Voltage-Doubler RF-to-DC Rectifiers for Ambient RF Energy Harvesting and Wireless Power Transfer Systems

Wireless Power Transfer (WPT) is promoted as a key enabling technology (KET) for the widespread use of batteryless Internet of Things (IoT) devices and for 5G wireless networks. RF-to-DC rectifiers are essential components for the exploitation of either ambient RF power or wireless transmitted power from a dedicated source. There are several alternative rectifier topologies which can be selected depending on the desired wireless charging scenario and may include one or more diodes. For full rectification, a minimum of two diodes are needed. The current chapter discusses various implementations of voltage-doubler designs, which revolve around the basic topology of two diodes and two capacitors. Schottky diodes are usually used, in combination with lumped capacitors. Off-the-shelf diodes include both separate diodes and integrated voltage-doubler topologies in a single package. Rectifiers are inherently narrowband, non-linear devices, and the RF-to-DC efficiency, which is usually the figure of merit, depends non-linearly on both the termination load and the received RF power. The bandwidth of the rectifier depends on the preceding matching network

Non-reciprocal balanced bandpass filters with quasi-elliptic response

This paper reports on the RF design and practical development of a non-reciprocal balanced bandpass filter (BPF) that exhibits a highly-selective quasi-elliptic response in the forward direction of propagation that is shaped by four transmission poles and two transmission zeros (TZs). By modulating some of the filterâ s resonators with phase-progressed AC signals, a non-reciprocal response is obtained in the differential mode. Its common-mode is also highly suppressed due to the incorporation of a balanced network that results in two additional TZs and resistive loss that are unique to the common-mode. The filter order can be increased by cascading additional resonators. For validation purposes, a microstrip prototype centered at 725 MHz was designed, manufactured, and measured. It showed a high isolation in the differential-mode reverse transmission of up to 62.1 dB. Moreover, the common-mode was suppressed by over 45 dB in a bandwidth greater than one octave

Novel selective feeding scheme integrated with SPDT switches for a reconfigurable bandpass-to-bandstop filter

This paper demonstrates a new technique for designing high performance reconfigurable bandpass-to-bandstop filters by employing a ring resonator and a selective feeding scheme integrated with single-pole double-throw switches (SPDT). The transformation from bandpass-to-bandstop mode and vice-versa is achieved by connecting or disconnecting two\lambda g/4 open-circuited stubs on the ring using PIN diodes. SPDT switches are employed for electronic switching between two different feeding line sections. In the bandpass state the resonator presents two transmission zeros near the edges of the passband and four attenuation poles inside the passband, enhancing the filter's performance, thus achieving excellent sharp rejection with high roll-off-rate (ROR20dB). On the other hand, high stopband rejection with wide bandwidth, good return loss and good skirt-band attenuation rates are achieved in the bandstop state. Even-and odd-mode analysis is adopted and closed-form expressions are derived to describe the filter's behaviour. To verify the validity of the proposed design, a prototype filter was fabricated and measured. In measurement, a 65% 3-dB bandwidth bandpass filter (BPF) with an insertion loss of 0.86 dB was switched to a 70% 20-dB bandwidth bandstop filter (BSF) with more than 40 dB stopband rejection

Dynamically Reconfigurable SIR Filter Using Rectenna and Active Booster

Obrađeni su populacijski parametri čaglja (Cannis aureus L.) u proteklom desetogodišnjem razdoblju. Istraživanjem su se obuhvatila lovišta koja pripadaju širem području plavljenja rijeke Save. Rezultati ovog istraživanja pomažu boljem razumijevanju dinamike populacije čaglja i širenju areala ove vrste koja je već prisutna na čitavom prostoru Republike Hrvatske

Demonstration of Reconfigurable BPFs with Wide Tuning Bandwidth Range Using 3λ/4 Open- and λ/2 Short- Ended Stubs

In this paper, two implementations of reconfigurable bandwidth bandpass filters (BPFs) are demonstrated both operating at a fixed center frequency of 2.4 GHz. The proposed reconfigurable bandwidth filters are based on a square ring resonator loaded with λg/4 open-ended stubs that are permanently connected to the ring and converted to either 3λg/4 open-ended stubs or λg/2 short-ended stubs by means of positive-intrinsic-negative(PIN) diodes to implement two reconfigurable bandwidth states for each case. Due to the symmetrical nature of the design, even- and odd-mode analysis is used to derive the closed-form to describe the reconfigurable filters’ behavior. The switching between narrowband and wideband is achieved using PIN diodes. In the first implementation (λg/4 open-ended stubs to 3λg/4 open-ended stubs), a reconfigurable bandwidth bandpass filter is proposed where additional out-of-band transmission zeros are generated by integrating a λg/2 open-ended stub at the input port. In the second implementation (λg/4 open-ended stubs to λg/2 short-ended stubs), further improvement in the upper stopband is achieved by utilizing a pair of parallel coupled lines (PCLs) as feeding lines and a pair of λg/4 high impedance short-ended stubs implemented at the input and output ports. To verify the validity of the simulated results, the prototypes of the proposed reconfigurable filters were fabricated. For the first case, measured insertion loss is less than 1.8 dB with a switchable 3-dB fractional bandwidth (FBW) range from 28% to 54%. The measured results for the second case exhibit a low insertion loss of less than 1 dB and a 3-dB fractional bandwidth that can be switched from 34% to 75%, while the center frequency is kept constant at 2.4 GHz in both cases

Applications of satellite remote sensing and GIS to urban air-quality monitoring: potential solutions and suggestions for the Cyprus area

This urban air quality has traditionally been monitored with networks of ground monitoring stations and the use of models that evaluate emissions and predict changes in air quality at discrete points. The increasing availability of earth observing satellite systems together with advances in digital image processing techniques provide a new avenue to monitor urban air quality at a citywide and regional scale. Aerosol monitoring is an important parameter in air quality studies. Aerosol characteristics can be retrieved using satellite remotely sensed data using image-based techniques. This work is primarily based on an assessment conducted at the Remote Sensing Laboratory at the Cyprus University of Technology on the potential use of satellite data to monitor urban air quality in the Cities of Limassol and Nicosia in Cyprus. Sun-photometers have been used to validate our retrieved values of the aerosol optical thickness found from the satellite images (Landsat TM-5 data)

On the Use of Tunable Power Splitter for Simultaneous Wireless Information and Power Transfer Receivers

The use of a tunable power splitter (PS) as a constituent component of a simultaneous wireless information and power transfer (SWIPT) system is discussed. Two varactor diodes are used to achieve a tunable output power ratio P2 : P3 varying from 1 : 1 to 1 : 10 under good matching conditions. The SWIPT system that operates at 2.4 GHz consists of a typical patch antenna, cascaded with the tunable PS, and a voltage doubler rectifier. The constituent components were implemented and tested as stand-alone devices and were subsequently combined in a measurement system using interconnectors. The effect of the tunable PS was explored with respect to the SNR measurements on the port that is intended for the information decoding receiver and the DC voltage measurements on the termination load of the rectifier that is connected directly on the energy harvesting port of the tunable PS. A spectrum analyzer is used for the SNR measurements while the input power is controlled using a signal generator. Both wireless power transmission and on-board measurements verify that the harvested energy can be maximized by using the minimum SNR at the information decoding branch at the expense of DC power consumption required for the biasing of the varactor diodes