Flexible spiral antenna with microstrip tapered infinite balun for wearable applications

In this paper we introduce a flexible, side-fed, ultra-wideband, spiral antenna with an integrated microstrip tapered infinite balun operating from 1-5GHz. It was fabricated using Rogers 5880 subtrate and specially coated to prevent oxidization. The simulation and measurements match quite well with S11 below -10dB throughout the frequency range and gain of close to 5dB and average efficiency of 65%. Most importantly, this antenna does not have an obtrusive center feed, and instead has a side feed, is flexible, compact, rendering many possible wearable antenna applications.