FCC G3C - 无线电波传播

#G3C01🔗

Which ionospheric region is closest to the surface of Earth?

哪个电离层区域最接近地球表面？

The D region

D区

✓ 正确答案

The E region

E区

The F1 region

F1地区

The F2 region

F2区

#G3C02🔗

What is meant by the term “critical frequency” at a given incidence angle?

给定入射角下的术语“临界频率”是什么意思？

The highest frequency which is refracted back to Earth

折射回地球的最高频率

✓ 正确答案

The lowest frequency which is refracted back to Earth

折射回地球的最低频率

The frequency at which the signal-to-noise ratio approaches unity

信噪比接近一致时的频率

The frequency at which the signal-to-noise ratio is 6 dB

信噪比为6 dB时的频率

#G3C03🔗

Why is skip propagation via the F2 region longer than that via the other ionospheric regions?

为什么通过 F2 区域的跳跃传播比通过其他电离层区域的跳跃传播更长？

Because it is the densest

因为它是最密集的

Because of the Doppler effect

由于多普勒效应

Because it is the highest

因为它是最高的

✓ 正确答案

Because of temperature inversions

由于逆温

#G3C04🔗

What does the term “critical angle” mean, as applied to radio wave propagation?

无线电波传播中的“临界角”一词是什么意思？

The long path azimuth of a distant station

远方站的长路径方位角

The short path azimuth of a distant station

远方站的短程方位角

The lowest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions

在特定电离层条件下将无线电波返回地球的最低起飞角

The highest takeoff angle that will return a radio wave to Earth under specific ionospheric conditions

在特定电离层条件下将无线电波返回地球的最高起飞角

✓ 正确答案

#G3C05🔗

Why is long-distance communication on the 40-, 60-, 80-, and 160-meter bands more difficult during the day?

为什么白天40米、60米、80米、160米频段的长途通信比较困难？

The F region absorbs signals at these frequencies during daylight hours

F 区域在白天吸收这些频率的信号

The F region is unstable during daylight hours

F区白天不稳定

The D region absorbs signals at these frequencies during daylight hours

D 区在白天吸收这些频率的信号

✓ 正确答案

The E region is unstable during daylight hours

E区白天不稳定

#G3C06🔗

What is a characteristic of HF scatter?

高频散射有什么特点？

Phone signals have high intelligibility

电话信号清晰度高

Signals have a fluttering sound

信号有颤动的声音

✓ 正确答案

There are very large, sudden swings in signal strength

信号强度出现非常大的突然波动

Scatter propagation occurs only at night

散射传播仅发生在夜间

#G3C07🔗

What makes HF scatter signals often sound distorted?

是什么导致高频散射信号听起来经常失真？

The ionospheric region involved is unstable

涉及的电离层区域不稳定

Ground waves are absorbing much of the signal

地波吸收了大部分信号

The E region is not present

E区不存在

Energy is scattered into the skip zone through several different paths

能量通过几个不同的路径分散到跳跃区域

✓ 正确答案

#G3C08🔗

Why are HF scatter signals in the skip zone usually weak?

为什么跳跃区的高频散射信号通常较弱？

Only a small part of the signal energy is scattered into the skip zone

只有一小部分信号能量被分散到跳跃区

✓ 正确答案

Signals are scattered from the magnetosphere, which is not a good reflector

信号从磁层散射，磁层不是一个好的反射器

Propagation is via ground waves, which absorb most of the signal energy

通过地波传播，地波吸收大部分信号能量

Propagation is via ducts in the F region, which absorb most of the energy

通过 F 区域的管道传播，吸收大部分能量

#G3C09🔗

What type of propagation allows signals to be heard in the transmitting station’s skip zone?

什么类型的传播允许在发射站的跳跃区域听到信号？

Faraday rotation

法拉第旋转

Scatter

分散

✓ 正确答案

Chordal hop

和弦跳

Short-path

短路径

#G3C10🔗

What is near vertical incidence skywave (NVIS) propagation?

什么是近垂直入射天波 (NVIS) 传播？

Propagation near the MUF

MUF 附近的传播

Short distance MF or HF propagation at high elevation angles

高仰角短距离中频或高频传播

✓ 正确答案

Long path HF propagation at sunrise and sunset

日出和日落时的长路径高频传播

Double hop propagation near the LUF

LUF 附近的双跳传播

#G3C11🔗

Which ionospheric region is the most absorbent of signals below 10 MHz during daylight hours?

白天哪个电离层区域最能吸收低于 10 MHz 的信号？

The F2 region

F2区

The F1 region

F1地区

The E region

E区

The D region

D区

✓ 正确答案

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FCC G3C - 无线电波传播

小节 G3C：无线电波传播