Do you think that US is an amateur when it comes to developing stealthy aircraft? American defense industry was researching and developing stealthy applications in the 1960s.
US and Russia were not fighting each other in Syria. Both were at odds with each other on a few occasions in Syria and F-35 was used during these occasions to strike designated targets but Russian defenses could not detect it or stop it. Israel have also used F-35 to test Russian and Iranian defenses. Please see this and this. Russian anti-stealth solutions and its derivatives in other countries are not up the task, therefore. Not difficult to understand.
J-31 is a Chinese attempt at developing something like F-35. However, J-31 structural rcs simulation data is missing whereas J-20 and F-35 structural rcs simulation data can be found in here. F-35 can deflect and absorb radar waves across frequency bands ranging from L to V with advanced RAM application that is disclosed in this post. Chinese RAM application is disclosed in following source:
In this article, a multifunctional and tunable radar absorber which can achieve dynamical modulation of absorbing frequency, bandwidth, and amplitude is presented. Such a tunable radar absorber is composed of a graphene capacitor layer and an active metasurface layer. By controlling the impedance characteristic of each layer through the external bias voltages, the absorber not only can achieve the ultrawideband electromagnetic (EM) absorbing performance, but also can be switched to a narrowband absorption mode, and its absorption amplitude can be further adjusted at each of the above operation modes. Both simulated and experimental results have demonstrated that the −10-dB reflection bandwidth ranging from 3.55 to 19.6 GHz can be realized, and the average reflection amplitude can be dynamically tuned between −3.8 and −11.5 dB. In addition, by changing the bias voltages, the absorber can also, respectively, switch its −10 dB reflection bandwidth to 3.5−11.1 GHz and 10.9−18.9 GHz, where the larger dynamic range of amplitude modulation is obtained. The equivalent circuit model is employed to explain the tunable absorption mechanism by analyzing the impedance matching characteristics. This hybrid design approach can effectively expand the EM reconfigurable functionalities of the current tunable absorber, which may further open a novel way of the graphene application in microwave frequencies.
https://onlinelibrary.wiley.com/doi/abs/10.1002/admt.202001050
This RAM application allows J-20 (or J-31) to deflect and absorb radar waves across frequency bands ranging from S to Ku. This is not on the level of F-35.
J-31 sensor package reportedly contains KLJ-5 radar system, A-STAR EOTS-86 EOTS, A-STAR EORD-31 IRST, and BM/KJ 8602C RWR. KLJ-5 has slotted antenna design and its SAR resolution is unknown - related information in here. This sensor package might have sensor fusion but to what degree is unknown. F-35 has state-of-the-art sensor package and fusion capabilities.
China is trying to develop an advanced stealth aircraft but it is premature to compare Chinese applications with American applications in the present.
