, limited heat dissipation, and lightweight requirements. Existing modular solutions often utilize commercially available off-the-shelf components to shorten development cycles, but these solutions reveal a series of shortcomings when integrated into actual flight platforms. Single-stage switches are used for transmit / receive switching in shared antenna paths, resulting in limited isolation capabilities and leakage of high-power signals from the transmit chain to the receive chain, causing saturation or cumulative damage to low-noise amplifiers. Faced with sudden high-power transient pulses from inside or outside the aircraft, the receive front-end lacks a rapid and controllable energy absorption and dissipation mechanism, leaving sensitive components under overstress. The lack of an integrated structure between the RF module and the UAV platform that balances electromagnetic shielding and heat conduction leads to high-frequency signal radiation leakage and localized heat accumulation. Therefore, ensuring stable isolation of the transmit / receive links, transient energy safety of front-end components, and synergy in overall electromagnetic and thermal management within a modular architecture constitutes a core technical challenge.

[0003] There is currently no effective solution to the above problems. Summary of the Invention

[0004] This application provides a modular radio frequency system and method for unmanned aerial vehicles (UAVs) to at least solve the technical problem of low isolation in the transceiver links of UAVs in related technologies.

[0005] According to one aspect of the embodiments of this application, a modular radio frequency system for an unmanned aerial vehicle (UAV) is provided, comprising: a transmitter chain, a receiver chain, and a multi-level isolation unit, wherein the transmitter chain and the receiver chain share the same antenna through the multi-level isolation unit, and the multi-level isolation unit is connected between the antenna interface, the transmitter chain, and the receiver chain; the multi-level isolation unit comprises: a first radio frequency switch, a second radio frequency switch, and an absorptive controllable attenuation unit.

[0006] In one exemplary embodiment, the transmit chain includes a power amplifier and an adjustable matching network; the receive chain includes a low-noise amplifier and a transient limiter or a controllable attenuator.

[0007] In one exemplary embodiment, the system further includes: a first terminal of the first radio frequency switch connected to the power amplifier, the power amplifier connected to the adjustable matching network, the adjustable matching network being used to receive a transmitted signal; a second terminal of the first radio frequency switch connected to the absorptive controllable attenuation unit, the absorptive controllable attenuation unit connected to the first terminal of the second radio frequency switch, and a second terminal of the second radio frequency switch connected to the transient limiter or controllable attenuator.

[0008] In one exemplary embodiment, the receiver chain further includes a bandwidth bandpass filter and a digitally controlled attenuator, and the system further includes a transient limiter or controllable attenuator connected to the bandwidth bandpass filter, the bandwidth bandpass filter connected to the digitally controlled attenuator, and the digitally controlled attenuator connected to the low-noise amplifier.

[0009] In one exemplary embodiment, the system further includes a transient overvoltage protection circuit connected between the antenna interface and the first radio frequency switch, the transient overvoltage protection circuit including a gas discharge tube and / or a transient voltage suppressor.

[0010] In one exemplary embodiment, the system further includes a monitoring and control unit, the monitoring and control unit including a directional coupler, a power detection circuit connected to the directional coupler, and a digital controller connected to the power detection circuit; the digital controller controls at least one of the following based on the forward power and / or reflected power detected by the power detection circuit: the attenuation amount of the absorptive controllable attenuation unit, the bias state of the power amplifier, and the bias state of the low-noise amplifier.

[0011] In one exemplary embodiment, the adjustable matching network includes a miniature radio frequency switch, and a microelectromechanical system switch, an adjustable capacitor array, or an adjustable inductor array. The digital controller is further configured to adjust the matching state of the adjustable matching network based on the standing wave ratio (VSWR) fed back from the directional coupler.

[0012] In one exemplary embodiment, the receiver chain further includes a high linearity low gain path connected in parallel with the low noise amplifier, and the digital controller is further configured to switch between the path where the low noise amplifier is located and the high linearity low gain path based on a real-time received signal strength indication or interference power level.

[0013] In one exemplary embodiment, the system further includes a redundancy backup module, which includes a backup power amplifier and / or a backup low-noise amplifier; when the digital controller detects a fault in the power amplifier and / or the low-noise amplifier, it switches to operation of the backup power amplifier and / or the backup low-noise amplifier.

[0014] In one exemplary embodiment, the system further includes a metal shielding cavity, in which the transmitting chain, receiving chain, and multi-level isolation unit are all encapsulated; the joints of the metal shielding cavity are provided with conductive elastic seals or metal springs.

[0015] In one exemplary embodiment, the system further includes a thermal management structure, which includes a thermally conductive interface material disposed at the bottom of the power amplifier and / or the low-noise amplifier, and a thermal clamp disposed on the bottom surface of the system. The thermal clamp is used to directly contact the heat dissipation structure of the UAV body to achieve electromagnetic shielding and thermal path sharing.

[0016] According to another aspect of the embodiments of this application, a modular radio frequency method for a drone is also provided, applied to the modular radio frequency system of the aforementioned drone, comprising:

[0017] In transmit mode, the reflected power detected by the directional coupler is read by the digital controller, and the standing wave ratio (SWR) is calculated. If the SWR is less than or equal to a preset threshold, the absorptive controllable attenuation unit is inserted, the bias of the low-noise amplifier is disconnected, the first RF switch is switched to the transmit path, the absorptive controllable attenuation unit is removed, the bias of the power amplifier is enabled, and the transmit power is gradually increased. In receive mode, the bias of the power amplifier is disconnected, the absorptive controllable attenuation unit is inserted, the first RF switch is switched to the receive path, the absorptive controllable attenuation unit is removed, and the bias of the low-noise amplifier is enabled.

[0018] In an exemplary embodiment, the method further includes: when the digital controller detects that a preset condition has been met, disconnecting the bias of the low-noise amplifier within a preset response time, inserting the absorptive controllable attenuation unit, and switching the first RF switch and / or the second RF switch to a safe terminal or open circuit state; the preset condition includes at least one of the following: a sudden increase in forward power exceeding a first threshold, a standing wave ratio greater than or equal to a second threshold, or a temperature or current exceeding a third threshold.

[0019] In one exemplary embodiment, the method further includes: in a transmission mode or prior to a transmission mode, the digital controller samples forward power and reflected power through the directional coupler and calculates the standing wave ratio (SWR); and iteratively adjusts the matching state of the adjustable matching network to reduce the SWR.

[0020] According to another aspect of the embodiments of this application, a computer-readable storage medium is also provided, wherein a computer program is stored therein, wherein the computer program is configured to perform the steps in any of the above method embodiments when executed by a processor.

[0021] According to another aspect of the embodiments of this application, a computer program product or computer program is provided, the computer program product or computer program including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, causing the computer device to perform the steps in any of the method embodiments described above.

[0022] According to another aspect of the embodiments of this application, an electronic device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to perform the steps of any of the above method embodiments through the computer program.

[0023] This application employs a multi-stage isolation unit comprising a first RF switch, a second RF switch, and an absorptive controllable attenuation unit. The transmit chain and receive chain share the same antenna through this multi-stage isolation unit, which is connected between the antenna interface, the transmit chain, and the receive chain. Through the series blocking of at least two stages of switches and the dissipation effect of the absorptive attenuation unit, the signal leakage energy from the transmit chain to the receive chain is significantly reduced under shared antenna conditions. This achieves the technical effect of protecting the front-end components of the receive chain from high-power signal impacts and improving the reliability of system transmit-receive isolation without increasing the number of antennas. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the system architecture of a modular radio frequency system for a drone according to an embodiment of this application. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the system architecture of a modular radio frequency system for a drone according to an embodiment of this application. Figure 2 ;

[0026] Figure 3 This is a schematic diagram of an optional modular radio frequency method for a drone according to an embodiment of this application. Figure 1 ;

[0027] Figure 4 This is a schematic diagram of an optional modular radio frequency method for a drone according to an embodiment of this application. Figure 2 . Detailed Implementation

[0028] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] According to one aspect of the embodiments of this application, a modular radio frequency system for a drone is provided, such as... Figure 1 The system architecture diagram shown includes: a transmit chain, a receive chain, and a multi-level isolation unit. The transmit chain and the receive chain share the same antenna through the multi-level isolation unit, which is connected between the antenna interface, the transmit chain, and the receive chain. The multi-level isolation unit includes: a first radio frequency switch, a second radio frequency switch, and an absorptive controllable attenuation unit.

