Simulation of compact high power antenna concepts loaded by double-positive metamaterials

Abstract

An ongoing effort to reduce the size of high power antennas in the VHF and UHF bands investigates loading novel composite materials into the antenna structure. A previous effort developed high dielectric constant composites with a high dielectric strength for high power antennas. The current work aims to develop metamaterials with greater-than-unity values of relative permittivity and permeability. By designing the relative permittivity and permeability, the wave velocity in the antenna can be reduced while also controlling the wave impedance. These new magnetodielectric composite materials provide additional design flexibility over conventional dielectric loading for both traveling wave antennas and resonant antennas in HPM and HPRF applications. While a previous demonstration of dielectric loading of a dielectric resonator antenna utilized a composite with a dielectric constant of approximately 100 for high peak power operation in a very compact form factor, the current work focuses on achieving similar reductions in antenna size using composites with relative permittivity and permeability values of less than 10. Preliminary simulation analyses using CST Microwave Studio have shown the effectiveness of this approach in compact horns and helical antennas operating at frequencies below 1 GHz. This work presents the simulation of antenna concepts using magnetodielectric materials with greater than unity values of the relative permittivity and permeability. Magnetodielectric loading is compared to antennas not loaded with dielectrics and antennas loaded with conventional dielectric or magnetic materials. It is shown that magnetodielectric materials can achieve similar antenna size reduction as antennas with conventional dielectric or magnetic loading while improving the bandwidth.