Antenna De-embedding of Radio Propagation Channel with Truncated Modes in the Spherical Vector Wave Domain

This paper proposes a novel approach to extracting the narrowband propagation channel from the communication link by de-embedding the impact of the antennas. In the proposed approach, the mode-to-mode mapping matrix M which is the expression of the propagation channel in the spherical vector wave domain, is estimated by applying pseudo-inverse computation to the channel transfer functions with dedicated spherical arrays. The estimated M is truncated and only the dominant modes within the spatial bandwidth of the fields radiated from the finite volume of the spherical array are considered. Two types of spherical array are investigated: an ideal array using tangential dipoles and a virtual array using dielectric resonator antenna (DRA). The ideal array is used for parameter investigation including the array radius and the spacing with regard to the size of M and the condition number of the excitation coefficient matrix, while the virtual DRA array is proposed as a practical implementation of the ideal array. The accuracy of the proposed approach has been validated numerically. The uncertainties of spherical array in practice, such as the influence of non-ideally embedded array elements, cables and fixtures, are considered in the validation. Moreover, the channel transfer functions reproduced by the deembedded M are analyzed given different target antennas at link ends. The gain and phase discrepancies as well as the antenna correlations of the reproduced channel transfer function are compared with the generated reference.