Objectives: To design high gain square slots loaded dual-band rectangular microstrip patch antenna having harmonic suppression capability and rectifier circuit (Rectenna (Antenna + Rectifier) for Radio Frequency Energy Harvesting (RFEH). Methods: To achieve the objectives, the square slots are loaded on the four corners of the rectangular microstrip patch in order to enhance the current distribution which resulted in improved impedance matching at desired frequencies with dual isolated bands. The proposed antenna is simulated in Computer Simulation Technology (CST) Studio Suite Three-Dimensional Electromagnetic Simulation (3DEM) software. A rectifier with an LC impedance matching network is designed, simulated, and optimized in Agilent Advanced Design System (ADS) software. Findings: The overall size of the proposed antenna operating at 2.49 GHz and 3.73 GHz (WiMax) is 57×48×2.5 mm 3 . The proposed antenna is assessed in terms of its simulated performance parameters: Return loss (S1,1), Impedance (Z1,1), Voltage Standing Wave Ratio (VSWR), Gain, Directivity, and Efficiency. The proposed antenna exhibits improved performance over the conventional rectangular patch antenna, in terms of (S1,1), Impedance (Z1,1) and Gain. The results obtained from the simulation indicate -35.47 dB and -37.42 dB of S1,1 at 2.49 GHz and 3.73 GHz respectively with the Gain of 4.74 dBi and 3.62 dBi respectively. Further, a rectifier circuit is proposed at 2.45 GHz. The complete rectenna system is simulated over a range of input power levels (1dBm-10dBm) for 4.7 kOhm load resistance. The simulated rectenna result presents the maximum output voltage of 3.34 V. Novelty and Applications: The proposed rectenna design with its harmonic suppression capability can be used for RFEH to drive the Internet of Things-Sensor Network (IoT-SN) and Wireless Sensor Network (WSN). The novelty of the proposed work is harmonic suppression capability. harmonic suppression capability is achieved by inserting the square slots at the four corners of the conventional square patch. https://www.indjst.org/