absorb radio waves
This is knownas the skip zone, or dead zone. This is particularly pronounced forhigh-frequency signals where ground waves fade away quicklyand skip distances may be a thousand miles or more. Summary For hams, an understanding of radio propagation is practicaland fascinating. Two essential components for global communication are a transmitter and a receiver. 1  Transmitting Antenna (transmitter) - A radio signal from a device travels to the transmitting antenna. 2  Receiving Antenna (receiver) - A receiving antenna picks up the radio wave. In effect, the layerappears to have “reflected” the signal.These “reflections” are affected by frequency and the radiowave’s angle of incidence. As frequency increases the amount ofrefraction decreases until a frequency is reached where the signalspass through the layer and on to the next. Radio waves are electromagnetic waves and travel at the speed of light which is 186, 280 miles per second (983,558,400 feet per second). The voltage in a radio wave alternates back and forth between plus and minus many times per second and we call this the frequency of the radio wave in cycles per second. These waves, called radio waves, are a type of electromagnetic radiation. Radio waves are not harmful; in fact they are an extremely useful method of global communication. Being a simple form of electromagnetic radiation, they move in waves from place to place with limited change. When a radio wave hits a material some of the power is reflected at the surface and some of the power is transmitted into and possibly through the material. 1  If the material is metal, almost all of the radio power is reflected within the first few atoms of the material. Electromagnetic radiation is transmitted in waves or particles at different wavelengths and frequencies. This broad range of wavelengths is known as the electromagnetic (EM) spectrum. The spectrum is generally divided into seven regions in order of decreasing wavelength and increasing energy and frequency. The E and F Layers As with the D layer, when signals enter the E and F layers theycause free electrons to vibrate. Here the air density is much lowerand there are fewer collisions. As a result, much less energy is lostand these layers affect radio signals in a different way. The common designations are radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma-rays. Radio waves have the longest wavelengths in the EM spectrum, according to NASA, ranging from about 1 millimeter (0.04 inches) to more than 100 kilometers (62 miles). They also have the lowest frequencies, from about 3,000 cycles per second or 3 kilohertz (kHz) up to about 300 billion hertz, or 300 gigahertz (GHz). Radio waves are a type of electromagnetic radiation, as are microwaves, infrared radiation, X-rays and gamma-rays.
A type of electromagnetic radiation.