Prediction of Grating Lobe Level Due to Antenna Array Element Mirroring or Sequential Rotation

Antenna arrays that use sequential rotation, feed-port mirroring, or tiling across multiple modules may produce grating lobes even when the chosen element spacing should be close enough to prevent such effects. Analysis reveals that grating lobes of this type are in a different class than those caused by quantization errors of the excitation coefficients, and that mitigation requires different techniques. A formula for predicting the location and amplitude of these grating lobes based on the individual element patterns is presented. The approach is verified using both finite and infinite array simulations of a microstrip patch array with mirrored feed locations.