In recent days, to meet the energy requirement of society, non-conventional energy resources are being explored by research fraternity. Large-scale ambient energy (example solar, wind and tide), is most widely available and large-scale technologies are being developed to efficiently capture it. Earth Energy harvesting can play an important role in this scenario. This book presents a novel idea of harvesting earth energy using antenna sensor as night time energy harvester. In this work, various antennas have been used to capture the infrared radiations that the earth radiates during night hours.This can be an environment friendly energy solution for the society.