A cross shaped spiral antenna radiating omnidirectional circularly and linearly polarized waves

A novel spiral antenna that simultaneously radiates circularly and linearly polarized waves is presented. The antenna achieved radiating omnidirectional circularly polarized waves by shaping a spiral antenna as its looks like a cross. Moreover, putting a parasitic element close to it, it succeeded in being utilized as a linear polarization antenna at the same time. This paper explains the reason why the antenna radiates multi-polarization waves and how the antenna is designed in order to utilizing frequencies. Experimental results of return losses, radiation patterns and axial ratios of a prototype antenna are shown for verifying its performance. The antenna can be expected to be used for multifunctional mobile communication devices, because it is a single feed and single layer printable antenna.