Log spiral antenna with CPW feed line for UWB application and circular polarization

Log spiral antenna is famous model for ultrawideband (UWB) application with circular polarization (CP) and coplanar waveguide (CPW) feed techniques for this antenna are noticed for wipe out the external balun. Therefore, in this letter, CPW feed is used for feeding the log spiral slot parts. The prototype antenna shows good performance for UWB application in the range of 2–11 GHz. The final antenna is covered 2–11 GHz with VSWR less than two in experimental. The antenna radiates Omnidirectionally in the E-plane and bidirectionally in the H-plane, and has a gain that varies between 3 and 7 dBi between 2–11 GHz, with an average gain of 4.5 dBi. The total size of the antenna is 70 × 45 × 1.6 mm3. The antenna has CP at 2.5, 5.5, and 8–9 GHz with axial ratio less than three. The simulated results of prototype antenna are obtained with HFSS and CST and final model antenna is fabricated on FR-4 low cost substrate. The experimental results are confirmed the simulation results. The additional elliptical slots are used for improve the CP in antenna. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:17–21, 2016