Question
In which direction or directions does an electrically small loop (less than 1/10 wavelength in circumference) have nulls in its radiation pattern?
Answer Options
- A) In the plane of the loop
- B) Broadside to the loop
- C) Broadside and in the plane of the loop
- D) Electrically small loops are omnidirectional
Correct Answer: B
Explanation
An electrically small loop antenna (often a Magnetic Loop Antenna) is characterized by having its dimensions much smaller than a half wavelength. This antenna’s radiation is primarily determined by its magnetic field component.
Unlike a dipole (which radiates broadside to the wire), the small loop antenna exhibits a radiation pattern that has deep nulls perpendicular to the loop’s plane. Therefore, the loop has deep nulls broadside to the loop (i.e., straight out the side of the loop). This characteristic makes them excellent receiving antennas for direction finding or noise suppression.
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