Design of Shared-Aperture Dual Circularly Polarized Filtering Waveguide Slot Antenna Array

In this paper, a dual circularly polarized (CP) ridged waveguide slot antenna array integrated with filters is proposed. The radiation layer and the filtering feed layer are integrated using ridged waveguide. The ridged waveguide is selected to reduce the overall volume, and filtering structure works to obtain high anti-interference capability. Both the right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) antenna elements are composed of 16 pairs of offset slots, i.e. longitudinal and tilted slots. The RHCP or LHCP is generated by the relative offset of the two slots. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 \times \boldsymbol{16}$</tex> elements RHCP (or LHCP) linear array achieves a filtering bandwidth of 15% <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\vert \mathbf{S}_{\boldsymbol{11}} \vert &lt; -\boldsymbol{10}\mathbf{dB})$</tex> and an axial ratio (AR) bandwidth of 12.8% (AR<3dB). A linear array with 2 pairs of RHCP and LHCP element antennas is developed. Both the RHCP and LHCP achieve a filtering bandwidth of 14.8% <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\vert \mathbf{S}_{\boldsymbol{11}} \vert &lt; -\boldsymbol{10}\mathbf{dB})$</tex> and an AR bandwidth of 8.7<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> (AR<3dB), with gains of 16.1dBi and 16.2dBi, respectively. Filtering antenna achieves integrated design and occupies much less space for communication system. The proposed antenna has the advantages of multi-polarization and out-of-band suppression, which can be applied to satellite communication.