A dual-band dual-polarized endfire antenna with high isolations and large frequency ratio

In this article, a novel single-layer dual-band dual-polarized endfire antenna with high isolation property is proposed and implemented. In this antenna, the single-sided spoof surface plasmon polariton (SSPP) structure, stimulated by a coplanar waveguide, is used to produce the horizontal polarization waves in the microwave band. Subsequently, the H-plane substrate integrated waveguide (SIW) structure innovatively shares an aperture with the metallic strip of the SSPP structure, radiating the vertical polarization waves in the millimeter wave band effectively. Due to the inherent low-pass characteristics of the SSPP structure and the high-pass characteristics of the SIW structure, the significant isolations between two ports can be obtained without additional sophisticated decoupling structures. To validate the scheme, an antenna prototype is simulated, fabricated, and measured. The measured results demonstrate that the proposed antenna achieves the -10 dB reflection coefficient bandwidths of 14.7% over the microwave band ranging from 3.15 to 3.65 GHz and 43.2% over the millimeter wave band ranging from 24.5 to 38 GHz. Moreover, the measured isolations exceed 50 dB in the microwave band and 42 dB in the millimeter wave band, respectively.