Han S T, Comfoltey E N, Shapiro M A, Sirigiri J R, Tax D S, Temkin R J, Woskov P P, Rasmussen D A
Plasma Science and Fusion Center, MIT, Cambridge, MA 02139-4294, USA; Korea Electrotechnology Research Institute, Changwon, Kyungnam 641-120, Republic of Korea.
Int J Infrared Millimeter Waves. 2008 Nov;29(11):1011-1018. doi: 10.1007/s10762-008-9404-3.
We report the measurement of small losses in transmission line (TL) components intended for high-power millimeter-wave applications. Measurements were made using two different low-power techniques: a coherent technique using a vector network analyzer (VNA) and an incoherent technique using a radiometer. The measured loss in a 140 GHz 12.7 mm diameter TL system, consisting of 1.7 m of circular corrugated waveguide and three miter bends, is dominated by the miter bend loss. The measured loss was 0.3±0.1 dB per miter bend using a VNA; and 0.22±0.1 dB per miter bend using a radiometer. Good agreement between the two measurement techniques implies that both are useful for measuring small losses. To verify the methodology, the VNA technique was employed to measure the extremely small transmission loss in a 170 GHz ITER prototype TL system consisting of three lengths of 1 m, 63.5 mm diameter, circular corrugated waveguide and two miter bends. The measured loss of 0.05±0.02 dB per miter bend may be compared with the theoretical loss of 0.027 dB per miter bend. These results suggest that low-power testing of TL losses, utilizing a small, simple TL system and a VNA, is a reliable method for evaluating performance of low-loss millimeter-wave TL components intended for use in high-power applications.
我们报告了用于高功率毫米波应用的传输线（TL）组件中小损耗的测量结果。测量使用了两种不同的低功率技术：一种是使用矢量网络分析仪（VNA）的相干技术，另一种是使用辐射计的非相干技术。在一个直径为12.7毫米、频率为140吉赫兹的TL系统中，该系统由1.7米的圆形波纹波导和三个斜接弯头组成，测量得到的损耗主要由斜接弯头损耗决定。使用VNA测量时，每个斜接弯头的损耗为0.3±0.1分贝；使用辐射计测量时，每个斜接弯头的损耗为0.22±0.1分贝。两种测量技术之间的良好一致性表明，它们都可用于测量小损耗。为了验证该方法，采用VNA技术测量了一个170吉赫兹ITER原型TL系统中的极小传输损耗，该系统由三段长度为1米、直径为63.5毫米的圆形波纹波导和两个斜接弯头组成。测得的每个斜接弯头的损耗为0.05±0.02分贝，可与理论损耗每个斜接弯头0.027分贝进行比较。这些结果表明，利用小型、简单的TL系统和VNA对TL损耗进行低功率测试，是评估用于高功率应用的低损耗毫米波TL组件性能的可靠方法。
