An antenna based on a metamaterial in an embodiment of the present invention comprises a metamaterial panel having an electromagnetic wave aggregation function and a signal source. The metamaterial panel comprises at least one metamaterial sheet layer. The metamaterial sheet layer comprises a sheet-like substrate and a plurality of artificial microstructures periodically arranged on the substrate. Refractive indexes of each metamaterial sheet layer are distributed in the same way. The metamaterial sheet layer comprises a circular region with a center of the metamaterial sheet layer as a circle center and a plurality of annular regions having the same circle center as that of the circular region. Refractive indexes in the circular region and the annular regions continuously reduce as a radius increases, and the same refractive index exists at the same radius. At least two adjacent first region and second region exist in multiple regions. Refractive indexes in the first region continuously reduce from n1 to n2 as the radius increases, refractive indexes in the second region continuously reduce from n3 to n4 as the radius increases, and n3>n2. The present invention also provides a microwave thermal therapy radiator and a microwave thermal therapy device. In the antenna based on a metamaterial, the microwave thermal therapy radiator, and the microwave thermal therapy device of the present invention, an electromagnetic wave signal diffused in a spherical wave form is converted to an electromagnetic wave signal remotely transmitted in a plane wave form by using the distribution of the refractive indexes in the metamaterial. The antenna has a small volume, has a simple manufacturing process, is convenient and flexible to design, and can be produced in a large scale.Linvention concerne une antenne basée sur un métamatériau qui, dans un mode de réalisation de la présente invention, comprend un panneau de métamatériau ayant une fonction dagrégation dondes électromagnétiques e
