DUAL-FREQUENCY ANTENNA

The present application discloses a coaxial dual-band antenna, including a waveguide tube, a ring groove, a high frequency feed, and a dielectric ring. The waveguide tube has a tubular structure, and is configured to transmit a first electromagnetic wave, the ring groove whose opening direction is the same as an output direction of the first electromagnetic wave is on a wall of the waveguide tube, and a frequency of the first electromagnetic wave is lower than a frequency of an electromagnetic wave transmitted by the high frequency feed. The high frequency feed is located in the waveguide tube, and has a same axis with the waveguide tube, and the first electromagnetic wave excites a transverse electric mode TE 11 in the waveguide tube. The dielectric ring is filled between the waveguide tube and the high frequency feed, the dielectric ring has a multi-layer structure, and has a same axis with the waveguide tube, area sizes of planes that are at layers of the dielectric ring and that are perpendicular to the axis alternately change, and a height of the dielectric ring is less than a height of the waveguide tube. In comparison with the prior art, the present application can avoid a loss of a high order mode in a waveguide tube, and a dielectric ring is omitted, so as to improve radiation efficiency of the coaxial dual-band antenna.