Mutual coupling in aperture-coupled patch antennas fed by orthogonal SIW line

In this paper, the mutual coupling of a rectangular microstrip patch antenna with an aperture-coupled feed by an orthogonal substrate integrated waveguide (SIW) feed line is presented. This feed design is beneficial for 2D array configurations in millimeter wave imaging systems due to the limited availability of space for such arrays. From the results, the proposed (compact size) antenna provides 7% bandwidth (|S
₁₁
| <; -10 dB), 65% total efficiency and 5 dB gain at 30 GHz. The mutual coupling of two antenna configurations (two antennas located collinearly with respect to their length and width) with center-to-center spacing of 0.4λ-1.5λ are studied. The results show that there is less mutual coupling when the antennas are located collinear with respect to their width (due to the polarization from feed network). In addition, -17 dB mutual coupling for antennas with spacing of 0.5λ is shown for both cases.