Intelligent antenna and reflecting surface designs for wireless communication systems

Wireless communication technologies, which were previously used only for voice communication and text messaging, are constantly evolving in line with diversifying and increasing user demands. With devices of many that we use in daily life getting smarter, the concept of Internet of Things (IoT) has emerged. The burden created by smart objects in wireless communication is increasing exponentially. Including the increase in the number of mobile users and the use of mobile networks by vehicles into that, the existing wireless communication infrastructures are insufficient to meet the requirements. It is aimed to solve these problems with new generation wireless communication systems by providing secure communication at higher speeds, lower delay and wider coverage areas. Intelligent reflecting surfaces (IRSs), which are designed for the next generation wireless communication systems, propose a more environmentally friendly solution not requiring expensive equipments with low energy consumption. IRSs are utilized by only locating them in the transceiver environments with the need of no hardware or software changes in the receivers and transmitters. Hence, they are promising in many issues such as reducing the data traffic in the RF spectrum, transferring data and energy in IoT networks, conveying the signal to the blind points where the signal can not reach and solving positioning problems. In this thesis study, firstly, two microstrip antennas operating at 2.4 GHz and 5 GHz, which are the operating frequencies of wireless fidelity (Wi-Fi) networks, are designed. Then, two different designs of frequency selective reconfigurable microstrip antenna are introduced by using PIN diodes. Finally, an IRS consisting of varactor diodes, microcontrollers and 3x4 reflecting elements, which operates in the 2.4 GHz frequency band, that can change the phase angles of the incoming signals is produced and the results of the design are presented.