Wideband circularly polarized patch array antenna with shared patches

In this paper, a novel wideband circularly polarized (CP) array antenna is proposed. The array element is composed of four driven patches, four parasitic patches, and a loop feeding structure. On the basis of the array element structure, 1 x 2 and 2 x 2 arrays with shared patches are formed separately. Compared with the traditional structure, the volume of the 1 x 2 array antenna which only shares the patches in the x direction is reduced by 15%, and the volume of the 2 x 2 array antenna which shares the patches in the x and y directions is further reduced by 28%. The cleverness of this method is that it can keep the impedance bandwidth almost unchanged. To validate the simulated results, antenna prototypes are fabricated and measured. The results of the measurements demonstrate that the impedance bandwidths of the 1 x 2 and 2 x 2 array antennas are 27.2% (5.40-7.10 GHz) and 35.7% (5.22-7.49 GHz), respectively, and the 3 dB axial ratio (AR) bandwidths are 22.7% (5.31-6.67 GHz) and 25.4% (5.47-7.06 GHz), respectively. In addition, the measured data show that the 1 x 2 array exhibits a peak gain of 11.1 dBic, and the 2 x 2 array achieves a peak gain of 12.6 dBic. Both of them achieve a flat gain with a maximum ripple of less than 1.3 dB over the whole operating band.