[0031] A transmitter chain refers to a complete signal path that modulates, up-converts, and amplifies the baseband signal to be transmitted to sufficient power for radiation through an antenna. In terms of connection, the transmitter chain's input receives the modulated signal from the UAV's baseband module, and its output connects to the first terminal of the first RF switch in a multi-stage isolation unit. Internally, the transmitter chain includes a power amplifier and an adjustable matching network. The adjustable matching network is located before the power amplifier; that is, the transmitted signal first undergoes impedance optimization through the adjustable matching network before being sent to the power amplifier for power enhancement. During transmission, the transmitter chain is enabled under the command of the system controller, and power output can only be initiated after a reliable transmit / receive switching sequence with the receiver chain is completed to avoid self-oscillation or damage caused by simultaneous conduction with the receiver chain.

[0032] A receiver chain refers to a complete signal path that performs low-noise amplification, filtering, and down-conversion processing on the received signal captured by the antenna to extract valid communication information. In terms of connection, the input of the receiver chain is connected to the second terminal of the second RF switch in the multi-stage isolation unit, and the output of the receiver chain is connected to the subsequent digitization or demodulation module. The receiver chain internally includes a low-noise amplifier and a transient limiter or controllable attenuator. The transient limiter or controllable attenuator is located at the very beginning of the receiver chain; that is, the received signal first enters the transient limiter or controllable attenuator after exiting the second RF switch, and then is sent to the low-noise amplifier.

[0033] A multi-stage isolation unit is a circuit structure composed of multiple series-connected radio frequency (RF) protection devices. Its function is to prevent high-power transmit signals from the transmit chain from leaking into the receive chain in a system with a shared transmit and receive antenna. In terms of connection, the multi-stage isolation unit is integrated between the antenna interface, the transmit chain, and the receive chain. Specifically, the antenna interface is connected to the common terminal of the multi-stage isolation unit, the transmit chain is connected to the transmit terminal of the multi-stage isolation unit, and the receive chain is connected to the receive terminal of the multi-stage isolation unit. Inside the multi-stage isolation unit, the first terminal of the first RF switch is connected to the transmit chain, the second terminal of the first RF switch is connected to one terminal of the absorptive controllable attenuation unit, the other terminal of the absorptive controllable attenuation unit is connected to the first terminal of the second RF switch, and the second terminal of the second RF switch is connected to the receive chain. In transmit mode, the first RF switch should switch to the transmit path, and the second RF switch should switch to disconnect the absorptive controllable attenuation unit from the receive chain. Simultaneously, the absorptive controllable attenuation unit can be set to minimum attenuation to avoid affecting transmit efficiency. In receive mode, the first RF switch should disconnect from the transmit chain, the second RF switch should connect to the receive chain, and the absorptive controllable attenuation unit can be set to the maximum attenuation to further absorb interference energy that may enter from the antenna end.

[0034] The first RF switch is the first-stage switching element in a multi-stage isolation unit, used for initial path selection between the antenna interface and the transmit or receive chain. In terms of connection, the common terminal of the first RF switch is connected to the antenna interface or its downstream circuitry (e.g., an external electrostatic discharge (ESD) surge protector). Its first throw point (first terminal) is connected to the output of the transmit chain, and its second throw point (second terminal) is connected to one end of an absorptive controllable attenuation unit. This switch is typically a single-pole double-throw or single-pole multi-throw structure. In the multi-stage isolation strategy, the isolation of the first RF switch and the isolation of the second RF switch are superimposed to form the overall transmit / receive isolation. The switching time of this switch must meet the requirements of the UAV communication system for transmit / receive switching time slots, typically in the microsecond to sub-microsecond range.

[0035] The second RF switch is the second-stage switching element in a multi-stage isolation unit, used for final path selection and isolation supplementation between the absorptive controlled attenuator unit and the receive or transmit chain. In terms of connection, the first terminal of the second RF switch is connected to the other terminal of the absorptive controlled attenuator unit, and the second terminal is connected to the input terminal of the receive chain (typically after passing through a transient limiter or controlled attenuator). When working in conjunction with the first RF switch, the common terminal of the second RF switch is connected to the absorptive controlled attenuator unit. In receive mode, the second RF switch should exhibit low insertion loss to ensure the sensitivity of the received signal.

[0036] An absorptive controlled attenuator is an electronic component that absorbs excess radio frequency energy and converts it into heat, while simultaneously adjusting its attenuation based on an external control signal. In terms of connection, one end of the unit is connected to the second terminal of a first radio frequency switch, and the other end is connected to the first terminal of a second radio frequency switch, i.e., connected in series between two stages of radio frequency switches. The core feature of the absorptive controlled attenuator is its internal design with an absorption resistor or absorption network to ground. When the port impedance is mismatched, the reflected energy is dissipated by these absorption structures, rather than being reflected back to the preceding circuitry as in traditional reflective attenuators. The operating frequency band of this unit must cover the communication frequency band of the drone. Its attenuation adjustment range should be set according to the system's requirements for absorbing leakage signals, typically covering a range from minimum insertion loss (e.g., 0.5dB or 1dB) to maximum attenuation (e.g., 20dB or 30dB). In transmit mode, the unit should be set to minimum attenuation to reduce transmit power loss; in receive mode, if strong interference is anticipated, the unit can be set to a larger attenuation to absorb interference energy entering from the antenna in advance, protecting the downstream receiver chain. The response time of this unit must meet the system's protection requirements for transient events, and should typically complete the increase in attenuation within microseconds after an anomaly is detected.

[0037] In one exemplary embodiment, the transmitter chain includes a power amplifier and an adjustable matching network.

[0038] The power amplifier boosts the lower-power RF signal output from the adjustable matching network to a predetermined transmit power level. In terms of connection, the power amplifier's input is connected to the output of the adjustable matching network, and its output is connected to the first terminal of the first RF switch. The power amplifier generates significant heat during operation; therefore, its base must maintain good contact with the heat dissipation structure via a thermally conductive interface material. In transmit mode, the power amplifier can only be activated after the system controller issues an enable command and the transmit / receive switch has been completed; upon receiving a shutdown command or detecting abnormal reflected power, the bias voltage must be quickly cut off to stop power output. For example, the power amplifier can support multiple adjustable output levels with a maximum output power of 33 dBm.

[0039] An adjustable matching network (AMR) is a configurable impedance transformation circuit located at the front end of the transmit chain. It dynamically adjusts the impedance characteristics at the power amplifier input or the impedance matching state between the power amplifier output and the antenna. In terms of connection, the AMR receives the transmit signal from the baseband module at its input, and its output is connected to the power amplifier input. Internally, the AMR contains miniature RF switches and microelectromechanical system (MEMS) switches, or adjustable capacitor or inductor arrays. Changing the switching combinations of these components alters the network's equivalent impedance. Its adjustment is based on VSWR feedback from the directional coupler. When excessive reflected power is detected, the digital controller sends commands to drive the switching elements in the AMR, gradually changing the values ​​of the capacitors or inductors until the forward power transfer efficiency is optimal.

[0040] The receiver chain includes a low-noise amplifier and a transient limiter or a controllable attenuator.

[0041] A low-noise amplifier (LNO) is an active amplification device in the receiver chain used to amplify extremely weak radio frequency (RF) signals received by the antenna with low noise while introducing as little additional noise as possible. In terms of connection, the LNO's input is connected to the output of a digitally controlled attenuator (DCA), and its output is connected to a subsequent digitization module (e.g., a power divider). A transient limiter or controllable attenuator is placed at the front end of the LNO to ensure that the signal power reaching its input is always below its safety threshold. The operating frequency band of the LNO must match the passband of the front-end filter, and its noise figure directly determines the lower limit of the sensitivity of the entire receiver chain.

[0042] For example, the low-noise amplifier has the following target noise figure: ≤1.5 dB in the critical subband (band-dependent); overall average control ≤2 dB. Linearity (anti-blocking): IIP3 target +5 dBm or more (ideally +10 dBm) to mitigate broadband strong interference intermodulation. Gain: 10–20 dB single-stage gain; approximately 14 dB net gain across the entire link (including back-end) (consistent with the solution description). Bias monitoring: with current and temperature sensing interfaces.

[0043] Transient limiters and controllable attenuators are used at the front end of the receiver chain to limit the maximum amplitude of the signal entering the low-noise amplifier. In terms of connection, the input of the transient limiter or controllable attenuator is connected to the second terminal of a second RF switch, and its output is connected to the input of a broadband bandpass filter. Regarding usage conditions, a transient limiter is a passive or semi-active device. When the input signal power is below its operating threshold, it exhibits low insertion loss, allowing the signal to pass normally. When the input signal power exceeds the operating threshold, a low-impedance path is formed internally within the limiter, reflecting or absorbing excess energy, thus clamping the output signal amplitude to a safe level. The transient limiter's response speed must be fast enough, typically on the nanosecond to microsecond scale, to handle sudden transient events such as lightning strikes or electromagnetic pulses.

