Compact Broadband 27 GHz Aperture-Coupled Stacked Patch MIMO Antenna Array

To enable testing of new waveforms and algorithms for future joint communication and sensing (JCAS) and radar applications, powerful and flexible multiple-input multiple-output (MIMO) testbeds are required. In the German research project Open6GHub, such a broadband massive MIMO testbed is being set up, which provides an extremely high number of channels in the frequency range from 24 GHz to 30 GHz. Therefore, very broadband antennas in the millimeter wave range are needed that can flexibly be used to design a variety of antenna arrays. The element design presented in this paper offers the required bandwidth of 6 GHz at a center frequency of 27 GHz with a small element size in the range of half the free-space wavelength. Based on this single element, an exemplary compact 8x8 antenna array was developed and measured.