C/X Dual-Band Circularly Polarized Shared-Aperture Antenna

A novel dual-band circularly polarized (CP) shared-aperture antenna is proposed in this letter. The overall structure consists of a substrate-integrated waveguide (SIW) slot antenna working in the
X
-band, which also serves as the top patch of a
C
-band microstrip-like antenna. The SIW slot antenna achieves CP radiation by etching a circular slot on the top surface of a dual-mode SIW cavity. The patch antenna realizes CP radiation by loading two pairs of asymmetric shorting vias. With this design method, the proposed antenna can achieve dual-band CP operation and high aperture reuse efficiency. Besides, the feeding pin of the SIW slot antenna inserts through one of the asymmetric shorting vias, that is, the shorting vias serves as both perturbations for the
C
-band operation and a feeding path for the
X
-band operation. This new feeding scheme can prevent signal crosstalk between the two bands.