Carpathian Journal of Electronic and Computer Engineering 11/1 (2018) 7-10 DOI: 10.2478/cjece-2018-0002 ISSN 1844 – 9689 7 https://www.degruyter.com/view/j/cjece Design of Pyramidal Horn Antenna for 2.45GHz in FEKO for Application in Experimental FSO/RF Hybrid System Michal Márton Department of Electronics and Multimedia Communications, Faculty of Electrical Engineering and Informatics University of Technology Košice Košice, Slovakia michal.marton@tuke.sk Ľuboš Ovseník, Ján Turán, Michal Špes, Department of Electronics and Multimedia Communications, Department of Energetic Engineering Faculty of Electrical Engineering and Informatics University of Technology Košice Košice, Slovakia lubos.ovsenik@tuke.sk, jan.turan@tuke.sk, michal.spes@tuke.sk Abstract — Communication technologies are growing for day to day because demand on data sharing is unstoppable. Users require availability of approach to network at all time. Implementation of smart technologies allows communication of all type of devices. Capacity of data flow have to grow. Video formats HD or 4K require transmit on high data speed. Based on the demands many types of different communication systems which are suitable for these speeds were designed. One of these systems is FSO (Free Space Optics). FSO system is based on transmission of optical beams which carry the information. This system allow high data speed comparable with standard optical fiber in range to 10km. One of drawbacks of this system is LOS (Light of Sight) between communication points. The other drawback is sensitivity to weather changes. Optical beams interfere with water particles and cause attenuation on transmission path. The solution is in implementation using hybrid FSO/RF system which combines optical communication system with RF (Radio Frequency) backup link. We realized FSO communication link on Technical University of Košice. Our research is focused on design of appropriate type of antenna for our RF backup link. Our results in this area were published. Keywords— FEKO, FSO/RF, horn antenna I. INTRODUCTION Today in the age of smart technologies we have to react to demand of users. Each of them would like to communicate, share data or information, stream or watch high quality video. Young generation is online oriented. On the base of these requirements we have to focus on increasing availabilities of services through growth of parameters of communication systems. Increase of speed of transmission, bandwidth and decrease of latency is one of the main points of research activities in communications field. Invention of optical fiber as transmission medium caused revolutionary change in communication systems. Transmission of light beams which carry information with possible reach speed of transmission about 40 Gbps was incredible. Optical fiber was the basic part of many communication systems, but the idea of transmission of light as carrier of information affects all types of communication systems. FSO system is based on transmission of optical beam carrying information through atmospheric channel. In comparison with optical fiber communication system FSO system offers comparable speed of transmission in short range (few km, to 10 km with speed of transmission 1 Gbps) without needs to implementation of optical fiber on transmission path. Implementation of FSO system is easy regarding to speed of installation. This system could be implemented during one day. We need to place only one optical head on both sides of communication nodes with ensured LOS (Light of Sight) between communication points. Application of these systems is effective in mountain areas or in densely build city, where it is very complicated to install standard optical fibers. Because the chosen communication medium at atmospheric channel with all inhomogeneities, the FSO system is sensitive to changes in atmosphere. These inhomogeneities are caused by concentration of water particles which are specific for each of type of weather. In case of critical concentration of inhomogeneities in atmosphere, the attenuation of optical beams grows significantly. In boundary cases it is possible to reach outage of services. We have to secure stabile connection at all times. Solution is in design of hybrid FSO/RF system which combines primary optical link and backup RF (Radio Frequency) link. We look for appropriate type of RF antenna operating in non-licensed frequency range with sufficient gain and low radiation power. Many studies were focused on a design of appropriate type of antenna. We are interested in design of pyramidal horn antenna operating on 2.45 GHz. This is the point of this paper. Our research activities focused on increasing availability of FSO system and analysis, searching