Microwave radar receiver protection structure

Abstract

The utility model discloses a microwave radar receiver protection structure and method, the microwave radar receiver protection structure comprises a cascade amplitude limiter, the cascade amplitude limiter is arranged behind an antenna sum-difference device, and the cascade amplitude limiter is arranged in front of a receiver radio frequency front end circuit. The cascade amplitude limiter comprises a waveguide plasma amplitude limiter, a micro-strip amplitude limiter and a waveguide coaxial converter, the micro-strip amplitude limiter is cascaded behind the waveguide plasma amplitude limiter, and the waveguide coaxial converter is cascaded behind the micro-strip amplitude limiter. The starting threshold of the micro-strip amplitude limiter is effectively improved compared with the working threshold of other amplitude limiters, so that echo signals can enter a receiver with low loss, and the sensitivity of the receiver is ensured. According to the cascade amplitude limiter, the standing-wave ratio near the working frequency is slightly larger than 1, the loss is low, and the use requirement is met. According to the utility model, two stages of amplitude limiters with different forms are used, so that the high power resistance and the fast response time are improved; a micro-strip amplitude limiter is used to raise a starting threshold.

Description

Technical Field

[0001] This utility model belongs to the field of microwave protection technology, and in particular relates to a protection structure for a microwave radar receiver. Background Technology

[0002] High-power microwave radar, by emitting high-power microwaves, can detect, jam, and destroy targets at close range. It features rapid battlefield response, low cost, no pollution, light-speed attack, no collateral damage, and all-weather standby, making it an advanced means of future battlefield confrontation. However, high-power microwave transmission signals have high pulse power (GW level) and narrow pulse width (ns level). When a high-power microwave radar receiver receives target echoes, the extremely strong electromagnetic radiation leaked (greater than 10MW level) can cause co-frequency electromagnetic leakage interference to the high-power microwave radar receiving channel through front-door coupling. The receiver, as the most direct front-door device, can be directly damaged, rendering the radar inoperable. High-power microwave protection technology has been a research hotspot both domestically and internationally, but it mainly focuses on non-co-frequency leakage interference, separate high-power microwave radar transmission and reception locations, and kW-level leakage power electromagnetic pulses. It cannot effectively protect against high-power electromagnetic pulses. Traditional limiters lack high-power tolerance, and ordinary waveguide plasma limiters have low activation thresholds, failing to meet the requirements of protecting against high-power echoes while still being able to receive strong echo signals, leading to target loss. Utility Model Content

[0003] The technical problem this invention aims to solve is that there is currently no limiter with GW-level transmission power, fast response, and high start-up threshold that can enable high-power microwave receivers to receive strong echo signals normally while ensuring that the equipment is not burned out. This invention provides a high-power microwave radar receiver protection structure with a cascaded limiter that can withstand high power, has an extremely short response time, a high start-up power threshold, and low leakage power.

[0004] This utility model is achieved through the following technical solution.

[0005] This utility model provides a microwave radar receiver protection structure, including a cascaded limiter. The cascaded limiter is placed after the antenna and differential, and before the receiver's radio frequency front-end circuit. The cascaded limiter includes a waveguide plasma limiter, a microstrip limiter, and a waveguide coaxial converter. The microstrip limiter is cascaded after the waveguide plasma limiter, and the waveguide coaxial converter is cascaded after the microstrip limiter.

[0006] Preferably, the waveguide plasma limiter includes a resonant cavity, a flange, a sealing window, and a discharge gap, and contains rare gases and radioactive elements.

[0007] Preferably, the cascaded limiter operates in the C-band, has a peak power tolerance greater than 10MW, a response time less than 2ns, a voltage standing wave ratio less than 1.4, a recovery time less than 1us, a leakage peak power less than 1W, and a start-up threshold greater than 10mW.

[0008] Preferably, the discharge gap is provided in two sets and located inside the resonant cavity. The discharge gap includes fixed electrodes and resonant diaphragms that are opposite each other, and the resonant diaphragms are symmetrically distributed on both sides of the fixed electrodes.

[0009] Preferably, the fixed electrode is oriented parallel to the narrow side of the sealing window, and the resonant diaphragm is oriented parallel to the sealing window.

