This paper presents design of a tri-band slotted patch antenna operating at millimetre-wave frequencies of 28 GHz, 38 GHz and 61 GHz. The proposed antenna carries an overall size of 5.1mm×5mm×0.254mm employing a single layer, slotted patch structure combining L- and F-shaped slots. It is excited by a single-feed microstrip line. The antenna is tested in free space as well as in wearable configurations and results show that it offers a good impedance matching, sufficient -10 dB bandwidth and wide radiation coverage at the three bands of interest effectively countering the effects of human body presence. It achieves a peak gain of 7.2 dBi in off-body and 8.3 dBi in on-body configuration. Minimum efficiency values are observed to be 85% in off-body while 54% in on-body scenarios. A comparative analysis with published relevant work shows that the proposed antenna is inexpensive, easy to integrate and works efficiently in tri-band wearable and implantable arrangements. These features make it a good candidate for current and future applications of Body-centric Networks operating at millimetre-wave ranges
