This work reports the design and fabrication process used to create a new class of ultrathin inkjet printed microwave absorbers. The arrangement is composed of a lossy Frequency Selective Surface (FSS) placed above a ground plane to form a resistive High Impedance Surface (HIS). The thickness of the three absorbers investigated range from λ/58 to λ/223. These extremely thin structures present design and manufacturing challenges to achieve the desired energy absorption (≥ 90%) over a useable (−10 dB) bandwidth. Numerical optimisation of the surface resistance and topology of the FSS pattern gives values of 7% (λ/58) and 1.5% (λ/223) for absorbers working at normal incidence. The digital settings used in a desktop ink jet printer to obtain the required surface resistance value of the metallised FSS patterns are obtained by curve fitting numerical simulations to experimentally obtained transmission coefficients.
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