A wideband circularly polarized DRA excited with meandered-line inductor for Wi-MAX/LTE2500 applications

Abstract

In this paper, a meander-line inductor has been utilized for the generation of wideband circularly polarized in dielectric resonator antenna (DRA). The proposed antenna structure involves of a meander-line inductor etched on the top of the FR4 substrate, partial ground plane placed in the bottom side of the substrate and cylindrical dielectric resonator (C-DR). In this structure, the generation of orthogonal mode is depending on the meander-line inductor length, partial ground plane and optimal dimension of C-DR. Here, meander-line inductor length is taken in such a way that it shows two orthogonal components having an equal magnitude with 90° phase difference between them, therefore generation of circular polarization in proposed antenna. From the distribution of electric field inside the C-DRA, it is confirmed that the HEM 11δ mode is excited in this structure. The proposed antenna shows −10dB input impedance bandwidth of 26.96%, ranging from 2.31 to 3.03 GHz and 3-dB axial ratio bandwidth of 12.26%, ranging from 2.45 to 2.77 GHz in θ = 0°, ϕ = 0°. The usable circular polarization (CP) bandwidth is found to be 12.26% (centered at 2.61 GHz), where both −10dB input impedance bandwidth and 3-dB axial ratio bandwidth are falling in the same passband. In broadside direction, the designed antenna radiates right handed circular polarization (RHCP) waves because it is stronger than the left handed circular polarization (LHCP). From the CP radiation pattern in broadside direction, the difference between RCHP and LHCP is above −17dB in the complete working band. The proposed antenna shows an average gain and radiation efficiency of 2.35dBic and 84.45%, respectively. In addition, designed antenna is made of single feeding technique, easy fabrication process and conventional shape of dielectric resonator, therefore is suitable for Wi-MAX (2.5–2.7 GHz) and LTE2500 (2.5–2.9 GHz) band applications.