Chapter 15: Personality Humanistic Perspective • Abraham Maslow and Carl Rogers Abraham Maslow’s Self-Actualizing Person • Self-actualization – according to Maslow, the ultimate psychological need ...
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BOOK REVIEW IN COMMUNICATIONS
CHAPTER 15 #
Electronic Communications System By Wayne Tomasi
ANTENNAS AND WAVEGUIDES
DEFINITIONS
1)
A metallic conductor system capable of radiating r adiating and capturing electromagnetic energy
2)
Couples energy from a transmitter to an antenna or from antenna to a receiver
3)
A special type of transmission line li ne that consists of a conduc conductin ting g metall metallic ic tube tube throu through gh whic which h high-f high-freq requen uen electromagnetic energy is propagated.
4)
Electrical energy that has escaped into free space in the form of transverse electromagnetic waves
5)
The plane parallel to the mutually perpendicular lines of the electric and magnetic fields.
6)
The ratio of radiated to reflected energy.
7)
Antenna wherein two conductors are spread out in in a straight line to a total length of one quarter wavelength.
8)
Another name for quarter wave antenna.
9)
A half-wave dipole.
10)
A special coupling device that can be used to direct the transmit and receive signals and provide the necessary isolation.
Prepared By : MA. ELAINE L. CORTEZ
TERMS
Antenna
Transmission Lines
Waveguide
Radio Waves
Wavefront
Radiation Efficiency
Quarter Wave Antenna
Vertical Monopole or Marconi Hertz Antenna
Diplexer
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BOOK REVIEW IN COMMUNICATIONS
Electronic Communications System By Wayne Tomasi
11)
A polar diagram or graph representing field strengths or power densities at various angular positions relative to an antenna.
12)
Radiation pattern plotted in terms of electric field strength or power density.
Absolute Radiation Pattern
13)
Radiation pattern plots field strength or power density with respect to the value at a reference
Relative Radiation
14)
The primary beam of an antenna.
15)
The major lobes that propagates and receive the most energy.
Front Lobe
16)
Lobes adjacent to the front lobe.
Side lobes
17)
The secondary beam of an antenna.
18)
Lobes in a direction exactly opposite the front lobe
19)
The ratio of the front lobe power to the back lobe power.
Front to Back Ratio
20)
The ratio of the front lobe to a side lobe.
Front to Side Ratio
21)
The line bisecting the major lobe, or pointing from the center of the antenna in the direction of maximum radiation.
22)
Antenna that radiates energy equally in all directions.
Prepared By : MA. ELAINE L. CORTEZ
Radiation Pattern
Major Lobes
Minor Lobes
Back Lobe
Line of Shoot or Point of Shoot
Omni-directional Antenna
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BOOK REVIEW IN COMMUNICATIONS
Electronic Communications System By Wayne Tomasi
23)
Radiates power at a constant rate uniformly in all directions.
24)
The direction in which an antenna is always pointing.
Maximum Radiation
25)
It is defined as an equivalent transmit power. It stands for Effective Isotropic Radiated Power.
EIRP
26)
The equivalent power that an isotropic antenna would have to radiate to achieve the same power density in the chosen direction at a given point as another antenna.
27)
The power density in space and the actual power that a receive antenna produces at its output terminals.
28)
It describe the reception properties of an antenna
Capture Area
29)
Another name for capture area.
Effective Area
30)
The relationship of captured power to the received power density and the effective capture area of the received antenna.
31)
It refers to the orientation of the electric field radiated from the antenna.
32)
The angular separation between the two half-power (-3dB) points on the major lobe of an antenna's plane radiation pattern.
33)
The frequency range over which antenna operation is satisfactory.
Prepared By : MA. ELAINE L. CORTEZ
Isotropic Radiator
Effective Radiated Power (ERP) or (EIRP)
Captured Power Density
Directly Proportional
Polarization
Antenna Beamwidth
Antenna Bandwidth
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BOOK REVIEW IN COMMUNICATIONS
Electronic Communications System By Wayne Tomasi
34)
Another name for antenna input terminal
35)
The feedpoint presents an ac load to the transmission line.
36)
The simplest type of antenna. Another names for elementary doublet Short Dipole, Elementary Dipole Hertzian Dipole
Feedpoint
Antenna Input Impedance
Elementary Doublet
37)
Any dipole that is less than one-tenth wavelength
38)
Hertz antenna is name after him and he was the first to demonstrate the existence of electromagnetic waves.
Heinrich Hertz
39)
A single pole antenna one quarter wavelength long, mounted vertically with the lower end either connected directly to ground or grounded through the antenna coupling network.
Marconi Antenna
40)
Main disadvantage of Marconi Antenna.
41)
A technique use to increase the electrical length of an antenna
Loading
42)
A coil added in series with a dipole antenna which effectively increases antenna's electrical length.
Loading Coil
43)
A loading coil approximately increases the radiation resistance of the antenna.
Prepared By : MA. ELAINE L. CORTEZ
Electrically Short
Must be close to the Ground
5 Ohms
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BOOK REVIEW IN COMMUNICATIONS
Electronic Communications System By Wayne Tomasi
An individual radiator, such as a half or quarter wave dipole. Two types of antenna elements Driven Parasitic Two Elements of a single antenna Two Wire Folded Dipole
44)
Antenna Element
45)
Its purpose is to increase the directivity and concentrate the radiated power within a smaller geographic area.
46)
Elements that are directly connected to the transmission line and receive power from the source.
47)
48)
Elements are not connected to the transmission line; they receive energy only through mutual induction wit a driven element.
A parasitic element that is shorter that its associated driven element.
49)
Radiation pattern depends on the relative phase of feeds.
50)
The simplest type of antenna arrays.
51)
A widely used antenna commonly uses a folded dipole as the driven element and named after two Japanese scientists.
Prepared By : MA. ELAINE L. CORTEZ
Array
Driven
Parasitic
Director
Driven
Broadside Arrays
Yagi Uda
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BOOK REVIEW IN COMMUNICATIONS
Electronic Communications System By Wayne Tomasi
52)
Typical directivity of a yagi-uda antenna.
53)
Formed by placing two dipoles at right angles to each other.
54)
A class of frequency-independent antennas.
55)
A broadband VHF or UHF antenna that is ideally suited for applications for which radiating circular rather than horizontal or vertical polarized electromagnetic waves are required. Modes of propagation: Normal Axial
7 dB and 9 dB
Turnstile Antenna
Log Periodic
Helical Antenna
56)
Antennas having half power beamwidths on the order of 1o or less. Three important characteristics: Front-to Back Ratio, Side-toSide Coupling Back-to-Back Coupling
Microwave Antenna
57)
Antenna that provides extremely high gain and directivity and are very popular for microwave and satellite communications link. Two main part Parabolic Reflector Feed Mechanism
58)
The effective area in a receiving parabolic antenna and is always less than the actual mouth area.
