4hw.com.cn: South Korean non-governmental organizations held an anti thad rally again on the 28th. The protestors believed that thad could not effectively defend against the North Korean threat, and would lead to the deterioration of South Korea's relations with China and Russia, which was not good for regional stability.
Reporter: 'I am now in front of the South Korean Ministry of defense. There is an anti thad rally being held by South Korean civic groups. They claim that park Geun hye has been dismissed, so the deployment decision of Park Geun hye's government is invalid. '
After the United States shipped two Sade launchers to South Korea on June 6, the South Korean Defense Ministry has been tight lipped about the specific progress of Sade deployment on the grounds of military security. However, the anti Sadr sentiment in South Korea has not yet subsided. Some non-governmental organizations have once again held demonstrations outside the Ministry of defense. They strongly condemn the Ministry of Defense's forcible deployment of Sadr in order to avoid overturning the deployment decision due to the change of regime. They believe that the deployment of Sadr is the biggest accumulated disadvantage of Park Geun hye's term of office, and Sadr can't defend North Korea's nuclear and missile, on the contrary, it deepens South Korea's relations with China and Russia The decision to deploy should be withdrawn immediately.
Wu meizheng, director of affairs of people who open up peaceful reunification, a South Korean citizen group, said: 'Sade's failure to intercept North Korea's nuclear and missile has nothing to do with South Korea's defense, but it will lead to conflicts between South Korea, China and Russia, making South Korea's security more dangerous. In terms of economy, it does not help South Korea's national interests. '
Some protestors said that in order to achieve peace on the peninsula, the deployment of Sadr should be stopped. At the same time, the decision to deploy Sadr is the diplomatic result of South Korea's yielding to us pressure.
Jin Xiufeng, chairman of Kaifeng religious circle of Yuan Buddhism, said: "we should stop increasing force first, and the DPRK will not increase force either. Only in this way can we get peace. At the same time, South Korea has not suffered a lot from Sadr! I think that the deployment of Sadr is not based on normal diplomatic decisions, but on humiliating diplomatic decisions to the United States. '
People in Sade, South Korea stand off with police to block construction vehicles from entering
Sad data map
On the 29th, South Korean residents of gyeongshang North Road, sing Chou Prefecture, blocked trucks trying to enter the 'Sade' deployment site for survey construction for three times in a row, and confronted the police.
Private groups in Xingzhou County told Xinhua that as of 21:00 local time on the 29th, vehicles related to the deployment site of "Sade" failed to pass through the obstacles set by local people. Local residents said that 'the passage will be guarded all night to prevent vehicles from entering'.
The person in charge of the citizen group "prevent & lsquo; sad & amp; quot; from deploying the national action in South Korea" told reporters by telephone that five trucks tried to enter the Xingzhou golf course in the morning, noon and afternoon of the same day, but they were blocked by the local people and peace activists with sit in demonstrations.
According to local residents, the police dispatched more than 10 police buses and more than 400 police officers on the same day. The police asked the people to disband on the grounds of violating the law on assembly and demonstration. About 150 local residents and anti deployment 'Sade' people moved stools to sit in the middle of the road, shouting slogans such as' don't Sade, want peace 'because Sade, can't live' and so on. At the same time, they used cars as roadblocks to block. The two sides continued tense confrontation.
According to Yonhap, the truck carrying the measuring instruments was sent by the Ministry of environment of the Republic of Korea. It was originally scheduled to go to Sade's deployment site for surveying construction.
A number of civic groups, such as the "withdrawal of Sade" and the "Star State struggle committee", said that the deployment of Sade was fundamentally invalid and illegal. So far, no agreement on deployment has been signed between South Korea and the United States, and there is no legal basis for the South Korean government to provide deployment land to the U.S. military.
Citizen groups and the public stressed that the deployment of "Sade" violates Article 60 of the constitution of the Republic of Korea and the right of consent of the national assembly, which is an unconstitutional act. In addition, they also said that the government abused public power and South Korea's Ministry of defense should immediately stop illegal activities.
South Korean media quoted unnamed military sources on the 29th as saying that the deployment of "Sade" is still progressing as planned, but he did not disclose the details and progress.
South Korea's defense ministry has previously confirmed that part of the 'Sade' system equipment has arrived in South Korea on June 6. South Korean media said that the equipment includes two launchers, and other related equipment will arrive in South Korea in one to two months, starting service as early as April.
How far can Sadr see
The decision of the United States and South Korea to deploy an anti missile system in South Korea has raised concerns among Chinese security experts. One technical reason for concern is that the Sadr radar in South Korea is too far away to spy on the flight data of China's intercontinental missile warheads. The governments of the United States and South Korea did not formally respond to this technical issue in public, but said 'this system is not targeted at other countries'.
On unofficial occasions, scholars have different views on the detection range of sad radar. We might as well divide them into long-range group and short-range group. The argument between them seems mysterious, but it is not difficult to understand.
Usually, the maximum detection range of radar is referred to as the detection range of radar. To calculate the detection range of radar, we need to know the working principle of radar. Radar uses its antenna to project radar wave (a kind of electromagnetic wave) outward. When the radar wave meets the target, it can be reflected back by the target, which is called radar echo. After the radar echo returns to the radar, it is received by the antenna and forms a signal in the radar. If the signal is significantly higher than the noise of the radar, then the radar can recognize the signal. At this time, we think that the radar can detect the target. If the signal generated by a target in the radar is just good enough to be recognized from the noise, then the target is just at the maximum detection range of the radar. If the target is too far away, the echo signal will be submerged in the noise.
