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RF Mathematics and Principles

This chapter delves into key concepts of radio frequency technology, covering topics such as LOS, power gain/loss measurements, VSWR, impedance, EIRP calculations, and RF behaviors. Gain insights into the fundamental principles of RF circuits and antennas.

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RF Mathematics and Principles

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  1. Faculty ofComputer Science & Engineering Chapter 02. Radio Frequency

  2. Question 1 • 1. When visual line of sight (LOS) is present, RF LOS will always be present. • A. This statement is always true • B. This statement is always false • C. It depends on the configuration of the antennas

  3. Question 2 • 2. When RF LOS is present, visual LOS will always be present. • A. This statement is always true • B. This statement is always false • C. It depends on the specific factors

  4. Question 3 • 3. What unit of measurement is used to quantify the power gain or loss of an RF signal? Choose all that apply. • A. dBi • B. dBm • C. Watts • D. dB

  5. Question 4 • 4. Using which of the following will reduce VSWR? Choose all that apply. • A. Cables and connectors that all have an impedance of 50 Ohms • B. Cables with a 50 Ohm impedance and connectors with 75 Ohm impedance • C. Cables and connectors that all have an impedance of 75 Ohms • D. Cables with 75 Ohm impedance and connectors with 50 Ohm impedance

  6. Question 5 • 5. In an RF circuit, what is the intentional radiator defined as? • A. The output of the transmitting device • B. The output of the last connector before the signal enters the antenna • C. The output as measured at the antenna element • D. The output after the first length of cable attached to the transmitting device

  7. Question 6 • 6. dBi is a relative measurement of decibels to which one of the following? • A. Internet • B. Intentional radiator • C. Isotropic radiator • D. Isotropic radio

  8. Question 7 • 7. Which one of the following is considered impedance in an RF circuit? • A. The inability to transmit RF signals • B. Interference of an RF signal during foul weather • C. Resistance to current flow, measured in Ohms • D. The frequency on which an RF transmitter sends signals

  9. Question 8 • 8. In RF mathematics, 1 watt equals what measurement of dBm? • A. 1 • B. 3 • C. 10 • D. 30 • E. 100

  10. Question 9 • 9. Which one of the following RF behaviors is defined as “the bending of a wave as it passes through a medium of different density”? • A. Diffraction • B. Reflection • C. Refraction • D. Distraction

  11. Question 10 • 10. Given an access point with 100 mW of output power connected through a 50-foot cable with 3 dB of loss to an antenna with 10 dBi of gain, what is the EIRP at the antenna in mW? • A. 100 mW • B. 250 mW • C. 500 mW • D. 1 W

  12. Question 11 • 11. Given a wireless bridge with 200 mW of output power connected through a 100 foot cable with 6 dB of loss to an antenna with 9 dBi of gain, what is the EIRP at the antenna in dBm? • A. 20 dBm • B. 26 dBm • C. 30 dBm • D. 36 dBm

  13. Question 12 • 12. Given an access point with an output power of 100 mW connected through a cable with a loss of 2 dB to antenna with a gain of 11 dBi, what is the EIRP in mW? • A. 200 mW • B. 400 mW • C. 800 mW • D. 1 W

  14. Question 13 • 13. Given an access point with an output power of 20 dBm connected through a cable with a loss of 6 dB to an amplifier with a 10 dB gain, then through a cable with 3 dB of loss to an antenna with 6 dBi of gain, what is the EIRP in dBm? • A. 18 dBm • B. 23 dBm • C. 25 dBm • D. 27 dBm

  15. Question 14 • 14. What is the net gain or loss of a circuit if it is using two cables with 3 dB loss each, one amplifier with a 12 dB gain, 1 antenna with 9 dBi gain, and an attenuator with a loss of 5 dB? • A. 5 dB • B. 10 dB • C. 15 dB • D. 20 dB

  16. Question 15 • 15. Which of the following is a cause of VSWR? • A. Mismatched impedances between wireless LAN connectors • B. Too much power being radiated from the antenna element • C. The incorrect type of antenna used to transmit a signal • D. Use of the incorrect RF frequency band

  17. Question 16 • 16. Radio waves propagate (move) away from the source (the antenna) in what manner? • A. In a straight line in all directions at once within the vertical and horizontal beamwidths • B. In circles spiraling away from the antenna • C. In spherical, concentric circles within the horizontal beamwidth • D. Up and down across the area of coverage

  18. Question 17 • 17. Why is the Fresnel Zone important to the integrity of the RF link? • A. The Fresnel Zone defines the area of coverage in a typical RF coverage cell • B. The Fresnel Zone must always be 100% clear of any and all blockage for a • wireless LAN to operate properly • C. The Fresnel Zone defines an area around the LOS that can introduce RF signal • interference if blocked • D. The Fresnel Zone does not change with the length of the RF link

  19. Question 18 • 18. The FCC allows how many watts of power to be radiated from an antenna in a point to multipoint wireless LAN connection using unlicensed 2.4 GHz spread spectrum equipment? • A. 1 watt • B. 2 watts • C. 3 watts • D. 4 watts

  20. Question 19 • 19. In regards to gain and loss measurements in wireless LANs, the statement that gains and losses are additive is: • A. Always true • B. Always false • C. Sometimes true • D. Sometimes false • E. It depends on the equipment manufacturer

  21. The END

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