A binomial array antenna is an array of non-uniform amplitudes in which the amplitude of the radiating sources is arranged according to the coefficient of successive terms of a binomial series. The binomial array acts as a multistate phase diversity antenna.
An antenna array is an assembly of individual radiating antennas in an electrical and geometrical configuration. It is arranged to produce a radiated field with particular radiation properties that cannot be achieved by using a single antenna; the performance of a single element antenna has limitations. In order to obtain higher directivity, low side lobes, narrow beam width and a preferred coverage pattern, antenna arrays are implemented. Binomial arrays possess the smallest side lobes.
When two in-phase plane waves reach the antenna from varied directions the resulting signal created is not necessarily the coherent sum of the incoming signals. The antenna radiation pattern consists of amplitude and phase properties. The phase characteristics vary as a function of the direction. The array antennas control these phase properties of the radiation pattern.
Binomial arrays implement directive beams having different phase patterns in comparison with each other. These beams can then be used to optimize the receiver system. In the designing of the binomial array, a genetic algorithm is used that generates the excitation amplitudes of the antenna array.