Reactive-to-Radiating Near-Field Propagation Behavior Measured on a Ka-Band Horn Antenna

The spatial and temporal evolution of the propagating fields in the transition region between the reactive and radiating near-field distances of a standard gain horn antenna operating within the Ka-band are presented. Electric-field distributions with amplitude and phase information are measured with minimal invasiveness by a vector-stabilized, electrooptic field-imaging system. Acquiring a complete vector-imaging data set, a comprehensive near-field propagation chart-which shows the detailed field development at each wavelength plane with full phase progression-is presented for an antenna frequency of 30 GHz.