[0044] For example, transient limiters are hybrid absorption or limiting structures, employing a PIN diode limiting network in parallel with an absorption terminal for optimized response. Typical operating time is < 10 μs (target < 1–5 μs for more stringent protection); recovery time is according to device specifications (tens of μs to ms). They can withstand short-time pulse power ≥ +40 dBm (depending on the device) and absorb any remaining energy at the terminal.

[0045] A controllable attenuator is an active device that changes its attenuation through an external control signal. It can pre-increase attenuation to protect downstream circuits when strong interference is predicted. Transient limiters and controllable attenuators can be used individually or in series. The transient limiter is responsible for handling sudden transient spikes, while the controllable attenuator is responsible for handling continuous medium-intensity interference.

[0046] In one exemplary embodiment, the system further includes: a first terminal of the first radio frequency switch connected to the power amplifier, the power amplifier connected to the adjustable matching network, the adjustable matching network being used to receive a transmitted signal; a second terminal of the first radio frequency switch connected to the absorptive controllable attenuation unit, the absorptive controllable attenuation unit connected to the first terminal of the second radio frequency switch, and a second terminal of the second radio frequency switch connected to the transient limiter or controllable attenuator.

[0047] In one exemplary embodiment, the receiver chain further includes a bandwidth bandpass filter and a digitally controlled attenuator, and the system further includes a transient limiter or controllable attenuator connected to the bandwidth bandpass filter, the bandwidth bandpass filter connected to the digitally controlled attenuator, and the digitally controlled attenuator connected to the low-noise amplifier.

[0048] A broadband bandpass filter is a passive device used for frequency selection in the receiver chain. Its function is to allow signals within a specific frequency range to pass through while suppressing interference signals outside the passband. In terms of connection, the input of a broadband bandpass filter is connected to the output of a transient limiter or a controllable attenuator, while the output is connected to the input of a digitally controlled attenuator. Regarding usage conditions, the passband of the broadband bandpass filter must cover the entire operating frequency band of UAV communication, while providing sufficient suppression depth for frequency components outside its passband. The insertion loss of the broadband bandpass filter should be as low as possible to avoid degrading the noise figure of the receiver chain. In some high-interference environments, the broadband bandpass filter can adopt a segmented structure or a multi-stage switchable sub-band filter bank, selecting a narrowband filter with lower insertion loss and steeper selectivity based on the current operating frequency. The broadband bandpass filter does not require an external power supply, but its performance is affected by ambient temperature. Under extreme temperature conditions, its center frequency and bandwidth may drift; therefore, sufficient temperature margin must be included in the design.

[0049] For example, the band-pass filter (BPS) (218 GHz) can be a segmented broadband filter or a multi-stage switchable subband BPF (where space permits, a switchable narrower-band BPF is preferred for higher selectivity). Insertion loss is controlled to ≤3 dB (wideband), and better suppression can be achieved when using a switchable filter in critical interference bands.

[0050] A digitally controlled attenuator (DCA) is an active device in the receiver chain that precisely controls the signal amplitude, dynamically adjusting the signal power level entering the low-noise amplifier (LNOA). In terms of connection, the DCA's input is connected to the output of a broadband bandpass filter, and its output is connected to the input of the LNOA. Regarding operating conditions, the DCA receives the attenuation setpoint from a digital controller via a digital control interface. Internally, it consists of multiple cascaded attenuation bits, each providing a fixed attenuation step. The DCA's attenuation range must cover the entire interval from minimum insertion loss to maximum attenuation; its step accuracy determines the fineness of amplitude adjustment. The DCA requires a stable supply voltage during operation. When the received signal is too strong, the digital controller increases the attenuation, reducing the signal power to within the linear operating range of the LNOA; when the received signal is weak, the digital controller decreases the attenuation or even bypasses the attenuator to ensure sufficient signal gain. The response time of the DCA should match the time constant of the receiver chain's automatic gain control loop.

[0051] For example, the digitally controlled attenuator has a range of 0 to 20 dB, in 0.5 dB steps. The digital control interface is either a serial communication protocol SPI interface or a four-wire parallel interface (control board driver).

[0052] In one exemplary embodiment, the system further includes a transient overvoltage protection circuit connected between the antenna interface and the first radio frequency switch, the transient overvoltage protection circuit including a gas discharge tube and / or a transient voltage suppressor.

[0053] A gas discharge tube is one of the transient overvoltage protection devices at the antenna interface, used to discharge extremely high voltage surges caused by lightning induction or electrostatic discharge. In terms of connection, the gas discharge tube is connected in parallel between the signal line and ground line of the antenna interface, typically located between the antenna interface and the first RF switch. The gas discharge tube is filled with inert gas, and the electrodes at both ends remain insulated. When the voltage across its terminals exceeds its breakdown voltage, the internal gas ionizes and forms a low-impedance plasma channel, rapidly discharging the surge current to ground, thereby clamping the voltage to a lower level. The breakdown voltage of the gas discharge tube needs to be set within a range higher than the peak voltage of the normal RF signal but lower than the maximum withstand voltage of the subsequent circuitry. While the gas discharge tube has high surge current withstand capability, its response speed is relatively slow, and it is usually used in conjunction with a transient voltage suppressor with a faster response speed to provide multi-stage overvoltage protection.

[0054] Transient voltage suppressors (VTS) are another type of transient overvoltage protection device at the antenna interface, used to quickly clamp residual voltage spikes. In terms of connection, the VTS is connected in parallel or series with a gas discharge tube between the signal line and ground line of the antenna interface, typically located after the gas discharge tube. A VTS is a device based on the avalanche breakdown principle of a semiconductor PN junction; its response speed is much faster than that of a gas discharge tube, operating within the picosecond to nanosecond range. When the voltage across the VTS exceeds its breakdown voltage, the device quickly enters a low-impedance conduction state, dissipating the overvoltage energy to ground. The breakdown voltage of the VTS must be precisely selected to ensure it is lower than the maximum safe operating voltage of sensitive devices such as subsequent RF switches. The clamping voltage of the VTS determines the residual voltage value actually applied to the subsequent circuitry during protection operation; this value should be low enough to ensure the safety of the subsequent circuitry.

[0055] In one exemplary embodiment, the system further includes a monitoring and control unit, the monitoring and control unit including a directional coupler, a power detection circuit connected to the directional coupler, and a digital controller connected to the power detection circuit; the digital controller controls at least one of the following based on the forward power and / or reflected power detected by the power detection circuit: the attenuation amount of the absorptive controllable attenuation unit, the bias state of the power amplifier, and the bias state of the low-noise amplifier.

[0056] Figure 2This is a system architecture diagram. A directional coupler is a passive RF component used to couple a small portion of the forward and reverse transmitted power from the main transmission path for use by the monitoring circuit without interrupting the main signal transmission. Directional couplers can be placed at multiple critical nodes, including near the antenna interface, after the transient limiter, and before and after the low-noise amplifier. They can be packaged in an integrated metal housing and connected to the aircraft fuselage or a dedicated heat sink via thermal clamps. The main transmission line of the directional coupler is connected in series in the RF signal path, and its coupling port outputs a small signal proportional to the main signal power to the power detection circuit. The directional coupler's directivity determines its ability to distinguish between forward and reflected power; high directivity helps in accurately measuring the VSWR. The directional coupler's operating frequency band must cover the entire frequency band of UAV communication, and the coupling degree should remain flat within its operating frequency band. For example, coupling degree: typically 20 to 30 dB (ensuring the measured power range while protecting the measurement circuit). The output is fed to the analog-to-digital converter (ADC) sampling channel for use by the protection and matching algorithms.

[0057] The power detection circuit is a module that converts the radio frequency (RF) signal coupled from the directional coupler into a DC voltage or digital signal, used to quantify the magnitude of forward and reflected power. In terms of connection, the input of the power detection circuit is connected to the coupling port of the directional coupler, and the output is connected to the analog-to-digital converter (ADC) input port of the digital controller. The power detection circuit typically contains devices such as detector diodes or logarithmic amplifiers to convert the amplitude of the RF signal into a DC voltage. The dynamic range of this circuit must cover the entire power variation range from weak signals to the maximum transmitted signal. The response time of the power detection circuit determines how quickly the system detects power changes. For transient protection applications, the power detection circuit needs a sufficiently fast response speed to transmit abnormal power information to the digital controller within microseconds. The power detection circuit requires a stable supply voltage and must be calibrated before operation to eliminate measurement errors caused by detector nonlinearity.

