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Antennas Quiz
RF Cafe Quiz #77

RF Engineering Quizzes - RF Cafe WebsiteAll RF Cafe Quizzes make great fodder for employment interviews for technicians or engineers - particularly those who are fresh out of school or are relatively new to the work world. Come to think of it, they would make equally excellent study material for the same persons who are going to be interviewed for a job. Bonne chance, Viel Glück, がんばろう, buena suerte, удачи, in bocca al lupo, 행운을 빕니다, ádh mór, בהצלחה, lykke til, 祝你好運. Well, you know what I mean: Good luck!

Click here for the complete list of RF Cafe Quizzes.

Note: Some material based on books have quoted passages.

Welcome to the RF Cafe Antenna Theory Quiz, a specialized assessment designed to test your knowledge of the radiating structures that define the success of any RF communications system. From fundamental dipole operation and feedpoint impedance to the critical nuances of gain, polarization, and pattern formation, a deep understanding of antenna physics is essential for any serious radio enthusiast or professional engineer. This quiz challenges you on key concepts, including the characteristics of Yagi-Uda arrays, the significance of front-to-back ratios, the dynamics of ground planes, and the practical challenges of matching networks. By evaluating your grasp of these essential antenna principles, you strengthen your ability to optimize your station’s performance, minimize standing waves, and maximize effective radiated power. Use this assessment to validate your theoretical foundation and ensure that your antenna modeling and deployments are grounded in the core physical realities of electromagnetic wave propagation. .

Select your answers, then click the "Submit" button.

1. What is the approximate free-space radiation resistance of a center-fed half-wave dipole?

377 ohms
50 ohms
73 ohms
300 ohms

 

2. Which antenna parameter describes the concentration of radiated power in a specific direction relative to an isotropic radiator?

Gain (dBi)
Front-to-Back Ratio
VSWR
Bandwidth

 

3. In a standard Yagi-Uda array, what is the function of the "reflector" element?

To increase bandwidth
To direct phase-shifted energy forward
To decrease impedance
To broaden the beamwidth

 

4. What effect does a ground plane have on a vertical monopole antenna?

It increases total resistance
It creates an "image" antenna, mimicking a dipole
It turns it into an omnidirectional circular radiator
It forces linear polarization

 

5. What happens to the feedpoint impedance of a dipole if it is brought closer to the ground?

Remains stable
Increases linearly
It fluctuates due to ground reflections and mutual coupling
Drops to zero

 

6. What does the "Front-to-Back Ratio" (F/B) primarily quantify?

The total efficiency of the antenna
The suppression of rearward radiation relative to forward gain
Impedance matching quality
Polarization purity

 

7. A "folded dipole" is commonly used because it provides which advantage over a standard dipole?

Higher feedpoint impedance (typically 300 ohms)
Smaller physical size
Better circular polarization
Lower wind load

 

8. What is the primary characteristic of an "Isotropic" antenna?

It radiates perfectly in one direction
It radiates equally in all directions (a theoretical point source)
It can only be used for reception
It has zero loss

 

9. In an antenna system, what is "aperture efficiency?"

The ratio of the effective area to the physical area
The power lost in the cable
The beamwidth at 3dB down
The speed at which the signal travels

 

10. What is "Cross-polarization discrimination" (XPD)?

A measure of how well an antenna rejects signals of orthogonal polarization
How fast the antenna rotates
The signal loss in the dielectric
The difference between horizontal and vertical gain

 

Quizzes from vintage electronics magazines such as Popular Electronics, Electronics-World, QST, Radio-Electronics, and Radio News were published over the years - some really simple and others not so simple. Robert P. Balin created most of the quizzes for Popular Electronics. This is a listing of all I have posted thus far.

RF Cafe Quizzes

Vintage Electronics Magazine Quizzes

Vintage Electronics Magazine Quizzes
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About the RF Cafe™ Website ©1996-2026

Kirt Blattenberger - RF Cafe WebmasterRF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a lady's voice announced "You've Got Mail" when a new message arrived...

Webmaster: Kirt Blattenberger  |     BSEE - KB3UON - AMA92498  |  USAF Radar Technician

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