What is Radio communication: Definition and 15 Discussions

Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing and other applications.
In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking and satellite communication among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location. In radio navigation systems such as GPS and VOR, a mobile receiver accepts radio signals from navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In wireless radio remote control devices like drones, garage door openers, and keyless entry systems, radio signals transmitted from a controller device control the actions of a remote device.
Applications of radio waves which do not involve transmitting the waves significant distances, such as RF heating used in industrial processes and microwave ovens, and medical uses such as diathermy and MRI machines, are not usually called radio. The noun radio is also used to mean a broadcast radio receiver.
Radio waves were first identified and studied by German physicist Heinrich Hertz in 1886. The first practical radio transmitters and receivers were developed around 1895–1896 by Italian Guglielmo Marconi, and radio began to be used commercially around 1900. To prevent interference between users, the emission of radio waves is regulated by law, coordinated by an international body called the International Telecommunications Union (ITU), which allocates frequency bands in the radio spectrum for different uses.

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  1. Johnm35

    Can a 19.8 kHz, 1 megawatt VLF tower melt metal?

    Not sure if this is the right place to post, but I am wondering, can this VLF station melt metal (details below post)? I recently did a scuba dive with a company in exmouth, WA, who provided some info on this station. They had been told that the control room is made entirely of wood, and even...
  2. Mzzed

    RF Power Meter / SWR Meter Equivalent Circuit

    I'm starting to get into RF electronics, and an upcoming project involves the use of a power meter / SWR meter. How do we model a power meter in terms of an equivalent circuit? i.e. is it just another impedance? or a transformer? or does it not effect the circuit at all, so we just don't include...
  3. Mzzed

    Impedance of RF Connectors

    I am just a bit confused as to how impedance is matched with RF connectors such as type-N or BNC connectors. I know Coaxial cabling and RF connectors come in common impedance ratings like 50 or 75 ohm but how is this all matched properly? For example many people have told me that when using...
  4. R

    Modern usage of non-navigational radio beacons

    How useful are non-navigational radio beacons (i.e., for determining current propagation conditions and testing) nowadays, whether microwave X band, HF, ELF, sub-mm wave, etc., considering the advent of computerized propagation modeling? Is the scarcity of non-amateur radio beacons a result of...
  5. A

    A question about radio receivers

    Could somebody explain me why it would not be sufficient for a radio receiver of an AM signal to simply consist in two elements: A very long antenna. A speaker/headphones. The set up would be as follows, the antenna is connected to the speaker and the other part of the speaker is grounded. My...
  6. anandzoom

    How a remote controlled car know which button is pressed?

    Let us assume a remote controlled car which operates at 2.4GHz frequency band. When the accelerate or left or right turn button is pressed what value changes so that the car detects which button was pressed?
  7. Alan Arqueza

    I Are Pagers More Reliable Compared to Phones?

    If true, can you explain how a pager is more reliable than a cellphone when a signal is deterministic of the complexity of the environment? (when a signal is received in a complex environment - how materials block radio signals).
  8. Hongo

    I Radio Comm Between 2 Points Diff Gravity: True?

    A source that is orbiting close to a singularity of a black hole is transmitting a radio frequency signal that lasts 60 seconds and is repeated infinitely. The signal is being transmitted using the amplitude modulation method (AM Radio). Let suppose that each minute passing in the transmitting...
  9. Geek007

    As the frequency increases so does the energy Em wave carry

    Hi everyone, As we move from left to right in EM spectrum the energy EM wave carries in creases as does the Frequency. Then why even after having a lot of energy waves can't penetrate hard me trials like rock. For example, Microwave aren't that good in penetration of tough objects but have...
  10. H Smith 94

    Understanding propagation loss: What does this output mean?

    Hi there! I am currently building a simulation to model the propagation of radio waves in seawater in terms of its propagation loss. I have previously discussed the models I've looked at but have settled on a model which depends primarily on the propagation distance ##r##, the carrier wave...
  11. H Smith 94

    How is radio wave propagation modelled in seawater?

    Before I start, I apologise for the information dump that is to follow. I don't expect all questions to be answered or all models to be addressed; I simply feel it is appropriate to provide the community with my current knowledge and stage of research so you may not have to search for it...
  12. M

    Radio communication from the galaxy's far side?

    Is it at all possible for radio communication to travel from the obscured part of our galaxy to Earth? If so, about how long would it take to reach us? I have an idea for fiction where we're able to receive communications from the far side of the Milky Way, but we can't figure out how to...
  13. B

    Radio Communication: Basics & Range Variation

    What is the basic concept behind radio communication? How does one vary range in it ?
  14. S

    Radio Communication: Starting Out - Tips for Beginners

    I'm a high school student working on an extracurricular activity where I'm trying to design and build a radio system to function similar to that of a rc vehicles. However, I'm just getting started, and my knowledge is mostly in mechanical engineering. Where should I start? Thanks