Modularism has a lot to do with cost. Warships are like products nowadays. You like high end, you want middle end or do you like low end.
For example, here is an example.
There are two versions of this AESA radar, the TRS-4D.
Here is the four sided fixed panel high end version, which is used on Germany's F125 class frigate.
Here you get the low end, single sided, rotating version, which will be used on the Freedom class LCS, starting from LCS 20. This may also be used on future USCG cutters, as the USCG has been using its predecessor, the TRS-3D.
The question I see where I find hard to estimate the 054B, would be where in the sliding bar of cost would it be. Is it going to be high end? Is it going to be low end?
where in the middle are you going to place it? How much is the PLAN willing to give it top end features, or keep it cheap and economical because there are other top end ships?
Before I continue, one of the concept Freedom class LCS did feature the SPY-1K. Its one of the ships in this artwork but the idea was axed. The Freedom class went with the TRS-3D instead, and now will be upgrading to the TRS-4D in the near future.
FFG(X) is armed with ESSM Block 2 as its main but there is always that option for SM-6. The ship doesn't have SPG-62 FCRs to supply target illumination, so it can only ARH guided missiles, like the ESSM Block 2, SM-6 and the next block of SM-2.
For its main radar, FFG(X) is equipped with a
three panel EASR, which is a downscaled SPY-6, smaller faces and reduced to three. Why three? Cheaper. For X-band GFCR, it uses the SPQ-9B, which is a small dual backed PESA. SPQ-9B is used on the Ticos, and other ships, like the Wasp class, where comparisons of it on this ship, and the new dual backed dual band AESA on the Type 075 is going to be made. It also shows up with USCG cutters, like the Legend class that is one of the FFG(X) candidates, which uses TRS-3D in conjunction with it. SPQ-9B is generally set high on top of a mast, for radar horizon, scanning for surface targets and spotting sea skimmers early. A sea skimmer search radar doesn't need that much range --- it only needs to peer out to 30 to 40km or so, depending on the ship's radar horizon, although these radars can have instrumented ranges in excess of 100km.
In contrast to this, the Admiral Gorshkov class uses a single faced S-band rotating search radar called Frunze on top, and just below it, it uses a fixed four sided X-band fire control radar called Poliment to help guide the 9M96E Redut missiles, which are active guided. The missiles are ARH, it doesn't need SARH target illumination, but the system still prefers to use X-band, and that's probably due to the tighter and faster tracking the X-band permits, at the expense of range. Despite having the Poliment fixed radar, the ship still has the Monolit X-band radar inside a white dome, also a phase array, not sure if its PESA or AESA, for antiship missiles, and in front of Monolit, the Puma gun fire control radar, also another X-band phase array. The Russians do not appear to like role consolidation in their radars; they still host them in separate sets, but the Chinese for instance, with the new fixed radar set on the 055, managed to consolidate the Type 364 SSR, 366 antiship radar and 344 gun FCR, all into that radar. Do note the Zaslon MFR on the Project 20385 heavy corvette under trials seems even more advanced than what the Gorshkov has.
You can go through with the world's frigates, one after another, and you will find a variety of configurations that its difficult to make use of one as a common example. It seems everyone seems to have their own ideas in making a frigate. Even if they agreed to use a common Type 26 platform, Australia, Canada and the RN all differ drastically on the radar setup. Are the missions for all these ships so different from each other to have such different radar approaches?
For speculating on the 054B, the lowest possible for the search radar would be a single faced, rotating S-band, something like the SR2410C that is used on export warships similar to the SMART-S Mk II. That is one end of the bar. Or make that larger, like the Funze on the Gorshkov. At the other end of the bar, there is fixed four faced S-band radar set that is yet small and light enough to be hosted on a mast (see CSSC export frigate design). In between, you can have dual backed S-band like SAMPSON, or even this new dual backed dual band radar we first saw on the 075.
For the fire control, the cheapest end of the bar is to retain the Type 344 and 366 radars used on previous ships, but offers no advancement. My personal favorite is to go with the high end, choose the fixed four faced X-band radars you already have on the top mast of the 055. That radar is expensive, but once they start producing them for more 055s, the 003 and other carriers, future 052 and 05X frigates, the prices will go down. Radar replaces the 364, 344 and 366 mechanical radar, that alone saves a lot of weight and mechanical issues, while vastly improving flexibility, antenna gain, and most of all, EW resistance, which is the one great motivator for migrating radar setups to AESA.
The SAMs used on the 054B, we don't know much about. Whether its HQ-16B, newer HQ-16 version, DK-10, a new quad packed MRSAM entirely, or HQ-9. But whether its ARH or SARH guided, a four fixed faced X-band can be adjusted for that.
Based on closely following Chinese naval radar developments, we can get better clues, but its like connecting dots, and hoping a new dot will arrive.
