While electromagnetic radiation, including radio waves at 7 MHz, can be described as being made up of photons, it's important to understand that the concept of entanglement is typically associated with the realm of quantum mechanics rather than classical electromagnetic waves. Photons are quantum particles, and their entanglement is a phenomenon that occurs at the quantum level.
Entanglement refers to a special correlation between quantum particles, where the state of one particle becomes dependent on the state of another, even when they are physically separated. However, in the case of classical electromagnetic waves, the concept of entanglement is not applicable because classical waves are described by continuous fields, not discrete particles.
Regarding the size of a photon at 7 MHz, photons themselves do not have a size in the classical sense. They are elementary particles that are considered point-like entities. The energy of a photon is directly related to its frequency. In the case of a radio wave at 7 MHz, the energy of individual photons is relatively low compared to higher-frequency electromagnetic radiation such as visible light or X-rays. However, determining the precise "size" of a photon is not a meaningful concept within the framework of quantum mechanics.
To summarize, classical electromagnetic waves, such as a 7 MHz radio transmission, are not typically associated with photon entanglement. Photons and their entanglement are concepts that primarily apply to the quantum realm.