Research On Compact Vivaldi Antenna Based On Loading Method

Miniaturization of the Vivaldi antenna is investigated in this paper, metallic loading, resistive loading, hybrid loading and parasitic element are used.Firstly, parasitic element is researched, and a novel printed dipole with parasitic elements is designed, fabricated and tested, a bandwidth ranging from 2.3GHz to 3.9GHz for VSWR<2 is achieved. Simulation and test results show that the parasitic element can improve the bandwidth and the gain. In the most of operation bandwidth, the gain is greater than 9dB. Then a novel metallic loading Vivaldi antenna with parasitic element is designed to improve the impedance match, ranging from 1.4GHz to 5GH for VSWR<2, it has the size of 0.16λ×0.23λ×0.09λ(length×width×height) .Secondly, a novel resistive loading Vivaldi antenna with parasitic elements is designed. A bandwidth ranging from 0.9GHz to 6.2GHz for VSWR<2 is achieved, and it has compact size of 0.26λ×0.15λ(length×width). It has planar structure and directional radiation. Parameter analyses indicate that UWB performance can be achieved by optimizing resistance value and the size of the parasitic elements.Finally, a novel hybrid antenna is designed, fabricated and measured including resistive loading and metallic loading. Measured VSWR < 2.2 ranging from 1GHz to 6.2GHz is achieved. It has very small size (0.28λ×0.17λ×0.13λ) and directional radiation. Parameter analyses indicate that UWB performance can be achieved by optimizing resistance value and the size of conductor patch, the radiation efficiency is greater than 38%, and the gain varies from -0.8dB-8.5dB.