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CCNP Wireless FAQ: Selecting Antenna Systems

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CCNP Wireless FAQ: Selecting Antenna Systems

Q1. When comparing light energy to wireless energy, a light bulb can be compared to what antenna element?

Answer: A light bulb can be prepared to the driven element of an antenna.

Q2. The orientation of an antenna’s E-field determines what characteristic of the antenna’s operation?

Answer: The orientation of an antenna’s E-field determines the polarization of the antenna.

Q3. Relative to each other, the E-field of a vertically polarized antenna and the E-field of a horizontally polarized antenna are what?

Answer: The E-fields of a vertically polarized antenna and a horizontally polarized antenna are cross-polarized (at right angles) with respect to one another.

Q4. Omnidirectional antennas are available with either vertical or horizontal polarization. True or false?

Answer: True.

Q5. A diversity receiving system can automatically select the best signal from one of two antennas. True or false?

Answer: True.

Q6. When using a diversity system, the two antennas must always be the same type and point in the same direction. True or false?

Answer: True.

Q7. Anyone who deploys an outdoor license-free wireless system can provide reliable wireless service. True or false?

Answer: False. Only those people who learn wireless principles and apply those principles correctly can provide reliable wireless service.

Q8. A strong signal arriving at your receiver from another wireless network increases your network throughput. True or false?

Answer: False. A strong signal from another network reduces the throughput on your network.

Q9. How much is the typical cross-polarization isolation between a horizontally polarized and a vertically polarized antenna?

Figure: Vertical Polarization

ccnp-wireless-faq-selecting-antenna-systems

Figure: Horizontal Polarization

ccnp-wireless-faq-selecting-antenna-systems.jpg9

Answer: The typical cross-polarization isolation between a vertically polarized and a horizontally polarized antenna is 20 dB.

Q10. A sectorized antenna system does not allow you to serve more end users. True or false?

Answer: False. A sectorized antenna system does allow you to serve more end users.

Q11. In a sectorized antenna system, all the sector antennas should be identical. True or false?

Answer: False. In a sectorized antenna system, the sector antennas do not have to be identical. The horizontal beamwidth, vertical beamwidth, gain, and polarization of each sector antenna should be chosen to best meet the needs of that sector.

Q12. Sector antennas in a sectorized antenna system should always be mounted perfectly vertical. True or false?

Answer: False. Sector antennas should be mounted with a downtilt angle that maximizes sector coverage and reduces interference from outside the sector.