E9E: Matching: matching antennas to feed lines; power dividers
E9E01:
What system matches a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places spaced a fraction of a wavelength each side of element center?
The delta matching system
The gamma matching system
The omega matching system
The stub matching system
E9E02:
What is the name of an antenna matching system that matches an unbalanced feed line to an antenna by feeding the driven element both at the center of the element and at a fraction of a wavelength to one side of center?
The gamma match
The delta match
The omega match
The stub match
E9E03:
What is the name of the matching system that uses a short perpendicular section of transmission line connected to the feed line near the antenna?
The stub match
The gamma match
The delta match
The omega match
E9E04:
What is the purpose of the series capacitor in a gamma-type antenna matching network?
To compensate for the inductive reactance of the matching network
To provide DC isolation between the feed-line and the antenna
To provide a rejection notch to prevent the radiation of harmonics
To transform the antenna impedance to a higher value
E9E05:
How must the driven element in a 3-element Yagi be tuned to use a hairpin matching system?
The driven element reactance must be capacitive
The driven element reactance must be inductive
The driven element resonance must be lower than the operating frequency
The driven element radiation resistance must be higher than the characteristic impedance of the transmission line
E9E06:
What is the equivalent lumped-constant network for a hairpin matching system on a 3-element Yagi?
L network
Pi network
Pi-L network
Parallel-resonant tank
E9E07:
What parameter best describes the interactions at the load end of a mismatched transmission line?
Reflection coefficient
Characteristic impedance
Velocity factor
Dielectric Constant
E9E08:
Which of the following measurements describes a mismatched transmission line?
An SWR greater than 1:1
An SWR less than 1:1
A reflection coefficient greater than 1
A dielectric constant greater than 1
E9E09:
Which of these matching systems is an effective method of connecting a 50-ohm coaxial cable feed-line to a grounded tower so it can be used as a vertical antenna?
Gamma match
Double-bazooka match
Hairpin match
All of these answers are correct
E9E10:
Which of these choices is an effective way to match an antenna with a 100-ohm terminal impedance to a 50-ohm coaxial cable feed-line?
Insert a 1/4-wavelength piece of 75-ohm coaxial cable transmission line in series between the antenna terminals and the 50-ohm feed cable
Connect a 1/4-wavelength open stub of 300-ohm twin-lead in parallel with the coaxial feed-line where it connects to the antenna
Insert a 1/2 wavelength piece of 300-ohm twin-lead in series between the antenna terminals and the 50-ohm feed cable
Connect 1/2 wavelength shorted stub of 75-ohm cable in parallel with the 50-ohm cable where it attaches to the antenna
E9E11:
What is an effective way of matching a feed-line to a VHF or UHF antenna when the impedances of both the antenna and feed-line are unknown?
Use the "universal stub" matching technique
Use a 50-ohm 1:1 balun between the antenna and feed-line
Connect a series-resonant LC network across the antenna feed terminals
Connect a parallel-resonant LC network across the antenna feed terminals
E9E12:
What is the primary purpose of a "phasing line" when used with an antenna having multiple driven elements?
It ensures that each driven element operates in concert with the others to create the desired antenna pattern
It prevents reflected power from traveling back down the feed-line and causing harmonic radiation from the transmitter
It allows single-band antennas to operate on other bands
It makes sure the antenna has a low-angle radiation pattern
E9E13:
What is the purpose of a "Wilkinson divider"?
It divides power equally among multiple loads while preventing changes in one load from disturbing power flow to the others
It divides the operating frequency of a transmitter signal so it can be used on a lower frequency band
It is used to feed high-impedance antennas from a low-impedance source
It is used to feed low-impedance loads from a high-impedance source
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