*Corresponding Author Asian Journal of Water, Environment and Pollution, Vol. 15, No. 3 (2018), pp. 103–106. DOI 10.3233/AJW-180048 Investigation of Fractal Antenna for RF Energy Harvesting System Shashi Bhushan Kumar* and Pramod Kumar Singhal 1 Dept. of Electronics & Communication, Bharati Vidyapeeth’s College of Engineering, New Delhi, India 1 Dept. of Electronics, Madhav Institute of Technology & Science, Gwalior, India * sbkumar2010@gmail.com Received March 14, 2018; revised and accepted March 31, 2018 Abstract: In this paper a fractal antenna for RF energy harvesting system has been proposed. In this design stacked structure of three layers with air medium has been presented. This antenna is specially designed for TV transmission as well as GSM mobile application in band of 700 GHz and 900 GHz respectively. Electromagnetic energy can be harvested and renewable energy can be generated using rectifer and DC motor, that can be a source of electrical power. As proposed antenna has signifcant amount of effciency, so antenna will work very effciently for harvesting RF energy from unbounded media. Proposed antenna has been designed and simulated using IE3D EM simulator. Key words: Fractal antenna, VSWR, return loss, RF energy, renewable. Introduction Using wireless device, RF energy harvesting can only be possible by using the antenna. Antenna should have very high effciency. There are two type of effciencies used for usable antenna, frst is antenna effciency, which includes mismatching impedance at the input terminals arising due to mismatching of characteristic impedance of TL and input impedance of antenna. Second is radiation effciency which includes structure of antenna losses i.e. conduction and dielectric losses (Balanis, 2005). Energy harvesting is an important application in which energy can be harvested from different sources such as ambient RF electromagnetic signals, solar energy and vibration. This paper focuses on harvesting energy from RF sounding signals at 700 GHz and 900 GHz frequency. RF energy harvesting system (Hasan and Giri, 2012) basically consists of antenna and rectifer. The function of rectifer is to convert the signals received by antenna to a DC voltage. There are many different types of antennas (Nambi and Wentworth, 2005) which can be used for energy harvesting system. However, paper presents the array type of antenna as it has the advantage of providing a higher gain and better antenna performance. There have been many researches about array antenna starting by studying a single patch (Hazila and Aljund, 2005), mircostrip antenna. Once the single patch designed has the suitable gain and good performance, array antenna can be designed. The single patch is frst optimized to achieve a high gain and good performance in terms of radiation pattern, bandwidth and return loss. The design of array antennas in the prior literatures evaluates the performance of array antenna base on patch’s shape (Sai Sandeep and Sreenath Kashyap, 2012) of the array antenna; for example, circular patch array can achieve gain of 10.7 dBi and return loss of –10 dB, whereas, rectangular patch can achieve gain of 10.6 dBi and return loss of –26 dB. Other literature