Design Challenges of Rectenna for Energy Harvesting from Microwave Pollution
We are always exposed to a significant amount of microwave energy emitted by the wireless fidelity (Wi-Fi), television broadcasting, and different wireless communication systems which has many adverse effects. However, by harvesting the microwave energy from the surrounding, the microwave pollution can be reduced as well as the microwave energy can be effectively utilized. Rectenna is an electronic device which is used to harvest the microwave pollution. In this paper, the design procedure of a rectenna system is described and the key design challenges are highlighted for wireless energy harvesting. The key design parameters include harmonic suppression, the design of low-power rectifier circuits and the effect of load conditions on the rectenna conversion efficiency. The effect of load conditions against rectenna performances is extracted using Advanced Design System (ADS). Effect of different rectifier circuits including Half Wave Configuration and voltage-doubler are in the context of wireless energy harvesting systems. The article gives a comprehensive exposure to the rectenna design, the possibilities of wireless energy harvesting and likewise useful for researchers working in the field of wireless power transfer systems.
In this section, an HWR based rectifier is designed for 2.4 GHz band using ADS software for wireless energy harvesting system. The schematic of a rectifier and matching parameter is shown in Figure 3 and Figure 4, respectively. The rectifier is designed for an FR4 substrate of dielectric constant 4.4 and thickness of 1.57 mm. A matched 50 Ω RF source is used to feed the rectifier. A microstrip bandpass filter is designed at 2.4 GHz which is connected to the Hitachi 1ss168 Schottky diode (D1). An additional diode (D2) is connected to protect the main diode which bypasses the negative half cycle.
Thereafter a matched microstrip liner and a 22 μF capacitor are connected to purify the pulsating DC coming out from the diode D1. A power probe is connected to measure the output for different input power and load conditions. The output power of the rectifier for different input power is shown in Figure 5.
It is evident that, as the input power level is increasing, the output power is increasing. The output power of the rectifier versus load is depicted in Figure 6. The input power level is set to 10 dBm and the load is varied to analyze the performance of the rectifier.
Initially, the load is set to 10 Ω and further changed to 50 Ω, 500 Ω, and 1 KΩ. It is evident that the rectifier performs well for a load of 50 Ω with a peak output power of above 38 mW. Whereas, for 10 Ω, 500 Ω, and 1000 Ω, the rectifier has poor performance. Thus, an optimized load is required to extract the maximum amount of wireless energy