A Compact Directional Slot Antenna and Its Application in MIMO Array

In this communication, a new design for the microstrip-fed slot antenna with a directive radiation pattern for WLAN/WiMAX application is presented. By utilizing a two-element array topology, a unidirectional radiation pattern is obtained. Without any directors and reflectors, the proposed slot antenna shows advantages in terms of compact size and high front-to-back gain ratio in the azimuthal plane. Four directional slot antennas are then placed in a square loop array to obtain nearly orthogonal patterns. Thus, a compact multiple input multiple output array with high isolation among those four elements is achieved. Simulated and measured results are presented to validate the practicality of the proposed antenna structures.