Efficiency Optimization of Folded Handset Antenna in User Scenarios Using Multiport Networks

The extra frame in the folded handset makes the user scenario complicated and provides opportunities for efficiency enhancement as well. In this letter, antenna efficiency in user scenarios is enhanced for folded mobile handset using multiport network. The radiation efficiency of the antenna is directly expressed by the impedance matrix of the multiport network and the electric field of each port. Different impedance matrices, which are controlled by port status, represent different antenna configurations. By optimizing the port status, the maximum radiation efficiency of the antennas in user scenarios is achieved using Nondominated Sorting Genetic Algorithm-II (NSGA-II). Following the approach, an efficient folded handset antenna working at 800 MHz to 960 MHz band is designed, with its working mechanisms explained. The radiation efficiency of −5.3 dB has been achieved in user scenarios, providing an improvement of 2.2 dB compared with the reference antennas.