Design of a Reduced-Size Crossed-Dipole Antenna

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 reducedsize 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
× 0.5λ
_o
× 0.005λ
_o
at 2.97 GHz) has an ιS
₁₁
ι <; -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 mmχ31 mmχ0.508 mm (0.21λ
_o
× 0.33λ
_o
× 0.0055λ
_o
at 3.25 GHz) has an ιS
₁₁
ι <; -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%).