Now Jeff you don't know what you are writing about. "that they used S-Band because of the technology available at that time", did you really type that? USN could've easily build the SPY series in C-band with passive phase array technology back in the 70's if it wanted to. The reason why they picked S-band had nothing to do with the lack of APAR technology.
First thing there are technological trade off to anything especially when following the same principle.
C-Bands has a shorter range but better resolution, smaller installation but degrades faster in high precipitation.
APAR has a stronger power outage with better beam magnification but difficult to design requiring higher technological skills.
From here on it's just a matter of design philosophy and the level of technology at hand.
In the early 70's the no nation had the technological capability to develop a APAR and PPAR was still at it's infancy. The US selected the S-band since a C-band PPAR would have had a very limited range of view in the range of under 100Km. Where as in S-band you can see further but can't really identify what there are tracking, so when they see something approaching they can launch a interceptor jet to see what is coming towards the battle group.
This may had worked in the 70's but after development of better missiles with longer range, fast speed and sea skimming capabilities a new philosophy of acquisition and identification of target at first contact became important.
This is when research of APAR started.
At the moment no matter how good the radars are you can't sea much beyond the horizon, so a target would need to be flying very high to be spotted from a sea level radar and no use for low incoming planes or missiles.
That rate is an example. Lower rain fall obviously would mean less degradation for all wavelength, but C-band would still be more affect to the same degree compare to S-band.
That chart is also misleading as well since it defines a band width in a single line which is basically ludicrous.
A radar band is just that a range of frequency in which C-band occupies 4～8GHz, with wave length between 37～75mm S-band occupies 2～4GHz with a wave length between 75～150mm. As you can see the two bands share the same frequency and wave length at the border. So in that chart the bands would actually be touching each other at the border.
The problem with the S-band at it's lowest frequency the target would be required to be relatively big to register on the radar screen.
The example you gave, AN/SPS-75 is the same of TRS-3D btw, all designed to the primary search radar for corvette sized warships. This class of warships don't have significant AAW capability anyway so a less capable radar will do. When fitted to first line medium sized warships of Azizuki's size, they backed up by longer wavelength radar with superior long range performance. MW-08 for example is often paired with L-band LW-08.
The Germans will absolutely go mad hearing that their F125-type Baden-Württemberg class frigate does not have AAW capabilities.
The C-band is utilized for search mode anyways. The Akizuki-class has another card up her sleeve in which she utilizes Gallium nitride semiconductor technology that the US only starting to do research to incorporate it into AMDR which enhances sensitivity of the radar boosting it's range.
So you are saying FCS-3 equipped warships, including Akizuki, have to always tag along with warships with superior long range radar in order to operate effectively?
Again writing out of ignorance of how a battle group works. The Kongo and Atago class having the long range radars has a primary mission to target and engage Ballistic missiles. Akizuki class are to escort these ships from incoming hostilities so they are undisturbed in accomplishing their mission.
Now do you understand?
