No, the most common type of convector heaters are not portable, as they tend to be fixed to the wall and connected by copper pipes to the central heating system.
They are commonly, but inaccurately, called 'radiators' - but they warm a room by convection, not by radiating heat.
Night storage heaters are filled with bricks or concrete - they can be moved, but are hardly portable!
(Actually, all heat is radiant, and this warms the air to provide convection).