(1) or (2) is made up of both electric

and magnetic fields.

(a)  

Whenever voltage is applied to the antenna, an (1) is set

up. At the same time, this voltage causes current to flow in the antenna, producing a (2).

(a)  

The electric and magnetic fields are at (1) angles to each other

(a)  

is an invisible force field created by a magnet

(a)  

component that is a type of electromagnet

(a)  

Where is a magnetic field generated

when current flows through a conductor?

(a)  

The strength and direction of the magnetic field

depend upon the (1) and (2) of the (3)

(a)  

invisible force field produced by the presence

of a potential difference between two conductors.

(a)  

The SI unit for electric field strength is (1)

(a)  

the dielectric constant of the material between the two conductors

(a)  

Note also that the direction of current flow in one wire is always (1) that

in the other wire.

(a)  

(1), unlike antennas, do not radiate radio signals efficiently.

(a)  

(1) is the preferred transmission line for most applications.

(a)  

acts as the interface between a transmitter or receiver and

free space.

(a)  

It either radiates or senses an electromagnetic field

(a)  

The radiation from a transmission line can be greatly improved by bending the

transmission line conductors so that they are at a (1) to the transmission line

(a)  

Optimum radiation occurs if the segment of transmission wire converted to an

antenna is (1) long at the operating frequency

(a)  

is a conductor or pair of conductors to which is applied the ac

voltage at the desired frequency

(a)  

In most practical applications,

the antenna is (1) from the transmitter and receiver, and a transmission line

is used to transfer the energy between antenna and transmitter or receiver.

(a)  

The (1) creates an electric

field and the (2)creates a magnetic field

(a)  

sinusoidally (1) magnetic field produces an electric i eld.

(a)  

The ratio of the electric field strength of a radiated wave

to the magnetic field strength is a constant called (1) or (2)

(a)  

Value of impedance of space

(a)  

The resistive component of an antenna

(a)  

This resistance does not

dissipate power in the form of heat, as in electronic circuits

(a)  

Antenna dissipates power as

(a)  

The electric and magnetic fields produced by the

antenna are at right angles to each other, and both are (1) to the direction of propagation of the wave.

(a)  

(1) and (2) of the magnetic

and electric fields vary in a sinusoidal manner depending upon the frequency of

the signal being radiated.

(a)  

Antennas actually produce two sets of fields: (1) and (2)

(a)  

the region directly around the antenna

where the electric and magnetic fields are distinct

(a)  

These fields are not the radio wave,

but they do indeed contain any information transmitted.

(a)  

Near fields weaken with the

distance from the antenna, approximately by the (1) of the distance.

(a)  

The

near field is also referred to as the (1).

(a)  

The far field that is approximately (1) wavelengths from the antenna is the radio

wave with the composite electric and magnetic i elds.

(a)  

Near field's strength also diminishes

with distance but only at the (1) of the distance.

(a)  

The far field is also called the

(1)

(a)  

Most wireless applications use the (1) wave

(a)  

The near field is rarely used,

but applications such as (1) and

(2) make use of the near field.

(a)  

refers to the orientation of magnetic and electric fields

with respect to the earth.

(a)  

If an electric field is parallel to the earth, the electromagnetic

wave is said to be (1)

(a)  

if the electric field is (1) to the

earth, the wave is vertically polarized.

(a)  

Polarization in which the electric and magnetic

fields rotate as they leave the antenna.

(a)  

Two types of circular polarization: (1) polarization and (2) polarization

(a)  

The electric field and the

accompanying magnetic field rotate at the (1)

(a)  

Looking from the transmitter to the distant

receiver, RHCP gives a (1) rotation to the electric field and LHCP gives a (2)

rotation.

(a)  

Theoretically, a vertically polarized wave will produce

how many volts in a horizontal antenna and vice versa?

(a)  

(1) means that the characteristics and performance of an

antenna are the same whether the antenna is radiating or intercepting an electromagnetic signal.

(a)  

(1) takes a voltage from the transmitter and converts it to an

electromagnetic signal.

(a)  

(1) has a voltage induced into it by the electromagnetic

signal that passes across it.

(a)  

device that keeps the transmitter energy out of the front end of the receiver

(a)  

a passive device that implements frequency-domain multiplexing

(a)  

It can be a length of wire, a metal rod, or a piece of tubing.

