![]() It is expected that the impedance is mismatched when the PIFA is touched by a hand. In order to design the impedance tuner, we measured input impedance of the PIFA under two scenarios of touched and untouched cases, as illustrated in Figure 2a. Impedance Measurement at Touched and Untouched States ![]() The design and fabrication processes are explained.ΔΆ.2. Its performance is numerically and experimentally demonstrated. The PIFA with the proposed impedance tuner is designed while using circuit and full-wave simulation. The stub length can be tuned by injecting a liquid metal alloy to the microfluidic channels. The proposed microfluidic impedance tuner is designed using a simple double-stub and the impedance is changed by tuning the stub length. Finally, the proposed microfluidic impedance tuner is tested with a planar inverted-F antenna (PIFA). In addition, the injection and extraction of liquid metal are controlled a microcontroller and micropump for practical implementation. Therefore, the injection and extraction are faster, easier, and reliable. In this work, the liquid metal is used as a switch in short fluidic channels. Previously, a microfluidic impedance tuner with a double stub structure has been proposed where the liquid metal is continuously injected into long fluidic channels. When compared to diode switches, the liquid metal switch provides advantages, such as wider switching range, high power capability, no bias network, and direct current (DC) power consumption, and less parasitic effect. In this paper, we propose a microfluidic impedance tuner while using liquid metal as a switch. Especially, liquid metal in microfluidic channels have been studied for flexible or reconfigurable radio frequency (RF) components, such as filters, sensors, absorbers, antennas, and MEMS switch. It can be implemented at a less complexity and low cost. Microfluidic technology has been developed to carry out analysis, screening, and detection of very small quantities of biomaterial and chemical samples. While circuits with many switching elements can have many tuning points, tuning is obtained at the expense of higher cost and insertion loss. Impedance tuning has been widely studied using active and passive components, such as microelectromechanical systems (MEMS) components or diode varactors. ![]() Conventional impedance tuners comprise mainly three different techniques, namely the single-stub, double-stub, and optimization methods. Impedance tuners are widely used to match impedances, such as antennas, power amplifier (PA) load-pull, and noise characterization, and so on. To solve this problem, the use of an impedance tuner is one of the representative methods of matching the antenna impedance. With the advances in the field of wireless communication systems, an increasing number of components are being incorporated in mobile handset design, reducing the space in which complex advanced antennas can be implemented into the handset. In particular, as parts of the human body get closer to the antenna, its performance suffers. Antennas significantly influence the performance of the entire application, as their impedance values vary significantly even in operating environments having small changes. The presence of a mismatched impedance between circuits results in an overall degradation in circuit performance impedance matching between circuits is therefore the basis of high frequency electronics.
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