Radio (RF)- Far field Antenna Theory (help on this please)

Radio waves are a subset of electromagnetic waves that also include light waves, x-rays, gamma. Radio/Light waves travel at the speed of light in a vacuum, and less when through or on any medium.

In a wire (conductor) RF can be thought of as an alternating current (just like the 60hz 120 VAC coming into your house). Free electrons on the surface (skin) of the conductor oscillate back and forth. This oscillation causes acceleration/deceleration of the free electrons. This acc/desl causes an electric field to be created (as well as a magnetic field, but the magnetic field drops off rapidly with distance so is used only for near field communications). The Electric field is used for far field communications.

The Electric field generated around the conductor is actually Photons being released from the conductor. The Electric field needs a conductor that is at least 1/2 the wave length to really release any quantity of Photons, since its tied to the acc/decl of electrons, so either you increase the force (amplifier), or use a larger conductor so you have more free electrons (bigger antenna).

Radio waves (Photons) in space disapate (spread out) at a rate of 4:1 (4 times wide for every time deep).They also move at the speed of light. On earth wierd things happen to deflect, absorb, reflect, disperse, consentrate the radio waves that are nearly impossible to acturately predict. (i.e. mountains, humidity, sun spots) and there speed is always less than the speed of light.

Photons are packets of energy. The amount of energy in a Photon is based solely on frequency. This is why high frequency RF can be used to cook food, and very high freq x-rays can cause cancer and Gamma rays can kill. Its strickly a function of energy. This is also why RF amplifiers are also dangerous, although the energy level of the photon maybe low, the total quantity of photons is high, so the total energy is high.

Photons of particular frequencies have different characteristics as far as how they react around matter. i.e. Most electromagnetic waves will not travel through water any distance except for very low RF frequencies just above human hearing. Certain RF waves will deflect off of certain layers in the atmosphere while others pass through and others are absobed. Cardboard will block light electromagentic waves, but pass RF and x-rays. The reasons are very complicated and deal with energy levels of the photons and energy levels of the matter being struck by the photons and how often the photons strike matter on the way to the final destination (the receiver).

Photons reaching the receivers antenna strike the conductor starting the electrons moving back/forth generating AC on the conductor. Larger conductors will receive more photons, although the receiving antenna does not have to be designed as critical as the transmitting antenna.