Design and analysis of a novel compact spanner-shaped ultra-wideband antenna for MIMO systems

In this communication, a novel compact spanner shaped ultra-wideband (UWB) antenna is designed for multiple input multiple output (MIMO) system applications. The proposed structure of size 24 x 32 mm(2) (0.24 lambda(0) x 0.32 lambda(0), lambda(0) is calculated at lower band frequency) is designed and fabricated on widely available FR4 dielectric material with a dielectric constant of 4.4 and loss tangent of 0.02. The proposed structure comprises two spanner shaped antennas, a defected T-shaped stub and a pair of small vertical strips. The defected T-shaped stub and vertical strips are used for getting a complete UWB bandwidth and good isolation between two elements. It is performing from 3.0 to 11.0 GHz with isolation more than 20 dB in most of the operating region. The parametric studies have been done for the required parameters and figured out the surface current distribution at different resonant frequencies within the working region. The MIMO antenna diversity performance is confirmed with low values of envelope correlation coefficient (ECC < 0.005), channel capacity losses (CCL < 0.04 bits/s/Hz), acceptable mean effective gain (MEG <= -3 dB, MEG ratio = 0 dB), and total active reflection coefficient (TARC <= -10 dB) values. The peak gain values are varying from 1.5 to 6.0 dBi, and the radiation efficiency values are above 83% for the entire operating region. The simulated and measured values are well matched.