Abstract
This paper presents a circularly polarized (CP) rectenna with the advantage of achieving high efficiency in both wide operating power and frequency ranges. The proposed rectenna is composed of a high-efficiency rectifier and broadband CP antenna. In the proposed rectifier, a novel wideband resistance compression technique is presented, highly improving the matching performance of the circuit in a wide range of input power and frequency. The technique is achieved by an impedance manipulation network and a coupled-lines-based resistance compression network (RCN). Theoretical analysis is carried out and closed-form equations are derived for the design of the rectifier. Simulated and measured results show that over 60% (up to 76%) conversion efficiency is achieved for the input power range of 5-17 dBm and frequency band of 1.7-2.9 GHz (mobile, Wi-Fi and ISM bands). Subsequently, unlike the conventional half-wavelength slot antenna, a compact CP antenna with a side length of quarter wavelength is designed by using a 1-wavelength loop slot and a coupled-line-based phase shifter. It has wide axial-ratio bandwidth and good radiation pattern. At last, by integrating the proposed rectifier together with the CP slot antenna, a broadband CP rectenna is completed with higher efficiency by about 18.6% than that without wideband RCN.
Highlights
Wireless power transfer (WPT) has gained increasing attention
Unlike the previous frequency-dependent resistance compression network (RCN) which can only maintain its function in a fixed frequency band, a novel wideband resistance compression technique is proposed in this paper
The proposed broadband circularly polarized (CP) antenna has a working frequency band of 1.68 - 2.72 GHz, and the wideband RCN-based rectifier with a wide dynamic power range achieves more than 60% efficiency (S11 < −15 dB) in the frequency range of 1.7 - 2.7 GHz
Summary
Wireless power transfer (WPT) has gained increasing attention. It is very significant in many applications, such as internet of things (IoT) devices [1], medical devices [2], low-power electronics [3], and simultaneous wireless information and power transfer (SWIPT) system [4], [5]. A broadband circularly polarized (CP) rectenna with wide operating power range is proposed It consists of a wideband RCN-based rectifier and a CP antenna. Unlike the previous frequency-dependent RCN which can only maintain its function in a fixed frequency band, a novel wideband resistance compression technique is proposed in this paper This technique can simultaneously improve the matching of the rectifier within wide input power and frequency ranges. It is realized by an impedance manipulation network and a coupled-lines-based resistance compression network (RCN). By using this technique, the diode impedance changing with the input power and frequency can be compressed, and the conversion efficiency of the rectifier can be enhanced. The parameters Z1, Z2, θ1, θ2 for both two impedance manipulation networks can be calculated according to (3), (4), (7), and (8)
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