[0058] The digital controller is the core of the entire RF system's management and decision-making, responsible for processing monitoring data and issuing control commands. In terms of connectivity, the digital controller's input is connected to the output of the power detection circuit, as well as the outputs of the temperature sensor and current monitoring unit. The digital controller's output is connected via digital interfaces to the control terminals of the absorptive controllable attenuator, the power amplifier's bias control, the low-noise amplifier's bias control, the adjustable matching network, the digitally controlled attenuator, and each RF switch. The digital controller can periodically read the forward and reflected power values, calculate the VSWR, and compare it with a preset threshold. When the VSWR exceeds the safety threshold, the digital controller should immediately execute a protection sequence, including disconnecting the low-noise amplifier bias, increasing the attenuation of the absorptive controllable attenuator, and switching the RF switches to a safe state.

[0059] In one exemplary embodiment, the adjustable matching network includes a miniature radio frequency switch, and a microelectromechanical system switch, an adjustable capacitor array, or an adjustable inductor array. The digital controller is further configured to adjust the matching state of the adjustable matching network based on the standing wave ratio (VSWR) fed back from the directional coupler.

[0060] In one exemplary embodiment, the receiver chain further includes a high linearity low gain path connected in parallel with the low noise amplifier, and the digital controller is further configured to switch between the path where the low noise amplifier is located and the high linearity low gain path based on a real-time received signal strength indication or interference power level.

[0061] The high-linearity, low-gain path is a backup receiving path connected in parallel with the main receiving path containing the low-noise amplifier (LNOA) to maintain reception capability in environments with strong interference. In terms of connection, the input of this path is connected to the output of a digitally controlled attenuator or the second terminal of a second RF switch, and its output is connected to the subsequent processing module, merging with the output of the LNOA. This path operates in parallel with the LNOA path, achieving a two-to-one or two-to-two operating mode by selecting a switch or controlling their respective bias states. Regarding usage conditions, the high-linearity, low-gain path does not contain a high-gain amplifier, or its amplifier operates under high bias current to achieve higher linearity, but with correspondingly lower gain. The linearity parameters of this path, such as the third-order intermodulation cutoff point, are much higher than those of the main LNOA, thus enabling it to withstand stronger input signals without significant distortion. When the digital controller detects that the current input signal power exceeds the linear range of the main LNOA through the power detection circuit or received signal strength indicator, it disconnects the bias of the main LNOA and simultaneously enables the high-linearity, low-gain path, sending the signal through this path to subsequent processing. The noise figure of this path is usually higher than that of the main path, so it is only used under strong signal conditions. Under weak signal conditions, it switches back to the main path low-noise amplifier to ensure sensitivity.

[0062] In one exemplary embodiment, the system further includes a redundancy backup module, which includes a backup power amplifier and / or a backup low-noise amplifier; when the digital controller detects a fault in the power amplifier and / or the low-noise amplifier, it switches to operation of the backup power amplifier and / or the backup low-noise amplifier.

[0063] The backup power amplifier is a component of the redundancy backup module, used to take over the operation of the main power amplifier when it fails. In terms of connection, the input of the backup power amplifier is connected to the output of an adjustable matching network or a pre-amplifier drive circuit via a switch, and its output is connected to the first terminal of a first RF switch via another switch, forming a parallel redundancy structure with the main power amplifier. Regarding usage conditions, the electrical performance and power capacity of the backup power amplifier should be the same as or similar to those of the main power amplifier. During normal operation, the backup power amplifier's bias is off, and its input and output are isolated from the signal path via RF switches. When the digital controller detects an anomaly in the main power amplifier through current monitoring, temperature monitoring, or output power monitoring, it first shuts down the main power amplifier's bias, then switches the input / output switches to connect the backup power amplifier to the path, and finally enables the backup power amplifier's bias. The switching time of the backup power amplifier must meet the system's tolerance requirements for communication interruption duration. The backup power amplifier also requires good thermal management; its bottom must be in contact with the heat dissipation structure through a thermally conductive interface material to ensure that it does not fail again due to overheating after taking over operation.

[0064] The backup low-noise amplifier (LNOA) is another component of the redundancy backup module, used to take over the operation of the main LNOA in case of failure. In terms of connection, the input of the backup LNOA is connected to the output of a digitally controlled attenuator or a broadband bandpass filter via a switch, and its output is connected to the subsequent processing module via another switch, forming a parallel redundancy structure with the main LNOA. Regarding operating conditions, the noise figure, gain, and linearity of the backup LNOA should be consistent with those of the main LNOA. During normal operation, the backup LNOA's bias is off. When the digital controller detects an abnormal current or output gain in the main LNOA, it determines that the main amplifier has failed, immediately shuts off the main amplifier's bias, and the switch connects the backup LNOA to the signal path, enabling its bias. The switching of the backup LNOA should be completed in the shortest possible time to minimize the interruption of received signals. The backup LNOA also requires protection from transient limiters and controllable attenuators; the backup path should be equipped with protection devices of the same level as the main path.

[0065] In one exemplary embodiment, the system further includes a metal shielding cavity, in which the transmitting chain, receiving chain, and multi-level isolation unit are all encapsulated; the joints of the metal shielding cavity are provided with conductive elastic seals or metal springs.

[0066] A metal-shielded cavity is a sealed metal enclosure that houses the entire radio frequency (RF) system, preventing internal RF signals from radiating outwards and external interference signals from entering. In terms of connectivity, the metal-shielded cavity encapsulates all components of the transmit chain, receive chain, and multi-stage isolation units within its internal space, forming a complete electromagnetically sealed environment. Conductive elastic seals or metal springs are installed at the cavity's seams to ensure good electrical continuity between different parts of the cavity. Regarding usage conditions, metal-shielded cavities are typically made of materials with good electrical and thermal conductivity, such as aluminum alloys or copper-nickel alloys, and the wall thickness must balance mechanical strength and weight constraints. The cavity interior can be divided into multiple isolated chambers according to function, placing the transmit, receive, and switching areas in different chambers. Signal interconnection is achieved through through-holes or feedthrough structures on the cavity walls, further improving the isolation between chambers. The conductive elastic seals at the cavity seams must maintain good elastic contact after repeated disassembly and assembly, and their compression must be specified during the design phase. Interfaces on the cavity used for signal input and output should employ filtered connectors or waveguide cutoff structures to prevent signal leakage along the interfaces. The metal shielding cavity also serves as part of the heat conduction path, and its bottom surface must be flat and smooth to ensure good contact with the thermal clamp.

[0067] In one exemplary embodiment, the system further includes a thermal management structure, which includes a thermally conductive interface material disposed at the bottom of the power amplifier and / or the low-noise amplifier, and a thermal clamp disposed on the bottom surface of the system. The thermal clamp is used to directly contact the heat dissipation structure of the UAV body to achieve electromagnetic shielding and thermal path sharing.

[0068] Thermal interface material is a heat-conducting medium that fills the gap between heat-generating components such as power amplifiers and low-noise amplifiers and the metal shielding cavity or heat dissipation structure to reduce contact thermal resistance. In terms of connection method, the thermal interface material is placed between the bottom of the power amplifier and low-noise amplifier and the thermal clamp or inner wall of the metal shielding cavity on the bottom surface of the system, and is pressed together to fully fill the microscopic gaps between them.

[0069] The thermal clamp is a mechanical structural component located on the bottom of the system, used to establish a low thermal resistance connection between the RF system and the UAV's heat dissipation structure. In terms of connection method, the upper surface of the thermal clamp contacts heat-generating devices such as power amplifiers and low-noise amplifiers through a thermally conductive interface material, while the lower surface directly contacts the UAV's heat dissipation structure, achieving a tight clamping fixation using bolts or quick-release clips. The design of the thermal clamp must consider the vibration and shock environment of the UAV platform, and its locking mechanism should have vibration-resistant and anti-loosening characteristics. In installation scenarios requiring electrical isolation, an insulating thermally conductive layer can be added between the thermal clamp and the UAV's heat dissipation structure; however, in high-frequency applications, attention must be paid to the impact of the insulation layer on the continuity of electromagnetic shielding.

