| Title |
Conduction Noise Absorption by Sn-O Thin Films on Microstrip Lines |
| DOI |
https://doi.org/10.3365/KJMM.2011.49.4.329 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
thin films; vapor deposition; electrical properties; electrical conductivity/resistivity; noise absorbers |
| Abstract |
To develop wide-band noise absorbers with a special design for low-frequency performance, this study proposes a tin oxide (Sn-O) thin films as the noise absorbing materials in a microstrip line. Sn-O thin films were deposited on polyimide film substrates by reactive sputtering of the Sn target under flowing O2 gas, exhibiting a wide variation of surface resistance (in the range of 100-105Ω) depending on the oxygen partial pressure during deposition. The microstrip line with characteristic impedance of 50Ω was used for the measurement of noise absorption by the Sn-O films. The reflection parameter (S11) increased with a decrease of surface resistance due to an impedance mismatch at the boundary between the film and the microstrip line. Meanwhile, the transmission parameter (S21) diminished with a decrease of surface resistance resulting from an Ohmic loss of the Sn-O films. The maximum noise absorption predicted at an optimum surface resistance of the Sn-O films was about 150Ω. For this film, greater power absorption is predicted in the lower frequency region (about 70% at 1 GHz) than in conventional magnetic sheets of high magnetic loss, indicating that Ohmic loss is the predominant loss parameter for the conduction noise absorption in the low frequency band. |