Linear and circular polarized electrically small antennas based on the employment of metamaterial-inspired sub-wavelength resonators

In this contribution, we present the design of efficient electrically small apertures loaded with metamaterial-inspired sub-wavelength resonators. The employment of omega and modified protractor resonators enables efficient radiation and automatic impedance matching, without increasing the physical dimensions of the aperture. This phenomenon is applied to the design of several microwave components, some of which are presented in the paper: a. linearly-polarized open-ended waveguides and horn antennas and b. linear-to-circular polarization transformers. The results are supported by proper numerical simulations and measurements.