3-D direction finding using a single antenna

A compact antenna planar antenna which presents an unique polarization at a specific direction in its far-field region is designed. Measuring the polarization of the radiated field of this antenna, the relative orientation of the receiver can be determined. The antenna structure is composed of a horizontal dipole, vertical dipole, and two circular loops connecting the adjacent arms of the dipole elements. The arc length and geometry of the loops are designed to generate circular polarization at the antenna´s boresight. Using a single feed point, it is shown that the antenna is cable of producing all polarizations in different directions with almost isotropic radiation pattern. To show the validity of the design an antenna structure over a ground was fabricated and measured at 2.58 GHz. The measured radiation pattern and polarization compares very well with the simulation results.