Abstract: An adjustable antenna enables far-field radiation from the antenna to be reduced, minimized, and/or substantially eliminated while near-field radiation from the antenna may be substantially maintained. In some embodiments, an antenna includes a first loop defining a first enclosed area and having a first phase center point defined by the geometric center point of the first enclosed area, a second loop coupled to the first loop and disposed substantially parallel to the first loop, the second loop defining a second enclosed area and a second phase center point defined by the geometric center point of the second enclosed area, and a third loop coupled to the first loop and the second loop and substantially parallel to the first loop, the third loop defining a third enclosed area and a third phase center point defined by the geometric center point of the third enclosed area.

Abstract: A positioning, communication, and detection system designed to provide a three dimensional location of an object, navigation tools, and bidirectional surface-to-subsurface communications, and methods of using the system. The system can include one or multiple transmitters comprising electromagnetic beacons, software defined radio receivers with an associated processing unit and data acquisition system, and magnetic antennas. The system may use theoretical calculations, scale model testing, signal processing, and sensor data.

Abstract: A positioning, communication, and detection system designed to provide a three dimensional location of an object, navigation tools, and bidirectional surface-to-subsurface communications, and methods of using the system. The system can include one or multiple transmitters comprising electromagnetic beacons, software defined radio receivers with an associated processing unit and data acquisition system, and magnetic antennas. The system may use theoretical calculations, scale model testing, signal processing, and sensor data.