The propagation of electromagnetic radiation has important applications in radio transmission and absorption. Radio transmitters are connected to an antenna via coaxial cables. When a radio wave is transmitted, it travels down the coaxial cable, up though the antenna, and into free space. However, as the radio wave travels towards the antenna, it can be reflected at areas of different impedance. The standing wave ratio (SWR) is a measure of this reflection and is used to calibrate transmitters with their associated aerials. A standing wave ratio of 1 means an antenna is at its optimum performance.
Instructions
1. Cut a suitable length of coaxial cable and put the coaxial plugs on both sides.
2. Connect the SWR meter in series (in between) the transmitter and the coaxial cable. Connect the end of the coaxial cable to the antenna.
3. Transmit a signal and read off a value of the SWR. If the SWR is high, there is a high amount of the radio wave being reflected either at the antenna or within the coaxial cable.
4. To match the coaxial cable with a low SWR rating, the following considerations are important: thicker coaxial cable has a lower signal loss; when constructing the cable, ensure that the braid is clean and continuous though all of the plugs and sockets used; ensure that all fittings on the coaxial cables are tight.
Tags: coaxial cable, radio wave, coaxial cables, ensure that, standing wave
