Progressive Ultra- Wideband Circularly Periodic High Impedance Surface Integrated with a Spiral Antenna

A progressive ultra-wideband (UWB) circularly periodic High Impedance Surface (HIS) is designed and integrated with a UWB spiral antenna while maintaining a low height profile. The HIS is designed to perform across the full frequency range between 1.1 GHz - 8.0 GHz. The proposed design methodology divides the HIS into two zones - heterogenous and homogenous zones. In the heterogenous zone, multiple HIS rings are designed at specific frequencies across the band of interest that correspond to the wavelength represented by the circumference of each ring. Simulations using concentric circular waveguides are used to verify that the 0° reflection-phase of each ring coincides with the frequency and wavelength represented by the circumference of each ring. The homogenous zone of the HIS consists of multiple rings that are designed to have 0° reflection-phase at a single frequency to provide additional frequency and spatial coverage. The UWB HIS is then integrated with a UWB spiral antenna placed at a height of 0.1λ above the HIS, with respect to the lowest frequency of operation. This progressive UWB HIS-backed spiral antenna is enclosed in an aluminum cavity to further suppress back-lobe radiation. Return loss S11, gain and radiation pattern data are presented to demonstrate UWB performance of the full antenna structure.