1) An optimum pyramidal horn antenna was designed to provide a gain of 20dB at a center frequency of 9.5GHz. 2) The horn was fabricated from aluminum sheet with dimensions of 13.5cm by 11.5cm. 3) The performance of the fabricated horn was evaluated both analytically and experimentally. Results showed good agreement between calculated and measured parameters including gain, directivity, impedance, and scattering parameters.