An alternative design approach for multi-feed spatial power combining reflectarray antenna

Abstract

Spatial power combining provides a viable solution at RF power levels not achievable at the circuit level. Recently, reflectarray antennas with multiple feeds have been investigated as an alternative means of spatial power combining. In these designs, the required phases of the reflectarray elements are derived via a total reflected field formulation [1]. However, a numerical optimization routine is required to derive these phases. In this paper, we propose a more efficient formulation for the phase derivation. In contrast to the total reflected field formulation in [1], we used the total incident field formulation to derive the required phases. In this new approach, the required phases can be computed in closed form without the need for any numerical scheme, making it highly efficient especially when the number of elements is large (usually in the thousands). For verification, the new formulation is applied to design two dual-feed spatial power combining reflectarray antennas. Both reflectarray antennas are modelled and simulated using a full-wave solver. For the first reflectarray antenna, its simulated results are in general agreement with those of [1]. For the second reflectarray antenna, it has been fabricated and measured. The measured results are in good agreement with the simulated results. Thus, we verified the new and numerically more efficient formulation.