What challenge is presented by a small wire-loop antenna for direction finding?
It has a bidirectional null pattern✓پاسخ درست
It does not have a clearly defined null
It is practical for use only on VHF and higher bands
All these choices are correct
توضیح
A small loop has two nulls exactly 180 degrees apart, so a single bearing cannot say which of two opposite directions the signal came from. Resolving that ambiguity requires either a sense antenna to convert the pattern to a cardioid or a second bearing from another location.