2. According to some western analysts, there were doubts that China was able to produce S-band modules of sufficient power in the early 2000s.
I prefer not to take their word for it. Western analysts are as wet on the Chinese defense industry as Gordon Chang's prophecies of the Chinese economy failing in the 2000s.
C-band modules would have been a more technologically greater issue than an S-band module given that C-band modules would have to be physically smaller than the S-band, which means that the square die for your LNA would have to be smaller and unable to take as much power as a bigger die on a larger PC board. Remember that one dimension in the C-band module would have to square with its wavelength. This does not mean that China is incapable of making a C-band module; at the turn of the decade, the PLA already has an AESA used for tracking artillery and mortar fire, and those things require X-band or Ku-band to be able to track shells. All this means is that an S-band module would be even less of a challenge than a C-band or an X-band module, the last requires significant miniaturization of its components.
My take is one that is the simplest and the least complicated.
Institute 14 NRIET has been developing radars, and has been developing an S-band AESA since the 1990s, competing with Institute 23, which developed the HQ-9 system. NRIET has since become the top radar institution in China, developing the radars for the J-8D, the J-10A/B/C, the J-11B, the FC-1, and J-20. Possibly for the J-11D too.
The Type 346 on the 052C has been S-band in the beginning, the Type 346A is an improved version of it, and the evolution goes forward with the Type 346B. They are building upon previous R/D work, evolving and improving in the process.
The use of the C-band engagement radar HT-233 does not necessarily mean the HQ-9 uses TVM/SARH. It only means the radar itself is using C-band. There might be issues why C-band is very very rarely used as an FCR and missile illumination radar, just about everyone else across every country and every company relies on X-band as an FCR and target illumination radar. Except for one distinct exception, and that is Raytheon with its MPQ-53 radar set for the Patriot system.
Maybe Raytheon has figured out something to let them use C-band for the Patriot, some secret sauce maybe. Its a hard sell that the Chinese figured the same thing out around the turn of the century, and even if they did, is it still better to use C-band over X-band. The reason why everyone else uses X-band is that its the best tool for the job.
For the HT-233 to use C-band, Western analysts assumed that the Chinese must have espionage this Raytheon. The intermediate culprits were the Israelis.
After the Coronavirus, I look back at this, and how people are so willing to believe in conspiracy theories, and evil Chinese stealing Western IP.
The problem with conspiracy theory is that the Chinese have their own engineers and even if they have stolen IP from Raytheon, the engineers still have to decide if C-band is still going to be better than X-band just for sheer technical merits, as use for fire control and missile illumination. The engineers still have the final say. Never mind that the Chinese has also gotten IP from the Russians and the French, all of whom whose fire control radars are X-band. For example, the Chinese has access to the S-300 FCR, the Flap Lid and Tombstone through their purchases. They also have access to the Russian S-300 and Buk missiles directly, from purchases. Its much easier to have reference models based on the Russian missiles that you already have than rely on espionaged information which maybe potentially unreliable, incomplete, and lacking a physical model to study.
The fact is when you look at the HQ-9 missile itself, it looks a lot more like the Russian 5V-55 missile used on the S-300 missile complex.
Now I go back to why the HT-233 was using C-band rather than X-band. Here is my explanation. A Flap Lid or Tombstone radar requires at least over 10,000 elements. This probably costs through the roof for the Chinese. In order to have a radar that match the range for a much lower cost, they choose to use C-band for the array to achieve the same range but using only 4,000 elements. The HT-233 has a horn feed that looks like a copy of the Flap Lid's, so it shows who the Chinese is copying really.
This still leaves you with the problem of TVM and SARH illumination of the missile. Did the Chinese figure this out for C-band? Here is another thing that came to my mind. Did the Chinese manage to master the trick of using C-band for fire control and target illumination? Maybe the HT-233 never had SARH illumination in the first place. Maybe what the Chinese really did was stuff an active guided seeker instead on the missile starting Day One. While ARH is more complex than SARH on the missile, it actually requires a less complex radar set up on the ground, eliminating the use of a long range illuminator that you have to add ICWI or FMCW circuits. This means a cheaper radar system on the ground, with the HT-233 being a purely pulse radar without any CWI circuit. You don't need to have a more powerful transmitter to compensate for the CWI which doesn't have the range of a pulse waveform.
As for S-band "power requirements", the Fregat or Top Plate radar can reach 300km on a bomber sized target and that's not a particularly powerful radar. Choosing S-band would be a shoo in for its cost --- requiring less elements than C-band, and achieving greater range for its cost.
