Abstract: A mobile radio transmitting and receiving device with a tunable antenna wherein, in order to provide a transmission/reception capability in different frequency bands, with a virtually constant, stable antenna gain, with the radio transmitting and receiving device, a dielectric body which is mounted such that it can be moved is guided by adjusting part, which are controlled by a control device, in a near area of an antenna body, such that the extent of an overlap of the two bodies in the near area of the antenna body is changed until at least one physical input variable, which represents the reception and transmission quality, reaches an optimum.