Dual circularly polarized antenna device

A dual circularly polarized antenna device, comprising:

• a multi-layer board;
• four antennas disposed on the multi-layer board, wherein each of the four antennas has a receiving pad and a transmission pad;
• four coupled microstrip lines respectively corresponding in position to the four antennas, wherein each of the four coupled microstrip lines is symmetrical in shape and includes:
• an intermediate shaft portion;
• two C-shaped portions disposed on two sides of the intermediate shaft portion, wherein each of the two C-shaped portions has an opening facing in a direction away from the intermediate shaft portion;
• and
• at least two fish bone portions connected to the intermediate shaft portion and the two C-shaped portions, wherein each of the at least two fish bone portions includes a main shaft segment and at least one extension segment connected to the main shaft segment, and the main shaft segment and the at least one extension segment are perpendicular to each other;
• and
• a coupling module disposed on the multi-layer board, wherein the coupling module is electrically coupled to the receiving pad and the transmission pad of each of the four antennas through the four coupled microstrip lines;
• wherein each of the four coupled microstrip lines has a first direction and a second direction perpendicular to the first direction, and a width of the main shaft segment of each of the at least two fish bone portions along the second direction and a width of the at least one extension segment of each of the at least two fish bone portions along the first direction are inversely proportional to a quantity of the at least one extension segment of each of the at least two fish bone portions, and wherein the dual circularly polarized antenna device is applicable to a transmission band, and a length of the at least one extension segment of each of the at least two fish bone portions along the second direction is greater than or equal to ¼ of a wavelength corresponding to a center frequency of the transmission band.