Radio Waves Propagation

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What happens to the electric field component of a circular polarized wave as it propagates?

It reverses its direction

It oscillates in a random direction

It remains fixed in one direction

It rotates 360 degrees with respect to the direction of propagation (correct)

What is the main reason for the attenuation of electromagnetic waves in free space?

The spreading of waves with distance from the transmitter (correct)

The reflection of waves by the ionosphere

The presence of obstacles in the path

The absorption of energy by the atmosphere

What is the purpose of a diplexer in a radio transmission system?

To filter out noise

To amplify the signal

To measure the field intensity

To permit two transmitters to operate with a single antenna (correct)

What happens to the power density of electromagnetic waves as they travel outward from their source?

It decreases with distance Signup and view all the answers

What is the term for the highest frequency that will be returned by the ionosphere at a given point?

Maximum Usable Frequency (MUF) Signup and view all the answers

What is the definition of free space in terms of radio wave propagation?

A vacuum that allows radio waves to propagate without any obstruction Signup and view all the answers

What is the term for the deviation of a wave as it passes an obstacle or passes through a small aperture?

Diffraction Signup and view all the answers

What is the unit of frequency above which microwave frequencies are defined?

1 gigahertz (GHz) Signup and view all the answers

What is the main purpose of using circular polarization in satellite wave propagation?

To minimize the effect of Faraday rotation Signup and view all the answers

What type of polarization has the electric field in the vertical direction with respect to the earth horizon?

Vertical polarization Signup and view all the answers

What is the relationship between the angle of incidence and the angle of refraction in reflection?

The angle of incidence is equal to the angle of refraction Signup and view all the answers

What is the phenomenon where a wave passes from one medium to another with different index of refraction?

Refraction Signup and view all the answers

What law relates the angles of incidence and refraction in refraction?

Snell's law Signup and view all the answers

What is the phenomenon where the angle of refraction is greater than 90°, resulting in the wave coming out of the second medium and back into the first?

Total internal reflection Signup and view all the answers

What is the relationship between the dielectric constant and the angle of refraction in refraction?

The angle of refraction increases with decreasing dielectric constant Signup and view all the answers

What is the type of polarization where the electric field rotates in a circular motion?

Circular polarization Signup and view all the answers

What type of wave propagation occurs at frequencies below 3 MHz?

Ground wave propagation Signup and view all the answers

At what frequency do the D and E layers absorb frequencies during the day?

Below 10 MHz Signup and view all the answers

What occurs when a wave is sent vertically toward the ionosphere?

The wave is reflected back to the transmitter Signup and view all the answers

What determines the electric field strength?

The formula ξ = 120 π I he / λd Signup and view all the answers

What is the critical frequency an indication of?

The maximum usable frequency Signup and view all the answers

What is the distance from the ground to the F2 layer?

400 km Signup and view all the answers

What are the three factors that affect the ability of the ionosphere to reflect a signal?

Operating frequency, ion density, and angle of incidence Signup and view all the answers

What type of wave propagation occurs at frequencies above 30 MHz?

Space wave propagation Signup and view all the answers