An Enhanced Spherical Vector Wave Approach for High-Fidelity Channel Emulation in MPAC

The plane wave synthesis (PWS) method is conventionally considered superior to the spherical vector wave (SVW) technique for two-dimensional (2-D) multiple-input multiple-output over-the-air (OTA) testing. This letter consummates this perception by identifying that the degradation of the conventional SVW stems primarily from sensitivity to the mode truncation number. To address this, we propose a robust enhanced SVW scheme formulated directly in the electromagnetic field domain. By exploiting the natural low-pass filtering property of the spherical sampling matrix, the proposed method inherently avoids the overfitting issue of high-order modes, thereby eliminating the truncation sensitivity. Our simulation results demonstrate that the proposed scheme ensures numerical stability and consistently outperforms the classic PWS in terms of reconstruction accuracy, rotational invariance, and test zone size. This work effectively revitalizes the SVW technique for high-precision 2-D OTA testing.