Additively Manufactured Dual-Mode Reconfigurable Filter Employing VO₂-Based Switches

Abstract

Modern wireless devices operate on multiple frequency bands, and thus can benefit from frequency reconfigurable Radio Frequency (RF) components, especially filters as they are typically larger in size and are required for every frequency band. In addition, many applications such as wearable electronics, desire stable performance from the devices when they are bent or flexed. However, most of the reconfigurable filters are built on rigid substrates and utilize expensive discrete RF switches, which need to be soldered to the filters. In this work, we present a fully printed filter that achieves reconfigurability through printed Vanadium Dioxide (VO2) based switches, which are extremely low cost and do not require any soldering for their attachment. The filter design is based on a dual-mode resonator which enables a second-order filter despite a single resonator, thus helping in making the filter compact. It also helps in maintaining a decent insertion loss (2.6 dB), despite relatively low conductivity of the metallic ink. The switches, when activated thermally through a printed heater at the backside, reconfigure the frequency from 4 GHz to 3.75 GHz. The filter has been realized on a flexible Kapton substrate, making the filter conformable to any surface. Measurements under various bending conditions reveal stable performance, making this filter design suitable for a number of wearable and Internet of Things applications.

Compact flexible and reconfigurable antenna using screen‐printed vanadium dioxide switch for wireless local area network and 5G electronic devices

“…Here, to achieve a better conductivity and a larger ON/OFF ratio, we have used a heater gun to heat the VO 2 switch, which provides a temperature of about 85 C. For practical use, the switch can be thermally activated by a resistive heater, which is attached to the backside of the switch. 19 The heater can be a meandered line structure or a coil. In order to active the switch, a DC current or a DC voltage is applied to the heater to generate the required temperature.…”

“…One of the solutions to this is to employ reconfigurable antennas, which can reconfigure the operating frequency bands, radiation patterns, and/or polarization of the antennas. 18,19 Using reconfigurable antennas in a communication system helps to avoid the use of multiple antennas in one system. Frequency reconfigurable antennas have the capabilities of reconfiguring the operating frequency bands using different types of switches, such as micro-electromechanical systems (MEMS), 20,21 varactor diodes, 22,23 and P-I-N diodes, [24][25][26] have been studied to achieve reconfigurability of antennas.…”

“…However, these switches are considered to be expensive and complex for fabrication. 18,19 Moreover, they require soldering or an additional epoxy for attachment to the antennas, which could alter the radiation patterns or shift the operating frequency bands. Moreover, these reported designs are only suitable for reconfigurable nonflexible applications.…”

“…As a result, for multisystems operation, multiple antennas might be required in one device, which would not be favorable for small devices. One of the solutions to this is to employ reconfigurable antennas, which can reconfigure the operating frequency bands, radiation patterns, and/or polarization of the antennas 18,19 . Using reconfigurable antennas in a communication system helps to avoid the use of multiple antennas in one system.…”

“…Frequency reconfigurable antennas have the capabilities of reconfiguring the operating frequency bands using different types of switches, such as micro‐electro‐mechanical systems (MEMS), 20,21 varactor diodes, 22,23 and P‐I‐N diodes, 24–26 have been studied to achieve reconfigurability of antennas. However, these switches are considered to be expensive and complex for fabrication 18,19 . Moreover, they require soldering or an additional epoxy for attachment to the antennas, which could alter the radiation patterns or shift the operating frequency bands.…”