Coplanar waveguide fed multiple input multiple output antenna with higher isolation and multi-sense circular polarization

Abstract

A coplanar waveguide (CPW)-fed multiple input multiple output (MIMO) antenna with higher isolation and multi-bandwidth circular polarization (CP) is presented. This antenna covers the impedance operations from 2.2 to 6.8 GHz with  < −10 dB,  < −14 dB and  < −10 dB. Employing two orthogonally placed T-shaped patches (TSP) and three L-shaped parasitic patches (LSPP) in the ground, the dual sense CP in the frequency band between 2.28 and 3.48 GHz (42.5%) and meanwhile between 6.03 and 6.28 GHz (4.1%) can be achieved when the left port (port_1) is excited, while the down port (port_2) is terminated by a 50 Ω load. When Port_2 is excited and port_1 is terminated by a 50 Ω load, the CP of the antenna in frequency band from 1.75 to 2.1 GHz (18.2%). On the other hand, CP from 4 to 4.47 GHz (11.1%) and 5.1 to 5.22 GHz (2.3%) can be obtained while both ports are excited. The CP frequency band covers the frequency bands for LTE (between 1.71 and 2.17 GHz), the WCDMA (between 1.92 and 2.17 GHz), the WiMax (between 2.3 and 2.5 GHz) and the WLAN. Meanwhile, the slot between these two TSP in the ground enhances the isolation of the proposed antenna. The measured and the simulated results are agreed with each other.

Keywords:

• Axial ratio (AR)
• multiple input multiple output (MIMO) antenna
• circular polarization (CP)
• T-shaped patches (TSP)
• L-shaped parasitic patch (LSPP)