Abstract: There is provided an electronic gain shaper for open loop adaptive optimising of broadband microwave circuits, the gain shaper comprising operating parameter selection means adapted for providing one or more operating parameters; and a lossy tuning element operably coupled to the operating parameter selection means, wherein, in use, the gain shaper is adapted for receiving an operating mode; retrieving an operating parameter from the operating parameter selection means in accordance with the operating mode; and configuring the lossy tuning element in accordance with the operating parameter.