Compact Wideband Dual Circularly Polarized Substrate Integrated Waveguide Horn Antenna

In this communication, a compact circularly polarized (CP) substrate integrated waveguide (SIW) horn antenna is proposed and investigated. Through etching a sloping slot on the common broad wall of two SIWs, mode coupling is generated between the top and down SIWs, and thus, a new field component as TE01 mode is produced. During the coupling process along the sloping slot, the difference in guide wavelengths of the two orthogonal modes also brings a phase shift between the two modes, which provides a possibility for radiating the CP wave. Moreover, the two different ports will generate the electric field components of TE01 mode with the opposite direction, which indicates the compact SIW horn antenna with a dual CP property can be realized as well. Measured results indicate that the proposed antenna operates with a wide 3-dB axial ratio bandwidth of 11.8% ranging from 17.6 to 19.8 GHz. The measured results are in good accordance with the simulated ones.