CN212542693U

CN212542693U - Radio frequency energy collection antenna with harmonic suppression function

Info

Publication number: CN212542693U
Application number: CN202021077810.4U
Authority: CN
Inventors: 孙虎成; 姚峰
Original assignee: Nanjing University of Information Science and Technology
Current assignee: Nanjing University of Information Science and Technology
Priority date: 2020-06-12
Filing date: 2020-06-12
Publication date: 2021-02-12
Anticipated expiration: 2030-06-12

Abstract

The utility model discloses a radio frequency energy collects antenna with harmonic suppression function, including a medium base plate and rectifier circuit, the positive and negative of medium base plate all is equipped with radiating element, a serial communication port, radiating element's structure is log periodic structure, including middle metal strip and the symmetry minor matters of parallel from top to bottom, and the minor matters interval symmetry cross arrangement of positive and negative, radiating element's size is through adjusting the broadband antenna many times, make the broadband antenna to correspond the higher harmonic frequency point and produce the suppression, each suboptimum optimizes on the basis of previous and confirms, radiating element on the medium base plate is connected with rectifier circuit. The utility model relates to a section can improve energy harvesting efficiency and the stable output's of voltage rectification antenna.

Description

Radio frequency energy collection antenna with harmonic suppression function

Technical Field

The utility model relates to a microwave technique and antenna technology field, a radio frequency energy collection antenna with harmonic suppression function specifically says so.

Background

The radio frequency energy collection technology can trace back to the experiment for verifying the existence of electromagnetic waves in 80 Hz in the 19 th century at the earliest; modern technology originated in the 50 th 20 th century, followed by the 1969 in which William Brown designed microwave energy transmission as a power source for helicopters. The radio frequency energy collection technology is developed on the basis of wireless energy transmission, and both the radio frequency energy collection technology and the radio frequency energy collection technology adopt a process of converting radio frequency energy into a direct current power supply by adopting a rectifying antenna. The radio frequency energy collection technology is mainly a process of converting radio frequency energy in the environment into a direct current power supply after collecting the radio frequency energy, and the direct current power supply is supplied to corresponding electronic equipment for use. The technology can solve the technical problem of continuous power supply of intelligent equipment such as low-power wireless sensors, wearable products and the like, and can also provide a miniaturized and convenient power supply device for the following short-board problems of equipment of Internet of things such as intelligent home, biomedical and the like due to small battery size, short service life, high maintenance cost and the like. The nonlinear characteristic of a diode in a rectification circuit in the prior radio frequency energy collection technology can generate higher harmonic waves in the rectification process, so that the rectification efficiency can be reduced. This patent therefore proposes a rectenna with improved energy harvesting efficiency and voltage stabilization output, which simplifies the structure of the whole energy harvesting system while improving efficiency compared to other rectennas.

Disclosure of Invention

The utility model aims at the not enough among the above-mentioned prior art, provide a radio frequency energy collection antenna with harmonic suppression function.

The utility model aims at realizing through the following technical scheme:

the utility model provides a radio frequency energy collects antenna with harmonic suppression function, includes a medium base plate and rectifier circuit, the positive and negative of medium base plate all is equipped with radiating element, its characterized in that, radiating element's structure is log periodic structure, including middle metal strip and the symmetry minor matters that is parallel from top to bottom, and the minor matters interval symmetry cross arrangement of positive and negative, radiating element's size through the size of many times adjustment broadband antenna, make the broadband antenna correspond the higher harmonic frequency point and produce the suppression, each suboptimum optimizes on the basis of previous time and confirms, radiating element on the medium base plate with rectifier circuit connects.

In the further design of the utility model, the above-mentioned dielectric substrate is Rogers Ro4350, thickness is 1.524mm, dielectric constant is 3.66, loss tangent is 0.004.

The utility model discloses following outstanding beneficial effect has:

(1) compared with the traditional receiving antenna, the antenna has the advantages of clear and simple structure and easiness in processing, and can conveniently realize the suppression of corresponding higher harmonic frequency points by adjusting the lengths of the antenna branches. The high-order harmonic waves are restrained, the radio frequency energy collected by the antenna can be effectively limited in the rectifying circuit to be rectified, and the radio frequency energy is not radiated outwards through the antenna. Meanwhile, a voltage stabilizing output circuit is loaded at the rear end of the rectifying circuit to promote the voltage output by rectification to be stably output.

(2) The utility model discloses carry out optimal design on log periodic antenna basis, make it miniaturized more, the less energy collecting system that makes of receiving antenna volume is more miniaturized and require the phase-match to the electronic equipment miniaturization in the modern wireless communication system.

