Scalable Millimeter Wave Wireless Power Receiver Technology for Space Applications

Technologies enabling the development of compact systems for wireless transfer of power through radio frequency waves (RF) continue to be important for future space-based systems. A typical wireless power receiver (WPR) consists of an antenna array and an RF to DC power conversion network. The physical size of a WPR is inversely proportional to its frequency of operation and directly depends on its power delivery capacity. The smaller form factor of the higher frequency WPRs makes them more attractive for space systems. However, they have to deal with: 1) Availability of high frequency power conversion components; and 2) Overall efficiencies in antenna arrays and power conversion networks. In this paper we present a new, compact, scalable, and low-cost slot antenna array technology for efficient receipt and conversion of power using RF waves at 94 GHz. Simulation of the performance of an individual slot suggests that the antenna can capture 93% of the RF energy. In an array form, this efficiency is also a function of the packing density of the slots and the ratio of energy stored in the antenna side lobes. Antenna simulation results suggest that the energy of the side lobes of each slot is more than 20 dB lower than that of the main lobe. As a result, slots can be placed very close to each other. A very small network located adjacent to each individual slot differentially converts the RF to DC power. This network consists of a coupling electrode, bypass capacitors, a matching transmission line, a rectifier, a low pass filter, and a DC storage capacitor. Details of the network and its fabrication over the slot array using additional layers of SiO2 and Au are described. Simulation results are also presented, which suggest that this technology is capable of realizing overall conversion efficiencies greater than 72%.