Improved Planar Wideband Antenna Element and Its Usage in a Mobile MIMO System

• Published in: IEEE antennas and wireless propagation letters Vol. 11; pp. 826 - 829
• Main Authors: Sonkki, M., Antonino-Daviu, E., Cabedo-Fabres, M., Ferrando-Bataller, M., Salonen, E. T.
• Format: Journal Article
• Language: English
• Published: IEEE 2012
• Subjects: Antenna measurements; Bandwidth; Broadband antennas; Complementary antenna; Dipole antennas; diversity antenna; envelope correlation; MIMO; MIMO efficiency; Mobile antennas; multiple-input-multiple-output (MIMO) antenna; wideband antenna
• ISSN: 1536-1225; 1548-5757
• DOI: 10.1109/LAWP.2012.2208615

A simple antenna structure for a multiple-input-multiple-output (MIMO) system in a mobile terminal with spatial diversity is presented. A single antenna element consists of a combination of an electric dipole and a square magnetic slot. The studies with a single quasi-complementary antenna element show that the electric dipole and the square-shaped magnetic slot are partially compensating the effect of the electric conductor closely spaced to the electric dipole (0.0037-0.01λ) . Simulations also show that by scaling antenna structure, a 0.7-2.1-GHz frequency bandwidth can be achieved. The measured -6-dB impedance bandwidth of the MIMO antenna prototype is from 2.0 to 5.6 GHz, corresponding to a 95% relative bandwidth. The measured S 21 is less than - 19 dB within the - 6-dB impedance bandwidth. The average measured total efficiency at the aforementioned bandwidth is - 0.85 dB. The measured radiation patterns are presented at 2 and 5 GHz with a maximum total gain of 2.8 and 5.7 dBi, respectively. The measured envelope correlation of the MIMO antenna is less than 0.04 with 90% MIMO efficiency within the -6-dB impedance bandwidth.