Chapter 15: Antennas and Waveguides - Review Notes

This is the summary notes of the important terms and concepts in Chapter 15 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.

CHAPTER 15

ANTENNAS AND WAVEGUIDES

Items	Definitions	Terms
1	A metallic conductor system capable of radiating and capturing electromagnetic energy	Antenna
2	Couples energy from a transmitter to an antenna or from antenna to a receiver	Transmission Lines
3	A special type of transmission line that consists of a conducting metallic tube through which high-frequency electromagnetic energy is propagated.	Waveguide
4	Electrical energy that has escaped into free space in the form of transverse electromagnetic waves	Radio Waves
5	The plane parallel to the mutually perpendicular lines of the electric and magnetic fields.	Wavefront
6	The ratio of radiated to reflected energy.	Radiation Efficiency
7	Antenna wherein two conductors are spread out in a straight line to a total length of one quarter wavelength.	Quarter Wave Antenna
8	Another name for quarter wave antenna.	Vertical Monopole or Marconi
9	A half-wave dipole.	Hertz Antenna
10	A special coupling device that can be used to direct the transmit and receive signals and provide the necessary isolation.	Diplexer
11	A polar diagram or graph representing field strengths or power densities at various angular positions relative to an antenna.	Radiation Pattern
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.	Major Lobes
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.	Minor Lobes
18	Lobes in a direction exactly opposite the front lobe	Back 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.	Line of Shoot or Point of Shoot
22	Antenna that radiates energy equally in all directions.	Omni-directional Antenna
23	Radiates power at a constant rate uniformly in all directions.	Isotropic Radiator
24	The direction in which an antenna is always pointing.	Maximum Radiation
25	It is defined as an equivalent transmits 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.	Effective Radiated Power (ERP) or (EIRP)
27	The power density in space and the actual power that a receive antenna produces at its output terminals.	Captured Power Density
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.	Directly Proportional
31	It refers to the orientation of the electric field radiated from the antenna.	Polarization
32	The angular separation between the two half-power (-3dB) points on the major lobe of an antenna's plane radiation pattern.	Antenna Beamwidth
33	The frequency range over which antenna operation is satisfactory.	Antenna Bandwidth
34	Another name for antenna input terminal	Feedpoint
35	The feedpoint presents an ac load to the transmission line.	Antenna Input Impedance
36	The simplest type of antenna. Another names for elementary doublet Ø  Short Dipole, Ø  Elementary Dipole Ø  Hertzian Dipole	Elementary Doublet
37	Any dipole that is less than one-tenth wavelength	Electrically Short
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.	Must be close to the Ground
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.	5 Ohms
44	An individual radiator, such as a half or quarter wave dipole. Two types of antenna elements Ø  Driven Ø  Parasitic Two Elements of a single antenna Ø  Two Wire Ø  Folded Dipole	Antenna Element
45	Its purpose is to increase the directivity and concentrate the radiated power within a smaller geographic area.	Array
46	Elements that are directly connected to the transmission line and receive power from the source.	Driven
47	Elements are not connected to the transmission line; they receive energy only through mutual induction with a driven element.	Parasitic
48	A parasitic element that is shorter that its associated driven element.	Director
49	Radiation pattern depends on the relative phase of feeds.	Driven
50	The simplest type of antenna arrays.	Broadside Arrays
51	A widely used antenna commonly uses a folded dipole as the driven element and named after two Japanese scientists.	Yagi Uda
52	Typical directivity of a yagi-uda antenna.	7 dB and 9 dB
53	Formed by placing two dipoles at right angles to each other.	Turnstile Antenna
54	A class of frequency-independent antennas.	Log Periodic
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: Ø  Normal Ø  Axial	Helical Antenna
56	Antennas having half power beamwidths on the order of 1º or less. Three important characteristics: Ø  Front-to Back Ratio, Ø  Side-to-Side Coupling Ø  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 Ø Parabolic Reflector Ø Feed Mechanism	Parabolic Reflector Antenna
58	The effective area in a receiving parabolic antenna and is always less than the actual mouth area.	Capture Area

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