Patent ID: 7969372

Claim:
An antenna apparatus comprising: a small loop antenna element having predetermined small dimensions and two feeding points; and a balanced signal feeding device configured to feed two balanced signals having a predetermined amplitude difference and a predetermined phase difference therebetween, respectively to two feeding points of the small loop antenna element, wherein the small loop antenna element comprises: a plurality of loop antenna portions having a predetermined loop plane and radiating a first polarized wave component parallel to the loop plane; and at least one connecting conductor provided in a direction perpendicular to the loop plane, the connecting conductor connecting the plurality of loop antenna portions and radiating a second polarized wave component orthogonal to the first polarized wave component, and a setting device configured to substantially equalize maximum values of antenna gains that the first polarized wave component and the second polarized wave component exhibit respectively when a distance between the antenna apparatus and a conductor plate is changed in the vicinity of the conductor plate, thereby making a composite of the first polarized wave component and the second polarized wave component substantially constant regardless of a change of the distance.