Phased Array Beam Pattern Calculator
Set up a uniform linear array — element count, spacing in wavelengths and steering angle — and read its beamwidth, gain, sidelobe level and grating lobes from the pattern.
A uniform linear array multiplies the pattern of one element by the array factor, which depends only on how the signals from the elements add up. With equal amplitudes and the phase at each element set so the beam points at the steering angle, the array factor is |sin(Nψ/2) / (N sin(ψ/2))| where ψ = 2π(d/λ)(sin θ − sin θ0), N is the number of elements and d/λ the spacing in wavelengths. The peak gain over a single element is 10 log10 N, the half-power beamwidth is measured on the pattern at −3 dB, and the first sidelobe is read at the highest point of the next lobe, approaching −13.3 dB for a uniform array with many elements; it is shown only when that lobe falls inside visible space. A grating lobe appears whenever the spacing is too wide for the steering angle, at sin θ = sin θ0 + m λ/d; the smallest spacing that avoids one is d/λ = 1/(1 + |sin θ0|). Elements are treated as isotropic radiators with no mutual coupling, no element pattern, no taper or nulling weights, no scan loss and no hardware errors, and the beam is assumed to be in the far field; the pattern is therefore the array factor alone, not a measured antenna pattern. Everything runs in your browser with no storage, uploads or network access.