Axial ratio reduced ultra wideband slot spiral on hybrid impedance surfaces

Abstract

This paper presents a low-profile ultra wideband slot spiral antenna backed by a hybrid impedance surface. A unique aspect of the spiral is its hybrid impedance surface cavity leading to reduced axial ratio over a wide bandwidth. This is an improvement over conventional cavity-backed wideband spirals. Measurements demonstrated that the slot spiral on the proposed hybrid impedance surface achieved a 10:1 bandwidth from 0.6 to 6 GHz with an axial ratio of <4 dB. The cavity depth is only 13 mm, corresponding to 0.03λ_600 MHz at its lowest operational frequency. As such, this slot spiral is attractive in enabling low-profile ultra wideband antenna with excellent RF performance for conformal and wearable applications.

Keywords:

• high impedance surface
• slot spiral
• axial ratio
• low-profile