8 × 2-Element 60-GHz-Band Circularly Polarized Post-Wall Waveguide Slot Array Antenna Loaded With Dipoles

In this paper, an 8 × 2-element 60-GHz band circularly polarized post-wall waveguide slot array antenna loaded with dipoles is proposed. The antenna is composed of a feeding circuit, radiating slots on radiating waveguides, and dipoles for polarization conversion. By integrating the feeding circuit and the radiating waveguides into a single dielectric layer, the total number of dielectric layers is reduced to two which greatly increases ease of mass production. The feeding circuit divides power into two and feeds the two radiating waveguides from their center. 8 × 2 radiating elements are composed of a slot and a dipole placed on the radiating waveguides. The elements are designed by standing-wave excitation. The antenna is fabricated by printed circuit board technology and its dimensions are 44.5 × 20.0 × 2.16 mm
³
. The measured results show a 2.1-dB axial ratio, 15.6-dBi gain, and 57.2% efficiency at 61.5 GHz. The proposed antenna realizes a circular polarized array antenna with the minimum number of dielectric layers and electric performance comparable to conventional antennas.