Compact self‐multiplexing antenna with high isolation and small‐frequency ratio.

In this paper, a miniaturized quarter‐mode substrate integrated waveguide (QMSIW)‐based self‐multiplexing antenna is designed to achieve high isolation in terms of small‐frequency ratios. First, the cross‐shaped slot is introduced to split the antenna into four parts with different dimensions, equivalent to four QMSIWs with different frequencies. By adjusting the slot position parameters, the QMSIW can be adjusted independently. Second, the antenna placement is optimized by adjusting the position of the slot and applying the frequency spacing technique. The designed antenna operates in four similar frequency bands (4.8, 5.15, 5.5, and 5.8 GHz). The isolation of adjacent units is more remarkable than 35.1 dB, while the isolation of relative units is more excellent than 22.7 dB. The structure of the proposed planar antenna is simple and suitable for handheld microwave devices. [ABSTRACT FROM AUTHOR]