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NEW Extra Class Exam Question Pool

effective 7/01/2016 thru 6/29/2020

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2016-E9E: Matching: matching antennas to feed lines; phasing lines; power dividers

2016-E9E01: What system matches a higher 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

2016-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 epsilon match

The stub match

2016-E9E03: What is the name of the matching system that uses a section of transmission line connected in parallel with the feed line at or near the feed point?

The stub match

The gamma match

The delta match

The omega match

2016-E9E04: What is the purpose of the series capacitor in a gamma-type antenna matching network?

To cancel the inductive reactance of the matching network

To provide DC isolation between the feed line and the antenna

To provide a rejection notch that prevents the radiation of harmonics

To transform the antenna impedance to a higher value

2016-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

2016-E9E06: What is the equivalent lumped-constant network for a hairpin matching system of a 3-element Yagi?

A shunt inductor



A series capacitor

2016-E9E07: What term best describes the interactions at the load end of a mismatched transmission line?

Reflection coefficient

Characteristic impedance

Velocity factor

Dielectric constant

2016-E9E08: Which of the following measurements is characteristic of 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

2016-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 choices are correct

2016-E9E10: Which of these choices is an effective way to match an antenna with a 100 ohm feed point 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

2016-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

2016-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

2016-E9E13: What is a use for a Wilkinson divider?

It is used to divide power equally between two 50 ohm loads while maintaining 50 ohm input impedance

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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Previous group:
2016-E9D: Directional antennas: gain; Yagi Antennas; losses; SWR bandwidth; antenna efficiency; shortened and mobile antennas; RF Grounding
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2016-E9F: Transmission lines: characteristics of open and shorted feed lines; 1/8 wavelength; 1/4 wavelength; 1/2 wavelength; feed lines: coax versus open-wire; velocity factor; electrical length; coaxial cable dielectrics; velocity factor
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