High-gain end-fire bow-tie antenna using artificial dielectric layers

This study presents a high-gain bow-tie antenna for applications in next generation base-stations operating from 2.5 to 3.9 GHz. The proposed structure consists of three circular sector patches that are attached laterally to the microstrip feed-line, which is etched on both sides of the common dielectric substrate to create symmetrical bow-tie antenna. By loading the antenna with a 2 × 5 array of enhanced end-coupled split-ring (EECSR) unit-cells results in significant enhancement in the antenna gain performance. This is because the EECSR unit-cells behave as parasitic radiators, which is analogous to Yagi-Uda antennas. The EECSR unit-cells provide a medium of high effective permittivity that effectively reduces the spacing between parasitic directors. As a consequence, a compact and miniature structure is achieved compared with conventional quasi-Yagi-Uda planar designs. The dimension of EECSR unit-cell is 33 × 36 mm² with inter-element spacing of 0.075λ₀ at 3.5 GHz. A prototype of the antenna was fabricated and its performance was measured to validate the simulation results. The measured peak gain of the antenna with 4 × 5 array of EECSR is 12.65 dBi at 3.73 GHz, constituting a peak gain enhancement of 7.45 dBi in the Worldwide Interoperability for Microwave Access band compared with an equivalent conventional bow-tie antenna.