Extra exam question E9A01
Subelement E9, ANTENNAS AND TRANSMISSION LINES· Group E9A
What is an isotropic radiator?
- A.A calibrated, unidirectional antenna used to make precise antenna gain measurements
- B.An omnidirectional, horizontally polarized, precisely calibrated antenna used to make field measurements of antenna gain
- C.A hypothetical, lossless antenna having equal radiation intensity in all directions used as a reference for antenna gain (correct answer)
- D.A spacecraft antenna used to direct signals toward Earth
WhyAn isotropic radiator is a hypothetical, lossless antenna that radiates equally in every direction, used as the reference point for antenna gain measurements in dBi. An isotropic radiator is a hypothetical, perfectly lossless antenna that radiates equally in every direction, a theoretical reference point used to define antenna gain (dBi) even though no real antenna can actually achieve this perfectly uniform pattern, answer C. It isn't a real, calibrated unidirectional or omnidirectional field-measurement antenna, and it isn't a spacecraft antenna, those are real physical devices, not the idealized mathematical reference isotropic radiators represent.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
Related questions
- E9A02What is the effective radiated power (ERP) of a repeater station with 150 watts transmitter power output, 2 dB feed line loss, 2.2 dB duplexer loss, and 7 dBd antenna gain?
- E9A03What term describing total radiated power takes into account all gains and losses?
- E9A04Which of the following factors affect the feed point impedance of an antenna?
- E9A05What does the term “ground gain” mean?
- E9A06What is the effective radiated power (ERP) of a repeater station with 200 watts transmitter power output, 4 dB feed line loss, 3.2 dB duplexer loss, 0.8 dB circulator loss, and 10 dBd antenna gain?