A lossless transmission line is terminated in a load resulting in VSWR of 1.5. If 50 W is the incident power on the load, what is the reflected power?

The VSWR is mathematically related to the reflection coefficient (Γ), which quantifies the fraction of incident power reflected back due to impedance mismatch between the transmission line and the load. The reflection coefficient is given by:

Γ = (VSWR - 1) / (VSWR + 1)

Given in the problem:

• VSWR = 1.5
• Incident power = 50 W

Step 1: Calculate the Reflection Coefficient (Γ):

Substitute the given VSWR value into the formula:

Γ = (1.5 - 1) / (1.5 + 1)

Γ = 0.5 / 2.5

Γ = 0.2

Step 2: Calculate the Reflected Power:

The reflected power (P_reflected) can be calculated using the relation:

P_reflected = Γ² × P_incident

Substitute the values:

P_reflected = (0.2)² × 50

P_reflected = 0.04 × 50

P_reflected = 2 W

Correct Answer:

The reflected power is 2 W, which corresponds to Option 2.