FCC E3A - 无线电波传播

#E3A01🔗

What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by EME?

通过 EME 通信的两个站之间沿地球表面测得的近似最大间隔是多少？

2,000 miles, if the moon is at perigee

2,000 英里（如果月亮位于近地点）

2,000 miles, if the moon is at apogee

2,000 英里（如果月球位于远地点）

5,000 miles, if the moon is at perigee

5,000 英里（如果月亮位于近地点）

12 ,000 miles, if the moon is “ visible ” by both stations

12,000 英里，如果两个站都“可见”月亮

✓ 正确答案

#E3A02🔗

What characterizes libration fading of an EME signal?

EME 信号的振动衰落有何特点？

A slow change in the pitch of the CW signal

CW 信号音调的缓慢变化

A fluttery , irregular fading

飘动的、不规则的褪色

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A gradual loss of signal as the sun rises

随着太阳升起信号逐渐丢失

The returning echo is several hertz lower in frequency than the transmitted signal

返回的回波频率比发射信号低几赫兹

#E3A03🔗

When scheduling EME contacts, which of these conditions will generally result in the least path loss?

在调度 EME 联系时，以下哪一个条件通常会导致路径损耗最少？

When the Moon is at perigee

当月亮位于近地点时

✓ 正确答案

When the Moon is full

当月亮满的时候

When the Moon is at apogee

当月球位于远地点时

When the MUF is above 30 MHz

当MUF高于30 MHz时

#E3A04🔗

In what direction does an electromagnetic wave travel?

电磁波沿什么方向传播？

It depends on the phase angle of the magnetic field

这取决于磁场的相位角

It travels parallel to the electric and magnetic fields

它平行于电场和磁场传播

It depends on the phase angle of the electric field

取决于电场的相位角

It travels at a right angle to the electric and magnetic fields

它与电场和磁场成直角传播

✓ 正确答案

#E3A05🔗

How are the component fields of an electromagnetic wave oriented?

电磁波的分量场如何定向？

They are parallel

它们是平行的

They are tangential

它们是相切的

They are at right angles

它们是直角

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They are 90 degrees out of phase

它们的相位相差 90 度

#E3A06🔗

What should be done to continue a long-distance contact when the MUF for that path decreases due to darkness?

当该路径的 MUF 由于黑暗而降低时，应该采取什么措施才能继续进行长距离接触？

Switch to a higher frequency HF band

切换到更高频率的 HF 频段

Switch to a lower frequency HF band

切换到较低频率的 HF 频段

✓ 正确答案

Change to an antenna with a higher takeoff angle

更换起飞角更大的天线

Change to an antenna with greater beam width

更换波束宽度更大的天线

#E3A07🔗

Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?

能够传播微波信号的大气管道通常形成在什么地理特征上？

Mountain ranges

山脉

Stratocumulus clouds

层积云

Large bodies of water

大型水域

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Nimbus clouds

雨云

#E3A08🔗

When a meteor strikes the Earth’s atmosphere, a linear ionized region is formed at what region of the ionosphere?

当流星撞击地球大气层时，电离层的哪个区域会形成线性电离区？

The E region

E区

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The F1 region

F1地区

The F2 region

F2区

The D region

D区

#E3A09🔗

Which of the following frequency ranges is most suited for meteor-scatter communications?

以下哪个频率范围最适合流星散射通信？

1.8 MHz - 1.9 MHz

1.8兆赫 - 1.9兆赫

10 MHz - 14 MHz

10兆赫 - 14兆赫

28 MHz - 148 MHz

28兆赫 - 148兆赫

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220 MHz - 450 MHz

220兆赫 - 450兆赫

#E3A10🔗

What determines the speed of electromagnetic waves through a medium?

什么决定了电磁波通过介质的速度？

Resistance and reactance

电阻和电抗

Evanescence

消逝

Birefringence

双折射

The index of refraction

折射率

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#E3A11🔗

What is a typical range for tropospheric duct propagation of microwave signals?

微波信号对流层管道传播的典型范围是多少？

10 miles to 50 miles

10 英里至 50 英里

100 miles to 300 miles

100英里至300英里

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1,200 miles

1,200 英里

2,500 miles

2,500 英里

#E3A12🔗

What is most likely to result in auroral propagation?

什么最有可能导致极光传播？

Meteor showers

流星雨

Quiet geomagnetic conditions

安静的地磁条件

Severe geomagnetic storms

强烈的地磁风暴

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Extreme low-pressure areas in polar regions

极地极低压区

#E3A13🔗

Which of these emission modes is best for auroral propagation?

以下哪种发射模式最适合极光传播？

连续波

✓ 正确答案

SSB

单边带

调频

RTTY

#E3A14🔗

What are circularly polarized electromagnetic waves?

什么是圆偏振电磁波？

Waves with an electric field bent into a circular shape

电场弯曲成圆形的波

Waves with rotating electric and magnetic fields

具有旋转电场和磁场的波

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Waves that circle Earth

环绕地球的波浪

Waves produced by a loop antenna

环形天线产生的波

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FCC E3A - 无线电波传播

小节 E3A：无线电波传播