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 an SIW slot antenna working in 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, feeding-pin of the SIW slot antenna inserts through one of asymmetric shorting vias, that is, the shorting vias serves as both perturbations for C-band operation and a feeding path for the X-band operation. This new feeding scheme can prevent signal crosstalk between the two bands.