A wide-slot waveguide antenna implemented on low-temperature cofired ceramic technology is presented. The overall antenna is excited by aperture coupling. The design is simulated and validated by experimental measurement. The measured result shows that a 10-dB return loss has been achieved across the bandwidth from 2.6 GHz to 12.8 GHz, thus amounting to 132.5%. The measured radiation pattern of the proposed antenna is also presented and discussed. (C) 2008 Wiley Periodicals, Inc.