Microfluidically Tunable Microstrip Filters

• Published in: IEEE transactions on microwave theory and techniques Vol. 63; no. 7; pp. 2245 - 2252
• Main Authors: Diedhiou, D. L., Sauleau, R., Boriskin, A. V.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Band-pass filters; Bandpass filters; Computer Science; Devices; Dielectric fluid; Electron tubes; Electronics; Engineering Sciences; Fluid dynamics; Fluid flow; microfluidics; Networking and Internet Architecture; Networks; Noise levels; Permittivity; Prototyping; reconfigurable; Resonant frequency; Resonators; Scattering parameters; Substrates; suspended microstrip (MS) line; tunable filters; Tuning; suspended microstrip (MS) line; microstrip circuits; tunable filters; high-permittivity dielectric fluid; microstrip filters; suspended substrate; loss 0.6 dB; plastic tubes; Electron tubes; microfluidically tunable microstrip filters; Substrates; Tuning; Dielectric fluid; reconfigurable; band-pass filters; tunable stub resonators; bandwidth 5 GHz; Resonant frequency; Scattering parameters; Permittivity; Microfluidics; fourth-order bandpass filter
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2015.2435704

A new approach for the development of tunable and reconfigurable microstrip (MS) devices is proposed. The basic idea consists of using a suspended substrate with an integrated network of plastic tubes, which can be selectively filled in with a high-permittivity dielectric fluid, e.g., water. The local change of the substrate effective permittivity achieved in such a way enables one to change, in a controlled and reversible manner, the electrical length of certain elements of MS circuits. As a proof-of-concept, tunable stub resonators based on suspended and inverted MS lines are designed and characterized in frequency and time domains. The same principle is then applied for the development of a fourth-order bandpass filter with 40% fractional bandwidth operating at 5 GHz. A tunable range of 19.5% with the insertion loss of 0.6 dB is demonstrated. The performance of the stub resonators and filter is validated successfully via prototyping.