Compact slot-loaded patch antenna for 868 MHz wireless body area networks

The development of a compact and highly efficient antenna operating at 868 MHz for communication in ISM-band body area networks is reported. With symmetrical slots and shorting pins on either side of the feed, the antenna exhibited a radiation pattern similar to that of a monopole/dipole antenna with an efficiency of 52.3% and an impedance bandwidth of 9.3 MHz (1.1%) when placed in close proximity (1 mm) from a muscle tissue phantom. The maximum dimension of the proposed design is reduced by more than 66% compared to a conventional lambda/2 microstrip patch antenna. Furthermore, for a simulated on-body path the performance of the new antenna was within 2 dB of a lambda/4 monopole.