The unguided media is the wireless media. It simply transports electromagnetic waves without using any physical conductor. Signals are normally broadcast through the air and thus are available to any one who has the device capable of receiving them. Unguided signals can be travelled from source to the destination in several ways. These ways include ground propagation, sky propagation and line of sight propagation.
In the ground propagation, the radio waves travel through the lowest portion of atmosphere, hugging the earth. These very low frequency signals emanate in all directions from transmitting antenna and follow the curvature of planet. In sky propagation, the higher frequency radio waves radiate upward into the ionosphere, where they are reflected back to the earth.
In the line of sight propagation, very high frequency signals are transmitted in straight lines directly from the antenna to antenna. Antennas must be directional, facing each other and either tall enough or close enough together not to be affected by curvature of the earth. The line of sight propagation is tricky as radio transmissions can not be completely focused. Infra red waves are used for the short range communication such as those between a PC and the peripheral device.
In the ground propagation, the radio waves travel through the lowest portion of atmosphere, hugging the earth. These very low frequency signals emanate in all directions from transmitting antenna and follow the curvature of planet. In sky propagation, the higher frequency radio waves radiate upward into the ionosphere, where they are reflected back to the earth.
In the line of sight propagation, very high frequency signals are transmitted in straight lines directly from the antenna to antenna. Antennas must be directional, facing each other and either tall enough or close enough together not to be affected by curvature of the earth. The line of sight propagation is tricky as radio transmissions can not be completely focused. Infra red waves are used for the short range communication such as those between a PC and the peripheral device.
