Abstract: An embodiment of an antenna system comprising a radio frequency (RF) current-sensing and current injecting antenna device for coupling RF energy, wherein the antenna device comprises an outer conducting non-magnetic housing, a magnetic core having a central aperture, said core insulated from said housing, and a first winding wound about said core, said first winding having a first end receiving said RF energy and a second end, said first winding insulated from said housing between said first end and said second end, wherein a conductor is positioned within said aperture, and said conductor has a length of at least 0.1 wavelength of said RF energy. Wherein, in a transmitting mode said antenna device couples RF energy, created in an RF transmitter, to the conductor. In a receiving mode said antenna device couples RF energy, developed in the conductor intercepting an RF field, to the input of an RF receiver.

Abstract: A TEM mode cell having an internal TEM element and at least one port on the cell comprising a stepped transmission line transformer coupling said element to the port. The cell comprises a hollow metallic housing having an enlarged center with opposite open ends, and a pair of end sections closing off said center open ends and tapering to a distal end of reduced cross sectional area. A connector at the distal end of each end section, and a stepped septum mounted within the housing and insulated therefrom, the septum coupled to and extending between the connectors. The septum having a central portion joining a pair of end portions each having a stepped contour reducing in size toward its connector. Each end portion has at least three steps in contour, with transition slopes between the steps being greatest leading to said central portion and the least leading to its connector.