| Microwave Power Transmission(MPT)is a long-range wireless energy transmission method using microwaves as a medium.It has many advantages such as large transmission distances,low transmission losses and a variety of applications,and has therefore received a great deal of attention and research in recent years.One of the essential aspects is that microwave energy needs to be converted to DC energy before it can be used in practice,which is the basic role of rectification circuits.However,due to the development of the Internet of Things and 5G technology,more and more frequency bands are being used for wireless communication and electromagnetic energy is more widely distributed.Therefore,it is necessary to design broadband rectifier.At the same time,the power levels of electromagnetic energy in different frequency bands in the natural environment vary considerably,while rectifier devices are non-linear and the best conversion efficiency can usually only be obtained at a specific power point.It is therefore equally important to design rectifier circuits that operate over a wide input power range.The design of rectifier that can combine a wide bandwidth with a wide input power range is a great challenge and of great practical importance.To address this issue,this thesis focuses on how to ensure that the rectifier circuit operates over a wide bandwidth and at the same time over a wide input power range,further enabling the rectifier to maintain a wide input power range at an ultra-broad bandwidth.The specific work is summarized as follows.(1)An ultra-broadband rectifier design based on resistive compression networks.The rectifier is designed using harmonic cycling structures and bending techniques to improve power conversion efficiency(PCE)while reducing size.A wideband resistive compression network(WRCN)and an impedance operation network(ION)are also used to match the rectifier to the input port at 50 Ω over the wideband range.The rectifier was simulated,fabricated and measured and experimental results show that a Microwave-DC PCE of greater than 50% was achieved at a frequency of 3.5 GHz and an input power range of 6 d Bm to 24 d Bm,with a maximum PCE of 75% obtained at an input power of 18 d Bm.The PCE is greater than 50% in the frequency band of 2.7 to 4.6 GHz with an input power level of 17 d Bm,when the fractional bandwidth exceeds 52%.(2)This thesis proposes a broadband rectifier with wide dynamic input power range,which is mainly used in low input power condition.The proposed rectifier uses unidirectional conductivity of Schottky diodes and a parallel-type circuit topology for rectification.In the proposed structure,a broadband impedance matching network consisting of a two-stage microstrip lines and a matching inductance are adopted to reduce the mismatch loss and achieve high radio frequency(RF)to DC power conversion efficiency(PCE)over the operating range,where the matching inductance is to offset the capacitance of the diode.The proposed rectifier is designed,optimized,simulated,fabricated and measured.The measured results agree well with the simulations.With an input power range of-1 – 10 d Bm and a bandwidth of 1.8 – 2.8GHz(fractional bandwidth of 43.4%),the PCE is greater than 50%.Besides,a peak PCE of76.4% is obtained at an input power of 10 d Bm.(3)This thesis presents a compact rectifier array with both broadband and wide input power range characteristics.The rectifier array consists of two rectifier units operating at lowpower and high-power levels,respectively,and an adaptive input power distribution network(AIPDN).AIPDN enables the automatic distribution of radio frequency(RF)energy and broadband impedance matching at different power levels.Two matching inductances are introduced to counteract the diode’s capacitance.Meanwhile,a strategy is proposed to enable a rectifier unit to be mismatched appropriately,together with the APIDN,to achieve a wide input power range.As a result,the high RF-DC power conversion efficiency(PCE)is achieved in both broadband and wide input power range.For demonstration,a prototype of the presented rectifier array is fabricated and measured.The measured results are in good accordance with the simulated results.With an input power range of 8–25 d Bm and a bandwidth of 1.82–2.75GHz(fractional bandwidth of 40.7%),the PCE is greater than 50%.At 2.4 GHz,the input power ranges from-5.5 to 27.5 d Bm with PCE greater than 50%.Besides,a peak PCE of 72.1% is obtained at an input power of 25 d Bm.(4)A super-broadband rectifier with expended input power range based on Dickson charge pump and impedance compression network is proposed and analyzed.Meanwhile,using an impedance compression network consisting of quadruple microstrip lines(QMLICN)with the topology of the dickson charge pump,high power conversion efficiency(PCE)and superbroadband impedance matching are achieved.In addition,the IPRs of the rectifier are also extended.The simulation results indicate that an IPR of 12 – 25 d Bm with a frequency range of 0.4 – 2.5 GHz(fractional bandwidth over 144%),the PEC exceeds 50% are realized,while at an input power of 19 d Bm,the rectifier reaches a peak PCE of 74.2%.(5)In this thesis,an ultra-broadband rectifier with expanded dynamic input power range is proposed and analyzed.Expanded dynamic input power range and broadband impedance matching are realized by utilizing an impedance compression network comprising of double microstrip transmission lines(DMLICN)with the topology of the paralleled voltage doubler.A proof-of-concept prototype shows an dynamic input power range of 8.5–23.5 d Bm,a frequency range of 0.33–2.61 GHz(fractional bandwidth of 155%),PCE is greater than 50%,and a peak PEC of 79.7%(achieved at an input-power level of 19 d Bm).The measurement results are in good agreement with simulation. |
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