You asked a very reasonable question. The EM spectrum from gamma to infrared is the emission of photons from excited electrons and other subatomic particles:
- Bombardment of a nucleus with high-energy particles mainly produces X-ray photons. The kinetic energy is partly converted into photons.
- The annihilation between a particle and its antiparticle leads to two, three or rarer more then three photons, of which at least two are in the gamma spectrum.
- The ohmic resistance is nothing more than the emission of infrared photons and some photons in the visible spectrum by the zigzagging of moving electrons inside the conductor. Bending or deforming a solid leads also to the emission of infrared photons.
- Deflecting electrons in a magnetic field (Lorentz force) also leads to photon emission, this time of lower and lower frequency in relation to the slowing down (moving in a spiral) electron.
Now let us create a radio wave by the technics I described above. This is impossible. The invention of wave generators and the use of antenna roads were the requirements for the production of radio waves. A lot of electrons are pushed inside the rod. All these accelerated electrons emit photons. But at the end a saturation of electrons (or of the absence of electron) occurs. The wave generator is responsible for the periodical change in the direction of flow of the electrons. As a result you get a periodical emission of photons which is the carrier frequency on which one tune the receiver.
Long speech, short story. Radio waves are modulated radiation with photons from infrared to gamma and by this they are technically part of the EM spectrum, but in a strong physical understanding, they should not. In physics this isn’t a point of discussion, but since you asked your question, this answer came into my mind.
The point is, that you can use even e very short rod, much much smaller the calculated wavelength and you get a radio wave. With a terrible efficiency and signal, far away a sine wave. The photons inside the radio wave depend from the accelerations of the electrons on the skin of the rod and in dependence from the power of the wave generator, the material and the shape of the rod, these photons could be from infrared to X-ray. I not recommend to be too close to a radar or a MF broadcast antenna.