Transmitter with two antenna output terminals (10, 11) for connecting to corresponding antenna terminals (101, 102) of an electrically short antenna for transmission of an electromagnetic signal, the transmitter comprising a capacitive energy storage, an output stage (31, 32) and a switching circuit having an open state and a closed state, the switching circuit being connected between an output of the output stage (31,32) and ground, the capacitive energy storage comprising a storage circuit and output capacitors (33,34) connected in series between the output of the output stage (31, 32) and the antenna terminal (10,11), and being adapted to form with the antenna when connected thereto a resonance circuit (2, 100) with a resonance frequency and a quality factor, the output stage (31, 32) being adapted to provide an electric transmission signal to the resonance circuit (2, 100), the switching circuit being connected to an antenna output terminal (10, 11) through the output capacitors (33,34) of the capacitive energy storage such that the maximum signal voltage occurring across the switching circuit in its open state is lower than the maximum signal voltage occurring across the antenna output terminals (10, 11), the storage circuit comprising 3 capacitances (21, 22, 23) being connected in series between the antenna output terminals (10, 11), the common connection between the first and second, and second and third of these capacitances respectively defining a first and a second node (26, 27) between them, a first tuning switch connected between the first node and signal ground, a second tuning switch connected between the second node and signal ground, the switching circuit comprises a first field effect transistor, FET, the transmitter is adapted to alter the quality factor by changing the series resistance of the switching circuit by switching the switching circuit between the open state and the closed state, wherein the series resistance of the switching circuit in its closed state is varied by varying the intrinsic on-resistance in the first FET, and further comprising a bandwidth controller adapted to control the series resistance of the switching circuit in its closed state. the transmitter comprising a capacitive energy storage, an output stage (31, 32) and a switching circuit having an open state and a closed state, the switching circuit being connected between an output of the output stage (31,32) and ground, the capacitive energy storage comprising a storage circuit and output capacitors (33,34) connected in series between the output of the output stage (31, 32) and the antenna terminal (10,11), and being adapted to form with the antenna when connected thereto a resonance circuit (2, 100) with a resonance frequency and a quality factor, the output stage (31, 32) being adapted to provide an electric transmission signal to the resonance circuit (2, 100), the switching circuit being connected to an antenna output terminal (10, 11) through the output capacitors (33,34) of the capacitive energy storage such that the maximum signal voltage occurring across the switching circuit in its open state is lower than the maximum signal voltage occurring across the antenna output terminals (10, 11), the storage circuit comprising 3 capacitances (21, 22, 23) being connected in series between the antenna output terminals (10, 11), the common connection between the first and second, and second and third of these capacitances respectively defining a first and a second node (26, 27) between them, a first tuning switch connected between the first node and signal ground, a second tuning switch connected between the second node and signal ground, the switching circuit comprises a first field effect transistor, FET, the transmitter is adapted to alter the quality factor by changing the series resistance of the switching circuit by switching the switching circuit between the open state and the closed state, wherein the series resistance of the switching circuit in its closed state is varied by varying the intrinsic on-resistance in the first FET, and further comprising a bandwidth controller adapted to control the series resistance of the switching circuit in its closed state.