The present invention relates to a method and an arrangement for
optimizing the efficiency of a power amplifier (1) that is utilized for
transmission of radio signals in a portable radio communication device,
such as a mobile phone. The impedance loading the power amplifier (1) is
controlled by a controller (5) in dependence on a transmission power of
the portable radio communication device, wherein the radiating impedance
of an antenna element (2) loading the power amplifier is controlled in
dependence of the desired load impedance. Preferably, the changing of
radiating impedance is performed by changing a capacitive coupling
between the antenna element and a ground element or by changing the size
of the antenna element. Better efficiency and bandwidth are thereby
attained.