In this letter, a compact broadband high-efficiency RF rectifier is presented for ambient RF energy harvesting (EH). A novel impedance matching network with an additional quarter-wavelength short-circuited stub was designed to achieve broadband impedance matching. After the branch was added, the parallel resonance point on track S₁₁ did not move, and the remaining points were compressed. The measurement results show that the proposed topology could realize a broadband high-efficiency rectifier for ambient RF EH, and the measured results were basically consistent with the simulation results. The measured efficiency is as high as 71.5% for an input power level of 8 dBm. A 1-2.4 GHz wide frequency band with an efficiency above 50% is achieved for an input power level of 5 dBm with a terminal load of 1.6 kΩ . Moreover, the circuit had wide dynamic input power characteristics, whose measured values remained above 50% with an input power of 3-14 dBm.

In this letter, a compact broadband RF rectifier is proposed and tested for ambient RF energy harvesting (EH). An uncomplicated impedance matching network with multistage transmission lines (quasi T-shaped) is presented. Quasi T-shaped network performs three different functions to complete the broadband matching process. The novel matching network widens working bandwidth using fewer transmission lines without via hole so that it has low loss and high conversion efficiency. After theoretical analysis and simulation, the rectifier is manufactured, and the measured results are consistent with the simulation results. The rectifier shows good broadband performance. The frequency range of rectifier efficiency over 50% is from 0.85 to 2.05 GHz (a bandwidth of 82.7%) at 5 dBm. The rectifier shows a bandwidth of 101.5% (0.8–2.45 GHz) with a power conversion efficiency (PEC) greater than 50% for an 8 dBm input power. In addition, the maximum conversion efficiency of the circuit is as high as 73.1% at the input power of 8 dBm.

This letter presents a broadband rectifier that can be applied to harvest ambient radio frequency (RF) energy. The matching network consists of three-stage transmission lines. A cross-shaped match stub of two one-eighth-wavelength transmission lines is proposed to realize efficient and broadband impedance compression. The proposed circuit has been optimized and manufactured, and the measured results show that the rectifier can achieve high RF-to-dc conversion efficiency and broadband characteristics. The simulation and measured results were basically consistent. When the input power is 8 dBm and the terminal load is 1.6 $\text{k}\Omega $ , a bandwidth of 81% (1–2.35 GHz) with an efficiency above 50% and a bandwidth 69% (1–2.05 GHz) with an efficiency above 60% are achieved. The highest conversion efficiency of the test circuit is up to 73.2% at an input power of 8 dBm. Moreover, when the input power changes from 1 to 11 dBm, the efficiency of the rectifier circuit is always above 50%.

In this letter, an ultra-broadband rectifier is proposed and tested to get more RF energy from ambient. The rectifier using the Dickson charge pump increases the bandwidth and improves the dc voltage of the output load. The upper branch uses an inductor in series to counteract the capacitance of the imaginary parts of the diode and at the same time acts as a booster circuit to increase the output voltage. A shunt open-circuit stub acts as part of the matching network, tuning the imaginary part of the input impedance of the high frequency to realize the impedance matching of the ultra-broadband rectifier. The manufactured rectifier is measured and the result shows a fractional bandwidth of 145.5% (0.6–3.8 GHz) with an RF-to-dc power conversion efficiency (PCE) exceeding 40% at 8 dBm input power. And the measured efficiency remains over 50% across the frequency range from 1.6 to 3.4 GHz (including GSM1800, GSM2100, and WiFi). In addition, the rectifier made a maximum conversion efficiency of 66.6%.

We propose a modified split-cylinder resonator (SCR) with open slits, which can suppress the majority of TM modes while lowering the quality factors of nonzero azimuthal mode TE modes compared with grooves or protrusions. Thereby, the interference of unwanted modes on the TE $_{0n1}$ measurements can be considerably reduced, which ultimately allows almost ten modes of TE $_{0n1}$ ( $n = 1$ –10) to be used for excellent broadband and high-accuracy measurement. In addition, we newly derive a rigorous analysis of the SCR with the coaxial-type slits based on the mode matching method in detail, along with a joint iterative algorithm for considering simultaneously flange and slit. Then the numerical validation results suggest the accuracy and validity of the scheme over a wide range of dielectric sample thicknesses and slit widths. Finally, two cavities operating at 10–40 GHz and 20–78 GHz, respectively, were machined for experiments, and the improved SCR method is further validated by measuring several specimens processed from well-known materials, such as PTFE and several commercial substrates. The results demonstrate that the proposed method can perform broadband and high-accuracy measurement of the complex permittivity for dielectric samples of different thicknesses. In addition, the main sources of measurement uncertainty are also analyzed.