Antenna system and base station antenna feeder system

An antenna system, comprising:

• a frequency selective surface;
• a first frequency band radiation element array;
• a second frequency band radiation element array;
• and a phase shifter, wherein:
• the frequency selective surface is disposed between the first frequency band radiation element array and the second frequency band radiation element array and is configured to reflect a signal of the first frequency band radiation element array and transmit a signal of the second frequency band radiation element array, wherein:
• the first frequency band radiation element array is disposed in a first radome having a first mounting structure connectable to an external structure;
• the second frequency band radiation element array is disposed in a second radome;
• and the first radome is connected to the second radome, the first frequency band radiation element array and the second frequency band radiation element array being arranged in a stacked manner;
• and the phase shifter comprises a cavity disposed at an edge of the frequency selective surface and a phase shift circuit disposed at the cavity, the cavity being configured to form a ground layer of the phase shift circuit, and a first extension direction of the cavity is consistent with a second extension direction of the first frequency band radiation element array.