COMPACT ANTENNAS WITH PARASITIC ELEMENTS FOR APPLICATIONS IN MICROWAVE AND MILIMETER WAVES COMMUNICATIONS SYSTEMS
Compact antennas, microstrip antennas, parasitic elements, multiband antennas, broadband antennas
The speed of transformation, due to technological recent advances, has been happening in a surprising way, particularly in communications systems. Less than half a century ago, studies of wireless communication systems were incipient. The first generation (1G) of wireless communication systems dates from the mid-70s. Today, we are waiting for the fifth generation (5G) of wireless communication systems, with all the inherent features, which comes with new services, greater efficiency, improved quality of life, faster services, safety and comfort to users. The need for compact devices to be used in these systems has been gradually increased, and the use of increasing frequencies leads to the reduction of their dimensions. Microstrip antennas stand out as a very important component in this scenario. Due to the inherent mobility of the system and the communication due to the connection with the modern communication processes, associated to the use of the Web, compact, broadband/multiband, and efficient antennas are required, for several applications. In this work, compact monopole antennas are presented with multiband behavior, ranging from low microwave frequencies, with possible Wi-Fi and WiMax applications, up to millimeter wave frequencies, for use in the LMDS (Local Multipoint Distribution Service) band and 60 GHz applications. The first structure investigated in this work is an annular microstrip monopole antenna. Thereafter, parasitic elements are added to this antenna structure, resulting in new antenna geometries that are investigated as well. Therefore, the initial structure is modified in order to obtain the desired antennas performances. Simulation of the antenna structures is done using the time domain finite integration method, implemented in the commercial software CST (Computer Simulation Technology). Preliminary results indicate agreement between simulation and measurement values. Suggestions are presented for the continuity of the work.