Merhawit, Berhane (PhD)Haftamu, Mekonen2020-10-092023-11-282020-10-092023-11-282020-01-09http://etd.aau.edu.et/handle/12345678/22633The upcoming fifth generation (5G) of mobile communication that can enhance the capacity and data rates attracts many attentions in recent years. One drawback of 5G technology is that it is more prone to interference comparing to the other technologies. To overcome this problem 5G infrastructure uses much smaller base stations instead of using the large cellular antenna that we use today. To cover large area multiple number of small cells can be used. This makes the antenna costy. So, nowadays omnidirectional circularly polarized antennas are commonly designed in 5G technology to reduce sector antenna and the interference. Hence. Due to the various advantages of omnidirectional circularly polarized antennas different methodology was used to design. However, getting a good performed antennas based on their gain, radiation efficiency, low reflection coefficient and small electrical size of antenna are the major challenges. Therefore, in this paper a circularly polarization omnidirectional antenna which is applied to 5G communication is designed to improve the gain. The essence of this research is combining two different kinds of antenna in High Frequency Structure Simulator (HFSS) to achieve the characteristic of omnidirectional radiation pattern and circular polarization. The two kinds of antenna are dipole and negative magnetic permeability zeroth-order resonator respectively. Because both of them are linear polarization and omnidirectional radiation pattern, the characteristic of omnidirectional radiation pattern and circular polarization can be achieved as long as they are combined in physical space with 90 degrees. The radiation pattern of antennas is simulated to generate the gain. For the antenna designed at 6 GHz the gain is 1.9 dBi and for the antenna at 28 GHz the gain is 2.0 dBi. Both antennas achieve circular polarization performance and Omni-directional radiation within the operational band. This research output can be especially applied to 5G small base stations in the future.en-USDipoleMNG-TLZeroth-order transmission lineOmnidirectional circularly polarized antennaThesis