7.7 Experiment Demonstrating Stationary Waves using Microwaves
Microwaves are a form of electromagnetic radiations. They are called "micro" waves because their wavelengths are typically of the order of millimetres or centimetres, much shorter than radiowaves. Stationary waves, also known as standing waves, can be produced by microwaves when they are confined to a specific region or cavity such as wave guides or resonant chambers. In these structures, microwaves can bounce back and forth, creating a standing wave pattern with nodes and antinodes. It occurs when the microwave frequency matches the resonant frequency of the cavity.
The stationary waves can be created using microwaves by the following simple method as shown in Fig. 7.10.
The experiment setup consists of a microwave source (transmitter), a probe detector and a metal reflector (a metallic plate for the reflection of microwave). Three of the mentioned are placed in line.
The waves coming out of microwave source are moving towards the metal plate and then reflected back. The reflected wave and incident wave superpose and create a stationary wave pattern. This can be detected by a probe detector placed between transmitter and metallic plate. The intensity of the signal can be observed by the detector. You can move the plate or detector to observe antinode and node. By finding the distance from one antinode to the next antinode, the wavelength of stationary wave can be found.