  Wireless Networks-on-Chip (WNoCs) are regarded as a disruptive alternative to
conventional interconnection networks at the chip scale, yet limited by the
relatively low aggregate bandwidth of such wireless networks. Hence, any method
to increase the amount of concurrent channels in this scenario is of high
value. In this direction, and since WNoC implies close integration of multiple
antennas on a chip anyway, in this paper we present a feasibility study of
compact monopole antenna arrays in a flip-chip environment at millimeter-wave
and sub-terahertz frequencies. By means of a full-wave solver, we evaluate the
feasibility to create, at will, concentrations of field in different spots of
the chip. This way, we set the steps towards spatial multiplexing that enables
concurrent multicast communications and also increases the aggregate bandwidth
of the wireless network. Our results at 60 GHz show two clearly separable
parallel channels that radiate simultaneously from two opposite corners of the
chip, achieving a Signal-to-Interference Ratio (SIR) of around 40 dB, which
proves that the channels are independent of each other even in such an enclosed
environment. Further, we see potential to expand our approach to three or more
concurrent channels, and to frequencies beyond 100 GHz.
