Ultra geniş bantlı vivaldi antenlerin tasarımı ve performans iyileştirmesi

Ultra-wideband technology has become a trending topic in the academic community since 2002 due to the release of the spectral mask by Federal Communications Commission, allowing the use of 3.6-10.1 GHz band for commercial and industrial applications. Being one of the fundamental components of ultra-wideband systems, ultra-wideband antennas are an important research area. In this research, Vivaldi antennas for ultra-wideband communications and several performance enhancement techniques for the antennas were studied. Antennas were designed and simulated using a commercially available three-dimensional electromagnetic simulation tool. First, a simple design of a Vivaldi antenna with a rectangular microstrip feed was obtained. The initial design has a -10 dB impedance bandwidth between 3.1 and 13.6 GHz and an average realized gain of 2.75 dBi. A method based on the alignment of the microstrip feed was described for adjusting the bandwidth of the initial design. Then, using several performance enhancement techniques such as implementation of corrugations and a parasitic patch, the antenna design was improved. Thanks to the applied methods, an antenna design with -10 dB impedance bandwidth extending from 1.33 to 10.1 GHz and an average realized gain of 6 dBi was achieved. Findings of this thesis study show that Vivaldi antennas having specific structures designed with the applied techniques are a promising solution for ultra-wideband communication systems, especially where antennas with directive radiation patterns are desired.