An Ultra-Wideband Printed Modulator for Millimeter-Wave Backscatter Communications

Millimeter-wave (mm-wave) backscatter communication (BC) offers the advantages of low power consumption and high data rates. Recent advancements in additional manufacturing and inkjet printing have made these communications increasingly cost-effective and flexible. However, their potential is limited by lossy substrates and narrow bandwidths. In this paper, we introduce an ultra-wideband (UWB) printed mm-wave modulator that is ideal for thin substrates. The proposed modulator, which provides a bandwidth of 86% from 20GHz to 50GHz, is based on a flexible polyimide (PI) substrate and a printed Vivaldi antenna. The modulator used a travelling-wave structure to achieve the wide bandwidth. Additionally, an AlGaAs Flip Chip PIN is utilized to achieve the desired modulation factor. Simulated results demonstrate that the proposed modulator can achieve reflection coefficient differences (RCD) of over 0.67 within the bandwidth. Moreover, mm-wave BC tests show the modulator performances within the frequency bands.