This article proposes two reduced-size crossed-dipole antennas that comprise two printed crossed-dipole arms and a pair of vacant-quarter printed rings to generate circularly polarized (CP) radiation. The T-shaped crossed-dipole antenna is similar to a conventional crossed-dipole antenna but differs that half of the crossed dipole is rotated 90°. This rotation reduces the dipole's area coverage by nearly half, resulting in a compact antenna that generates CP radiation with performance similar to that of a conventional crossed-dipole antenna. A compact folded E-shaped crossed dipole with good CP radiation characteristics is formed by folding the arms of the T-shaped antenna. The performance of these compact reduced-size crossed-dipole antennas is discussed. The T-shaped antenna with an overall radiator size of 30.3 mm × 51.4 mm × 0.508 mm (0.29 λ o × 0.5λo × 0.005λ o at 2.97 GHz) has an S11 < - 10 dB bandwidth of 2.58-3.42 GHz (28%) and a 3 dB AR bandwidth of 2.78-3.16 GHz (12.8%). The folded E-shaped crossed-dipole antenna with overall dimensions of 19.6 mm × 31mm × 0.508 mm ( 0.21λo × 0.33λo × 0.0055λ o at 3.25 GHz) has an S11 < -10 dB bandwidth of 2.92-3.44 GHz (16.4%) and a 3 dB AR bandwidth of 3.06-3.44 GHz (11.7%).
Manuscript received January 21, 2020; revised June 7, 2020; accepted July 8, 2020. Date of publication August 19, 2020; date of current version February 3, 2021. This work was supported in part by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) under Grant 2018R1D1A1A02086071 and in part by \u201cHuman Resources Program in Energy Technology\u201d of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea, under Project 20184030202220. (Corresponding author: Ikmo Park.) Kam Eucharist Kedze, Heesu Wang, and Ikmo Park are with the Department of Electrical and Computer Engineering, Ajou University, Suwon 16499, South Korea (e-mail: kamcharist@gmail.com; wanghs90@gmail.com; ipark@ajou.ac.kr).
