For the lobe width, which of the following descriptions is correct is (). (Select 3 Answers)

• A.The pattern usually has two or more lobes
• B.The narrower the lobe width, the better the directivity, the longer the radiation distance, the stronger the anti-interference ability
• C.Only within the coverage of the half power angle, the terminal can receive the signal
• D.Within the range of the main lobe, the power density relative to the maximum radiation direction is reduced by half (3dB) Angle

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For the polarization of electromagnetic waves, which of the following descriptions is correct is (). (Select 3 Answers)

• A.The polarization of the antenna refers to the direction of the magnetic field strength formed when the antenna radiates
  , The direction of the electric field changes according to a certain rule
• B.If the electric field direction of the electric wave is perpendicular to the ground, we call it a vertically polarized wave
• C.The antenna radiates electromagnetic waves to the surrounding space
• D.If the transmitting antenna is circularly polarized, the receiving antenna must also be circularly polarized, and the polarization direction of the two must be the same.

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If connected to the same SSID Of wireless clients want to start from a AP Roam to another AP, Then two AP The area where the signal overlaps between. What is the general range ()?

• A.100%
• B.10%-15%
• C.No need to overlap
• D.50%

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802.11g What rates can be supported?

• A.6, 9, 12, 18, 24, 36, 48, 54 Mbps
• B.6,9,12,18,24,30,36,48,54 Mbps
• C.1,2,5.5,11&6,9,12,18,24,30,36,48,54 Mbps
• D.1,2,5.5,11&6,9,12,18,24,36,48,54 Mbps

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In an 802.11 frame, what kind of control message () should be sent by the terminal to obtain access to the wireless medium?

• A.ACK
• B.CTS
• C.PS-Poll
• D.RTS

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