| 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. |
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| Key Words |
| thin films, vapor deposition, electrical properties, electrical conductivity/resistivity, noise absorbers |
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