| beacon |
a radar or radio transmitter that emits radio waves at fixed intervals to provide navigational guidance. [1/7 definitions] |
| cordless phone |
a telephone that consists of a battery-operated handset that communicates across short distances via radio waves to an electrically-powered unit that must be connected to a telephone line in order to function. |
| cosmic noise |
interference from radio waves beyond the earth; galactic noise. |
| direction finder |
a device for ascertaining the direction of incoming radio waves or signals, consisting of a loop antenna that rotates. |
| E layer |
a thick layer of ions located at a height of about sixty to ninety miles in the E region of the earth's outer atmosphere and having the ability to deflect radio waves. |
| electromagnetic wave |
a wave that contains a magnetic and electric component and that is created by an accelerating electric charge, such as a radio wave, x-ray, or light. |
| galactic noise |
radio waves originating from within the Milky Way. |
| ground wave |
a radio wave traveling on or near the earth's surface and affected by its curvature, atmosphere, and the like. |
| Hertzian wave |
an electromagnetic wave, such as a radio wave, produced when electricity is oscillated in a conductor. |
| high frequency |
a radio wave between three and thirty megahertz. |
| long wave |
a low-frequency electromagnetic wave, usu. a radio wave that is longer than one thousand meters and below three hundred kilohertz in frequency. |
| magnetic resonance imaging |
a non-invasive medical imaging technology using radio waves and powerful magnetic fields to make the interior of the human body visible in three dimensions and in real time.(abbrev.: MRI) |
| medium frequency |
any radio wave with a frequency of between three hundred and three thousand kilohertz. |
| MRI |
abbreviation of "magnetic resonance imaging," a non-invasive medical imaging technology using radio waves and powerful magnetic fields to make the interior of the human body visible in three dimensions and in real time. |
| omnidirectional |
able to receive radio waves or the like from, or broadcast them in, all directions. |
| pulsar |
any of various astronomical objects, probably rapidly rotating neutron stars, that emit short, repeating pulses of radio waves. |
| quasar |
any of numerous astronomical objects that emit powerful radio waves and have red shifts associated with great distance from earth; quasi-stellar radio source. |
| radar |
a means of discovering the position, range, and velocity of distant objects by timing the return of high frequency radio waves bounced off their surfaces and analyzing the direction of this return. [1/2 definitions] |
| radio astronomy |
the study of the universe by observation and analysis of extraterrestrial radio waves. |
| radio beacon |
a stationary source of radio waves that emits a distinctive signal as a navigational aid for ships and aircraft. |
| radio compass |
a navigational aid consisting of a radio receiver that determines the transmission direction of incoming radio waves. |