These vessels are modified versions of the Oliver Hazard Perry class Frigate.
Originally the ROCN intended to build only 2 ships to the normal Perry standard, with the remainder of the class being modified with an advanced combat system.
This article makes mention of a "ADAR-N" system, which I found no references for. The first drawing as based on this idea, using this image as a template. The second, AEGIS equipped drawing is a more likely proposal, carrying the SPY-1F and associated SPG-62.