impedanssihäviön

Impedanssihäviö, known in English as impedance mismatch loss, refers to the reduction in power transfer efficiency that occurs when the electrical impedance of a source does not match the impedance of the load it is connected to. This mismatch causes some of the signal energy to be reflected back towards the source rather than being fully absorbed by the load. The magnitude of the loss depends on the degree of impedance mismatch.

In many electronic systems, particularly those involving radio frequency (RF) or microwave signals, maintaining a consistent impedance is crucial for optimal performance. A common impedance standard in these applications is 50 ohms. When a source, such as an antenna or a transmitter, is connected to a load with a different impedance, such as a cable or a receiver, reflections occur at the interface. These reflections can lead to several undesirable effects, including reduced signal strength reaching the load, increased standing wave ratio (SWR), and potential damage to the source due to reflected power.

To minimize impedance mismatch loss, matching networks are often employed. These are circuits designed to transform the impedance of the load to match that of the source, thereby maximizing power transfer and minimizing reflections. The concept of impedance matching is fundamental in areas like antenna theory, transmission line theory, and the design of high-frequency electronic circuits.