Reconfigurable wide band circularly polarized antenna array for WiMAX, C-Band,a and ITU-R applications with enhanced sequentially rotated feed network
In this article, a wide-band circularly polarized slot antenna array with reconfigurable feed-network for WiMAX, C-Band, and ITU-R applications is proposed. Different novel methods are used in proposed array to improve antenna features such as impedance matching, 3 dB axial-ratio bandwidth (ARBW), gain, and destructive coupling effects. Miniaturized dual-feed square slot antenna, with one attached L-shaped strip and a pair of T-shaped strip at ground surface for improving impedance matching and circular polarization (CP) purity, is presented. For further enhancement of CP attributes, reconfigurable sequentially rotated feed network is utilized to obtain wider 3 dB ARBW. Furthermore reconfigurable property of network gives controlling Right and Left handed CPs, respectively. Finally, a special form of Electromagnetic Band gap structure is employed on top layer of substrate that provides high isolation between radiating elements and array feed network to enhance overall performance of antenna. The measured results depict 3 dB ARBW from 4.6 to 7.2 GHz, impedance bandwidth from 3.3 to 8.8 GHz for VWSR<2, and peak gain of 10 dBi at 6 GHz.  2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:825833, 2015.
antenna sequentially rotated feeding networks circular polarization microstrip wideband