[0070] The system also includes a power supply control board, which receives a wide range of DC power from the UAV platform, with an input voltage range of +12V to +40V, and is equipped with input protection circuitry, including reverse connection protection diodes, transient voltage suppression diodes (TVS), and multi-stage π-type filter networks to suppress surges, static electricity, and high-frequency noise introduced by the power lines.

[0071] The power supply control board includes multiple independent regulated output circuits, which provide precise, low-ripple bias voltages (e.g., LNA negative bias -5V, PA gate voltage +3V, attenuator control voltage 0~5V) to the low-noise amplifier (LNA), front-end transient limiter, digitally controlled attenuator, RF switch, and bias control circuit. Each output has a soft-start function, which powers on sequentially according to a preset timing sequence to avoid stress damage to RF devices caused by instantaneous current surges during power-on.

[0072] The power supply control board has a built-in fast power-off path, which is directly controlled by the Field-Programmable Gate Array (FPGA) hardware logic. When overvoltage, overcurrent, overtemperature or transient overpower at the RF port is detected, the power supply to all power amplifiers and low-noise amplifiers can be forcibly cut off within 10 microseconds, achieving hardware-level emergency protection.

[0073] Meanwhile, the board is equipped with a local microcontroller unit (MCU) and an FPGA. The FPGA monitors the directional coupler sampling signal, temperature sensor and current detection circuit in real time, and executes transient protection logic and switching timing control. The MCU is responsible for running the adaptive matching algorithm, managing the communication interface (CAN / UART), performing power-on self-test (BIST) and firmware remote upgrade, so as to realize module-level autonomous operation and system status reporting.

[0074] The power supply control board is equipped with a high-precision analog-to-digital converter (ADC) and digital-to-analog converter (DAC) for real-time closed-loop monitoring and control of the RF front end. The high-speed ADC channel (sampling rate no less than 5 MS / s) is dedicated to acquiring directional coupler coupling signals from the antenna side, the power amplifier output, and the low-noise amplifier input / output, simultaneously obtaining transient waveforms of forward and reflected power. This high-speed sampling channel employs a parallel or multi-channel interleaved sampling architecture to ensure complete capture of energy changes even under sudden pulses (such as lightning strikes or switching transients).

[0075] The low-speed ADC channel (sampling rate 1–10 kS / s) is used to continuously acquire the power amplifier operating current, low-noise amplifier bias current, and temperature signals of key components inside the module, supporting overcurrent protection, thermal management, and long-term reliability assessment.

[0076] The DAC is used to generate control voltages for the digitally controlled attenuator, adjustable matching network, and RF switch, thereby achieving accurate output of analog control signals.

[0077] In terms of control architecture, the power supply control board internally forms a local real-time control bus via SPI and I²C buses, connecting the MCU, FPGA, ADC, DAC, and various RF sub-modules (such as attenuators, switches, and limiters) to achieve low-latency, highly deterministic local control interaction. Externally, the board exchanges data with the UAV platform's main control unit via CAN or UART communication interfaces, uploading power status, temperature, and fault event logs, and receiving mission commands.

[0078] Even if the platform controller fails, communication is interrupted, or the system crashes, the power supply control board can still automatically trigger hardware-level protection actions (such as cutting off the PA bias voltage, inserting an absorption attenuator, or switching to a safe path) within 10 microseconds based on real-time ADC sampling data, ensuring the safety of front-end devices and significantly improving the system's availability and fault tolerance in complex electromagnetic and vibration environments.

[0079] The RF package is encapsulated in an integrated metal shielded cavity. Its shell material is made of high-strength aluminum alloy or copper-nickel alloy, which takes into account both lightweight (weight ≤300 g) and excellent thermal conductivity. The wall thickness is designed to be 1–2 mm, which comprehensively meets the synergistic requirements of flight platforms for structural strength, weight reduction and thermal management.

[0080] The mating surfaces of the housing (such as the top cover and base, and the module interface) are electromagnetically sealed with conductive rubber sealing strips or metal finger-stocks to ensure that electromagnetic leakage at the joints is effectively suppressed under vibration, thermal cycling and long-term use conditions; all mating surfaces are equipped with EMI conductive gaskets to reduce contact impedance and ensure shielding continuity.

[0081] Inside the module, a local metal shield is set for sensitive radio frequency sub-modules (such as low noise amplifiers (LNAs), front-end limiters, and high-speed switching circuits). The shield is made of high conductivity material (such as tin-plated copper or aluminum alloy) and is stamped and formed. It is connected to the main shell by welding or bolting to achieve a low impedance electrical connection, ensuring that the shield and the main shell are at the same potential, and avoiding secondary radiation caused by antenna effect or potential difference.

[0082] The shielding cavity and thermal clamp are designed as an integrated structure: the bottom surface of the outer shell serves as the heat dissipation contact surface, and is directly pressed with the heat sink of the UAV body through a thermal interface material (such as a thermal pad or thermal silicone), realizing the shared function of electromagnetic shielding and heat conduction path - that is, while suppressing radio frequency leakage, the shielding cavity also serves as the main heat dissipation channel, significantly reducing the junction temperature of the device and improving the long-term reliability of the system.

[0083] The RF module's circuit board adopts a 4-6 layer multilayer printed circuit board (PCB) structure. Its layer stack-up design is as follows: the outer layer (L1 and L5) is the signal and control trace layer, the inner layer (L2 and L4) is a continuous and complete ground plane, and L3 is the power layer or secondary signal layer, so as to achieve efficient isolation between RF signals and power supply.

[0084] Key RF paths (including antenna input, LNA input / output, PA output, and coupler interface) are all located on the top layer (L1) and implemented with a microstrip line structure. Their characteristic impedance is strictly controlled to 50 Ω, and Rogers RT / duroid 4350B or equivalent low-loss substrate (εr≈3.48, tanδ<0.002) is used to reduce high-frequency insertion loss and signal distortion.

[0085] To suppress high-frequency cross-regional crosstalk and electromagnetic leakage, via fences are installed at the boundaries of the shielded area (such as the local shielded area, between LNA and PA) and between sensitive circuits and high-power / digital circuits. The via aperture is 0.2–0.3 mm, and the center-to-center spacing between adjacent vias does not exceed 0.5 mm. This ensures that at the highest operating frequency of 18 GHz (wavelength λ≈16.7 mm), the via fence spacing meets the shielding continuity requirement of maintaining a spacing much less than λ / 20, effectively blocking surface waves and edge radiation.

[0086] All high-frequency traces adopt a short path and few corners design, with bends using rounded arcs or 45° angled transitions to avoid impedance abrupt changes and radiation caused by 90° right angles; differential signal pairs (such as control buses and high-speed ADC interfaces) maintain equal length and spacing, and single-ended signal lines are kept away from power supplies and digital signals to achieve strong anti-interference capabilities.

[0087] All vertical interconnect access (via) channels are directly connected to the nearest L2 or L4 ground plane. Power decoupling capacitors are placed close to the device pins and the ground plane to form a low inductive loop, further reducing high-frequency noise coupling.

[0088] To improve the thermal stability of the module under high power and long-term operation, an integrated thermal management architecture is adopted. The bottom package surfaces of key heat-generating components such as the low-noise amplifier (LNA) and power amplifier (PA) are in close thermal contact with the metal base at the bottom of the module through a high thermal conductivity interface material (such as thermally conductive silicone pads or thermally conductive epoxy), ensuring that heat is efficiently conducted from the device junction area to the heat dissipation substrate.

[0089] The power amplifier (PA) uses high-efficiency gallium nitride (GaN) devices, and its heat dissipation power is kept at a low level under continuous cruise output power of 20 dBm. At the same time, the PA design can withstand short burst power output of ≤33 dBm (about 2 W), which meets the instantaneous high power requirements of UAVs in strong interference environments or emergency communication scenarios. Its thermal design margin ensures that the junction temperature does not exceed the limit during the 33 dBm transient.

[0090] The bottom surface of the module has a press-fit thermal contact surface, which is polished and integrally formed with the metal shell, serving as the main heat conduction channel. The module is directly pressed onto the heat sink (such as an aluminum thermally conductive bracket or heat sink) on the UAV body via bolt fastening or quick-clamping structure, making the body structure itself the main heat dissipation path of the module, realizing a low thermal resistance heat flow path of "module → body → environment".

[0091] To meet electrical safety and electromagnetic compatibility requirements, the thermal contact interface uses insulating thermally conductive materials (such as alumina-based thermal pads) to achieve electrical insulation. At the same time, low-impedance metal connections (such as copper springs and conductive washers) are used in the contact area between the metal base and the body to ensure the continuity of shielding grounding, thus achieving an integrated design of "thermal conduction" and "electromagnetic shielding" functions.

