Effect of plasma on the transmission of electromagnetic wave on micro-strip line

The effect of uniform plasma on the electromagnetic wave (EMW) transmittance on micro-strip line is investigated by simulations. The dependence of transmission coefficients of EMW on the plasma frequency (density), the electron-molecule collision frequency, the thickness and width of the plasma layer etc are obtained under large and small gaps on the line. The results show that before filled with plasma in the gap, EMW with higher frequency can pass the gap while that with lower frequency cut off. After filled with dense plasma layer of appropriate thickness and width, the gap allows the low-frequency EMW to transfer. The transmittance increases with the plasma frequency, but decreases with the collision frequency. On the other hand, the filled plasma causes an attenuation peak at high-frequency band with position being proportional to the plasma frequency but independent on the collision frequency. The discharge plasma is feasible to be used to control the EMW transmission on the micro-strip lines.