Broadband FDTD analysis of infinite phased arrays using periodic boundary conditions

Since the aperture of the AUT is smaller than the quiet-zone, the position of the AUT within the quiet-zone can be varied. The AUT positions in the quiet-zone were chosen so that the ripple was < 1.3dB. The measured radiation patterns are presented in Figs. 2 and 3. The results are in good agreement with those obtained in the far-field down to sidelobes similar to 30dB below peak. At lower levels, the ripple in the quiet-zone, and the reflections from the surroundings and the structure supporting the hologram, affect the measured power level. The quality of the quiet-zone can be Improved by using an anechoic chamber and by separating the left side (see Fig. 1) from the right side with a wall. The gain comparison technique with a 20dBi standard gain horn was used to determine the. AUT gain. The AUT gain measured with the hologram CATR at 39.3 GHz is similar to 35dBi, which is 2dB lower than the gain measured in the far-field.