What is the purpose of a dummy load versus an antenna in transmitter testing?

• A. Antenna allows real-world radiation patterns.
• B. Dummy load provides a safe, non-radiating load for calibrations.
• C. Dummy load increases transmitter power.
• D. There is no difference; both perform identical functions.

Answer: (B)

When testing a transmitter, you want a known, non-radiating load to measure what the transmitter is doing without introducing radiation or environmental variables. A dummy load serves this purpose by absorbing RF power as heat while presenting a stable, matched impedance (typically 50 ohms). This lets you calibrate power meters, check output levels, and inspect the transmitter’s behavior (like drive, linearity, and stability) without the complexities that come with radiating an actual signal into air.

Using a real antenna during tests would cause the energy to be radiated, exposing people to RF, potentially causing interference, and introducing variables such as the antenna’s radiation pattern, feed-point impedance changes with frequency, and environment. Those factors can obscure what the transmitter itself is producing, making precise calibration harder. The dummy load isolates the transmitter from those factors, giving a safe, predictable load for bench testing.

The other options miss the purpose: a dummy load does not increase transmitter power—it simply absorbs it; and a setup with an antenna is not a “same function” scenario, since they serve different testing goals (calibration versus real-world radiation measurements).