In this paper, we propose a compact and highly efficient Rectenna design (rectifying antenna), operating on ISM band with the centre frequency of 2.4 GHz. A RF to DC conversion through Schottky diode (HSMS2860) is used to generate the dc voltage to operate a battery-less IoT Sensor for RF power harvesting using the designed Rectenna. We have achieved more than 80% efficiency through Advanced Design System (ADS-2016) simulation software at different power densities. Further a rectenna circuit is designed using RF to DC Schottky detector diode and a microstrip patch antenna. The rectenna circuit design is simulated through ADS 2016 simulation software. The Battery less sensor requires 2V- 2.5V dc voltage to perform an optimum performance. As per simulation and theoretical/practical modeling we have achieved more than 80% efficiency at single Schottky diode and its operating from 915 MHz to 5.8 GHz. Rectenna operates at lower power densities start from 0.4uW/cm. The proposed rectenna design is a possible candidate to be used as sensors/devices at frequency of 2.4GHz with current technologies e.g. ZigBee, Wi-Fi, BLE etc and future probable application could be long range radio sensor using the latest new generation LoRa technology its line of sight range between 10km-20km