FCC G9C - 天线与馈线系统

#G9C01🔗

Which of the following would increase the bandwidth of a Yagi antenna?

以下哪项会增加八木天线的带宽？

Larger -diameter elements

较大直径的元件

✓ 正确答案

Closer element spacing

更近的元素间距

Loading coils in series with the element

与元件串联的加载线圈

Tapered-diameter elements

锥形直径元件

#G9C02🔗

What is the approximate length of the driven element of a Yagi antenna?

八木天线的驱动元件的长度大约是多少？

1/4 wavelength

1/4波长

1/ 2 wavelength

1/ 2 波长

✓ 正确答案

3/4 wavelength

3/4波长

1 wavelength

1个波长

#G9C03🔗

How do the lengths of a three-element Yagi reflector and director compare to that of the driven element?

三元件八木反射器和导向器的长度与驱动元件的长度相比如何？

The reflector is longer, and the director is shorter

反射镜较长，导向器较短

✓ 正确答案

The reflector is shorter, and the director is longer

反射镜较短，导向器较长

They are all the same length

它们的长度都相同

Relative length depends on the frequency of operation

相对长度取决于操作频率

#G9C04🔗

How does antenna gain in dBi compare to gain stated in dBd for the same antenna?

对于同一天线，以 dBi 为单位的天线增益与以 dBd 为单位的增益相比如何？

Gain in dBi is 2.15 dB lower

dBi 增益降低了 2.15 dB

Gain in dBi is 2.15 dB higher

增益 (dBi) 提高 2.15 dB

✓ 正确答案

Gain in dBd is 1.25 dBd lower

增益（dBd）降低了 1.25 dBd

Gain in dBd is 1.25 dBd higher

增益（dBd）高出 1.25 dBd

#G9C05🔗

What is the primary effect of increasing boom length and adding directors to a Yagi antenna?

增加吊杆长度和在八木天线上添加导向器的主要效果是什么？

Gain increases

增益增加

✓ 正确答案

Beamwidth increases

波束宽度增加

Front-to-back ratio decreases

前后比减小

Resonant frequency is lower

谐振频率较低

#G9C07🔗

What does “front-to-back ratio” mean in reference to a Yagi antenna?

八木天线的“前后比”是什么意思？

The number of directors versus the number of reflectors

导向器数量与反射器数量

The relative position of the driven element with respect to the reflectors and directors

驱动元件相对于反射器和导向器的相对位置

The power radiated in the major lobe compared to that in the opposite direction

主瓣辐射功率与相反方向辐射功率相比

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The ratio of forward gain to dipole gain

正向增益与偶极子增益之比

#G9C08🔗

What is meant by the “main lobe” of a directive antenna?

定向天线的“主瓣”是什么意思？

The magnitude of the maximum vertical angle of radiation

最大辐射垂直角的大小

The point of maximum current in a radiating antenna element

辐射天线元件中的最大电流点

The maximum voltage standing wave point on a radiating element

辐射元件上的最大电压驻波点

The direction of maximum radiated field strength from the antenna

天线辐射场强最大的方向

✓ 正确答案

#G9C09🔗

In free space, how does the gain of two three-element, horizontally polarized Yagi antennas spaced vertically 1/2 wavelength apart typically compare to the gain of a single three-element Yagi?

在自由空间中，垂直间隔 1/2 波长的两个三元件水平极化八木天线的增益通常与单个三元件八木天线的增益相比如何？

Approximately 1.5 dB higher

约高 1.5 分贝

Approximately 3 dB higher

约高 3 分贝

✓ 正确答案

Approximately 6 dB higher

约高 6 分贝

Approximately 9 dB higher

约高 9 分贝

#G9C10🔗

Which of the following can be adjusted to optimize forward gain, front-to-back ratio, or SWR bandwidth of a Yagi antenna?

可以调整以下哪项来优化八木天线的前向增益、前后比或 SWR 带宽？

The physical length of the boom

动臂的物理长度

The number of elements on the boom

动臂上的元件数量

The spacing of each element along the boom

沿吊杆的每个元件的间距

All these choices are correct

所有这些选项都是正确的

✓ 正确答案

#G9C11🔗

What is a beta or hairpin match?

什么是 Beta 赛或发夹赛？

A shorted transmission line stub placed at the feed point of a Yagi antenna to provide impedance matching

放置在八木天线馈电点处的短路传输线短截线以提供阻抗匹配

✓ 正确答案

A 1/4 wavelength section of 75-ohm coax in series with the feed point of a Yagi to provide impedance matching

75 欧姆同轴电缆的 1/4 波长部分与八木的馈电点串联，以提供阻抗匹配

A series capacitor selected to cancel the inductive reactance of a folded dipole antenna

选择串联电容器来消除折叠偶极子天线的感抗

A section of 300-ohm twin-lead transmission line used to match a folded dipole antenna

一段 300 欧姆双引线传输线，用于匹配折叠偶极子天线

#G9C12🔗

Which of the following is a characteristic of using a gamma match with a Yagi antenna?

以下哪项是使用伽马匹配与八木天线的特性？

It does not require the driven element to be insulated from the boom

不需要从动元件与动臂绝缘

✓ 正确答案

It does not require any inductors or capacitors

它不需要任何电感器或电容器

It is useful for matching multiband antennas

对于匹配多频段天线很有用

All these choices are correct

所有这些选项都是正确的

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FCC G9C - 天线与馈线系统

小节 G9C：天线与馈线系统