A novel technique for coupling reduction between closely spaced on-chip antennas for millimeter-wave applications

In this paper, a novel technique for reduction of coupling between closely spaced on-chip antennas is presented. The efficiency of the technique in reduction of mutual coupling between on-chip inverted-L monopoles and PIFAs operating at 60GHz is successfully demonstrated. It is shown that in an on-chip four-antenna system composed of two inverted-L monopoles and two PIFAs an isolation of better than 25dB over a minimum of 7 GHz band around 60 GHz is achieved. The reduced coupling, however, is achieved at the cost of gain reduction especially for the inverted L design. This is a shortcoming in implementing on-chip antennas using high conductivity silicon processes that already suffer from inherent low gain, but, the solution is very promising for low loss CMOS processes where a higher antenna gain is attainable.