RADIO WAVE PROPAGATION

Question 1

This wave is composed of two components, the magnetic field (H) and the electric field (E).

Answer 1

TRANSVERSE ELECTROMAGNETIC WAVE (TEM)

Question 2

Each field varies sinusoidally in time at a fixed point in space

Answer 2

TRANSVERSE ELECTROMAGNETIC WAVE (TEM)

Question 3

is transverse in nature and hence its direction of propagation is perpendicular to its two components

Answer 3

TRANSVERSE ELECTROMAGNETIC WAVE (TEM)

Question 4

The velocity of the TEM waves depends on the medium where it travels. It travels fastest at free space at approximately 3x108 m/s.

Answer 4

WAVE VELOCITY

Question 5

The number of cycles an electromagnetic wave completes in one second, expressed in Hz

Answer 5

FREQUENCY (F)

Question 6

The distance that the radio wave travels in the time of one cycle, expressed in m

Answer 6

WAVELENGTH

Question 7

This refers to the physical orientation of the E field on space

Answer 7

POLARIZATION

Question 8

TYPES OF POLARIZATION

Answer 8

LINEAR POLARIZATION
CIRCULAR POLARIZATION
ELLIPTICAL POLARIZATION
RANDOM POLARIZATION

Question 9

E field has a particular direction in space either vertical or horizontal

Answer 9

LINEAR POLARIZATION

Question 10

E field is rotating about the axis of the direction of propagation

Answer 10

CIRCULAR POLARIZATION

Question 11

Similar to circular polarization except that E and H are unequal

Answer 11

ELLIPTICAL POLARIZATION

Question 12

Polarization with no fixed pattern

Answer 12

RANDOM POLARIZATION

Question 13

A line drawn along the direction of propagation of the wave

Answer 13

RAY

Question 14

A surface of constant phase of the wave

Answer 14

WAVEFRONT

Question 15

The definite ratio between the electric field intensity and magnetic field intensity

Answer 15

INTRINSIC CHARACTERISTIC IMPEDANCE (ZO)

Question 16

For free space: 120n or approximately 377 ohms

Answer 16

INTRINSIC CHARACTERISTIC IMPEDANCE (ZO)

Question 17

This refers to the rate at which energy flows through a unit area of surface in space

Answer 17

POWER DENSITY (PD)

Question 18

This states that power density is inversely proportional to the square of the distance from the source

Answer 18

INVERSE SQUARE LAW

Question 19

The bending of radio wave as it passes from one medium to another at an angle due to the changing of direction and speed of an EM wave as it passes from one medium to another

Answer 19

REFRACTION

Question 20

The ratio of the speed of radio wave in free space to speed of radiowave in a specific medium

Answer 20

Index of refraction (n)

Question 21

This is dependent on the material and the number of electrons in a given medium

Answer 21

Index of refraction (n)

Question 22

Occurs when incident wave strikes the boundary of two media aand some or all the incident power does not enter the second material.

Answer 22

REFLECTION

Question 23

Reflection at irregular and rough surfaces

Answer 23

Diffuse Reflection

Question 24

Also called mirror like reflection this refers to the reflection at very smooth surface

Answer 24

Specular Reflection

Question 25

This states that a semirough surface will reflect as it if were smooth surface if the cosine of the angle of incidence is grtear than λ/8d

Answer 25

Rayleigh criterion

Question 26

This refer to the redistribution of energy within wavefront when it passes near the the edge of an opaque object while allowing seconday waves to sneak around the corner of an obstacle.

Answer 26

DIFFRACTION

Question 27

This states that any point on a wavefront of light may be regarded as the source of secondary waves.

Answer 27

Huygen’s Principle

Question 28

this occur when two waves that left one source and travelled by different paths arrive at a point

Answer 28

INTERFERENCE

Question 29

Modes of Wave Propagation

Answer 29

Ground/surface wave propagation Sky wave propagation Space wave/LOS propagation

Question 30

is an Earth-guided electromagnetic wave that travels over the surface of the Earth

Answer 30

Ground Wave Propagation

Question 31

It follows the contour of the Earth and given enough transmit power, it can communicate between any two locations in the world.

Answer 31

Ground Wave Propagation

Question 32

It can be used with frequencies up to 2 MHz and must be vertically polarized.

Answer 32

Ground Wave Propagation

Question 33

As the ground wave move further away from the source, it can experience tilting and eventually disappear

Answer 33

Ground Wave Propagation

Question 34

Effective on VLF, LF and MF frequency bands and commonly used in AM radio broadcasting.

Answer 34

Ground Wave Propagation

Question 35

Also called ionospheric propagation

Answer 35

Sky Wave Propagation

Question 36

strikes the ionosphere and is reflected back to the ground

Answer 36

Sky Wave Propagation

Question 37

Employed on the HF band

Answer 37

Sky Wave Propagation

Question 38

The highest frequency that will be returned down to Earth when beamed vertically upward

Answer 38

Critical frequency

Question 39

Measured using an ionosode in a process called ionospheric sounding

Answer 39

Critical frequency

Question 40

The highest frequency that will be returned down to Earth at a given distance when beamed at specific angle other than the normal.

Answer 40

Maximum Usable Frequency (MUF)

Question 41

The frequency that gives the most consistent communication

Answer 41

Optimum Working Frequency (OWF)

Question 42

It is chosen to avoid irregularities of the ionosphere

Answer 42

Optimum Working Frequency (OWF)

Question 43

It is chosen to be 15% lower than the MUF

Answer 43

Optimum Working Frequency (OWF)

Question 44

It is the apparent height of the ionized layer and measured by sending a wave vertically to the layer and measuring the time it takes to come back at the receiver.

Answer 44

Virtual height

Question 45

Measured using an ionosode.

Answer 45

Virtual height

Question 46

is the area that is between the outer limit of the ground wave range and the inner edge of the energy of return from the ionosphere.

Answer 46

Skip zone

Question 47

is the distance between the originating site and the beginning of the atmospheric return.

Answer 47

Skip distance

Question 48

Also called the Line -of-Sight (LOS) propagation

Answer 48

Space Wave Propagation

Question 49

Employed on VHF and UHF

Answer 49

Space Wave Propagation

Question 50

This refers to the boundary line beyond which direct rays of the radio waves cannot be propagated over the Earth’s surface.

Answer 50

Radio Horizon

Question 51

This is usually 4/3 greater than the optical horizon.

Answer 51

Radio Horizon