An ultrasound system comprises: a probe having a transducer array of n transducer elements for transmitting ultrasound signals, said n transducer elements being associated with respective scan lines; a steering angle calculating unit for calculating steering angles of the scan lines by using series determined by a relation between the steering angles of at least two scan lines; and a control unit for controlling transmission of the ultrasound signals such that the ultrasound signals can be focused along the scan lines based on the calculated steering angles of the scan lines.