K band spiral antennas conjugated with a metal waveguide

Two planar spiral antennas conjugated with the standard metal waveguide and operating in the millimeter range are proposed. The first antenna has the bandwidth of 5.83 GHz and second 6.7 GHz. The axial ration of both antennas does not exceed -3dB in the frequency band 34.2 - 37 GHz. The elevation angle of peak directivity close the zenith for single planar spiral antenna, is oriented and at θ=20° for the double planar spiral antenna. The radiation pattern shape is practically the same within the operational frequency band for both antennas. The nature of axial ratio changing is explained from the analysis of near-field distributions at two orthogonal polarizations. The proposed antennas can be used for different practical applications in the millimeter range.