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New for September 2011! A grating lobe occurs when you steer too far with a phased array and the main beam reappears on the wrong side. Elements must be spaced properly in order to avoid grating lobes. The equation for maximum spacing is a function of wavelength of operation and maximum look angle:
Thus for a 30 degree look angle, dmax is (2/3)xlambda, while for a 60 degree look angle, dmax is 0.54 lambda.
The following images were contributed by Luke (thanks!) here we have a phased array that is being scanned past its intended 45 degree range. One of these days we'll knit all the images together into a video.
NEW for May 2017! We knew if we waited long enough, someone else would step up and do the knitting. Ryan was able to make an animated gif file (below) from the images that Luke sent us back in 2011 (below the gif). Thanks to both of you!