Planar circular disc monopole antennas using compact impedance matching networks for ultra-wideband (UWB) applications

Two planar circular disc antennas that utilize compact impedance matching networks for current and future ultra-wideband (UWB) applications are investigated. The proposed designs have a physically small size (30 mm × 35 mm) and simple geometry, and offer a relatively large bandwidth (BW). Input energy is launched through a 50-¿ feedline (attached to a K-Connector) and broadband antenna matching is improved by introducing transitions between the feedline and the printed circular discs. Specifically, two designs are investigated using single- and dual-microstrip line transitions. By using this antenna matching technique, respective BWs (|S₁₁|<-10 dB) of 3.18 to 11.74 GHz and 3.47 to 31.94 GHz are obtained. Results are compared to an analogous UWB monopole with no matching network transitions. Measured and simulated radiation patterns are presented along with reflection loss values up to 40 GHz.