Slot antenna

Multiple slots act as a directive array antenna and can emit a narrow fan-shaped beam of microwaves.

A slot antenna's main advantages are its size, design simplicity, and convenient adaptation to mass production using either waveguide or PC board technology.

Thus the radiation pattern of a slot can be calculated by the same well-known equations used for rod element antennas like the dipole.

Slots up to a wavelength long have a single main lobe with maximum radiation perpendicular to the surface.

[2][3] Prior to its use in surface search radar, such systems used a parabolic segment reflector, or "cheese antenna".