Came across this here:
http://www.selex-sas.com/EN/Common/files/SelexSAS_UK/pdf_datasheet/radar/picosar2.pdf

For all those, who wondered what the minimum real-world number of T/R elements for a AESA could be. And these elements are not overly sophisticated, so I guess a 400cm² array isn’t too much to expect. Would nicely fit a, say, Standard or a Harpoon.

Can’t wait so see such a seeker in a missile!