Yes, microwaves have antennas. Microwave ovens use a special type of antenna called a magnetron to generate electromagnetic waves in the microwave frequency range. The magnetron is a vacuum tube that converts electrical energy into microwaves.
Inside the microwave oven, the magnetron is connected to a waveguide, which directs the microwaves into the cooking cavity. The microwaves bounce around inside the cooking cavity and are absorbed by the food, causing water molecules to vibrate and generate heat. This is how microwave ovens heat and cook food efficiently.
The design and placement of the antenna (magnetron) are essential for ensuring that the microwaves are distributed evenly within the cooking cavity, so that the food is heated uniformly. This is why you may notice a rotating turntable or a stirring fan inside a microwave oven - they help achieve more even cooking by distributing the microwaves more uniformly across the food.