I just ask. If I look at a glowing something with an antenna, I will not get any signal, I think. This is, I believe, because the radiation comes as photons, more or less, because it is a result of thermal motion. Each of the myriads of electrons in the glowing material moves independently and each emits the energy as a photon. The antennas can not see photons. They can see only electromagnetic waves.
To get electromagnetic waves, I must have an ordered motion, some oscillating current of some kind. In the optical region of frequencies we have lasers which also produce coherent radiation, i.e. something looking more like a wave than as a stream of individual photons, as R. J. Glauber
got a 2005 Nobel prize for explaining in the sixties. The laser light I cannot detect by antenna, because that does not work. But many atomic processes due to lasers confirm this picture, the intense pulses are not just streams of photons. They are coherent. This is what I work with.
Having this is mind, I then wonder. How is this with the cosmic microwave background