Effect of dielectric permittivity on infinite arrays of single-polarized Vivaldi antennas

The effect of dielectric substrate on the performance of infinite arrays of single-polarized Vivaldi antennas is studied by computing the input impedance of an antenna in an array environment by using full wave method of moments techniques. It is found that dielectric permittivity plays an important role in the wideband performance of such arrays, and comparison with dielectric-free cases for similar geometries is also included to bring out the impact of the substrate. In particular, increasing dielectric permittivity improves the bandwidth considerably (bandwidth up to 10:1 is predicted). The parametric variation due to permittivity is presented in detail, and optimization involving other design parameters is discussed. Results from a parallel plate waveguide simulator technique employed to assess and compare the array performance of Vivaldi with different dielectric permittivities qualitatively support the predicted effect of dielectric substrate.