Implementation of dynamic Hadamard diffuser as a frequency selective surface for W‐band active millimeter wave imaging

We present the design, construction and testing of dynamic 2 × 2 Hadamard diffuser used to reduce speckle, produced by coherent millimeter-wave sources in active imaging. The 1's and −1's binary entities of the Hadamard matrix constitute the inputs for the construction of sets of orthogonal matrix pattern, corresponding to illumination patterns. The sequence of orthogonal phase patterns was obtained by changing the frequency of the incident beam. Hadamard phase cells were designed on a single wafer considering three grounded sub-arrays of different slot lengths for the first three quadrants and the artificial magnetic conductor for the last quadrant. We designed the FSS arrays with the finite integral technique, fabricated with etching techniques, and characterized the vector S-parameters with a free space network analyzer. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1440–1445, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24363

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