Circularly polarized multiple input multiple output transparent antenna

Abstract

Circular polarization technology can improve mobile connectivity and mitigate signal losses caused by absorption, reflection and refraction by utilizing all planes in transmitting waves. In this thesis, Circularly Polarized (CP) transparent antenna designs are investigated for broadband applications. Two designs are introduced namely Single Input Single Output (SISO) and Multiple Input Multiple Output (MIMO) transparent antennas. A silver coated polyester film which is a Transparent Conductive Oxide (TCO) in the shape of film is incorporated in both designs. The film is cut according to design and attached to a glass substrate. SISO antenna is fed by Coplanar Waveguide (CPW) with a circular ring patch radiating element. The existence of tapered split gap and the inequality in CPW ground arm’s length has contributed to a 3 dB axial ratio bandwidth from 5.4 to 6.2 GHz. Results show that the proposed antenna has a gain of 0.92 dB and an efficiency of 14% at 5.8 GHz. It is shown that the electron mobility, a parameter that is determined by the material development is a primary limiting factor seen from the 14% efficiency of transparent antenna. The proposed antenna obtained a reflection coefficient response from 2.55 to 6 GHz which covers the desired frequency band. MIMO is designed by combining two aforesaid SISO CP antenna designs, mirrored 180° at y-axis and separated by 1 mm. Measurement results show |S11| and |S22| bandwidth from 2.65 to 6.23 GHz with good isolation of 27 dB at the 5.8 GHz band. Envelope Correlation Coefficient (ECC), Mean Effective Gain (MEG) and Diversity Gain (DG) with measurement values of 0.0007, 0 dB and 10 dB accordingly were discussed in the thesis. These values were calculated using scattering parameters data obtained from the measurement. Both designs are meeting the objectives of this project.