Compact and printed multiband antennas for 2G/3G/4G smartphones

This paper presents a compact multiband antenna system for mobile handsets capable of covering 2G, 3G and 4G cellular frequency bands. The antenna system is composed of two antennas that are etched diagonally on the non-grounded portion of the substrate board. The substrate board used is FR-4, of relative permittivity 4.35 and loss tangent of 0.02, with overall dimensions of 136 × 70 × 0.8 mm³. The antenna for covering 4G and WLAN frequency bands is a direct fed printed monopole antenna whereas, the antenna for covering the 2G and 3G cellular services is a coupled fed monopole antenna. Two inverted-L shaped metallic extensions, etched on the bottom layer of the substrate, were introduced to improve the isolation between antennas. The isolation achieved is better than 16 dB in the lower band and 22 dB in the upper bands, leading to an envelope correlation coefficient of less than 0.251. The simulated and measured results corroborate a good performance of the proposed antenna system.