This Letter deals with the problem of seeking an electromagnetic signal source using a group of autonomous robots by designing an event-triggered communication scheme. First, the finite difference method based on radial basis functions is used to estimate the gradient of the scalar field generated by the signal source. Second, a consensus controller is proposed to control multiple robots to seek the signal source along the gradient ascend direction. At the same time, an event-triggered communication scheme is designed such that the burden of communication can be lightened. Finally, simulation and experimental results show the effectiveness of the proposed event-triggered communication scheme for the problem of seeking an electromagnetic signal source.