What is a link budget and what are its main components?

• A. Pt and feeder losses only
• B. Pt, Gt, Gr, path loss, feeder losses, receiver sensitivity
• C. Receiver sensitivity only
• D. Path loss only

Answer: (B)

A link budget shows how much signal power arrives at the receiver by adding gains and subtracting losses from the transmitter to the receiver, and checks that this power meets the receiver’s minimum needs. The key pieces are the transmitter power, the gains of both the transmitting and receiving antennas, the losses along the path, the feeder losses in the cables, and the receiver’s sensitivity (the minimum signal level required for acceptable performance). Transmitter power is the actual RF power sent out; the transmitting antenna gain describes how well that power is focused in the direction of the receiver; receiving antenna gain indicates how effectively the antenna collects the incoming signal. Path loss accounts for the reduction in power as it propagates through space and through the environment, while feeder losses are the extra attenuation in cables and connections. Receiver sensitivity is the threshold the received power must meet or exceed for reliable operation. A complete budget combines these factors to determine if the received power will be sufficient, which is why the full set—Pt, Gt, Gr, path loss, feeder losses, and receiver sensitivity—is the correct description.