A guided wave probe for use in guided wave testing of plate structures. The probe comprises a cup having a flat or nearly flat bottom, and a guided wave sensor, such as a magnetostrictive sensor, placed in the bottom of the cup. The sensor and/or cup are coupled to the plate structure, such that ultrasonic energy from the sensor is transmitted to the cup and the plate surface. The sensor is incrementally rotated in the cup, and sensor data is acquired at each incremental position.