IMPACT OF USERS' FINGER ON THE AMOUNT AND DIRECTION OF RADIATED POWER FROM A 28 GHZ 4-ELEMENT MIMO ANTENNA MOBILE TERMINAL

This paper investigates the effect of index finger position and distance on the radiated power of 4-element MIMO antenna, operating at 28 GHz. The antenna elements (AEs) are located at the top corner of the user terminal and separated at a distance of half a wavelength. Four different finger placements were investigated, one placement over each AE with six interaction distances between the AEs and the finger at each position starting from 0 up to 2.5 mm. When the finger is placed on an edge AE, the other edge AE maintained above 85% of its free space radiated power irrespective of the interaction distance. However, the radiated power of each AE was severely affected when the finger was placed on it or on the AE adjacent to it. This effect ranged from total blockage at direct interaction with the element (with a distance of 0mm) to maintaining more than around 60% of free space radiated power after the interaction distance is increased to more than 2.0 mm. Besides the effects of the index finger on the amount of radiated power, this work also investigated the direction of radiated power resulting from the influence of this finger.