[0092] The modular RF interface employs SMP (Sub-Miniature Push-on) blind-mating coaxial connectors or aerospace-grade vibration-resistant coaxial connectors to achieve high reliability, low reflection, and fast connection at the antenna input / output ends. This interface features an anti-misfit structure, metal housing shielding, and spring-loaded pin design to ensure 50 Ω impedance matching and ≥85 dB contact stability under high vibration and frequent insertion / removal conditions, meeting the low-loss and high-isolation requirements of the 2–18 GHz frequency band.

[0093] The power and control signal interfaces use locking circular multi-pin connectors or board-to-board high-frequency connectors with locking mechanisms to ensure that they will not loosen under flight impact or thermal cycling environments, thus achieving physical locking of electrical connections and guaranteeing signal integrity.

[0094] The modular mechanical structure design incorporates precision guide pins and a twist-lock mechanism (or a four-point snap-lock quick-release structure) to achieve rapid positioning and reliable fastening of the module within the mounting slot, preventing displacement or poor contact due to vibration. The installation process requires no tools and supports one-handed operation, improving battlefield or field maintenance efficiency.

[0095] The overall weight of the module is controlled to ≤300 g. Under the conditions of shielding cavity, thermal clamp, multi-layer PCB and multi-level RF device integration, the lightweight goal is achieved through material optimization (such as using aerospace aluminum alloy shell and lightweight substrate) and structural topology design, which is suitable for the payload constraints of small and medium-sized UAVs.

[0096] Building upon the scenarios described above, the aforementioned technical solutions can also be applied to other wireless communication devices requiring high reliability. For example, in vehicle-mounted millimeter-wave radar systems, where the transmit and receive paths share an antenna, this modular RF system can prevent high-power transmit signals from blocking the echo reception channel. Similarly, in handheld satellite phone terminals, this system can protect the internal receiver from damage when near strong base station signals. Furthermore, in wireless sensor nodes of the Industrial Internet of Things (IIoT), this system can prevent high-power transmissions from neighboring nodes from damaging the local receiving circuitry when multiple nodes time-division multiplex the same frequency band.

[0097] According to another aspect of the embodiments of this application, a modular radio frequency method for a drone is also provided, applied to the modular radio frequency system of the drone described above. The method may include the following steps:

[0098] In the launch mode, such as Figure 3 The steps shown are as follows:

[0099] Step S302: Read the reflected power detected by the directional coupler through the digital controller and calculate the standing wave ratio;

[0100] Step S304: When the VSWR is less than or equal to a preset threshold, insert the absorptive controllable attenuation unit, disconnect the bias of the low noise amplifier, switch the first RF switch to the transmit path, remove the absorptive controllable attenuation unit, enable the bias of the power amplifier and gradually increase the transmit power.

[0101] In transmit mode, a digital controller reads the reflected power detected by the directional coupler in real time and calculates the standing wave ratio (SWR). The current antenna matching status is determined by comparing the SWR with a preset threshold. Under the premise that the SWR meets the safety conditions, the transmit preparation is performed in the following order: first, inserting an absorptive controllable attenuation unit to absorb any possible reflected energy; then, disconnecting the low-noise amplifier bias to eliminate its potential interference to the receiver chain; then, switching the first RF switch to the transmit path to establish a signal path; subsequently, removing the absorptive controllable attenuation unit to reduce the insertion loss of the transmit path; and finally, enabling the power amplifier bias and gradually increasing the transmit power. This achieves the goal of ensuring that the antenna matching status is within a safe range before and during the transmit process, and avoiding the burning out of the power amplifier due to reflected energy caused by high SWR. This achieves the technical effect of safe start-up and reliable operation of the transmit chain under varying operating conditions. At the same time, the graded action sequence avoids the cumulative damage to the front-end components caused by transient impacts.

[0102] In receive mode, such as Figure 4 The steps shown are as follows:

[0103] Step S402: Disconnect the bias of the power amplifier, insert the absorptive controllable attenuation unit, switch the first RF switch to the receiving path, remove the absorptive controllable attenuation unit, and enable the bias of the low noise amplifier.

[0104] In the receiving mode, the sequence of actions is as follows: first, the power amplifier bias is disconnected to completely cut off the power output of the transmit chain; then, an absorptive controllable attenuator is inserted to absorb any residual interference energy that may enter from the antenna end; next, the first RF switch is switched to the receiving path to establish a signal path from the antenna to the receiving chain; then, the absorptive controllable attenuator is removed to reduce the insertion loss of the receiving path and ensure that weak signals are not additionally attenuated; finally, the low-noise amplifier bias is enabled to bring it into normal working condition. Through this strict timing control, it is ensured that the transmit chain is completely turned off and the absorptive attenuator provides a temporary protective barrier before the receiving chain is turned on. This achieves the goal of preventing residual energy from the transmit chain or reflected energy at the moment of switching from entering the low-noise amplifier during the transmit-receive switching process. Thus, the technical effect of safe wake-up of the receiving chain and high-sensitivity reception in complex electromagnetic environments is achieved, while ensuring a balance between the speed of transmit-receive switching and the safety of the devices.

[0105] In an exemplary embodiment, the method further includes: when the digital controller detects that a preset condition has been met, disconnecting the bias of the low-noise amplifier within a preset response time, inserting the absorptive controllable attenuation unit, and switching the first RF switch and / or the second RF switch to a safe terminal or open circuit state; the preset condition includes at least one of the following: a sudden increase in forward power exceeding a first threshold, a standing wave ratio greater than or equal to a second threshold, or a temperature or current exceeding a third threshold.

[0106] The second threshold is greater than the preset threshold in the above embodiments. In this embodiment, the digital controller continuously monitors multi-dimensional parameters such as forward power, VSWR, temperature, and current, and compares these real-time measured values ​​with their respective preset thresholds to determine whether the protection trigger condition is met. When any one of the following conditions is met—forward power suddenly increasing beyond the first threshold, VSWR greater than or equal to the second threshold, or temperature and current exceeding the third threshold—the system executes the following actions in parallel or sequentially within a preset response time: disconnecting the low-noise amplifier bias to cut off the sensitive amplification link of the receiver chain; inserting an absorptive controllable attenuation unit to dissipate the incoming abnormal energy; and switching the first RF switch or the second RF switch, or both simultaneously, to a safe terminal or open circuit state to physically isolate the energy transmission path between the antenna and the internal circuit. This achieves the goal of completely isolating the receiver chain from the antenna port and guiding the incoming energy to the absorptive terminal in a very short time after detecting an abnormal event. This achieves the technical effect of rapid hardware-level protection for sensitive devices such as low-noise amplifiers under abnormal conditions such as sudden high-power pulses, antenna mismatch, or overheating and overcurrent. This protection action does not rely on the response delay of the upper-layer software, significantly improving the transient survivability and long-term reliability of the system.

[0107] In one exemplary embodiment, the method further includes: in a transmission mode or prior to a transmission mode, the digital controller samples forward power and reflected power through the directional coupler and calculates the standing wave ratio (SWR); and iteratively adjusts the matching state of the adjustable matching network to reduce the SWR.

[0108] In this embodiment, before or during the transmission mode, a digital controller uses a directional coupler to sample the forward and reflected power in real time and calculates the current standing wave ratio (SWR). By using this SWR value as a quantitative indicator of the antenna matching state, the combination state of the miniature RF switches and adjustable capacitor arrays or adjustable inductor arrays in the adjustable matching network is adjusted iteratively. After each adjustment step, the SWR is resampled and recalculated. The direction of the next adjustment is determined based on the trend of the SWR until the SWR is reduced to an acceptable range. This achieves the goal of dynamically restoring the impedance matching state when the antenna impedance drifts due to changes in the UAV's attitude, ambient temperature, or radome deformation during flight. This achieves the technical effects of maximizing the transmission efficiency of transmitted energy from the power amplifier to the antenna, minimizing reflection loss, and avoiding overheating or damage to the power amplifier due to excessively high SWR. This adaptive matching process can be completed during transmission gaps or low-power probe signal injection without affecting normal communication tasks.

