FDTD analysis of a strip dipole for a circularly polarized printed array fed by stripline

CP-PASS is a type of circularly polarized series-fed arrays, and the feed loss is smaller than that of corporate-fed arrays. The basic element for circular polarization consists of a strip dipole and a slot. They are fed in series by a microstrip line, and produce circular polarization in the broadside direction. The main advantages of this antenna are the simplicity of the element and feed line as well as the compatibility with integrated circuits. On the design of this antenna, a generation of the parallel plate mode has to be taken into account when the antenna is fed by the stripline. We previously reported how to calculate the power of the parallel plate mode by using the FDTD method and showed the probe reduced the parallel plate mode generated from the strip dipole with the window by 6 dB. In this paper, we calculate the propagation pattern of the parallel plate mode generated from the strip element by using the FDTD method.