Broadband Circularly Polarized Crossed-Dipole Antenna with a Square Loop

This paper presents a curved,broadband, dipole circularly polarized(CP) antenna fed with coaxial cable. The antenna consists of two crossed-dipoles connected with two quarter-gap phase delay rings and surrounded by a metallic square loop. The proposed antenna has simple structure and low profile and by bending the cross dipole and loading the square loop on its periphery, the antenna generates two circular polarized modes in a wide range centered at 2 GHz. The overall size of the antenna is 0.51 lambda(0)x0.51 lambda(0)x0.2 lambda(0). The final design yielded an vertical bar S11 vertical bar<-10 dB bandwidth of 1.6 GHz (1.4-3.0 GHz) and 3-dB AR bandwidth of 1.01 GHz (1.53-2.54 GHz) and has a stable gain of 4.0 +/- 0.5 dBi.