Variable directivity antenna apparatus provided with antenna elements and at least one parasitic element connected to ground via controlled switch

A variable directivity antenna apparatus comprising:

• four parasitic elements including first, second, third and fourth parasitic elements;
• three antenna elements each provided in proximity to the three parasitic elements which are selected from the four parasitic elements to be adjacent to each of the antenna elements so as to be electromagnetically coupled to the three parasitic elements thereof;
• and
• four switches connected to the four parasitic elements, respectively, each changing over whether or not to ground the connected parasitic element,
• wherein the three antenna elements and the first to third parasitic elements are located substantially at vertexes of a regular hexagon, respectively, so that each of the three antenna elements and each of the first to third parasitic elements are alternately located,
• wherein the fourth parasitic element is located substantially at a center of the regular hexagon,
• wherein variable directivity antenna apparatus further comprises a controller for changing a radiation pattern from the variable directivity antenna apparatus by outputting four control signals for turning on or off the four switches to change over whether or not the four parasitic elements operate as reflectors, respectively.