Impedance Matching of an Archimedean Spiral Antenna

This paper describes the design and impedance matching of an Archimedean spiral antenna using multi-section quarter wave transformers as well as exponential tapered line transformers. Each design starts with a paired strips transmission line configuration and gradually changes to a microstrip layout while also transforming the impedance value. Each transformer was then simulated using HFSS on their own and then again with the antenna attached. The reflection coefficients for each design were recorded and the designs were considered desirable if these values remain below -15dB, and acceptable with values below -11 dB, for the design frequency range of 4GHz to 12GHz. The use of exponential tapers for both the signal and ground lines provided the best result.