Stealth behavior of axisymmetric PEC reflectors

It has been observed that the monostatic radar cross section (RCS) for axial incidence of some canonical reflectors exhibits very low minima at certain equally spaced frequencies. This behavior is explained by using physical optics (PO) and verified via a full-wave analysis. In particular, it is shown that for a parabolic reflector the minima predicted by PO always equal zero. Relations between the geometrical parameters of the reflectors and the characteristic values of the RCS (notch frequencies, minimum and maximum value) are provided. Practical limitations to this phenomenon are also considered.