Effects of dielectric substrate on performance of UWB Archimedean Spiral Antenna

This paper presents the design of the Archimedean Spiral Antennas (ASA) backed by a metal plate. The dimension of the spiral arm was designed to operate between 3.1 - 10.6 GHz and different permittivity of the dielectric substrate was employed between the spiral arm and the backing plate with specified electrical thickness of λ_g/4 at the lowest frequency range. The CST simulated results shows that when the dielectric permittivity, ε_r increases, the performance of the ASA in terms of return loss, axial ratio, efficiency, pattern and gain deteriorates.