Design of Reconfigurable Antennas for Wireless and 5G Applications

Abstract

In the following thesis, a brief survey of frequency reconfigurable antennas is pre- newlinesented. Novel reconfigurable antenna structures are designed, analyzed, fabricated and tested. In the first design, a wideband co-planar feed monopole triangular patch antenna is designed. A dumb-bell structure Defected Ground Structure (DGS) is made on partial ground plane which acts like a slot resonator. These dumbbell-shaped DGS is operat- ing at 3.2 GHz and 5.8 GHz and create stop bands at these frequencies. This results newlinein band rejection in the operating band of a conventional partial ground plane antenna. newlineThe simulated -10dB and this antenna has a impedance bandwidth of 12.90 % covering newlinefrom 2.9 to 3.3 GHz and 20.68 % from 5.2 to 6.4 GHz separately among the lowest and newlinehighest bands. Later, we investigated the pin diode integration and the effect of bias- newlineing on the multiband antennas for frequency reconfiguration. Pin diodes are commonly newlineused to design reconfigurable antennas due to sufficient switching isolation, lower cost newlineand ease of fabrication. The effect of biasing conditions of a pin diode Radio Frequency (RF) switch on frequency reconfigurable antenna is demonstrated. The contribution of the forward diode current and the reversed biased voltage is investigated in terms of the shift in the operating band, the impedance matching, and the radiation efficiency. Differ-ent approaches of modelling pin diode RF switch in Ansys Electromagnetic Simulator and their merits and demerits are highlighted. A significant mismatch between simu-lated and measured operating bands, impedance matching, and radiation efficiency is observed for different biasing conditions and switch models. The defects in the ground newlineplane or radiator affect the antenna impedance matching and radiation pattern. To elim- newlineinate these limitations, we have further used external parasitic elements and pin diode newlinecircuits to reconfigure the frequency. A Frequency Reconfigurable Microstrip circular newlinepatch antenna for Bluetooth with on and off switches, Worldw