Conference Papers


A Compact Slot Loop Rectenna for Dual-Band Operation at 2.4- and 5.8-GHz Bands

A compact dual-band square slot loop rectenna fed by a microstrip line (MSL) for 2.4- and 5.8-GHz bands is presented. Instead of exploiting resonances of integer multiples of full wavelength in conventional dual- or multi-band slot loop antenna design, it is for the first time that the half-wavelength and one-wavelength resonant modes of MSL-fed slot loop antennas are exploited in the design of dual-band rectenna. Due to the distinct impedance behaviors at the two resonances, a matching circuit is inserted in between the rectifier circuit and slot loop radiator for simultaneous conjugate match at the two resonances. For verification, a prototype of the proposed compact slot loop rectenna for operation at 2.4- and 5.8-GHz bands is fabricated and tested. The conversion efficiencies of 49% and 66% are achieved, respectively. The prototype rectenna measures only 13 mm × 24 mm or 0.106λ0 × 0.196λ0 at 2.45 GHz.

A 2.45-GHz High-Efficiency Loop-Shaped PIFA Rectenna for Portable Devices and Wireless Sensors

An efficient compact rectenna based on a novel asymmetric loop-shaped planar inverted-F antenna (PIFA) is proposed for portable devices and wireless sensors. The antenna element, or the loop-shaped PIFA, has a compact uniplanar structure and exhibits higher radiation efficiency. The rectifier used is a half-bridge boost converter, which can double the output dc voltage. In between the rectifier and loop-shaped PIFA is a matching circuit with harmonic suppression capability, further enhancing the conversion efficiency. For the 2.45-GHz prototype design, the peak conversion efficiency of 61.4% is achieved as the incident power density is 7.4 mW/m2 and the load resistance is 510 Ω.

Miniaturized SRRs-Loaded Loop Structure for Enhanced Wireless Power Transmission

A miniaturized design of metamaterial-inspired split-ring-resonators- (SRRs-) loaded loop structure is proposed for enhanced wireless power transmission (WPT) applications. The magneto-inductive coupling between transmitting and receiving loops is enhanced by respectively embedding a pair of SRRs inside the loops. The sizes of both the loop and SRRs are reduced by capacitive loading. The fabricated 13.56-MHz prototype design is very compact and measures only 49 mm  49 mm. Though small in size, the impedance matching is also achieved by the capacitive loading. The proposed structure exhibits a satisfactory level of power transmission efficiency (PTE) of about 58%, comparable to the 64.2% PTE obtained in [1] with diameter of 80 mm.

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