On the planarity errors of the hologram of the CATR

Conventional compact antenna test ranges (CATR) are based on reflectors, the problem of which is a very tight requirement on the surface accuracy. A hologram is a transmission type of device, thus the required surface accuracy of the hologram is not so stringent, and the manufacturing of the hologram is much less expensive than that of the reflector. The effect of the planarity errors of the hologram on the quiet-zone field are simulated (with a method based on the two dimensional finite difference time domain method (FDTD) and physical optics), and the simulation results are compared with a simple theoretical path length approximation.