Tunable antenna impedance matching for 4G mobile communications

We analyze a Π-network for tunable antenna impedance matching in 4G mobile communications. Fundamental limits on designability and practical limits on implementation of the network are presented. The performance of the network is evaluated in terms of coverage (the area on Smith chart that can be matched) and the maximum achievable tuning bandwidth. We also derive the required component values and component Q from coverage, bandwidth, as well as the efficiency of the network. We conclude that the Π-network (synthesized for the maximum achievable bandwidth) is able to cover E-UTRA Band 4 and 10 for VSWR up to 8 and all other bands for VSWR up to 10. To achieve that, in a 50Ω RF environment, it requires a maximum capacitance within the range 13.64-2.7 pF, and a maximum inductance in the range 34.1-6.8 nH in frequency range 700-3500 MHz. If the power loss is limited to 0.5-0.6 dB, it requires Q_L of 70 and Q_C of 70-100.