An Energy-Density Antenna for Independent Measurement of the Electric and Magnetic Field

A new way of reducing the signal fading encountered on a mobile radio transmission path is being investigated. 1 One source of fading is due to the fact that plane waves propagating in opposite directions at the same frequency produce a standing wave with nulls in the electric field every half free-space wavelength. The magnetic field also has nulls like the electric field but displaced a quarter wavelength from the electric field nulls. The electromagnetic energy density of such a pure standing wave is constant. If we sample E and H in free space and amplify the signals by the appropriate relative gains, square and add them, we obtain a signal proportional to electromagnetic energy density w = {,E2 + nil2). (1)