Enhanced Quad‐Band WO₃ Antennas with 1.46 THz Cutoff Frequency via Indium Nanosheets between Stacked Layers

Herein, stacked films of WO 3 separated by indium nanosheets are fabricated as quad‐band antennas suitable for high‐frequency applications. The amorphous WO 3 films and indium nanosheets are coated onto each other using the thermal evaporation technique under a high vacuum pressure of 10 − 5 mbar. The stacked layers of Pt/WO 3 /In/WO 3 /Pt are structurally and electrically characterized. The tunneling‐type quad‐band antennas are tested in the driving frequency domain of 0.01–1.80 GHz and a low signal amplitude of 0.10 V. It is observed that the insertion of indium nanosheets between layers of WO 3 remarkably increases the width of the tunneling barrier from 55 to 70 nm without altering the tunneling barrier height. This also enhances the cutoff frequency at a quad‐band frequency of 1.80 GHz from 10 GHz to 1.46 THz and increases the return loss values from ≈5 to 21 dB. A widely tunable cutoff frequency extending from 0.30 GHz to 1.46 THz can be obtained based on the selected driving signal frequency. The microwave‐controlling features of the Pt/WO 3 /In/WO 3 /Pt devices, with their high cutoff frequency and high power transmission ratios at the quad‐band frequency, make them attractive for 6G technology.