Probability of direction indications for two unresolved signals

A direction-finding (DF) antenna (or an antenna array) with a beam shape which is aproximated by a cosine or a sine function is analyzed. The analysis applies to both peak-type and notch-type DF patterns for signals arriving from two fixed directions separated by less than the antenna beamwidths. It is shown that the statistical distribution of the direction indications depends on the signal parameters and also on the shape of the antenna radiation pattern. A probability density function is found for the direction indications for two unresolved co-channel signals present under Rayleigh fading conditions. Direction finding situations are simulated computer programs and comparisons are made beween the analytical and the simulation results.