
An early radio, ca.1930
Radio was the name of a20th centurydevice which was used to transmit or receive sound or signals by means ofradio waves. This name was also used todescribe signals which were transmitted on a specific bandwidth. Methods of radio transmission includedamplitude modulation andfrequency modulation. Aradio program was a type of radio broadcast forrecreational purposes.
Uses[]

Radio Repair
In1930,CaptainJames T. Kirk (who had traveled back in time from2267) andEdith Keeler passed by a radio repair shop on the streets ofNew York City, where a radio was playing the songGoodnight Sweetheart. (TOS: "The City on the Edge of Forever")
In analternate timeline,communications officerHoshi Sato analyzed radio signals from theplanetEarth during1944. Among the transmissions was a speech byWinston Churchill and a broadcast ofThe Shadow. (ENT: "Storm Front")
In1957, a group ofVulcanscientists includingT'Mir observed Earth radio broadcasts concerning the launch of satelliteSputnik I. Later that year, when T'Mir andMestral were stranded inCarbon Creek, they overheard part of abaseball game on the radio. (ENT: "Carbon Creek")
In1967, a youngHenry Starling listened torock and roll music on his portable transistor radio during acamping trip in theHigh Sierras. (VOY: "Future's End")
When theUSSEnterprise (from 2267) accidentally traveled back in time to1969, the crew received a radionews broadcast about the first mannedMoon shot scheduled for thatWednesday. (TOS: "Tomorrow is Yesterday")
During another time travel incident, the USSEnterprise (from2268) traveled back to1968 in a mission to study that period of Earth history by listening to radio and other broadcast communications. (TOS: "Assignment: Earth")
In1986, the pair ofHumpback whales known asGeorge and Gracie were equipped with a special radio transmitter with afrequency of 401megahertz when they were flown to theBering Sea off ofAlaska. (Star Trek IV: The Voyage Home)
In1996, theSETI project used radio broadcasted signals to contact possible alienlifeforms. (VOY: "Future's End", "Future's End, Part II")
In2168, theHorizon used conventional radio to send out a distress call soon after visiting the planetSigma Iotia II, which resulted in the transmission being intercepted a hundred years later. (TOS: "A Piece of the Action")
Subspace radio was an advanced radio system. (TOS: "The Cage")
In2266, the USSEnterprise received a radio transmitteddistress signal from aplanet identical to Earth. (TOS: "Miri")
In2267, theEnterprise found theSSBotany Bay floating in space, transmitting an old radio signal. (TOS: "Space Seed")
In2268,EkosianNazi Party captiveIsak asked fellow captives James Kirk andSpock if they had a radio when he observed them removingrubidium crystals from their arms. Later that year,LieutenantUhura monitored several radio broadcasts on the planet892-IV. (TOS: "Patterns of Force", "Bread and Circuses")

Kirk inspecting the inside of a vacuum tube radio
Radio was a popular broadcasting medium onSigma Iotia II in the same year, featuring music andcommercials.Commander Spock also used a local radio frequency to contact the USSEnterprise. During the same mission, Kirk disassembled avacuum tube radio and used itscopperwire to create atripwire. (TOS: "A Piece of the Action")
Whilestar charting on the outer fringe of theMilky Way Galaxy in2269, theEnterprise discovered a source of mysterious radio emissions originating from aninsectoidpod ship trapped inorbit of the deadstarQuestar M-17. (TAS: "Beyond the Farthest Star")
TheV'ger entity used late-20th century radio signals to call its "Creator" while approaching Earth in the mid-2270s. (Star Trek: The Motion Picture)
FictionaldetectiveDixon Hill had a radio set in his office in theholonovel adaptations based on theseries of novels featuring the character. (TNG: "Manhunt")
In2367, theUSSEnterprise-D studied radio broadcasts of the planetMalcor III in preparation for a possiblefirst contact. (TNG: "First Contact")
Aspaceborn race existed in the24th century which communicated through radio signals. (TNG: "Galaxy's Child")
Amelia Earhart'sairplane signaled an "SOS" distress call on AM radio from aClass L planet in theDelta Quadrant in2371. The signal was intercepted by the radio of a1936Ford truck found floating in space by theUSSVoyager. (VOY: "The 37's")
In2372,The Doctor andDanara Pel listened to the song "My Prayer" byThe Platters on a car radio of a1957Chevrolet in theholodeck. (VOY: "Lifesigns")
In a holodeck recreation ofSainte Claire,France duringWorld War II on the USSVoyager, invaded by a group ofHirogen hunters in2374, the Allied forces used radio news broadcasts to transmit messages to theFrench Resistance. TheNazis also used radio for communication, which the Resistance had tosabotage. (VOY: "The Killing Game", "The Killing Game, Part II")
In the same year,Tom Paris listened to surf rock music on a portable radio in hisGrease Monkeyholoprogram while working on a1969ChevyCamaro automobile. (VOY: "Vis à Vis")
Still in the same year, in CaptainBenjamin Sisko's vision fromProphets of1953 New York City,Benny Russell had a radio set in his home. (DS9: "Far Beyond the Stars")
InThe Adventures of Captain Proton holonovel series, characters (includingDoctor Chaotica) often used radio transmissions as a way of interspace communication. (VOY: "Night", "Thirty Days", "Bride of Chaotica!")
Scientists onKelemane's planet used radio broadcasts to transmit their messages to the "Sky Ship" (USSVoyager) during one period of the planet's history in2376.Seven of Nine received their transmissions which led CaptainJaneway to send The Doctor on anaway mission to the surface. (VOY: "Blink of an Eye")
