What type of feed will radiate energy from a guide cut at certain positions in a waveguide?

A slotted array is designed specifically to radiate energy from various positions in a waveguide. It typically features a series of slots cut into the waveguide structure at predetermined intervals. When a feed is introduced, these slots allow the electromagnetic waves to radiate out from the waveguide, creating a radiation pattern. This method is particularly useful in applications requiring controlled radiation patterns or directivity while still maintaining a compact design.

In contrast, the other options do not achieve the same effect. A looped array typically involves loops of conductive materials that create a different type of field distribution, whereas a dipole array generally consists of dipole antennas that radiate energy based on their orientation and size. A pyramidal array focuses on a specific geometric arrangement that may not utilize waveguide slots effectively. Therefore, the slotted array stands out for its unique functionality in terms of radiating energy from specific positions in a waveguide.