dummyloads

A dummy load is an electrical device used to simulate a real electrical load in testing and calibration of equipment while preventing the emission of signals to an antenna or other active circuit. In radio and communications work, the term typically refers to a high‑impedance, well‑matched resistive load that absorbs transmitted power as heat.

In RF practice, the dummy load is usually designed to present an impedance close to 50 ohms, so that transmitters can be tested without radiating a signal. Power handling varies from a few watts in handheld devices to kilowatts in high‑power transmitters. Common forms include fixed coaxial or sealed box loads, broadband resistor assemblies, and water‑ or air‑cooled units for very high power. Some loads use noninductive, air‑ or oil‑immersed resistor networks to minimize stray reactance across wide frequency ranges.

Operation and performance hinge on proper impedance matching and thermal management. A good dummy load dissipates all the input power as heat with minimal reflected energy, yielding a low standing-wave ratio (SWR). Realistic wideband loads are designed to minimize parasitic inductance and capacitance, but practical designs exhibit frequency‑dependent losses and residual reflections at the band edges.

Applications include transmitter testing, calibration of wattmeters, antenna-system alignment, and protection of equipment during maintenance or development. They are preferred when a real antenna is unavailable or undesirable due to safety, regulatory, or environmental concerns. Safety considerations include adequate heat sinking, ventilation, and adherence to power ratings to avoid overheating. See also RF load, calibrated load, and coaxial resistor assemblies.