CTE CTE Wireless & RF Engineering

Question 1

What is the Friis transmission equation used to calculate in RF engineering?

Accepted Answer

Received power in a line-of-sight link given transmit power and antenna gains

Answer

The Friis transmission equation calculates received power as a function of transmit power, antenna gains, wavelength, and free-space path distance.

Question 2

Which modulation scheme provides the highest spectral efficiency in a wireless link?

Accepted Answer

256-QAM

Answer

256-QAM encodes 8 bits per symbol, giving the highest spectral efficiency among the listed schemes, though it requires a high SNR.

Question 3

What does VSWR measure in an antenna system?

Accepted Answer

Impedance mismatch between transmission line and antenna

Answer

Voltage Standing Wave Ratio (VSWR) quantifies impedance mismatch; a VSWR of 1:1 indicates perfect match with no reflected power.

Question 4

In cellular network planning, what is the primary purpose of frequency reuse?

Accepted Answer

To increase network capacity by using the same frequencies in non-adjacent cells

Answer

Frequency reuse assigns the same frequency channels to geographically separated cells, multiplying overall network capacity.

Question 5

Which multiple access technology does LTE use on the downlink?

Accepted Answer

OFDMA

Answer

LTE downlink uses Orthogonal Frequency Division Multiple Access (OFDMA), which divides bandwidth into sub-carriers assigned to different users.

CTE - Certified Telecommunications Engineer Practice Test