A primary difference between photons would be:
- Absorption/emission events, Hz, and eV associated with sunlight photons
- Optical photons mostly travel in uG vacuum with less gas
- RF Photons travel through the absorption medium of N2/O2 in much higher densities
- RF Photons frequency modulation with carrier waves to encode information
Radio waves (3 kHz to 30 GHz) have lower frequencies of all types of EMR, and their photons carry less amount of energy. Interactions with matter depends on wavelength and energy density and create EM charges with absorption or emission.
Microwaves (30-300GHz) don’t bend (diffract) around hills or mountains, they don’t reflect back from the ionosphere (Micu, 20230). With higher frequency, microwaves penetrate more than RF waves transmit data over wireless networks, to communicate with satellites and spacecraft.
It suggests you need a lot more to carry the same energy, and just one RF photon can't do much by itself, such as cause a significant electron transition or break or excite an atomic or molecular bond.
It doesn't say anything about how big they are. RF photons can be very large - such as wide as an antenna and as long as the time the beam is coherent (times the speed of light).
It is interesting to note that ambient (~300K) thermal photons ~10um lambda are in between radio and light. Such things come to play e.g. when comparing fundmental limits on signal/noise perfomance of microwave link vs optical link. Optical link might be limitedby photon statistics while microwave link is limited by thermal noise (considering some idealistic cases of course).
Also, one should note that for reativistic observer the photon energy can be any times higher or lower.
Yes, if you are travelling fast enough towards an RF photon it can be Doppler shifted to an optical photon - or a gamma ray.
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