Dual-band antenna

A dual-band parabolic antenna, comprising:

• a primary reflector;
• a secondary reflector;
• and
• a coaxial dual-band antenna, the coaxial dual-band antenna comprising a waveguide tube, a ring groove, and a high frequency feed, wherein:
• the waveguide tube has a tubular structure, and is configured to transmit a first electromagnetic wave, wherein 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 wherein a frequency of the first electromagnetic wave is lower than a frequency of an electromagnetic wave transmitted by the high frequency feed;
• and
• the high frequency feed is located in the waveguide tube, and has a same axis with the waveguide tube, and wherein the first electromagnetic wave excites a transverse electric mode TE11 in the waveguide tube.