E9A01 - Amateur Extra Class

E9A01 : 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
D A spacecraft antenna used to direct signals toward Earth
Correct Answer: A hypothetical, lossless antenna having equal radiation intensity in all directions used as a reference for antenna gain