Circularly Polarized Crossed Dipole on an HIS for 2.4/5.2/5.8-GHz WLAN Applications

A triband circularly polarized (CP) crossed-dipole antenna is introduced for 2.4/5.2/5.8-GHz wireless local area network (WLAN) applications. It employs a single feed and only two crossed trident-shaped dipoles as the primary radiating elements. To achieve a compact radiator size, two techniques are utilized, namely, insertion of a meander-line segment in the middle branch of the tridents and termination of all trident arms with arrowhead-shaped tips. The crossed trident-shaped dipoles are backed by a high impedance surface (HIS) to achieve a broadband characteristic and unidirectional radiation pattern at three bands. The measured impedance bandwidths, based on the -10-dB reflection coefficient values, are 2.21-2.62 GHz (410 MHz), 5.02-5.44 GHz (420 MHz), and 5.62-5.96 GHz (340 MHz), and the measured 3-dB axial-ratio bandwidths are 2.34-2.58 GHz (240 MHz), 5.14-5.38 GHz (240 MHz), and 5.72-5.88 GHz (160 MHz). The proposed antenna exhibits right-hand circular-polarized radiation with high gain.