[0109] The following explains the process of receiving signals via a connection:

[0110] The signal processing begins at the antenna interface. The electromagnetic waves sensed by the external antenna are converted into radio frequency (RF) current and transmitted to the antenna interface via the antenna feeder. After successfully passing through the antenna interface, the signal enters the external ESD protection circuit. This circuit can handle sudden high-energy transient events, such as lightning strikes or electrostatic discharge. After passing through the ESD protection circuit, the signal enters a multi-stage isolation and protection unit. This unit contains a first RF switch SW_TX / RX_1, an absorptive controllable attenuation unit, and a second RF switch SW_RX_2. In receive mode, the first RF switch is switched to the receive path, meaning its common terminal is connected to the end connected to the absorptive controllable attenuation unit, while simultaneously disconnecting from the transmit chain. The absorptive controllable attenuation unit is typically set to an appropriate attenuation level in receive mode, the specific value depending on the current electromagnetic environment. When the system anticipates potentially strong interference, the attenuation unit is set to a larger attenuation level to absorb interference energy entering from the antenna in advance, protecting sensitive downstream components. After passing through the absorptive controllable attenuation unit, the signal enters the second RF switch. This switch, in receive mode, is switched to connect to the subsequent circuitry, allowing the signal to pass smoothly. The series connection of the two RF switches provides high transmit / receive isolation, ensuring that even when the transmit chain is operating, leaked transmit signals will not enter the receive channel. The absorption resistor inside the absorptive controllable attenuation unit ensures that any reflected energy generated at this stage is dissipated, preventing secondary radiation from being reflected back to the antenna. After passing through this unit, the signal amplitude may be reduced to some extent due to the attenuation unit's design, but interference components are also correspondingly attenuated.

[0111] After passing through multiple isolation and protection units, the signal enters the front-end transient limiter. This limiter is a fast-response passive protection device with a built-in limiting network composed of PIN diodes and parallel absorption terminals. Within the normal received signal power range, the PIN diodes are in a high-impedance state, and the limiter exhibits extremely low insertion loss, allowing the signal to pass through almost without loss. The core function of this device is to handle sudden high-power transient pulses, such as emission leakage spikes that the multi-stage isolation units fail to completely block or externally coupled electromagnetic pulses. When such transient pulses arrive, the limiter responds in a very short time, typically less than 10 microseconds. The PIN diodes quickly switch to a low-impedance state, guiding the excessively high voltage spikes to the parallel absorption terminals for dissipation, thus clamping the signal amplitude output to subsequent circuits to a safe level.

[0112] After passing through the front-end transient limiter, the signal enters the broadband bandpass filter. The function of this filter is to perform frequency filtering on the received signal, allowing only signal components within the operating frequency band to pass through, while attenuating interference components outside the operating frequency band.

[0113] After passing through a broadband bandpass filter, the signal enters a digitally controlled attenuator. This attenuator is a programmable amplitude adjustment device, and its attenuation is set by a digital controller via a digital interface. In receive mode, the digital controller sends a command to the attenuator to set an appropriate attenuation based on its assessment of the current signal strength. When the received signal is strong, the digital controller sets a larger attenuation, such as 10 dB or 20 dB, so that the signal power output to the subsequent low-noise amplifier is reduced to within the amplifier's linear operating range, preventing the amplifier from entering the saturation region and causing nonlinear distortion. When the received signal is weak, the digital controller sets a smaller attenuation or even zero attenuation, allowing the weak signal to reach the low-noise amplifier with minimal loss, thereby obtaining sufficient gain to overcome the noise of the subsequent circuitry.

[0114] After passing through a digitally controlled attenuator, the signal enters a low-noise amplifier. This amplifier is the core active amplification device in the receiver chain, tasked with initially amplifying the weak signal while injecting as little additional noise as possible. Once in the amplifier, the signal's amplitude is significantly increased by internal transistors or field-effect transistors. After passing through this amplifier, the originally weak received signal is boosted to a sufficiently high power level to drive the subsequent power divider and digitization module. The amplifier's high linearity ensures that, even when faced with a certain level of in-band interference, the intermodulation distortion component is kept at a low level, preventing significant interference with the demodulation of the useful signal. The amplifier's output signal carries all the information received by the antenna, only with a significantly increased amplitude, and the noise component is correspondingly amplified as well.

[0115] After passing through a low-noise amplifier, the signal enters a power divider. This power divider splits the single input signal into two equal output signals. After passing through the power divider, the original single signal becomes two identical signals carrying the same information. These two signals can be sent to two different downstream processing modules, or to two different input channels of the same module, to achieve diversity reception or coherent processing. For example, the power divider is a 1:2 equal-division power divider with amplitude and phase balance better than ±3° and amplitude imbalance ≤ ±0.5 dB (more stringent calibration is possible for coherent parallel processing).

[0116] After passing through the power divider, the signals enter two output interfaces. These interfaces utilize lightweight Sub-Miniature Push-on (SMP) RF connectors or lightweight board-to-board RF contact structures to transmit the two RF signals from this module to the next-level receiving digitization module. SMP connectors support floating mating within a certain range, suitable for interconnecting modules with mechanical tolerances. Lightweight board-to-board contact structures use flexible contacts for direct contact, eliminating the need for additional cables, reducing weight, and improving vibration resistance. When the signal passes through this interface, the insertion loss causes a slight additional reduction in signal energy; the impedance matching quality of the interface determines whether some signal energy is reflected at the connection point. After passing through this interface, the two RF signals leave the RF front-end module and enter the next-level module for processing. At this point, the signal still exists in analog RF form, but the amplitude has been boosted to a sufficiently high level by a low-noise amplifier, out-of-band interference has been attenuated by filters, and the signal amplitude has been precisely adjusted by a digitally controlled attenuator.

[0117] After passing through two output interfaces, the signal enters the next-level receiving digitization module. This module is the post-processing unit of the RF front-end, responsible for converting the analog RF signal into a digital signal and performing subsequent processing. The signal first enters the downconverter, where it is mixed with the local oscillator signal to down-convert the RF signal to the intermediate frequency or directly to the baseband frequency. The down-converted signal enters the analog-to-digital converter, where it is sampled and quantized into a digital signal, converting the continuous amplitude of the analog signal into discrete digital values. The converted digital signal enters the digital signal processor for demodulation, decoding, protocol parsing, and other processing, ultimately recovering data information that the UAV can understand, such as flight control commands or image transmission data sent by the ground station. This module also communicates bidirectionally with the digital controller of the RF front-end through the control bus. On the one hand, it receives telemetry information such as VSWR, temperature, and fault status reported by the RF front-end; on the other hand, it sends configuration commands such as operating mode switching, attenuation setting, and matching network adjustment to the RF front-end.

[0118] The process of the transmitting chain transmitting signals is explained below:

[0119] The baseband module is the starting point for the transmitted signal processing. This module generates a signal carrying the information the UAV needs to transmit. After generation, the signal is fed into the input of the adjustable matching network via on-board transmission lines or inter-board connectors. Located before the power amplifier, the adjustable matching network pre-adjusts the signal's impedance characteristics, ensuring optimal transmission efficiency before the signal enters the power amplifier. This network contains miniature RF switches and microelectromechanical system (MEMS) switches, adjustable capacitor arrays, or adjustable inductor arrays. Changing the combination of these components alters the network's equivalent impedance. Before initiating transmission or during transmission intervals, the digital controller samples the forward and reflected power via a directional coupler and calculates the current standing wave ratio (VSWR). It then iteratively adjusts the state of the adjustable matching network until the VSWR falls below a preset threshold. After passing through this network, the signal power level remains essentially unchanged, but the source impedance characteristics are optimized, maximizing the power transmission efficiency at the input port of the subsequent power amplifier and reducing signal reflection and power loss caused by impedance mismatch. The network's adjustment accuracy determines the optimal level of impedance matching, and its adjustment range determines its ability to adapt to changes in antenna conditions.

[0120] After passing through the adjustable matching network, the signal enters the input terminal of the power amplifier. The power amplifier is the final active amplification device in the transmit chain, tasked with boosting the lower-power RF signal input from the previous stage to a predetermined transmit power level. Once in the power amplifier, the signal amplitude is significantly amplified. The amplifier generates a significant amount of heat during operation; therefore, its base must be in good contact with the heat dissipation structure via a thermally conductive interface material to ensure the junction temperature remains within acceptable limits. The amplifier's output signal enters the first RF switch through its output terminal.

