题目内容
（请给出正确答案）
A.在导行系统横截面上电场是驻波 ，且完全确定。
B.导模是连续的
C.导模之间相互正交、独立、无耦合
D.导模具有截止特性
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更多“有关导模的叙述错误的是”相关的问题
A．半影导致影像的模糊
B．半影越大，影像锐利度越差
C．肢—片距越大，影像锐利度越好
D．焦—片距离大，半影小，影像锐利
E．阳极端影像锐利度大于阴极端
电磁波频谱如以下表格：Electromagnetic spectrumFrequency (Hz)PhotonenergyeV NameWavelength () Gamma ray < 0.02 nm > 15 EHz > 62.1 keV X-ray 0.01 nm – 10 nm 30 EHz – 30 PHz 124 keV – 124 eV Ultraviolet 10 nm – 400 nm 30 PHz – 750 THz 124 eV – 3 eV Visible light 390 nm – 750 nm 770 THz – 400 THz 3.2 eV – 1.7 eV Infrared 750 nm – 1 mm 400 THz – 300 GHz 1.7 eV – 1.24 meV Microwave 1 mm – 1 m 300 GHz – 300 MHz 1.24 meV – 1.24 µeV Radio 1 mm – 100 km 300 GHz – 3 kHz 1.24 µeV – 12.4 feV Microwaves travel solely by line-of-sight paths; unlike lower frequency radio waves, they do not travel as ground waves which follow the contour of the Earth, or reflect off the ionosphere (skywaves). Although at the low end of the band they can pass through building walls enough for useful reception, usually rights of way cleared to the first Fresnel zone are required. Therefore, on the surface of the Earth, microwave communication links are limited by the visual horizon to about 30–40 miles (48–64 km). Microwaves are absorbed by moisture in the atmosphere, and the attenuation increases with frequency, becoming a significant factor (rain fade) at the high end of the band. Beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies (see graph at right). Above 100 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that it is in effect opaque, until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges. 下面描述错误的是：
A、微波工作频率介于射频及红外之间。
B、微波通信受大气吸收影响较大，衰减会随工作频率增加而加大。
C、微波导行系统一般功耗很大，无法长距离传输
D、微波通信有地波和天波 2 种模式
Microwave engineering pertains to the study and design of microwave circuits, components, and systems. Fundamental principles are applied to analysis, design and measurement techniques in this field. The short wavelengths involved distinguish this discipline from Electronic engineering. This is because there are different interactions with circuits, transmissions and propagation characteristics at microwave frequencies. Some theories and devices that pertain to this field are antennas, radar, transmission lines, space based systems (remote sensing), measurements, microwave radiation hazards and safety measures. 微波工程（Mocrowave Engineering）主要涉及的领域包括：
A、Design of microwave circuits, components, and systems. 【设计微波电路、元件及系统】
B、Fundamental principles are applied to analysis, design and measurement techniques in this field. 【微波原理、应用、测试技术等】
C、低频电子线路（ low frequency Electronic Circuit)
D、antennas, radar, transmission lines, space based systems (remote sensing), measurements, microwave radiation hazards and safety measures. 【天线、雷达、传输线、遥感/遥测 等】
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