Abstract: An antenna system provides a substantially spherical radiation pattern about a structure located above ground level, by locating the individual radiation pattern of each of a plurality of individual antennae, each positioned to have a radiation pattern covering only a portion of the desired sphere, and then applying all antenna signals, during either transmission or reception time intervals, through space-diversity and/or time-diversity apparatus, to cause the patterns of all of the antennae to combine into the desired substantially-spherical pattern. The antennae may have substantially hemispherical patterns, with each antenna of a pair thereof being directed in a direction generally opposite to the other antenna of that pair.

Abstract: Transmissions from a moving, vehicle-mounted transmitter to a remote station are pre-compensated at the transmitter for doppler shift by measuring the doppler shift of signals from the remote station and compensating by the use of a digital multiplier the frequency of transmissions to the remote station in the opposite sense and in an amount equal to the ratio of the nominal transmission to reception frequencies times the measured doppler shift. Application to full and half duplex radios and provisions for frequency shift keying systems are disclosed.