Bandwidth enhancement of a circularly polarized printed monopole antenna

In authors' previous studies, a printed rectangular monopole antenna for circular polarization has been proposed. The simulated bandwidth of 3dB-axial ratio with 10dB-return loss is approximately 53%. In order to enhance the bandwidth further, in this paper, a printed monopole antenna installing a slot with a T-shaped element in a rectangular patch and installing two T-shaped slits in a ground plane is proposed. The bandwidth of 3dB-axial ratio with 10dB-return loss of the proposed antenna is approximately 90%. The gain at high elevation angle is stable within the frequency range.