FDTD analysis of circularly polarized printed array considering periodic cell boundary

A circularly polarized printed array composed of strips and slots (CP-PASS) was proposed and improved as a new type of series-fed circularly polarized printed antennas. Pairs of a strip and a slot are electromagnetically coupled to a stripline, and the spacing between the two elements is about a quarter guide wavelength. The main advantages of the array are the simplicity of the antenna structure as well as the compatibility with integrated circuits. The strip element of the CP-PASS consists of the strip dipole, window, and the probe. The window is an aperture to construct a strip dipole on the substrate. The bandwidth of the strip element increases with an increase of the width of the window. The probe, a small strip, couples to both the feed line and the strip dipole to reduce the spurious radiation from the window. The probe also reduces the generation of the parallel plate mode. We investigate the array by using the FDTD method with periodic cell boundaries.