FCC T9A - 天线与馈线系统

#T9A01🔗

What is a beam antenna?

什么是波束天线？

An antenna built from square aluminum beams

由方形铝梁制成的天线

An omnidirectional antenna invented by Clarence Beam

Clarence Beam 发明的全向天线

An antenna that concentrates signals in one direction

一种将信号集中在一个方向上的天线

✓ 正确答案

An antenna that focuses the signal into two intense rays

将信号聚焦成两束强射线的天线

#T9A02🔗

Which of the following describes a type of antenna loading?

以下哪一项描述了天线负载的类型？

Electrically lengthening by inserting inductors in radiating elements

通过在辐射元件中插入电感器进行电气加长

✓ 正确答案

Inserting a resistor in the radiating portion of the antenna to make it resonant

在天线的辐射部分插入电阻使其谐振

Installing a spring in the base of a mobile vertical antenna to make it more flexible

在移动垂直天线的底座中安装弹簧，使其更灵活

Strengthening the radiating elements of a beam antenna to better resist wind damage

加强波束天线的辐射元件以更好地抵抗风害

#T9A03🔗

How is the polarization of an antenna described?

如何描述天线的极化？

By the shape of the driven element

按从动元件的形状

By the orientation of the electric field

通过电场的方向

✓ 正确答案

By the orientation of the magnetic field

通过磁场的方向

By the direction of radiation

按辐射方向

#T9A04🔗

What is a disadvantage of a handheld radio transceiver’s short flexible antenna compared to a full-sized quarter-wave antenna?

与全尺寸四分之一波长天线相比，手持无线电收发器的短柔性天线有什么缺点？

It has low efficiency

它的效率很低

✓ 正确答案

It transmits only circularly polarized signals

它只传输圆极化信号

It is more susceptible to receiver desensitization

更容易受到接收器脱敏的影响

It only works on analog signals, not digital ones

它仅适用于模拟信号，不适用于数字信号

#T9A05🔗

Which of the following increases the resonant frequency of a dipole antenna?

以下哪项增加了偶极天线的谐振频率？

Lengthening it

加长它

Inserting coils in series with radiating wires

插入与辐射线串联的线圈

Shortening it

缩短它

✓ 正确答案

Adding capacitive loading to the ends of the radiating wires

在辐射线的末端添加电容负载

#T9A06🔗

Which of the following types of antennas offers the greatest gain?

以下哪种类型的天线提供最大增益？

5/8 wave vertical

5/8波垂直

Isotropic

各向同性

J pole

J极

Yagi

八木

✓ 正确答案

#T9A07🔗

What is a potential drawback of using a handheld VHF transceiver inside a vehicle that lacks an externally mounted antenna?

在没有外部安装天线的车辆内使用手持式 VHF 收发器的潜在缺点是什么？

Signal strength is reduced due to the shielding effect of the vehicle

由于车辆的屏蔽作用，信号强度降低

✓ 正确答案

The bandwidth of the antenna will decrease, increasing SWR

天线的带宽会降低，增加驻波比

The SWR might decrease, decreasing the signal strength

SWR 可能会降低，从而降低信号强度

The handheld will overheat due to reflected power in the vehicle

由于车辆中的反射功率，手持设备会过热

#T9A08🔗

Why is a 19-inch-long vertical antenna often used on 2 meters?

为什么19英寸长的垂直天线常用在2米上？

It has high gain

它具有高增益

It is a resonant half-wave

这是一个谐振半波

It is a resonant quarter -wave

这是一个谐振四分之一波

✓ 正确答案

It has low RF radiation exposure

它具有低射频辐射暴露

#T9A09🔗

What is an advantage of a 5/8-wavelength whip antenna for VHF or UHF mobile service compared to a 1/4-wave antenna?

与 1/4 波长天线相比，用于 VHF 或 UHF 移动服务的 5/8 波长鞭状天线有何优势？

It has more gain

它有更多的收获

✓ 正确答案

It radiates at a higher angle

它以更高的角度辐射

It has lower SWR

它具有较低的 SWR

It has lower impedance

它具有较低的阻抗

#T9A10🔗

In which direction does a half-wave dipole antenna radiate the strongest signal?

半波偶极子天线在哪个方向辐射最强的信号？

Equally in all directions

各个方向都一样

Off the ends of the antenna

关闭天线的两端

In the direction of the feed line

在馈线方向

Broadside to the antenna

天线宽边

✓ 正确答案

#T9A11🔗

What is antenna gain?

什么是天线增益？

The additional power that is added to the transmitter power

添加到发射器功率的附加功率

The additional power that is required in the antenna when transmitting on a higher frequency

以更高频率传输时天线所需的额外功率

The increase in signal strength in a specified direction compared to a reference antenna

与参考天线相比，指定方向上信号强度的增加

✓ 正确答案

The increase in impedance on receive or transmit compared to a reference antenna

与参考天线相比，接收或发射阻抗的增加

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FCC T9A - 天线与馈线系统

小节 T9A：天线与馈线系统