Design Of Rectenna With Improved RF-To-DC Power Conversion Efficiency For RF Energy Harvesting

This thesis presents novel techniques for the design of rectenna for RF energy harvesting which allow for the realization of wireless microwave energy transfer. Energy harvesting is a rapidly growing area in many scientific and engineering related fields due to the need for finding solutions to the world’s power issues. Based on the previous works, there are many limitations and drawbacks exists in currently used technique such as low RF-to-DC power conversion efficiency or increase in the number of antenna elements enlarges the overall aperture size of the rectenna, the resulting devices are large and more difficult to install which limits the potential of further enhancement in the conversion efficiency. Therefore, the overall objective of this research work is to develop an effective rectenna for RF energy harvesting system. These rectenna have an advantage of high gain and high efficiency properties which optimized the overall rectenna performance. All the rectenna designs were developed based on stacked air-gap rectenna technology by integrating the rectifying circuit with the high gain antenna. In order to validate the concept, all rectenna designs were manufactured and measured. The experimental results show excellent agreement with the simulated performance. Both antennas and rectifiers have been designed by using Computer Simulation Technology (CST) and Advance Design System (ADS) respectively. A low cost 4.6 permittivity FR4 substrate has been used in the fabrication process. For rectifier, the highest output voltage that can be achieved is 14.52 V when the input power is at 30 dBm. On the other hand, the most optimized antenna amongs all can achieved gain of 9.01 dB and return loss of more than -22 dB. The highest measured RF-to-DC conversion efficiency of the optimized rectenna design is 85% when the input power is 20 dBm applied to the circuit. The main benefit of the rectenna designs are high gain, high RF to DC power conversion efficiency, high DC output voltage as well as being able to easily integrate with other planar devices at a low cost and using standard printed circuit board process. This new class of rectenna is considered suitable for applications, particularly where the gain can be tolerated and the RF-to-DC power conversion efficiency is very important, such as in the case of agriculture and health sensors of wireless sensor networ

Dual-band aperture coupled antenna with harmonic suppression capability

The paper presents an aperture-coupled dual-band linearly-polarized antenna with harmonic suppression capability, operating at frequency 2.45 GHz and 5.00 GHz. In purpose of improving the directivity of antenna at the operating frequency of 2.45 GHz and 5.00 GHz, a modified inverted π-shaped slot-etched patch on the lower layer of the stacked antenna is introduced alongside the 50 Ω feed line. The harmonic suppression capability is achieved by the introduction of U-slot and asymmetrical left-right-handed stub at the transmission feed line, suppressing unwanted harmonic signals from 6.00 GHz up to 10.00 GHz. The final design of the antenna has produced very good reflection coefficient of -18.87 dB at 2.45 GHz and -19.57 dB at 5.00 GHz with third and higher order harmonic suppression up to -4 dB

An Investigation of Electromagnetic Field Effect On a Human Skin Cell Using Numerical Method Approaches

Abstract—the investigation between electromagnetic waves (conduction current) and human cell as lossless material has received renewed attention recently. This propagation can come from many sources such as cellular phone. The structure of a human cell were studied from many school of thinking such as biochemical in cell, cytoplasm, nucleus and membrane and the understanding obtained have been used as the basis in the developing of mathematical model. The main objective of this project is to analyze the behavior and determine the parameters of the interaction and propagation in a single cell when expose to electromagnetic wave from lossy material to lossless material such as the attenuation coefficient, electric field and skin depth. The Maxwell equations were used as the basis of the modeling in this project with aid of numerical method approaches specifically Finite-Difference Time Domain (FDTD) techniques and applications. To develop the model MATLAB tool and Graphical Users Interface (GUI) were used. Results obtained from the developed model ware verified with known result obtained from others researchers and with experimentally

Enhancement algorithm for reverse loop technique on planar reverse loop antenna

Finding a trade-off balance between wireless transfer efficiency (WTE) and distance is a key issue in wireless energy transfer (WET). This paper presents a method of reducing the radical alteration in WTE versus distance, by using a reverse loop technique on planar reverse loop antenna (PRLA). The design focuses on 13.56 MHz Near Field Communication (NFC). The first stage uses mathematical modelling, based on an analytical approach, to determine the size of the reverse loop using Matlab. The proposed model predicts the size of the reverse loop to stabilize the WTE at a closer distance. Next, full-wave electromagnetic simulations are applied, using the computer simulation technology (CST) MICROWAVE STUDIO®, to determine the WTE effect with distance changes with mismatch condition. Planar loop antennas (PLAs) are fabricated on glass-reinforced epoxy laminated sheets (FR4). A validation of the simulation result in a real test scenario, using these PLAs and PRLA, confirms a stability enhancement in WTE at closer distance using the reverse loop technique, compared to conventional designs

