Isolation Enhancement Between Two Packed Antennas With Coupling Element

This letter introduces a coupling element to enhance the isolation between two closely packed antennas for 2.4-GHz wireless local area network (WLAN) application. The proposed structure occupies two antenna elements and a coupling element in between. By putting a coupling element that artificially creates an additional coupling path between the antenna elements, the antenna isolation can be enhanced. The advantage of this design is that no extra space is needed for antenna elements. With the proposed design, more than 15 dB isolation can be achieved for two parallel individual inverted-F antennas (IFAs) with 5-mm spacing. Parametric studies for the design are also included to show how to increase isolation bandwidth and control the isolation frequency.