Antenna-Filter-Splitter Function Reconfigurable Microwave Passive Device Based on VO2

We designed and fabricated a three-in-one function reconfigurable microwave passive device, which can be functionally reconfigured to operate either as a radiating antenna, bandpass filter, or a two-way T-type power splitter. The device's function reconfigurability is enabled by locally sputtering vanadium dioxide (VO
₂
) phase transition thin films, which adjust the shape of conductor resonance patch and interconnect to electrically connect or isolate copper planar transmission lines and the patch on a sapphire substrate. Controlling the combination of the phases of four VO
₂
thin-films interconnects effectively matches impedance and guides microwave signals, enabling the device's electromagnetic response to be reconfigured without reconstructing the physical structure. For different functions, the return loss and realized gain of patch antenna are 21 dB and −0.98 dBi at 4.75 GHz, respectively; the insertion loss of bandpass filter is 2.8 dB with bandwidth of 150 MHz (4.66–4.81 GHz); the dividing loss of power splitter is 5.0 dB at 4.7 GHz with power and phase imbalance within ±0.5 dB and ±7° from 4.4 to 5.0 GHz, respectively. Combining three devices in series enables more than 13 types of operation, which are suitable for different microwave systems.