Spectrum attributes of frequency-steerable phased array antennas

When considering phased array radar systems it is important to consider the possible differences in the spectral content of radar emissions when comparing boresight to off-boresight. This detail is important as it can accentuate potential electromagnetic interference (EMI) effects between radar and other devices competing for space in a crowded spectrum. In order to analyze the potential impact of off-boresight radar emissions to other electronic devices, a MATLAB and electromagnetic model of a simple eight element slotted waveguide linear array operating at 3.5 GHz was simulated with an element spacing of a half-wavelength. The model was stimulated utilizing continuous wave (CW), pulsed amplitude, and linear Frequency Modulated Continuous-Wave (FMCW) waveforms. The spectral content of these emissions in the far-field was assessed at a variety of angles with respect to boresight. It was concluded that the eletromagnetic emissions power may be under measured if out of band emissions of a waveguide slot array are measured only at boresight resulting in compliance testing issues. This could result in the interference to other electronic devices being underestimated.