FCC G9A - 天线与馈线系统

#G9A01🔗

Which of the following factors determine the characteristic impedance of a parallel conductor feed line?

以下哪些因素决定平行导体馈线的特性阻抗？

The distance between the centers of the conductors and the radius of the conductors

导体中心之间的距离和导体半径

✓ 正确答案

The distance between the centers of the conductors and the length of the line

导体中心之间的距离和线路的长度

The radius of the conductors and the frequency of the signal

导体的半径和信号的频率

The frequency of the signal and the length of the line

信号的频率和线路的长度

#G9A02🔗

What is the relationship between high standing wave ratio (SWR) and transmission line loss?

高驻波比（SWR）与传输线损耗之间有什么关系？

There is no relationship between transmission line loss and SWR

传输线损耗和驻波比没有关系

High SWR increases loss in a lossy transmission line

高 SWR 会增加有损传输线路中的损耗

✓ 正确答案

High SWR makes it difficult to measure transmission line loss

高 SWR 使得测量传输线损耗变得困难

High SWR reduces the relative effect of transmission line loss

高 SWR 降低了传输线损耗的相对影响

#G9A03🔗

What is the nominal characteristic impedance of “window line” transmission line?

“窗线”传输线的标称特性阻抗是多少？

50 ohms

50欧姆

75 ohms

75欧姆

100 ohms

100欧姆

450 ohms

450欧姆

✓ 正确答案

#G9A04🔗

What causes reflected power at an antenna’s feed point?

是什么导致天线馈电点出现反射功率？

Operating an antenna at its resonant frequency

在谐振频率下操作天线

Using more transmitter power than the antenna can handle

使用超出天线承受能力的发射器功率

A difference between feed line impedance and antenna feed point impedance

馈线阻抗和天线馈点阻抗之间的差异

✓ 正确答案

Feeding the antenna with unbalanced feed line

使用不平衡馈线向天线馈电

#G9A05🔗

How does the attenuation of coaxial cable change with increasing frequency?

同轴电缆的衰减如何随着频率的增加而变化？

Attenuation is independent of frequency

衰减与频率无关

Attenuation increases

衰减增加

✓ 正确答案

Attenuation decreases

衰减减少

Attenuation follows Marconi’s Law of Attenuation

衰减遵循马可尼衰减定律

#G9A06🔗

In what units is RF feed line loss usually expressed?

射频馈线损耗通常用什么单位表示？

Ohms per 1,000 feet

每 1,000 英尺欧姆

Decibels per 1,000 feet

每 1,000 英尺分贝

Ohms per 100 feet

每 100 英尺欧姆

Decibels per 100 feet

每 100 英尺分贝

✓ 正确答案

#G9A07🔗

What must be done to prevent standing waves on a feed line connected to an antenna?

为了防止连接到天线的馈线上出现驻波，必须采取哪些措施？

The antenna feed point must be at DC ground potential

天线馈电点必须处于直流接地电位

The feed line must be an odd number of electrical quarter wavelengths long

馈线的长度必须为奇数个电四分之一波长

The feed line must be an even number of physical half wavelengths long

馈线的长度必须是偶数个物理半波长

The antenna feed point impedance must be matched to the characteristic impedance of the feed line

天线馈电点阻抗必须与馈线的特性阻抗相匹配

✓ 正确答案

#G9A08🔗

If the SWR on an antenna feed line is 5:1, and a matching network at the transmitter end of the feed line is adjusted to present a 1:1 SWR to the transmitter, what is the resulting SWR on the feed line?

如果天线馈线上的 SWR 为 5:1，并且调整馈线发射机端的匹配网络以向发射机呈现 1:1 SWR，则馈线上的最终 SWR 是多少？

1:1

5:1

✓ 正确答案

Between 1:1 and 5:1 depending on the characteristic impedance of the line

介于 1:1 和 5:1 之间，具体取决于线路的特性阻抗

Between 1:1 and 5:1 depending on the reflected power at the transmitter

介于 1:1 和 5:1 之间，具体取决于发射器的反射功率

#G9A09🔗

What standing wave ratio results from connecting a 50-ohm feed line to a 200-ohm resistive load?

将 50 欧姆馈线连接到 200 欧姆电阻负载会产生什么驻波比？

4:1

✓ 正确答案

1:4

2:1

1:2

#G9A10🔗

What standing wave ratio results from connecting a 50-ohm feed line to a 10-ohm resistive load?

将 50 欧姆馈线连接到 10 欧姆电阻负载会产生什么驻波比？

2:1

1:2

1:5

5:1

✓ 正确答案

#G9A11🔗

What is the effect of transmission line loss on SWR measured at the input to the line?

传输线损耗对线路输入端测得的 SWR 有什么影响？

Higher loss reduces SWR measured at the input to the line

较高的损耗会降低线路输入端测得的 SWR

✓ 正确答案

Higher loss increases SWR measured at the input to the line

较高的损耗会增加线路输入端测得的 SWR

Higher loss increases the accuracy of SWR measured at the input to the line

较高的损耗提高了线路输入端测量的 SWR 的准确性

Transmission line loss does not affect the SWR measurement

传输线损耗不影响 SWR 测量

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FCC G9A - 天线与馈线系统

小节 G9A：天线与馈线系统