Stripline-based spiral antennas with integrated feed structure, impedance transformer, and dyson-style balun

Abstract

This work covers the design and experiment of a finite-ground stripline-based spiral antenna with a Dyson-style balun and feed network (including broadband impedance transformer) that have been integrated into a multi-layer (via-free) structure. The spiral antenna uses the finite grounds of the stripline feed network (including the balun and impedance transformer) as one arm of the spiral, and the center conductor of the stripline provides the complimentary spiral arm. This configuration provides a means to impedance match a spiral antenna by tailoring its spiral constant K (related to slot-to-metal ratio) to match the desired characteristic impedance of the stripline at the Dyson-style balun and accommodate very small feature sizes. The resulting structure maintains the typical radiation behavior and broadband operation of spiral antennas, but can be fabricated with IC processes and integrated with other components. Experimental results for an Archimedean spiral antenna are included to demonstrate the design.