A Low-Profile Circularly Polarized Magnetic-Electric Dipole Antenna Array

A low-profile circularly polarized (CP) magneto-electric dipole (MED) antenna array is presented in this paper. By tilting the vertical walls of a MED with two protruded stubs being orthogonal to the horizontal patches and by using a staircase-shaped feeding strip, a wideband CP MED antenna is formed. In comparison to the conventional MED, the profile of the antenna is reduced from 0.25 lambda(c) to only 0.07 lambda(c) at the center frequency of the operating band. The sequentially rotated feeding (SRF) network is employed to construct a 2x2 array with enhanced 3 dB axial-ratio (AR) bandwidth The overall size of the array is as compact as 1.33 lambda(c)x1.33 lambda(c)x 0 . 07 lambda(c), and the measured results show that the usable overlapped bandwidth of the reflection coefficient vertical bar S11 vertical bar< -10 dB and AR< 3 dB is 31.2%, covering 1.76 GHz to 2.41 GHz. The peak gain of the array is 12.9 dBic with the gain variation being less than 3 dB within the 1.85-2.32 GHz band, and the front-back-ratio (FBR) is greater than 20 dB. The proposed array is promising in the applications for portable and individual communication devices for wireless communications.