I think periscope detection is only possible since the 1970s
The opportunity to detect periscopes was exploited in early radar experiments that prompted the development of the AN/APS-116 radar manufactured by Texas Instruments in the 1970s. The AN/APS-116 is an Xband, high-resolution, fast scanning system developed specifically to provide a periscope detection capability on the carrier-based S-3 aircraft. The AN/APS-137 is an upgrade of this radar used primarily on the S-3; a limited number are also used on the land-based P-3 aircraft.
https://www.jhuapl.edu/Content/techdigest/pdf/V18-N01/18-01-...