(3) The rectifying antenna improves the efficiency of a radio frequency energy collecting system, and simultaneously removes the loading of a filter circuit in a rear-end rectifying circuit, thereby simplifying the system structure.

Drawings

FIG. 1 is a simplified structural diagram of basic parameters of a log periodic antenna in an embodiment;

FIG. 2 is a front view of an embodiment of a broadband antenna;

FIG. 3 is a side view of an embodiment of a broadband antenna;

FIG. 4 is a diagram of S parameter changes of the first antenna and the broadband antenna in the embodiment;

FIG. 5 is a diagram showing simulated S parameter changes of the first antenna and the second antenna in the embodiment;

FIG. 6 is a diagram showing simulated S parameter changes of the antenna II and the antenna III in the embodiment;

FIG. 7 is a diagram showing simulated S parameter changes of the third antenna and the fourth antenna in the embodiment;

FIG. 8 is a schematic diagram of a rectifier circuit in an embodiment;

FIG. 9 is a schematic diagram of a rectifier circuit in an embodiment;

FIG. 10 is a graph of energy collection efficiency of a notch rectifier circuit versus a broadband rectifier circuit in an embodiment;

FIG. 11 is a flow chart of a radio frequency energy harvesting system;

in the figure, 1-notch antenna, 2-rectifying circuit, 3-upper radiating element, 4-lower radiating element, 5-middle metal strip, 6-branch and 7-dielectric substrate.

Detailed Description

The present invention will be further explained with reference to the drawings and the embodiments.

Examples

The utility model discloses can become the trapped wave antenna that has harmonic suppression function for various broadband antenna optimal design, provide a scheme that can the problem of solving, this embodiment uses log periodic antenna to carry out optimal design as the basis, introduces the radio frequency energy who has harmonic suppression function and collects the antenna preparation, other antennas relatively, log periodic antenna simple structure, easily processing is convenient for realize comparatively complicated function with simple antenna.

Fig. 1 is a simplified structural diagram of basic parameters of a log periodic antenna, wherein Ln is the length of the antenna branch,d _nis the distance between two branches of the antenna,R _nthe antenna stub is the vertical distance to the top corner. The antenna structure model is composed of scale factorsτThe interval factorθAt an angle ofαThe three main parameters are determined, and the relationship among the parameters is as follows:

（1）

in a computer, HFSS simulation software is used to optimize the preliminary shape structure and size of a radiating element of a log periodic antenna, determine the type of a dielectric substrate of the antenna, and adjust an antenna transmission line to match the impedance of the antenna, so as to obtain a broadband antenna, wherein the dielectric substrate in this embodiment is Rogers Ro4350, the thickness is 1.524mm, the dielectric constant is 3.66, and the loss tangent is 0.004. Fig. 2 and fig. 3 are optimized and designed into a broadband antenna based on the log periodic antenna of fig. 1, wherein the parameters of the broadband antenna structure are as follows:

（2）

（3）。

then, the length of the branch is optimized and adjusted for four times on the basis of the broadband antenna, and the specific process is as follows:

according to antenna theory, when fed from a short stub port, energy is transmitted along parallel transmission lines. When the length of the branch is close to half wavelength, resonance occurs, the input impedance is pure resistance, the current is large, and a strong radiation area can be formed. The other regions are a transmission region and a non-excitation region (large input impedance and small high-frequency current generation). When the operating frequency of the antenna changes, the length and frequency of the minor node to which it responds become inversely related. At this time, the length of the branch is adjusted to increase the resistance, so that the impedance is mismatched and the corresponding frequency is suppressed, and therefore, the length of the branch corresponding to the harmonic frequency point is adjusted to suppress the specified frequency point, thereby forming a desired notch antenna.

Adjusting the size of the broadband antenna for multiple times in a computer through HFSS simulation software to enable the broadband antenna to generate suppression on corresponding higher harmonic frequency points, wherein each optimization is optimized on the basis of the previous optimization, and referring to fig. 4-7, fig. 4-7 show the result change diagram of the antenna which is simulated on the HFSS software and is optimally designed into a notch antenna from the broadband antenna:

firstly, on the basis of a broadband antenna, a second harmonic, a third harmonic and a four-parameter change diagram are suppressed, and a first antenna with a high-order frequency band suppression function and no notch function is obtained.

Secondly, on the basis of the first antenna, the length of the antenna branch is adjusted, so that a trapped wave is generated between the third harmonic and the fourth harmonic, and the second antenna is obtained.

