Wideband Circularly Polarized Antenna And Its Application In Radio Frequency Energy Collection

Internet of Things is considered a promising market with a high expectation for the future.At present,the power supply problem is one of the great challenges of restricting the development of internet of things.Replacing a large number of batteries every year will result in great waste.At the same time,the environmental pollution caused by batteries and the high cost of manual maintenance are bound to seriously restrict the development of the Internet of Things.The RF energy harvesting can provide a stable power and ensure the normal work of internet of things equipment.In the case of mastering its basic principle,a broadband circularly polarized antenna and a broadband circularly polarized question mark rectenna usted for RF energy harvesting are designed.The details are as follows:1)A new wideband circularly polarized(CP)antenna is proposed.It has two parts,the first part is a circular patch with curved branches and inverted L-shaped slots,and the second one is a circular ground plane with curved branches.By commending inverted L-shaped slots on the patch and loading end shorting vias at the ends of the arced branches in the patch and ground plane,a wideband of impedance and axial ratio are obtained.The realized antenna has dimensions of 43 ? 43 ? 3.2 mm3,equals to 0.73?0 ? 0.73?0 ? 0.054?0(?0 is the wavelength at the lowest operating frequency).The tested results illustrated that the impedance and axial ratio(AR)bandwidth are 26.98 %(5.29-6.94 GHz)and 25.33 %(5-6.45 GHz),respectively.The results of the actual test are basically agreement with the simulated one.2)A novel broadband circularly polarized question mark(?-shaped)rectenna is proposed.It consists of a question-mark antenna and a rectifier circuit.The question-mark antenna consists of three parts: ?-shaped(question-mark)patch,a rectangular ground etched a fan-shaped slot,and a dielectric substrate.By etching fan-shaped slot on the ground plate,the impedance bandwidth and AR bandwidth of the antenna are extended.The rectifier circuit consists of capacitors,the diode of HSMS2862 and resistor.Both of the antenna and the rectifier circuit are printed on FR4 dielectric substrate with dielectric constant of 4.4,the size of the ?-shaped antenna is 28 mm ? 26 mm ? 1.6 mm.The tested results illustrated that the available bandwidth is from 4.8 GHz to 6.5 GHz,and the highest efficiency is 45 %.