Paper-based UWB filtering antenna via screen-printing of low-temperature sinterable silver paste

Abstract The growing demand for compact, high-performance wireless systems has intensified the need for integrated radio-frequency components that combine miniaturization with enhanced functionality. Traditional ultrawideband (UWB) antennas often suffer from poor out-of-band suppression, leading to interference in crowded spectral environments. While filter-antenna co-design has been proposed to address this, most existing approaches rely on rigid substrates and complex fabrication processes, limiting their applicability in flexible and wearable systems. This work presents a flexible UWB filtering antenna fabricated on a low-cost photographic paper substrate using screen-printed low temperature sinterable conductive silver paste. By integrating a stepped impedance resonator (SIR) structure fed via a coplanar waveguide (CPW), the proposed antenna achieves controlled resonance distribution, sharp roll-off, and significantly improved upper stopband rejection. The final device, with dimensions of 44.5 mm × 14 mm × 0.27 mm, exhibits a −10 dB impedance bandwidth of 111.75% (3.08–10.88 GHz), flat in-band response, and exceptional out-of-band suppression, with return loss below 1 dB at 12 GHz. Systematic material and process optimizations—including thermal analysis, microstructure characterization, and electrical testing of the silver paste—validate the feasibility of the paper-based approach. The synergistic integration of SIR not only facilitates miniaturization but also enhances frequency selectivity and harmonic suppression without additional circuitry. The study demonstrates a promising pathway toward green, low-cost, and high-performance flexible RF devices for next-generation communication systems, with potential applications in wearable electronics, IoT, and sustainable wireless technologies.