Flexible UWB antenna fabricated on polyimide substrate by surface modification and in situ self-metallization technique

A flexible ultra-wideband (UWB) antenna using polyimide (PI) as the substrate is presented in this work. The required flexible UWB antenna structure was fabricated by surface modification and in situ self-metallization technique at room temperature. The design proposal, fabrication process , and performance testing were described in details. The −10 dB simulated and measured impedance bandwidth covered by the proposed antenna is 1.40–16.40 GHz and 1.35–16.40 GHz respectively, which both contains the entire standard 3.1–10.6 GHz UWB band. The realized gain is all above 2.8 dB in the standard UWB band. The antenna has an acceptable omnidirectional radiation pattern at both 2.45 and 5.2 GHz. Under bending conditions, the flexible UWB antenna maintains its omnidirectional radiation pattern, and also the formed silver layer presents excellent adhesion with PI films. This technique provides an optional approach for fabricating flexible antennas with no expensive equipment, vacuum condition and high-temperature thermal annealing .