Radio is just like light, except the wavelength is longer. Apart from transmitters made by people, there are natural sources as well, ordinary stars and particularly things like quasars which give off radio fequency radiation (and other radiation too) when stuff is falling into them - probably black holes. So these things can be detected, measured and located by radio in some cases where even the Hubble telescope can't see them. Radio astronomy can be used day and night so it is pretty popular among astronomers. No night work? Yay!
On Earth radio waves are created by lightning among other things, so it is possible to find where lightning is by using directional radio antennas. It seems that just before earthquakes some big electrical currents flow in stressed wet rock and this can create some radio waves.
Chemists use radio waves in two main instruments. One is the Inductively Coupled Plasma Quantometer. In this a sample is sprayed in an argon stream through a small coil. The coil is connected to a strong radio transmitter and the intense radio frequency field near the coil strips the electrons of the atoms, or at least some of them. When the spray comes out of the strong field, the electrons fall back in place, that fall emits light in the form of visible and ultra violet. The light is broken up by a spectrometer and passes to photomultiplier tubes where it is amplified and measured. This instrument is mostly used for analysis of metal ores and alloys.
The other instrument is used in organic chemistry and is called a Nuclear Magnetic Resonance spectrometer. All protons have "spin" which gives them a tiny magnetic field. In atoms with an even number of protons this spin is opposite to each other and cancels out, but atoms like hydrogen have one proton and therefore they have a tiny field.
Normally this tiny field is orientated one way or another and is difficult to shift. But if you put the atoms in a strong magnetic field it becomes much easier and it can be done with a moderately strong radio signal which feeds in just enough energy.
As the protons flip they absorb or give off a little radio frequency signal themselves and this can be detected and sorted out by a special receiver close to the sample. Since the hydrogen atoms in organic compounds are bound to and slightly influenced by bigger atoms like carbon and nitrogen, the exact frequency at which this happens changes just slightly, so with an unknown compound it's possible to tell how many hydrogen atoms are bound to nitrogen how many to carbon and so forth. It is also possible to get a good idea of the shape of some parts of the molecule.
This technique has been around since at least the early 1960s and was commonly available even in modest universities by 1970 or so.
The technique has been adapted to detect what kind of chemicals are inside the human body, it is called magnetic resonance imaging or MRI. They dropped the "nuclear" as they realised it would frighten some people.
Another medical use has been around for a long time and is just a small transmitter attached to electrodes placed on muscle groups. When the transmitter is turned on, the muscles get a little warmer. This has been used by physiologists to treat injuries.
Another technique is terrain penetrating radar. Instead of digging a lot of holes to find what is underground, it's possible to use radar to get an idea of geological structures down to a few metres at least.
That's a few thing I can think of offhand. Aviation is full of radio engineering, so is space flight.