Design of a wideband dual circularly polarized microstrip antenna

In order to meet the design demand of mobile terminal with function of multi-mode satellite navigation, a new wideband dual-circular-polarization microstrip antenna is designed. The antenna consists of modified planar inverted-F antenna (PIFA) and a ground with a quadrate branch which is in the same side with PIFA. The impedance bandwidth is improved by dual-branch PIFA. Circular polarization is realized by modification of current distribution when a quadrate branch is added to the ground. Two PIFA structures are placed symmetrically on the diagonal of ground to realize dual circular polarization. The measured results show that the bandwidth of two ports in which return loss is less than -10dB is 1.22GHz~ 2.04GHz and 1.23GHz~2.05GH. The bandwidth for AR (axial ratio) <;3dB is 1.2GHz~1.95GHz with relative bandwidth of 49.2%. The isolation between two ports is larger than 17dB. The proposed antenna is suitable for mobile terminals in multi-mode satellite navigation for its wide bandwidth and compact structure.