Mobile-communications bands continue to attract more users across a growing number of frequency bands, calling for either more antennas per system or antenna designs that can handle multiple frequency bands. Experimenters in Sweden and Denmark pursued the latter, developing a multimode, multiple-input, multiple-output (MIMO) antenna system for mobile terminal applications. It incorporates cellular and Wi-Fi antenna structures for wide frequency coverage and is designed for mobile terminals.
With multimode excitation, the cellular MIMO antenna can handle frequency bands of 830 to 900 MHz, 1.7 to 2.2 GHz, and 2.4 to 2.7 GHz. The Wi-Fi antenna operates at 2.4 to 2.5 GHz and 5.2 to 5.8 GHz. The MIMO antenna system features a metal ring design that operates primarily in loop mode for effective performance with both voice and data communications.
The researchers explored the effects of a user’s body on antenna performance, through simulation and actual measurements. Effects in the cellular bands were trivial when tested with a human-body model and with a real human. Due to the limited space inside a mobile terminal, this combination of antennas and bands within a single compact system provides an effective solution for mobile terminals. The relative immunity to human-body impedance-mismatch effects enables the antenna to operate at a high-performance level, even when a mobile terminal is carried by a user.
See: “Body-Insensitive Multimode MIMO Terminal Antenna of Double-Ring Structure,” IEEE Transactions on Antennas and Propagation, May 2015, p. 1925.