Joint Antenna-Channel Modelling for in-to-out-Body Propagation of Dairy Cows at 868 MHz

Abstract

In this paper, for the first time, the in-to-out-body path loss between a capsule antenna placed inside the cows' rumen and a distant gateway was characterized at 868 MHz. Measurements were conducted on five different fistulated cows in a dairy barn. The in-body antenna gain was then de-embedded from the wireless channel. The difference between free space measurements and in-to-out-body path loss assessment was used to quantity the path loss increase due to the cows' body. Results have shown an increase of the path loss on average (all cows) by 50.6 dB, with a variation between 43.7 and 55.3 dB. The obtained results were used to calculate the range of a LoRa (Long range) based network accounting for the antenna channel. With an input transmit power of 14 dBm, ranges up to 175 m in indoor and 364 m in outdoor were obtained depending on the used bit rate.