Pattern shaping using a reactively loaded wire loop antenna

A method for obtaining continuous beam steering of +/-30 degrees from bore-sight by reactively loading a one-wavelength square wire loop antenna placed over a ground plane is presented. By introducing a small gap at the middle of one of the two non-radiating sides, the phase difference of current on the two radiating sides of the wire loop can be adjusted. This is done by varying a single reactive load at the middle of the opposite non-radiating side. As a result, the far-field radiation pattern of the antenna can be controlled in the plane perpendicular to the radiating sides. The input VSWR for the arrangement is shown to be insensitive to loaded reactance variation. An analytical explanation for the behavior of the antenna is given, together with experimental verification.