A novel planar endfire circularly polarized (CP) antenna is presented and explored by using concentric annular sector complementary dipoles. The antenna is composed of a semicircular disk radiator operating at TM 11 mode and a concentric annular sector dipole operating at one-half wavelength mode. A set of closed-form formulas is derived to reveal the operation principle and employed to determine the geometrical parameters of the proposed CP antenna. The design approach is both numerically and experimentally validated. Good agreement between the theoretical, numerical and experimental results has demonstrated its endfire radiation beam in parallel with its plane. The fractional impedance bandwidth for |S 11 | < 210 dB is up to 6.45%, and axial ratio (AR) bandwidth of less than 3 dB is up to 14.43% in fraction, in addition to its simple geometry with only seven design parameters. K E Y W O R D S circularly polarized antenna, complementary dipoles, endfire, planar antenna Int. J. RF Microw. Comput. Aided Eng. 2016; 26: 829-838 wileyonlinelibrary.com/journal/mmce V C 2016 Wiley Periodicals, Inc. | 829
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.