Ka-/W-Band Shared-Aperture Antenna Array Based on Stacked Continuous Transverse Stub

In this article, a planar Ka-/W-band shared-aperture antenna is proposed for millimeter-wave detection radars. This antenna is based on the stacked continuous transverse stub (SCTS) structure and the hybrid waveguide, which work as the slow wave waveguide at Ka-band and the pure imaginary characteristic impedance (PICI) waveguide at W-band. The proposed SCTS structure consists of an upper W-band CTS antenna and a lower Ka-band CTS antenna. The upper W-band antenna can operate without the downward leakage due to the PICI waveguide. For the Ka-band antenna, the high-frequency structure can be equivalent to an inductive surface at Ka-band to achieve better impedance matching. The advantages of low profile, high isolation, and high aperture efficiency at both bands can be achieved. The overall height of the antenna is only 7.5 mm, about 2.5 times the wavelength of the high frequency.