A Low-Profile and Compact Multi-Functional ENG-TL Inspired Antenna with Hybrid Polarizations for LTE/UMTS, WiMAX, and WLAN Applications

Abstract

A novel low-profile, compact tri-band linearly and dual-sense circularly polarized (CP) antenna realized using via-less epsilon negative transmission line (ENG-TL) is investigated in this paper. The antenna miniaturization has been achieved by the zeroth-order resonance (ZOR) property of ENG-TL, which is actuated by connecting closed-loop octagonal ring radiator to an elliptical stub through a meandered-line structure. Circular polarization is accomplished by etching an L-shaped slot in the partial ground plane. The measured S11 result demonstrates that the proposed antenna features triple-band characteristics spanning from 2.42 to 2.50 GHz, 3.29 to 3.59 GHz and 5.43 to 5.55 GHz with centre frequencies of 2.46, 3.44, and 5.49 GHz, respectively. The antenna is offering linear polarization (LP) in the first and third bands while radiates left-handed CP in the + Z direction in the second band. An exceptional axial ratio (AR) of 0.062 dB has been achieved at 3.49 GHz with 3 dB axial ratio bandwidth (ARBW) extending from 3.35 to 3.67 GHz. This antenna offers an average simulated gain of 1.7 dBi across the CP band while 2.06, 1.75 and 3.67 dBi are acquired at 2.59, 3.53 and 5.62 GHz, respectively. Beside low-profile (0.013λ0 height) and miniaturized size (0.287λ0 × 0.205 λ0 ), intended antenna exhibits extended −10 dB impedance bandwidth, wide 3 dB AR bandwidth and reasonable radiation performance. It covers relevant frequency bands; therefore, it has the potential to be employed in 2.5 GHz LTE/UMTS, 3.5 GHz WiMAX, and 5.5 GHz WLAN applications.