A wideband WLAN 2.4/5.2/5.8GHz MIMO antenna based on cavity mode in full metal cover tablet computer

A very small antenna for full metal housing tablet computer that can provide WLAN 2.4/5.2/5.8 GHz operations is presented, which is designed for multiple-input multiple-output (MIMO) antennas. The dimension of the proposed antenna is 6×7mm
²
and it is only 0.1λ at 2.4 GHz frequency. Antenna size miniaturization and multiband resonances are achieved by combining the loop antenna self-resonant mode, and a cavity mode with proper excitation. The bandwidth of this antenna reaches 9% (2.29-2.51 GHz) at 2.4 GHz, and 30% (4.37-5.9 GHz), which covers all WLAN 2.4/5.2/5.8 bands. The proposed cavity mode is used to operate at 2.4 GHz, which is excited by the loop antenna. Here, some short vias are added to make this cavity mode excited in 2.4 GHz exactly. All bands here are S
₁₁
> -10 dB, S
₂₁
> -15 dB. Directional radiation patterns with 7.5 dBi, 8.9 dBi at 2.4 GHz and 5.5 GHz average gain are attained. The simulated efficiencies are at 2.4 GHz and 5.5 GHz are 94%, 97%, respectively. This antenna system can be suitable for multi element MIMO devices such as wireless communication devices.