Disclosed is a method of forming a transmission beam with a transducer array comprising a plurality of transducers, the method comprising: receiving at least one desired property for an intended transmission beam; determining an optimised operation parameter for a transducer of the transducer array based on the received at least one desired property and an array model for modelling a relationship between at least one beam property and at least one transducer protection property whilst taking into account of an acoustic mutual coupling of the plurality of transducers of the transducer array; and generating the transmission beam using the optimised operation parameter on the transducer array.