The 2*1 Microstrip Antenna Array with Low Coupling using Periodic Paperclip-shaped Slots

The periodic paperclip-shaped (PPS) structure has been employed to suppress strong mutual coupling between antenna elements formicrostrip antenna array in MIMO wireless communication system. The special decoupling structure consists of three paperclip-shaped units periodically placed at the centre of the two narrow patches with the adjacent patches spacing of 0.1λ(λfree space frequency), providing the bandstop characteristic to keep out the strong mutual coupling between antenna elements. By using the proposed special bandgap structure, more than 36 dB mutual coupling reduction between microstrip antenna elements is achieved at the centre frequency 5.0 GHz without any resonant frequency shift. Note that inserting periodic paperclip-shaped structure could concentrate on strong power towards the particular side by changing current distribution and propagation direction, so the slight gain enhancement has been obtained by comparing to the antenna array without PPS structure. Additionally, this PPS structure is also suitable for antenna array with other frequency by adjusting size of the PPS structure.