an invisible force field created by a magnet, generated around a conductor when current flows through it

(a)  

The SI unit for magnetic field strength
is

(a)  

(a)   is also an invisible force field produced by the presence of a potential difference between two conductors

(a)   is the dielectric constant of the material
between the two conductors.

The (a)   lines are fully contained by the outer shield of the cable, so none are radiated.

The direction of the (a)   reverses once per cycle

The inner and outer (a)   cancel one another, and so a coaxial cable does not radiate any electromagnetic energy.

Any conducting surface looks like a mirror to a radio wave, and so radio waves are
(a)   by any conducting surface they encounter along a propagation path.

Radio wave reflection follows the principles of (a)   . That is, the angle of reflection is equal to the angle of incidence,

The angel of (a)   is the angle between the incoming line of the wave and a perpendicular line to the reflecting surface.

The angle of (a)   is the angle between the reflected wave and the perpendicular line.

The reflection process (a)   the polarity of a wave. This is equivalent to a 180°
phase shift

(a)   is the bending of a wave due to the physical makeup of the medium through
which the wave passes

The degree of bending depends on the (a)   of a medium n, obtained by dividing the speed of a light (or radio) wave c in a vacuum and the speed of a light (or radio) wave v in the medium that causes the wave to be bent.

If an obstacle appears between a transmitter and receiver, some of the signal is blocked,
creating what is known as a (a)  

the bending of waves around an object

(a)  

Diffraction is explained by what is known as (a)   , based on the assumption that all electromagnetic waves, light as well as radio waves, radiate as spherical wave fronts from a source

the phenomenon where electromagnetic waves (like light or radio waves) bend around the sharp edge of an opaque obstruction and propagate into the geometric shadow area

(a)  

Decrease in signal Strength with respect to the distance traveled. Electromagnetic waves are ______(ed) as they travel outward from their source and this_______ is proportional to the square of the distance travelled.

(a)  

The source of energy of the electromagnetic waves is transferred to the atoms and molecules of space. If humidity is increased or if there is rain or snow, then (a)   is greatly increased.

Occurs when two waves combine in such a way that the system performance was degraded (collision). This happens very often in high-frequency sky-wave propagation and microwave space-wave propagation

(a)  

Surface or (a)   leave an antenna and remain close to the earth, it follow the curvature of the earth and can, therefore, travel at distances beyond the horizon

Ground waves must have (a)   polarization to be propagated from an
antenna.

(a)   polarized waves are absorbed or shorted by the earth.

Ground wave propagation is strongest at the _____ and _____frequency
ranges

(a)  

The better the conductivity, the l____ the attenuation and the ______ the
distance the waves can travel.

(a)  

(a)   signals are radiated by the antenna into the upper atmosphere, where they are bent back to earth.

This bending of the signal is caused by refraction in a region of the upper atmosphere known as the
(a)  

The D and E layers, the farthest from the sun, are (a)   ionized. They exist only during daylight hours, during which they tend to absorb radio signals in the medium-frequency range from 300 kHz to
3 MHz

The F1 and F2 layers, the closest to the sun, are the most (a)   ionized and have the greatest effect on radio signals.

The (a)   layers exist during both day and
night.

The direction of bending depends on the angle at which the radio wave
enters the ionosphere and the different degrees of ionization of the layers,
as determined by (a)  

The third method of radio signal propagation is by direct waves, or
(a)  

A (a)   travels in a straight line directly from the transmitting antenna to the receiving antenna.

Direct wave/Space Wave radio signaling is often referred to as (a)  
communication.

A (a)   is a combination of a receiver and a transmitter operating on separate
frequencies

The “ultimate” repeater is,

(a)  

The receiver- transmitter combination within the satellite is known as a


(a)  

Power level is (a)   if the antenna has gain because of improved directivity.

As a signal leaves an antenna, it immediately begins to become (a)  

(a)   wave signals are greatly attenuated by objects on the earth, which
block the signals and reduce their level at the receiver.

(a)   wave propagation, the ionospheric conditions and the number of hops
determine the signal level at the receiver, with each hop further reducing the
signal level.

(a)   wave signals are simply absorbed and attenuated by objects in their
path such as trees or walls.

(a)   is the variation in signal amplitude at the receiver caused by the characteristics of the signal path and changes in it. It causes the received signal to vary in amplitude, typically making it
smaller

(a)   is also caused by objects coming between the transmitter and receiver.

One of the worst sources of fading is (a)   interference, which is sometimes called
Rayleigh fading.v

One of the worst sources of fading is multipath interference, which is sometimes called
(a)   fading.

When the transmitter is in a car, plane, or other vehicle, rapid movement toward or away
from the receiver introduces a signal frequency change called a (a)  

Fading can also be minimized by using what is called a (a)   . It uses multiple transmitters, receivers, or antennas to mitigate the problems caused by multipath signals.

With (a)   diversity, two separate sets of transmitters and receivers operating
on different frequencies are used to transmit the same information simultaneously

(a)   diversity system uses two receiver antennas spaced as far apart as possible to receive
the signals.