Wireless based Smart Parking System using Zigbee

One of main issues of developing big parking space for shopping complexes, office complexes and other types of building that requires large parking space is to notify the visitors of occupied and nonoccupied parking space. Most of the visitors might spending up to 30 to 45 minutes just to find an empty parking space. In most recent technology, some parking lot system offered a system that could automatically count when the car entering the empty car space and blocking an infrared signal thus notify the system to count for it. However, this type of sensors actually has an increase of budgeting in order to install and to be maintained. In this project, we have developed a unique solution by providing cost effective solution by using Zigbee technology in parking lot system technology. Instead of using and maintain cable that need to be installed at the ceiling of the parking lot, we developed a system that use wireless technology of Zigbee and it could notify the visitors of empty and non-empty parking lot

A systematic optimization procedure of antenna miniaturization for efficient wireless energy transfer

This paper presents a systematic optimization procedure to determine the reduced antenna size aimed at obtaining the best efficiency or at least equal performance with the initial large antenna design in a wireless energy transfer (WET) system. A low-cost, square-shaped planar loop antenna designed on each side of FR4 substrate is used as both the miniature transmitter and receiver antennas operating at 13.56 MHz for the near-field communication (NFC) band. The effect of distance and antenna size on the link parameters such as inductance, resistance and mutual coupling is studied, prior to the study of their effects on WTE. The accuracy of the procedure is cross-validated using two methods; analytically and using full wave simulations. The simulation then is verified using lab measurement setup at real scene environment. Trends of the resulting curves using both methods indicated good agreements, and optimal miniature antenna for the best wireless transfer efficiency (WTE) is able to be quickly determined. A miniature antenna is able to achieve 4% wireless transfer efficiency improvement with 47% antenna size reduction. Such method can be applied to efficiently estimate a low-cost WTE system setup, besides enabling the integration of self-tuning or reconfigurability features in such systems for a known initial antenna size to mitigate changes to its operating distance

Design of Low-Loss Coaxial Cavity Bandpass Filter with Post-Manufacturing Tuning Capabilities

This paper presents a low-loss of coaxial cavity bandpass filter with post-manufacturing tuning capabilities.A systematic filter development using the lowpass prototype as a starting point to produce 4th degreeChebyshevbandpass response is demonstrated. The coaxial cavity filter based upon TEM mode of propagation has the center frequency of 2.5 GHz and bandwidth of 168MHz. The insertion loss of 0.15 dB insertion loss and return loss better than 15 dB areobtained particularly in the passband. This type of microwave filter would be useful in any microwave systems where the low insertion loss and high selectivity are crucial, such as in a base station, radar and satellite transceivers

Rectangular Microstrip Patch Antenna Based on Resonant Circuit Approach

This paper presents the investigation based upon the resonant circuit approach to characterize the rectangular microstrip patch antenna from the low-pass prototype lumped element. The physical layout of the rectangular microstrip patch antenna based on single-mode and dual-mode will be established. An improvement on bandwidth of the antenna can be achieved by increasing the number of modes. In the paper, the understanding of microwave filter synthesis technique is applied in order to obtain the resonance at 2 GHz. A notch technique is used in the design to produce dual-mode frequencies on the microstrip patch antenna. The prototype circuit and proposed physical layout of the single and dual-mode microstrip patch antennas are demonstrated through the analysis of circuit and EM simulations in order to proof the proposed concept. This study would be useful to realize antenna for broadband applications as well as to investigate the appropriate technique for integrating antenna and microwave filter

Dual-Band Aperture Coupled Antenna With Harmonic Suppression Capability

The paper presents an aperture-coupled dual-band linearly-polarized antenna with harmonic suppression capability, operating at frequency 2.45 GHz and 5.00 GHz. In purpose of improving the directivity of antenna at the operating frequency of 2.45 GHz and 5.00 GHz, a modified inverted π-shaped slot-etched patch on the lower layer of the stacked antenna is introduced alongside the 50 Ω feed line. The harmonic suppression capability is achieved by the introduction of U-slot and asymmetrical left-right-handed stub at the transmission feed line, suppressing unwanted harmonic signals from 6.00 GHz up to 10.00 GHz. The final design of the antenna has produced very good reflection coefficient of -18.87 dB at 2.45 GHz and -19.57 dB at 5.00 GHz with third and higher order harmonic suppression up to -4 d