Near the electrostatic plasma frequency, plasma exhibits a relative permittivity near zero, and this property has been used to make transient plasma waveguides at microwave and optical wavelengths by ionizing gases with pulsed electromagnetic fields and laser radiation. However, to our knowledge, no one has constructed a steady-state RF-excited plasma waveguide for the purpose of studying its microwave attenuation and dispersion characteristics. We report here the results of investigations at 2.8–3.7 GHz of a variable-length plasma waveguide up to 30 cm long in which the plasma’s relative permittivity was as low as 0.2. De-embedded S-parameter power loss is as low as 4.6 dB and the dispersion is largely consistent with theory, although further work remains to be done.

中文翻译：

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稳态微波等离子体波导的色散和衰减特性

在静电等离子体频率附近，等离子体的相对介电常数接近零，该特性已被用于通过脉冲电磁场​​和激光辐射使气体电离，从而在微波和光波长下制作瞬态等离子体波导。然而，据我们所知，没有人为了研究其微波衰减和色散特性而构造出稳态的射频激励等离子体波导。我们在这里报告了在2.8–3.7 GHz范围内长达30 cm的变长等离子体波导的研究结果，其中等离子体的相对介电常数低至0.2。去嵌入的S参数功率损耗低至4.6 dB，并且色散在很大程度上与理论一致，尽管还有更多工作要做。