License Exam Quiz #320

de Steve, AE8AT 

Dwight Isbell, co-inventor of the log periodic antenna was born in Seattle, 23 May 1929. He is credited as being the co-inventor of antenna while a student at University of Illinois. A search did not turn up much on either Dwight or the creation of the antenna design; perhaps a good research project for someone! The quiz topic this week is the log-periodic antenna. The question pools are very thin on questions specific to this antenna, so questions about the closely related Yagi antenna are included.

T9A01 What is a beam antenna?

A. An antenna built from aluminum I-beams

B. An omnidirectional antenna invented by Clarence Beam

C. An antenna that concentrates signals in one direction

D. An antenna that reverses the phase of received signals

G9D07 Which of the following describes a log-periodic antenna?

A. Element length and spacing vary logarithmically along the boom

B. Impedance varies periodically as a function of frequency

C. Gain varies logarithmically as a function of frequency

D. SWR varies periodically as a function of boom length

E9D05 Approximately how long is a Yagi’s driven element?

A. 234 divided by frequency in MHz

B. 1005 divided by frequency in MHz

C. 1/4 wavelength

D. 1/2 wavelength

Answers:

T9A01 = C

G9D07 = A

E9D05 = D