(a)  

Length of most antennas: (1) and (2)

(a)  

All the most common types of antennas used in the communication industry are based on a basic (1)

(a)  

This antenna is also formally known as the Hertz antenna

(a)  

Also called doublet

(a)  

is two pieces of wire, rod, or tubing that are one-quarter wavelength long at the

operating resonant frequency

(a)  

The dipole

has an impedance of (1) ohms at its center, which is the (2).

(a)  

(1) varies depending on the conductor thickness, the ratio of diameter to length, and the proximity of the dipole to

other objects, especially the earth.

(a)  

As the conductor thickness increases with respect to the length of the antenna, the radiation resistance (1)

(a)  

(1) is a phenomenon caused by any support insulators used

at the ends of the wire antenna and has the effect of adding a capacitance to the end of each wire.

(a)  

At frequencies up to about 30 MHz, end effect shortens the antenna by about

(1) percent.

(a)  

Using (1) materials also shortens the length by

a factor of about 2 or 3 percent.

(a)  

Because the antenna is one -half wavelength at only one

frequency, it acts as a (1) circuit

(a)  

The resistance of the antenna is called the (1)

(a)  

The bandwidth of an antenna is determined by the

(1) and the Q of the antenna according to the familiar relationship: (2)

(a)  

Antenna with high SWR causes (1)

(a)  

A length-to-diameter ratio of 25,000 results in a Q of about (1)

(a)  

A ratio of 1200 results

in a Q of about (1)

(a)  

A typical wire antenna has a bandwidth in the range of (1) to

(2) percent of the resonant frequency

(a)  

The center radiation resistance of a (1) is much higher than the 73 V

usually found when straight-wire or tubing conductors are used.

(a)  

equation of the center impedance of a conical antenna

(a)  

Cones are difi cult to make and expensive, and a popular and equally effective variation of the conical antenna is the (1).

(a)  

The primary advantage of (1) are their tremendous bandwidth

(a)  

This type of mounting also makes it easier to attach the transmission line and route it to the transmitter or receiver.

(a)  

The (1) of any antenna is the

shape of the electromagnetic energy radiated from or received by that antenna

(a)  

The radiation pattern of a half-wave dipole has the shape of a (1)

(a)  

a (1)

is what is known as a directional antenna.

(a)  

the maximum amount of energy is radiated at right angles to the dipole, at (1) and (2) degrees.

(a)  

For optimal signal

transmission, the transmitting and receiving antennas must be (1) to each other

(a)  

The measure of an antenna’s directivity is(1), the angle of the radiation

pattern over which a transmitter’s energy is directed or received

(a)  

a (1) antenna can radiate more power in a given direction and in this “favored” direction, it acts as if it had gain

(a)  

(1) is expressed as the ratio of the effective radiated output power Pout to the input power Pin.

(a)  

The power radiated by an antenna with directivity and therefore gain is called the

(1)

(a)  

The gain of an antenna is usually expressed in reference to either the dipole or an

(1)

(a)  

An (1) is a theoretical point source of electromagnetic

energy.

(a)  

the value of the power gain of a dipole

over an isotropic source: (1) ratio, (2) in decibels

(a)  

a dipole that consists of two parallel conductors connected at the ends with one side open at the center for connection to the transmission line

(a)  

Impedance of folded dipole

(a)  

Another widely used antenna is the one-quarter wavelength vertical antenna, also called a (1) or (2).

(a)  

It is similar in operation to a vertically mounted dipole antenna.

However, it offers major advantages because it is one-half the length of a dipole antenna.

(a)  

antennas which transmit an equal amount of energy in the horizontal

direction, are called (1)

(a)  

One-half of the

pattern is below the surface of the earth. This is called a (1)

(a)  

Once a good electrical connection to the

earth has been made, the earth becomes what is known as a (1).

(a)  

horizontal wires at the base of the antenna are referred to as

(1).

(a)  

The entire ground-plane collection of radials is often referred to as a (1)

(a)  

The impedance of a vertical ground-plane antenna is approximately (1)

(a)  

One way to adjust the antenna’s impedance is to use “(1)” radials

(a)  

The (1) brings the antenna back

into resonance at the desired frequency.

(a)  

(1) increases

the capacitance to surrounding items, bringing the antenna back into resonance

(a)  

are ideal for long-distance communication. such antennas has about a 3-dB gain over a basic dipole and one-quarter wavelength vertical antenna.

(a)  

is widely used in the VHF and UHF bands, where its length is

not a problem. It is very useful in mobile radio installations, where omnidirectional

antennas are necessary but additional gain is needed for reliable transmission over longer distances.

(a)