Abstract: An antenna circuit for a mobile telecommunication device. The circuit comprises a power amplifier for amplifying, in use, a signal to be transmitted. An antenna transmits signals output from the power amplifier. Switching means introduces, dependent upon the gain setting of the power amplifier, an attenuator between the output of the power amplifier and the antenna.

Abstract: The invention provides a simple solution for a broadband transmitter/receiver for which the working bandwidth is split into at least two non-contiguous sub-bands. The invention uses a filtering means 50 which comprises at least two band-pass filters 51 and 52 provided with switching means 53 and 54. The use of two switched filters 51 and 52 makes it possible to use a single synthesizer 6 to scan two sub-bands of the working bandwidth. The frequency synthesizer 6 operates for one sub-band in supradyne mode and for the other sub-band in infradyne mode. In a variant, the invention uses a third filter and divides the bandwidth into three sub-bands.