Radio Wave Properties and Interference

A radio wave is an energy wave where an electrical field is perpendicular to a magnetic field.

The speed of radio waves is 300 million meters per second in a vacuum.

The plane of polarization of an electromagnetic wave is the plane of the electrical field.

The distance between two consecutive peaks or troughs of a wave.

The number of wave cycles that pass a fixed point per unit time.

Low Frequency radio waves, commonly used for long-distance communication, e.g., transmitting signals over a wide area.

Medium Frequency radio waves, used for medium-range terrestrial communication.

Very High Frequency, Ultra High Frequency, and Super High Frequency. VHF and UHF are used for TV and short-range communication, SHF for shorter range, higher-frequency applications.

Unwanted electrical signals that reduce communication clarity and navigation accuracy.

A measure of the strength of the desired signal compared to the amount of interference.

Alternating strengthening and weakening of a received signal due to signals arriving out of phase.

Increasing power increases transmission range, but by the square of the distance.

The ability of a receiver to process weak signals, increasing effective range.

Radio signal strength decreases with the square of the distance from the transmitter.

Frequencies where static interference from weather, human, and geological sources is less significant.

Layer in the Earth's atmosphere where radio waves can collect interference at all frequencies.

A measure of how much power is concentrated in a narrow beam.

Different ways radio waves travel through the atmosphere.

Radio waves that travel along the Earth's surface.

Radio waves that bounce off the ionosphere.

Radio waves that travel in a straight line.

Radio wave propagation affected by the ionosphere.

Radio wave propagation not affected by the ionosphere.

The bending of radio waves around obstacles.

Radio waves traveling through the ionosphere, bouncing off its layers, and reaching long distances.

Radio waves traveling directly along the Earth's surface.

A layer in Earth's ionosphere that reflects radio waves, especially at low frequencies.

A layer in Earth's ionosphere that reflects radio waves, especially at high frequencies.

Radio waves bouncing multiple times between the ionosphere and Earth's surface, extending the communication range.

The longest distance a sky wave can travel before the signal weakens too much.

Ideal for short-range communication over land areas.

Used for long-range communication over ocean and remote areas due to the limitations of VHF.

The angle at which a radio wave must enter the ionosphere to be refracted back to Earth. This angle depends on the frequency and ionization level.

The distance from the transmitter to the point where the first returning sky wave appears at the surface.

The area between the transmitter and the point where the first returning sky wave appears. No signal is detected in this area.

When a radio wave refracts back towards the normal as it exits the ionosphere. This occurs when the wave is at the critical angle.

Refraction of radio waves up to 2 MHz occurring in the E-layer of the ionosphere. Lower frequency, lower height.

Refraction of radio waves between 2 - 50 MHz occurring in the F-layers of the ionosphere. Higher frequency, higher height.

The E- and F-layers of the ionosphere refract radio waves at different heights depending on frequency. This influences signal reach and communication range.

A process where two frequencies (RF and AF) are combined, producing new frequencies at their sum and difference. This results in the original radio frequency remaining unchanged, while the audio frequency is split into two sidebands.

Frequencies created when a radio frequency (RF) is modulated by an audio frequency (AF). These sidebands extend upwards (USB) and downwards (LSB) from the original RF, carrying the information from the AF.

The higher frequency created by the heterodyning process, extending upwards from the original RF.

The lower frequency created by the heterodyning process, extending downwards from the original RF.

The range of frequencies used in a modulated signal. It equals twice the audio frequency used for modulation.

In AM modulation, the power of the audio frequency is divided equally between the two sidebands. Only one third of the total signal power carries information.

The information (audio signal) from the original audio frequency is contained within both the upper and lower sidebands.

Traditional AM modulation is not very efficient as only one third of the total signal power carries the information.