For pt.I see ibid., vol.39, no.11, p.1575-81 (1991). The impedance and radiation patterns of a dipole-fed horn antenna in a ground plane are experimentally investigated at microwave and millimeter-wave frequencies. The agreement with the full-wave analysis technique presented in part I is good. The results indicate that for a 70 degrees flare-angle horn, horn apertures from 1.0 lambda -square to 1.5 lambda -square with dipole positions between 0.36 and 0.55 lambda yield good radiation patterns with a gain of 10-13 dB a cross-polarization level lower than -20 dB, and resonant dipole impedances between 40 Omega and 120 Omega . It is also found that the impedance measurements can be safely used for 2-D horn arrays, but the radiation patterns differ because of the Floquet modes associated with the array environment. The integrated horn antenna is a high-efficiency antenna suitable for applications in millimeter-wave imaging systems, remote-sensing, and radioastronomy.<>
