This paper presents a multiband feed system intended to operate at S, X, K, and millimetre bands for a classical Cassegrain type radio telescope. The feed system consists of an ellipsoidal reflector confocal with the hyperboloidal reflector of the Cassegrain system. A ring of feeders, for different bands of operation, is placed in the backside of the paraboloidal reflector structure. Thus, only a rotation movement is needed to change the operation band, to situate one of the focuses of the ellipsoid at the correct feeder phase centre. This feed system avoids changing the hyperboloidal reflector each time the radio telescope is going to operate in a different band, while it achieves high efficiency, making the radio telescope highly competitive.