And thirdly, on the basis of the second antenna, the length of the antenna branch is adjusted, so that a trapped wave is generated between the second harmonic and the third harmonic, and the third antenna is obtained.

Fourthly, on the basis of the third antenna, the length of the antenna branch is adjusted to enable the frequency point | S of the second harmonic and the third harmonic₁₁And if the I is larger than-5 dB, the suppression is further enhanced, and a fourth antenna, namely the notch antenna 1 with the harmonic suppression function is obtained.

According to the obtained size, the antenna radiation unit is printed on the dielectric substrate 2 to obtain the notch antenna 1, and the notch antenna is connected with the rectifying circuit to obtain the notch rectifying antenna, namely the radio frequency energy collecting antenna with the harmonic suppression function.

The radio frequency energy collecting antenna with the harmonic suppression function comprises a dielectric substrate 7 and a rectification circuit 2, wherein radiation units are arranged on the front side and the back side of the dielectric substrate and are respectively an upper radiation unit 3 and a lower radiation unit 4, the radiation units are of a logarithmic periodic structure and comprise middle metal strips 5 and symmetrical branches 6 which are parallel up and down, the branches 6 on the front side and the back side are symmetrically arranged in a crossed mode at intervals, the sizes of the radiation units are determined through the manufacturing method, and the radiation units on the dielectric substrate 7 are connected with the rectification circuit 2. The dielectric substrate 7 was Rogers Ro4350, 1.524mm in thickness, 3.66 in dielectric constant, and 0.004 in loss tangent.

The parameters of the notch antenna structure are shown in table 1.

TABLE 1 trap antenna Structure parameter units mm

According to the operating characteristics of the notch antenna, a rectifying circuit with the operating frequency of 2.45GHz is designed to be matched with the notch antenna, and the rectifying circuit is shown in figures 8 and 9. The 2.45GHz rectifying circuit is subjected to simulation design on ADS software, and because circuit load has certain influence on rectifying efficiency, the load resistance value is finally determined to be 800 omega after simulation optimization, the dielectric substrate is Rogers4350B, the dielectric constant is 3.66, and the thickness is 0.762 mm.

In order to verify the performance of the notch antenna, the broadband antenna and the notch antenna are respectively combined with the same 2.45GHz rectifying circuit to form a broadband rectifying antenna without harmonic suppression and a notch rectifying antenna with harmonic suppression.

Fig. 10 is a comparison graph of the measured energy collection efficiency of two types of rectennas performed in a laboratory, and the highest energy collection efficiency reaches 67.5% when the received power is 7.9dBm in the measured notch rectenna. In the actual measurement process of the non-harmonic suppression rectifying antenna, when the received power is 8.5 dBm, the highest energy collection efficiency is 63.4%. The actual measurement shows that the energy collection efficiency of the harmonic suppression rectification antenna is 4.1% higher than that of a rectification antenna without harmonic suppression, and the actual measurement result shows that the suppression of higher harmonics can effectively improve the radio frequency energy collection efficiency, and meanwhile, the design of a filter circuit in a rectification circuit is also omitted, so that the structure of a radio frequency energy system is further simplified.

The notch antenna is combined with a rectifier circuit matched with the notch antenna to form a notch rectifier antenna for collecting radio frequency energy, namely the radio frequency energy collecting antenna with a harmonic suppression function. Specific application referring to fig. 11, fig. 11 is a schematic diagram of a specific flow of a radio frequency energy collecting system collecting radio frequency energy in a free environment, a receiving antenna is used for collecting the radio frequency energy in the free environment, a rear-end rectifying circuit is used for converting the radio frequency energy collected by the receiving antenna into a direct current power supply, and a load includes a power supply management module and aims to stably output the direct current power supply to an application electric device to provide energy supply.

Above is the utility model discloses a preferred embodiment, all rely on the utility model discloses the change that technical scheme made, produced functional action does not surpass the utility model discloses during technical scheme's scope, all belong to the utility model discloses a protection scope.

Claims

1. The utility model provides a radio frequency energy collects antenna with harmonic suppression function, includes a medium base plate and rectifier circuit, the positive and negative of medium base plate all is equipped with radiating element, its characterized in that, radiating element's structure is log periodic structure, including middle metal strip and the symmetry minor matters that is parallel from top to bottom, and the minor matters interval symmetry of positive and negative alternately sets up, radiating element on the medium base plate with rectifier circuit connects.

2. The radio frequency energy harvesting antenna with harmonic suppression function according to claim 1, wherein the dielectric substrate is Rogers Ro4350, the thickness is 1.524mm, the dielectric constant is 3.66, and the loss tangent is 0.004.