Combinatory Feeding Method for Mobile Applications

This letter presents a method for implementing frequency reconfigurability without lumped elements. The method is based on feeding an antenna element simultaneously at different locations with differently delayed and amplified signals and dynamically manipulating the number of active feeds. To demonstrate the concept, an example design of a handset antenna that is compatible with most modern mobile phones is presented. The proposed antenna geometry is simple and practical, consisting only of a folded rectangular sheet and four feeding points. The simulated efficiency of the antenna is higher than ${{50\%}}$ from nearly 0.7 to 7 GHz with the highest efficiency being above ${{90\%}}$ in $2\times 2$  multiple-input–multiple-output (MIMO) operation.