Antena vivaldi de faixa ultra larga e defasador de RF baseado em metamateriais para 5G NR

Abstract

This dissertation presents the development of two radio frequency (RF) devices for fifth-generation mobile networks (5G), namely: an ultra-wideband Vivaldi antenna and a RF phase shifter. The proposed Vivaldi antenna is based on a three-dimensional structure with magnetic dipoles and aluminum plates to improve the impedance matching bandwidth in the lower frequency range. Additionally, the corrugation technique was applied to improve the impedance matching around 15.0 GHz. 3D printing and machining of aluminum plates were used in the manufacturing process. In general, there is excellent agreement between numerical and experimental results. The antenna presented bandwidth from 0.59 to 26.0 GHz, performed 191.12% fractional band. The final antenna dimensions were 0.190λmax x 0.229λmax x 0.129λmax, where λmax is the wavelength of the bandwidth lowest frequency. It was obtained measured gains good agreement with simulated results. Measured gain of 2.15 dBi at 0.75 GHz, 7.09 dBi at 1.80 GHz, 4.09 dBi at 2.10 GHz, 6.69 dBi at 3.50 GHz, 8.17 dBi at 10.0 GHz and 8.44 dBi at 26.0 GHz. The RF phaser shifter was based on metamaterials and designed to operate in the millimeter-wave band, including FR2 of the 5G New Radio (5G NR). More specifically, the RF phase shifter provides low insertion loss, due to the use of a metamaterial cell, whose propagation vector, electric field, and magnetic field form a left-handed triad (left handed (LH)) and a right-handed triad ( right handed (RH)). In addition, beam steering for millimeter-wave applications is performed using a Varicap diode. The phase shifter performance was numerically evaluated, as a function of the reflection coefficient, insertion loss, and phase variation. It was achieved insertion loss below 4.27 dB and a phase shift of 44.11° varying by 10°. The phase-shifter is capable of operating in the range of 24.00 to 25.73 GHz with a reflection coefficientbelow -10 dB.