[0010] Preferably, the flanges are distributed on both sides of the resonant cavity.

[0011] Preferably, the sealing windows are distributed on both sides of the resonant cavity.

[0012] Preferably, the rare gas is a mixture of argon and water vapor.

[0013] Preferably, the radioactive element is gaseous tritium.

[0014] The present invention discloses a protection method for a microwave radar receiver protection structure. When the microwave radar normally receives the echo, the power of the radar echo signal entering the cascaded limiter is less than the operating threshold of the microstrip limiter. The cascaded limiter is equivalent to a bandpass filter, allowing the echo signal to pass smoothly into the downstream receiver. During the high-power pulse transmission of the radar, the pulse power incident on the cascaded limiter increases instantaneously. When the pulse power exceeds the ignition power of the cascaded limiter, the discharge gap of the waveguide plasma limiter ionizes the internal rare gas to generate plasma, which, combined with the microstrip limiter, performs secondary limiting, thereby reflecting the incident power and protecting the receiver.

[0015] The beneficial effects of this utility model are as follows:

[0016] This invention's microstrip limiter has an effectively higher start-up threshold compared to other limiters, ensuring that the echo signal can enter the receiver with low loss and guaranteeing the receiver's sensitivity. The VSWR of the cascaded limiter near its operating frequency is slightly greater than 1, and its low loss meets usage requirements. This invention uses two different types of limiters to improve high-power tolerance and fast response time; by using a microstrip limiter to raise the start-up threshold, this invention, based on a cascaded limiter protection structure, is suitable for receiver protection in high-power microwave radar. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is a schematic cross-sectional view of the waveguide plasma limiter of this utility model;

[0019] Figure 3 This is a cross-sectional view of the waveguide plasma limiter of this utility model;

[0020] Figure 4 This is a performance simulation verification diagram of the cascaded limiter of this utility model;

[0021] Figure 5 This is a schematic diagram illustrating the use of this utility model;

[0022] In the diagram: 1-Cascaded limiter, 2-Antenna, 3-Differentiator, 4-Waveguide plasma limiter, 41-Resonant cavity, 42-Flange, 43-Sealed window, 44-Discharge gap, 45-Conical fixed electrode, 46-Resonant diaphragm, 5-Microstrip limiter, 6-Waveguide coaxial converter, 7-Receiver. Detailed Implementation

[0023] The technical solution of this utility model is further described below, but the scope of protection is not limited to what is described.

[0024] Example

[0025] like Figures 1 to 5 As shown, a microwave radar receiver protection structure includes a cascaded limiter 1. The cascaded limiter 1 is placed after the receiving antenna 2 and the differential 3, and before the radio frequency front-end circuit of the receiver 7. The cascaded limiter 1 includes a waveguide plasma limiter 4, a microstrip limiter 5, and a waveguide coaxial converter 6. The microstrip limiter 5 is cascaded after the waveguide plasma limiter 4, and the waveguide coaxial converter 6 is cascaded after the microstrip limiter 5.

[0026] The waveguide plasma limiter 4 includes a resonant cavity 41, a flange 42, a sealing window 43, and a discharge gap 44. Rare gases and radioactive elements are contained inside the waveguide plasma limiter 4.

[0027] The cascaded limiter 1 operates in the C-band, has a peak power tolerance greater than 10MW, a response time less than 2ns, a voltage standing wave ratio less than 1.4, a recovery time less than 1us, a leakage peak power less than 1W, and a start-up threshold greater than 10mW.

[0028] The discharge gap 44 has two sets located inside the resonant cavity 41. The discharge gap 44 includes two opposing conical fixed electrodes 45 and resonant diaphragms 46, with the resonant diaphragms 46 symmetrically distributed on both sides of the conical fixed electrodes 45. The purpose of this arrangement is to enhance the local field strength inside the waveguide plasma limiter 4, which is beneficial for the rapid breakdown of the working gas to form plasma.

[0029] The conical fixed electrode 45 is parallel to the narrow side of the sealing window 43, and the resonant diaphragm 46 is parallel to the sealing window 43. The purpose of this arrangement is to discharge and break down the working gas to form plasma.

