Large-Scale Tri-modal Electromagnetic Structure for Ambient RF Energy Harvesting

In this paper, a large-scale electromagnetic (EM) structure is designed and demonstrated for collecting ambient cellular power between 930 to 960 MHz. The novelty of the EM structure is that it is scalable in terms of size or gain, and can produce three high-gain radiation beams pointing to three different directions simultaneously. The construction of the proposed large-scale EM structure consists of a tri-modal patch antenna acting as the basic radiating element. Then, four basic elements are concatenated by three custom-made feed networks forming a 3-port sub-array. When the sub-arrays are linked together into an array and the corresponding three ports are subject to different phase weightings, the EM structure is capable of harnessing low power ambient RF energy concurrently with three different incident angles.