A theoretical study of measurement of cross‐polarization power ratio (XPR) in mobile communication environments

Methods for evaluating the crosspolarization power ratio (XPR) in mobile communication include the one using a crossed dipole, the one using a dipole antenna and a turnstile antenna, and that using a dipole antenna and a loop antenna. However, measurement errors in these methods have not been investigated. In this paper, the measurement error characteristics of various XPR measurement methods are analyzed theoretically. By finding the factors causing degradation of measurement accuracy, this paper proposes a method with more accuracy and clarifies its measurement error characteristics. It is found that the measurement error depends on the XPR and the measurement accuracy is degraded significantly because the measuring antenna does not have an isotropic characteristic and the antenna for horizontal polarization has a vertical polarization pattern. To improve this deficiency, a method is proposed in which a cylindrical slot antenna is used for the horizontal polarization because the sensitivity of this antenna to the vertical polarization can be made sufficiently low. It is pointed out that the measurement error with this antenna can be improved significantly.