[0030] The flanges 42 are distributed on both sides of the resonant cavity 41. The function of the flanges 42 is to connect the receiver 7 protector, the waveguide plasma limiter 4, and the microstrip limiter 5.

[0031] The sealing windows 43 are distributed on both sides of the resonant cavity 41. The function of the sealing windows 43 is to transmit microwave energy and maintain plasma.

[0032] The rare gas is a mixture of argon and water vapor. Using this mixture can effectively improve the protection against high-frequency, high-power microwave energy.

[0033] The radioactive element is gaseous tritium. Choosing gaseous tritium has the advantages of being safe and effective, and having abundant radioactive electrons, which can provide an initial electron source for discharge gap discharge.

[0034] A protection method for a microwave radar receiver protection structure is disclosed. When a high-power microwave radar normally receives echoes, the power of the radar echo signal entering the cascaded limiter 1 is less than the operating threshold of the microstrip limiter 5. The cascaded limiter 1 is equivalent to a bandpass filter, allowing the echo signal to pass smoothly into the downstream receiver. During the radar's high-power pulse transmission, the pulse power incident on the cascaded limiter 1 increases instantaneously. When the pulse power exceeds the ignition power of the cascaded limiter 1, i.e., the activation threshold power, the discharge gap 44 of the waveguide plasma limiter 4 discharges and ionizes the internal rare gas to generate plasma. This plasma, combined with the microstrip limiter 5, performs secondary limiting, reflecting the incident power and protecting the receiver.

[0035] The limiting performance of the microstrip limiter 5 was verified, as shown in the table below:

[0036]

[0037] As shown in the table above, the start-up threshold of the microstrip limiter 5 is around 13.5 dBm, which is significantly higher than the operating threshold of other limiters. This ensures that the echo signal can enter the receiver 7 with low loss, thus guaranteeing the sensitivity of the receiver 7.

[0038] The performance of cascaded limiter 1 was verified by simulation, and the results are as follows: Figure 4 As shown, the VSWR near the operating frequency of cascaded limiter 1 is slightly greater than 1, and the loss is low, meeting the usage requirements.

Claims

1. A protective structure for a microwave radar receiver, characterized in that: The system includes a cascaded limiter (1), which is placed after the antenna (2) and the differential (3) and before the receiver's radio frequency front-end circuit. The cascaded limiter (1) includes a waveguide plasma limiter (4), a microstrip limiter (5), and a waveguide coaxial converter (6). The microstrip limiter (5) is cascaded after the waveguide plasma limiter (4), and the waveguide coaxial converter (6) is cascaded after the microstrip limiter (5).

2. The microwave radar receiver protection structure as described in claim 1, characterized in that: The waveguide plasma limiter (4) includes a resonant cavity (41), a flange (42), a sealing window (43), and a discharge gap (44). Rare gases and radioactive elements are provided inside the waveguide plasma limiter (4).

3. The microwave radar receiver protection structure as described in claim 1, characterized in that: The cascaded limiter (1) operates in the C-band, has a peak power tolerance greater than 10MW, a response time less than 2ns, a voltage standing wave ratio less than 1.4, a recovery time less than 1us, a leakage peak power less than 1W, and a start-up threshold greater than 10mW.

4. The microwave radar receiver protection structure as described in claim 2, characterized in that: The discharge gap (44) is provided in two sets and is located inside the resonant cavity (41). The discharge gap (44) includes fixed electrodes (45) and resonant diaphragms (46) that are opposite each other. The resonant diaphragms (46) are symmetrically distributed on both sides of the fixed electrodes (45).

5. The microwave radar receiver protection structure as described in claim 4, characterized in that: The fixed electrode (45) is parallel to the narrow side of the sealing window (43); the resonant diaphragm (46) is parallel to the sealing window (43).

6. The microwave radar receiver protection structure as described in claim 2, characterized in that: The flanges (42) are distributed on both sides of the resonant cavity (41).

7. The microwave radar receiver protection structure as described in claim 2, characterized in that: The sealing window (43) is distributed on both sides of the resonant cavity (41).

8. The microwave radar receiver protection structure as described in claim 2, characterized in that: The radioactive element is gaseous tritium.

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