MEMS Tunable Frame Antennas Enabling Carrier Aggregation at 600 MHz

The goal of this paper is to propose a tunable antenna system, that aims to cover the LTE low band (699-960 MHz), medium band (1710-2100 MHz) and high band (2100-2690 MHz), as well as the 600 MHz bands by tuning. The architecture consists of four multiband antennas, made up of different radiators, placed in the frame of the mobile handset at the optimized distance of 0.5 mm from each other. Simulations including MEMS tunable capacitors prove that, it is possible to reconfigure the dual resonance in low band, without deteriorating the antennas performance. The tuning ability of the fabricated structure is tested with the PNA and measurements of the total efficiency are performed in the MVG SG24. The results of the measurements are in accordance with the simulations and confirm that the operating frequency of the proposed frame antenna array in low band can be tuned down to the starting point of band 71, with a –6 dB impedance bandwidth of 32 MHz, without altering the antennas behavior in medium and high band. The resulting peak value of the total efficiency of –5.3 dB at 615 MHz is acceptable, considering the mobile phones in the market. Moreover, the analysis of the user effects, carried out via simulations both in data and in talk mode, reveals a reduced total efficiency of 4 and 8 dB on average, due to the user hand and the user hand-head respectively, compared with the performance in free space.