Abstract
Demand for green energy is in tremendous growth in the last decade. The continuous growth in production of portable RF systems increase the consumption of batteries and electrical energy. Batteries and conventional electrical energy increase the environmental pollution. Compact wideband efficient antennas are crucial for energy harvesting commercial portable sensors and systems. Small antennas have low efficiency. The efficiency of 5G, IoT communication and energy harvesting systems may be improved by using wideband efficient antennas. Ultra-wideband portable harvesting systems are presented in this chapter. This chapter presents new Ultra-Wideband energy harvesting system and antennas in frequencies ranging from 0.15GHz to 18GHz. Three wideband antennas cover the frequency range from 0.15GHz to 18GHz. A wideband metamaterial antenna with metallic strips covers the frequency range from 0.15GHz to 0.42GHz. The antenna bandwidth is around 75% for VSWR better than 2.3:1. A wideband slot antenna covers the frequency range from 0.4GHz to 6.4GHz. A wideband fractal notch antenna covers the frequency range from 6GHz to 18GHz. Printed passive and active notch and slot antennas are compact, low cost and have low volume. The active antennas may be employed in energy harvesting portable systems. The antennas and the harvesting system components may be assembled on the same, printed board. The antennas bandwidth is from 75–200% for VSWR better than 3:1. The antennas gain is around 3 dBi with efficiency higher than 90%. The antennas electrical parameters were computed by using 3D electromagnetic software in free space and in vicinity of the human body. There is a good agreement between computed and measured results.