Spherical near-field measurement of the offset vehicle antenna mounted on a vehicle

For the vehicle antenna measurement mounting on a vehicle, the offset mounting of the antenna will increase the maximum spherical wave expansion modes, with the increasing calculation time and the increasing risk of introducing environmental reflection noise. Therefore, basing on the matrix form of the traditional spherical wave expansion (TSWE) algorithm, this paper introduces the offset spherical wave expansion (OSWE) algorithm of the offset mounting antenna under test (AUT) aiming to decrease the maximum modes, shorten the calculation time and reduce the environmental noise with the method of spherical wave expansion. Taking LTE antenna and GPS antenna as examples, this paper analyzes the improved performance of OSWE algorithm comparing with TSWE algorithm on the vehicle antenna mounting on a vehicle, as well as the parameters like equivalent noise level (ENL), omnidirectional standard deviation (σ).