This paper reports experimental results of characteristics of the junction-excited waveguide radiators, which the numerical results have been presented in . The junction-excited waveguide radiator is proposed as an array element of a spherical array self-mixing oscillator antenna. There are two configurations of waveguide radiators, ie., normal aperture and 15° inclined aperture waveguide radiators. Each waveguide radiator has one Gunn diode as junction-excited that provides oscillations and self-mixing operations. These waveguide radiators can oscillate at 10GHz with bias voltage of 9.4V. The transmitted power of normal aperture and 15° inclined aperture waveguide radiators are 14.533 and 13.903dBm, respectively. The radiation patterns obtained from experiment are compared with calculated results. The self-mixing performance shows that the normal aperture and 15° inclined aperture waveguide radiators have conversion loss of 36.754 and 35.921dB, respectively for IF frequency of 400MHz.