In this work, a planar monopole ultra-wideband (UWB) antenna with an L-shaped stub on the ground plane is proposed. The novel extended L-stub in conjunction with the UWB radiator achieves an ultra wideband impedance matching with a compact size. The proposed antenna is fabricated and measured showing an ultra wide operating frequency range from 2.3 to over 14 GHz (VSWR < 2) with a unidirectional gain from 3-6.5 dBi and efficiency from 70-85% within the UWB band from 3.1-10.6 GHz. The proposed antenna provides a new way to improve ultra wideband impedance matching other than the frequently used tapered microstrip feed line. It also provides a way to improve the lower frequency bandwidth of the antenna without increasing the antenna's physical size, which is the most common method to use.
2. Wu, Q., R. Jin, J. Geng, and M. Ding, "Compact CPW-fed stacked circle monopole antenna with very wide bandwidth," Microwave Opt. Technol. Lett., Vol. 49, No. 5, 1192-1194, 2007.
3. John, M. and M. J. Ammann, "Optimization of impedance for printed rectangular monopole antenna," Microwave Opt. Technol. Lett., Vol. 47, No. 2, 153-154, 2005.
4. Liang, J., C. C. Chiau, X. Chen, and C. G. Parini, "Study of a printed circular disc monopole antenna for UWB systems," IEEE Trans. Antennas Propag., Vol. 53, No. 11, 3500-3504, 2005.
5. Zhang, Y., T. Nakata, and T. Miyashita, "A miniature circular disc monopole UWB antenna with a tapered feed line and a circular ground," China-Japan Joint Microwave Conference, 411-414, 2008.
6. Ren, Y. G. and K. Chang, "Ultra-wideband planar elliptical ring antenna," Electron. Lett., Vol. 42, No. 8, 447-449, 2006.
7. Abbosh, A. S. and M. E. Bialkowski, "Design of ultra wideband planar monopole antennas of circular and elliptical shape," IEEE Trans. Antennas Propag., Vol. 56, No. 1, 17-23, 2007.
8. Moghadasi, M. N., H. Rousta, and B. S. Virdee, "Compact UWB planar monopole antenna," IEEE Antennas Wireless Propag. Lett., Vol. 8, No. 22, 1382-1385, 2009.
9. Locatelli, A., D. Modotto, F. M. Pigozzo, S. Boscolo, E. Autizi, C. DeAngelis, A.-D. Capobianco, and M. Midrio, "Increasing directionality of planar ultra-wideband antennas," Microwave Opt. Technol. Lett., Vol. 52, No. 1, 78-82, 2010.