The experimental results presented in this paper focus on the performance of a rectenna array by studying the effect of mutual coupling between two rectennas. The measurements in several planes of the space are investigated and used to help us to define the minimum distance for future rectenna arrays that can be used at a low power density level. The single element chosen for the array is composed of a rectifier circuit and a CSPA (Circular Slot Patch Antenna). This study shows that at a distance greater than 6 cm (>λ/2) between two rectennas in reception, we observe that the DC received voltage is constant in the Y plane. While, in the X plane, the DC received voltage remains constant whatever the distance is. We deduce that these rectennas are uncoupled in this case. We can consider each rectenna like an independent system. 1. Introduction Recently, the emergence of various wireless power technologies [1], [2] to eliminate the last cable has generated significant research interest in this area. The concept is to eliminate in the future the need for problem-prone wiring and constraints battery replacement. Indeed, this study is motivated by two types of applications: (a) powering of low-power sensor and (b) RF energy recycling being aware of the energy consumption to the natural environment. In this study we focused our attention on the power collecting system: the rectenna (the RF/DC converter) [3]. Due to the safety regulations, we considered low power level densities. But in order to increase the collected power we have to use a rectenna array. The challenge is to maximize the rectenna array power conversion efficiency for low input power levels density. To this end, we have chosen to experimentally study the effects of the mutual coupling of two rectennas in two planes of the space on the RF/DC conversion. The single element rectenna is composed of a compact circular slot patch antenna (CSPA), coupled with a simple and efficient rectifying circuit. The article begins with the study of the rectenna design. In this section, all the advantages to the CSPA antenna design are developed. The optimization of the rectifying circuit at f 0 =2.45GHz, using a matching quadripole (four-ports) between its input impedance and the antenna impedance, is also presented. Finally, the overall test setup and experimental results on the mutual coupling between two rectennas are described and discussed in the subsequent parts.