Reduction in mutual coupling characteristics of slot-coupled planar antenna due to rectangular elements

In this paper, we proposed a broadband ACPA that integrated a filter function. By installing multiple rectangular elements in the Rx antenna, the mutual coupling between the Tx and Rx antennas was reduced from -24 dB to -29.8 dB(min. -36 dB). At the same time, the broadband resonance of the antenna and external size were maintained after adding the filter function. By investigating the current distribution on the rectangular elements, we found that the current on the second rectangular element changes its direction when the frequency is higher than f_trap. This enables the antenna to function as a low-pass filter.