An RFID (radio frequency identification) -Sensor tag for internet of things applications is evaluated for various signal integrity and electromagnetic radiation measures in this paper. It is found that the placement of digital circuit with respect to the radiating element has to be optimized and the entire system layout, digital and RF parts has to be co-simulated to be able to capture the detuning of operating frequency. Port impedance plots are generated via full-wave simulations to show this impact. The coupling between ports is also inspected by monitoring transmission coefficient (S21). One possible application of this sensor device is for on-body temperature measurements; therefore, back radiation of the tag and specific absorption rate (SAR) plots are reported as well.