The Sade system is deployed in South Korea with the stated purpose of intercepting North Korean missiles. Therefore, the detection range of Sadr for incoming warheads from North Korea should be able to cover the whole territory of North Korea. This distance needs about four to five hundred kilometers, set at 500 kilometers. Short range scholars believe that the detection range of Sadr radar is only 800 km, of which about 500 km is used to detect the trajectory of North Korean missiles, and the remaining 300 km redundant detection range will indeed extend to China. However, China should not be worried about the extremely limited coverage of China's territory and the extremely small chance of detecting the trajectory of China's intercontinental missile warhead. According to the long-range faction, the detection range of sad radar can reach 2000 kilometers. Less than a quarter of the range is used to detect North Korean missiles, and most of the other detection range can be used to detect the trajectory of Chinese intercontinental missile warheads passing through northeast China. The focus of the dispute between the two sides is: how far the detection range of Sadr radar is beyond the territory of North Korea; the cause of the dispute is that some technical parameters obtained from the public data are uncertain.
In fact, we can look at this issue from a different perspective, and infer the detection range completely according to the purpose of deploying the Sade system claimed by the United States and South Korea, so the dispute may be less.
The line of sight of Sadr radar in South Korea should be a fan shape, with the central line of the fan pointing to the north and slightly West, so as to cover the whole territory of North Korea. Extending along this line of sight, it will cover the northeast of China and the Far East of Russia. If China launches a nuclear counterattack, part of the orbit of the intercontinental missile launched from central and eastern China is just within this line of sight. This is the horizontal line of sight coverage of Sadr. In the vertical direction, if the detection range of the Sadr radar to the Chinese nuclear counterattack warhead is less than two or three thousand kilometers, the height of the Chinese intercontinental missile orbit is enough to offset the curvature of the earth, so that these orbits are exposed to the line of sight of the Sadr radar. If the detection distance is longer, the line of sight of sad radar will be blocked by the horizon. In the following calculation, we do not assume that the Sadr radar can significantly change the surveillance direction, we only consider the Chinese nuclear counterattack intercontinental missile warhead flying through the northeast.
If North Korea attacks South Korea with missiles, its missiles are flying south. Therefore, what Sadr sees is the front end of the warhead that North Korea is attacking. China's nuclear counterattack warheads fly northward in the northeast region, so what Sadr sees is the side rear of China's nuclear counterattack warheads. Due to the huge difference of radar cross section in different directions of warhead, the detection range results from the above two perspectives are very different.
Here we get a simplified physical problem: what is the relationship between the radar detection range and the radar cross section of the target when the radar parameters remain unchanged? Next, we deduce this relationship step by step according to the working principle of radar.
When a radar projects a radar wave outward, the radar wave will propagate forward in a cone shape. Therefore, the power density of the radar wave per unit area is inversely proportional to the square of the detection range R. When the radar wave reaches the target, it will be reflected by the target. The power of the reflected radar echo is proportional to the RCS. The radar echo needs to travel the detection range R from the target to the radar. Therefore, the power of the radar echo detected by the radar is inversely proportional to the square of R. Therefore, the signal strength of the target received by the radar is directly proportional to the RCS of the target and inversely proportional to the fourth power of the detection range R. By comparing the target signal strength with the radar noise strength, an equation can be obtained to determine the detection range of the radar. In this equation, except the radar cross section of the target, other parameters are the technical parameters of the radar. If we assume that the parameters used by Sadr in detecting Korean incoming warheads and Chinese nuclear counterattack warheads are the same, then the detection range R of Sadr is proportional to the radar cross section RCS of the target, or the detection range R is proportional to the root of the radar cross section RCS of the target.
With the above relationship, we can substitute the data to estimate the detection range of the sad radar. According to Dr. o Donnell's lecture notes, the radar cross section of the rear side of the warhead is 0.75 square meters; the radar cross section of the forward side of the warhead is 0.001 square meters. The ratio of the two is 750, and the root of the fourth power of the ratio is 5.2. In other words, the detection range of radar to the rear of a warhead is five times of that to the front.
If the detection range of Sadr to the front of the North Korean warhead is 500 km, then the detection range to the rear of the Chinese nuclear counterattack warhead passing through the northeast region may reach 2500 km. There is no consideration of the redundancy of the detection range left by Sadr to detect the incoming warheads from North Korea. If the redundancy of 300 km is added, the detection range of Sadr to the incoming warhead from North Korea will reach 800 km. At this time, the interception range of Sadr radar to the Chinese nuclear counterattack warhead passing through the northeast can theoretically reach 4000 km. That is to say, before the Chinese nuclear counterattack warhead passing through the Northeast disappears below the horizon, its side and rear may be within the detection range of Sadr radar Within.
The quantitative conclusion of the above calculation is that even if the redundancy left by the Sadr in the detection range is small, its detection range for the Chinese nuclear counterattack warhead passing through the northeast is also very large, reaching thousands of kilometers. According to the radar parameters given by the short range faction, considering the different radar cross sections of the warhead in different directions, we get the long range radar parameters