The present invention relates to an electrically controllable/tunable microwave device comprising a ferroelectric substrate with a variable dielectric permitivity and conducting electrodes, arranged on said substrate, and the capacitance of which depends on applied voltage C/V), the microwave device comprises at least two sections or parts of the substrate/electrodes for each of which different electrical field strengths are generated upon voltage application. Said generated electrical field strengths are controlled by means of the design of the device and/or the voltage application such that the slope (dC(dV) of the voltage dependence of the capacitance (C(V) of the microwave device can be controlled.