[0121] After the signal is output from the power amplifier, it enters a multi-stage isolation and protection unit. In transmit mode, the first RF switch in this unit is switched to the transmit path, meaning its common terminal is connected to the first terminal connected to the power amplifier. The absorptive controlled attenuator is typically set to its minimum attenuation level in transmit mode, such as its minimum insertion loss value, to reduce wasted transmit power. In transmit mode, the low-noise amplifier's bias is off, and the transient limiter and low-noise amplifier in the receiver chain are physically isolated from the antenna by two stages of switches, preventing high-power transmit signals from leaking into the receiver chain and causing saturation or damage to the low-noise amplifier. The isolation ratings of the two RF switches are multiplied, and combined with the basic isolation provided by the absorptive controlled attenuator even at minimum attenuation, they constitute the total transmit-receive isolation. After passing through this unit, the transmit signal power remains essentially unchanged, but any reflected energy generated during the switching and attenuator process is dissipated by the absorption resistor inside the absorptive controlled attenuator, preventing reflection back to the power amplifier and thus avoiding output VSWR degradation.

[0122] After passing through multiple isolation and protection units, the signal reaches the external ESD surge protection circuit. This circuit consists of a gas discharge tube and a transient voltage suppressor, both connected in parallel between the signal line and ground. Under normal transmission power levels, the gas discharge tube is in an insulated off state, and the transient voltage suppressor is in a high-impedance non-conducting state; neither has any substantial impact on the transmitted signal. The transmitted signal passes through this stage with almost no attenuation. The purpose of this stage is to protect against reverse paths, that is, to protect the internal circuitry from damage when the antenna is subjected to lightning strikes or electrostatic discharge.

[0123] After passing through the external ESD protection circuit, the signal reaches the antenna interface. From there, the signal enters the antenna feed line and ultimately reaches the antenna itself. As a transducer, the antenna converts the radio frequency current transmitted on the feed line into electromagnetic waves that are radiated outwards.

[0124] Throughout the entire signal transmission path from the power amplifier to the antenna, the directional coupler remains operational. The main transmission line of the directional coupler is connected in series in the RF signal path. Its coupling port outputs a small signal proportional to the forward power of the main path to the power detection circuit, while the other coupling port outputs a small signal proportional to the reflected power of the main path. In transmit mode, the signal output from the forward coupling port is converted into a DC voltage or digital value by the power detection circuit and sent to the digital controller to monitor whether the actual transmitted forward power matches the expected value. The signal output from the reflected coupling port is also detected and sent to the digital controller to calculate the current VSWR. When the VSWR calculated by the digital controller based on the reflected power exceeds a preset safety threshold, protection actions are triggered, including shutting down the power amplifier bias and inserting an absorptive controllable attenuation unit. Simultaneously, the digital controller uses the VSWR information to adjust the state of the adjustable matching network to optimize impedance matching at the antenna end. This monitoring process is integrated throughout the entire signal processing but does not interfere with the main transmitted signal itself, as the coupler only extracts a very small percentage of energy for detection.

[0125] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0126] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as read-only memory (ROM) / random access memory (RAM), magnetic disk, optical disk), and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0127] It should be noted that the above modules can be implemented by software or hardware. For the latter, they can be implemented in the following ways, but are not limited to: all the above modules are located in the same processor; or, the above modules are located in different processors in any combination.

[0128] Embodiments of the present invention also provide a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the method described in any of the preceding claims.

[0129] In one exemplary embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard disk, magnetic disk, or optical disk.

[0130] Embodiments of the present invention also provide an electronic device including a memory and a processor, the memory storing a computer program and the processor being configured to run the computer program to perform the steps in any of the above method embodiments.

[0131] In one exemplary embodiment, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0132] Specific examples in this embodiment can be found in the examples described in the above embodiments and exemplary implementations, and will not be repeated here.

[0133] Obviously, those skilled in the art should understand that the modules or steps of this application described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0134] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A modular radio frequency system for a drone, comprising: include: The system includes a transmit chain, a receive chain, and a multi-level isolation unit. The transmit chain and the receive chain share the same antenna through the multi-level isolation unit, which is connected between the antenna interface, the transmit chain, and the receive chain. The multi-level isolation unit includes: a first radio frequency switch, a second radio frequency switch, and an absorption-type controllable attenuation unit.

2. The system of claim 1, wherein, The system also includes: The transmitter chain includes: a power amplifier and an adjustable matching network; The receiver chain includes a low-noise amplifier and a transient limiter or a controllable attenuator.

3. The system according to claim 2, characterized in that, The system also includes: The first terminal of the first radio frequency switch is connected to the power amplifier, the power amplifier is connected to the adjustable matching network, and the adjustable matching network is used to receive the transmitted signal; The second terminal of the first RF switch is connected to the absorptive controllable attenuation unit, the absorptive controllable attenuation unit is connected to the first terminal of the second RF switch, and the second terminal of the second RF switch is connected to the transient limiter or controllable attenuator.

4. The system according to claim 3, characterized in that, The receiver chain further includes: a bandwidth bandpass filter and a digitally controlled attenuator; the system further includes: The transient limiter or controllable attenuator is connected to the bandwidth bandpass filter, the bandwidth bandpass filter is connected to the digitally controlled attenuator, and the digitally controlled attenuator is connected to the low-noise amplifier.

5. The system according to claim 1, characterized in that, The system also includes: A transient overvoltage protection circuit is connected between the antenna interface and the first radio frequency switch. The transient overvoltage protection circuit includes a gas discharge tube and / or a transient voltage suppressor.

6. The system according to claim 2, characterized in that, The system also includes: The system also includes a monitoring and control unit, which includes a directional coupler, a power detection circuit connected to the directional coupler, and a digital controller connected to the power detection circuit. The digital controller controls at least one of the following based on the forward power and / or reflected power detected by the power detection circuit: the attenuation of the absorption-controlled attenuation unit, the bias state of the power amplifier, and the bias state of the low-noise amplifier.

7. The system according to claim 6, characterized in that, The adjustable matching network includes miniature radio frequency switches, as well as microelectromechanical system switches, adjustable capacitor arrays, or adjustable inductor arrays. The digital controller is also used to adjust the matching state of the adjustable matching network based on the standing wave ratio (VSWR) fed back from the directional coupler.

8. The system according to claim 6, characterized in that, The receiver chain also includes a high linearity low gain path connected in parallel with the low noise amplifier, and the digital controller is further configured to switch between the path where the low noise amplifier is located and the high linearity low gain path based on a real-time received signal strength indication or interference power level.

9. The system according to claim 1, characterized in that, The system also includes a redundancy backup module, which includes a backup power amplifier and / or a backup low-noise amplifier. When the digital controller detects a fault in the power amplifier and / or the low-noise amplifier, it switches to the operation of the backup power amplifier and / or the backup low-noise amplifier.

10. The system according to claim 1, characterized in that, The system also includes a metal shielding cavity, in which the transmitting chain, receiving chain, and multi-level isolation unit are all encapsulated; the joints of the metal shielding cavity are provided with conductive elastic seals or metal springs.

11. The system according to claim 2, characterized in that, The system also includes a thermal management structure, which includes a thermally conductive interface material disposed at the bottom of the power amplifier and / or the low-noise amplifier, and a thermal clamp disposed on the bottom surface of the system. The thermal clamp is used to directly contact the heat dissipation structure of the UAV body to achieve electromagnetic shielding and thermal path sharing.

12. A modular radio frequency method for unmanned aerial vehicles, applied to the system according to any one of claims 1 to 11, characterized in that, include: In transmit mode, the reflected power detected by the directional coupler is read by the digital controller, and the standing wave ratio is calculated. When the standing wave ratio is less than or equal to a preset threshold, insert an absorptive controllable attenuation unit, disconnect the bias of the low-noise amplifier, switch the first RF switch to the transmit path, remove the absorptive controllable attenuation unit, enable the bias of the power amplifier and gradually increase the transmit power. In receive mode, the bias of the power amplifier is disconnected, the absorptive controllable attenuation unit is inserted, the first RF switch is switched to the receive path, the absorptive controllable attenuation unit is removed, and the bias of the low-noise amplifier is enabled.

13. The method according to claim 12, characterized in that, The method further includes: When the digital controller detects that a preset condition has been met, it disconnects the bias of the low-noise amplifier within a preset response time, inserts the absorption-controlled attenuation unit, and switches the first RF switch and / or the second RF switch to a safe terminal or open circuit state. The preset conditions include at least one of the following: a sudden increase in forward power exceeding a first threshold, a standing wave ratio greater than or equal to a second threshold, or a temperature or current exceeding a third threshold.

14. The method according to claim 12, characterized in that, Also includes: In or before the transmission mode, the digital controller samples the forward power and reflected power through the directional coupler and calculates the standing wave ratio; The matching state of the adjustable matching network is adjusted iteratively to reduce the standing wave ratio.

15. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 12 to 14.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, wherein the computer program, when executed by a processor, implements the steps of the method according to any one of claims 12 to 14.

17. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 12 to 14.

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