I would not say comparable to the Patriot in terms of engagement sphere.. but rather to the Buk missile system. Different only in that the Buk missile is based on the TELAR system for launch engagement while while the AKASH relies only on the Rajendra for engagement. In essence, a single BuK vehicle can in theory engage a target on its own without support but the AKASH needs the Rajendra vehicle for search and guidance.
Please do not go on believed. The range quoted is the effective engagement range.. in which the AKASH has a high chance of scoring a kill. After that range.. the kinematics of the missile deteriorate and its ability to get a kill also goes down exponentially.Actually Akash's range is believed to be much more than 25or 30 KM. This is range is the range when missile do a lots of maneuvers to chase plane.