High order folded dipole antenna and wide power dynamic range energy harvesting system

Abstract

The application discloses a high-order folded dipole antenna and a wide-power dynamic range energy collection system, and the antenna comprises folded dipole arms, a dielectric plate, a metal ground, a metal reflecting plate and coaxial lines, the folded dipole arms are four, the four folded dipole arms form two groups of folded dipoles, the two groups of folded dipoles are symmetrically arranged on the upper layer of the dielectric plate, the two folded dipole arms of each group of folded dipoles are symmetric to each other, the metal ground is arranged on the lower layer of the dielectric plate, the metal reflecting plate is located below the dielectric plate, the coaxial lines are two, the outer metal shielding layers of the two coaxial lines are respectively welded to the metal ground, and the inner cores of the two coaxial lines pass through the dielectric plate and are connected to the two groups of folded dipoles one by one. The flat radiation gain can be realized, the forward gain can be improved while the backward radiation is suppressed, and the gain roll-off outside the target direction is increased.

Description

Technical Field

[0001] This invention relates to a high-order folded dipole antenna and a wide power dynamic range energy harvesting system, belonging to the field of microwave wireless power transmission technology. Background Technology

[0002] With the rapid development of wireless communication and smart cities, microwave wireless power transfer technology has received increasing attention. A microwave wireless power transfer system first converts direct current (DC) energy into microwave energy, then transmits it directionally to a receiver. The receiver rectifies the received microwave signal back into DC power to transfer energy to the load. This process involves a conversion from electrical energy to microwave and back to electrical energy, thus achieving energy transfer without a physical connection. This technology is gradually becoming a power supply method for many small-power electronic devices, such as sensor nodes and RFID tags in the Internet of Things (IoT). The key technology in this process is radio frequency (RF) energy harvesting technology.

[0003] Radio frequency (RF) energy is ubiquitous in the surrounding environment (including 2G, 3G, 4G, and 5G signals), making RF energy harvesting systems based on receiving antennas and rectifiers (rectifying antennas) a promising candidate. However, using a directional receiving antenna requires alignment with the signal transmitter to achieve optimal performance; while omnidirectional antennas do not require alignment, they typically have lower gain, significantly increasing the overall link budget burden and potentially interfering with other communication signals. Therefore, an antenna that balances gain and coverage is needed, such as an antenna with a flat-top radiation pattern.

[0004] Currently, the main method for realizing flat-top radiation pattern antennas is array weighting. This not only requires multiple antenna elements to form an array, but also requires the design of a complex feeding network to control the amplitude and phase of the port, which greatly increases the development and maintenance costs of the system.

[0005] Wireless radio frequency signals are also susceptible to multipath effects, resulting in power fluctuations at the receiver and causing unstable output voltage. Therefore, it is necessary to widen the power dynamic range to reduce the impact of power fluctuations. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a high-order folded dipole antenna that can achieve a flat radiation gain and can improve the forward gain and increase the gain roll-off outside the target direction while suppressing back radiation.

[0007] Another object of the present invention is to provide a wide power dynamic range energy harvesting system.

[0008] The objective of this invention can be achieved by adopting the following technical solutions:

[0009] A high-order folded dipole antenna includes folded dipole arms, a dielectric substrate, a metal ground, a metal reflector, and coaxial lines. The four folded dipole arms form two sets of folded dipoles, which are symmetrically arranged on the upper layer of the dielectric substrate. The two folded dipole arms in each set are symmetrically positioned. The metal ground is located on the lower layer of the dielectric substrate. The metal reflector is located below the dielectric substrate. Two coaxial lines are included, with their outer metal shielding layers welded to the metal ground. The inner cores of the two coaxial lines pass through the dielectric substrate and are connected to the two sets of folded dipoles in a one-to-one correspondence.

[0010] Furthermore, the two folded dipole arms of each set of folded dipoles are connected by a junction. Each folded dipole arm includes a first bend, a second bend, and a third bend. The first bend, the second bend, and the third bend are sequentially disposed between the center and the edge of the dielectric plate, and the lengths of the first bend, the second bend, and the third bend increase sequentially.

[0011] Furthermore, the first bending portion is formed by bending three times along the direction perpendicular to the folded dipole arm, with a length of 5mm-6mm; the second bending portion is formed by bending three times along the direction perpendicular to the folded dipole arm, with a length of 7mm-8mm; and the third bending portion is formed by bending four times along the direction perpendicular to the folded dipole arm, with a length of 11mm-12mm.

[0012] Furthermore, the metal ground has an H-shaped slit etched in the middle and two ports for welding coaxial lines.

[0013] Furthermore, the distance between the H-shaped gap and the edge of the metal ground is 1mm-3mm.

[0014] Furthermore, the four corners of the dielectric plate are fixedly connected to the metal reflector via nylon pillars.

[0015] Furthermore, the dielectric substrate is a square dielectric substrate with a side length of 150mm-170mm.

[0016] Furthermore, the metal reflector is a square reflector with a side length of 190mm-210mm.

[0017] Another objective of this invention can be achieved by adopting the following technical solution:

[0018] A wide power dynamic range energy harvesting system includes a wide power dynamic range rectifier circuit and the aforementioned high-order folded dipole antenna, wherein the high-order folded dipole antenna is connected to the wide power dynamic range rectifier circuit via a power divider phase shifter.

[0019] Furthermore, the wide power dynamic range rectifier circuit is composed of two rectifier branches connected in parallel, namely the first rectifier branch and the second rectifier branch.

[0020] The first rectifier branch includes a first microstrip line, a first DC blocking capacitor, a first rectifier diode, a first filter capacitor, and a first load resistor. The first microstrip line, the first DC blocking capacitor, and the first rectifier diode are connected in series in sequence, then connected in parallel with the first filter capacitor, and then connected in series with the first load resistor.

[0021] The second rectifier branch includes a second microstrip line, a second DC blocking capacitor, a second rectifier diode, a second filter capacitor, and a second load resistor. The second microstrip line, the second DC blocking capacitor, and the second rectifier diode are connected in series in sequence, then connected in parallel with the second filter capacitor, and then connected in series with the second load resistor.

[0022] The first rectifier branch and the second rectifier branch are connected in parallel through an open-circuit microstrip line and a tapered microstrip line, and the ends of the first rectifier branch and the second rectifier branch are both grounded. The length of the first microstrip line is less than the length of the second microstrip line.

[0023] The present invention has the following advantages over the prior art:

[0024] 1. This invention employs a folded dipole on the upper layer of the dielectric substrate. By changing the dimensions of the bend, the radiation pattern is shaped, achieving a flat radiation gain without the need for array weighting methods. Simultaneously, a metal reflector is added to the lower layer of the dielectric substrate, which can suppress back radiation while increasing forward gain and increasing gain roll-off outside the target direction, thereby improving the overall performance of the system. It eliminates the need for a complex amplitude / phase weighted feeding network, requiring only a double-sided dielectric substrate for the antenna itself, resulting in lower cost and a more compact overall size.

[0025] 2. The high-order folded dipole antenna designed in this invention has a flat radiation gain within the target coverage area, ensuring reception performance; at the same time, outside the target range, the gain roll-off is significant, avoiding interference with other useful signals.

[0026] 3. The high-order folded dipole antenna designed in this invention can avoid drastic changes in efficiency under the condition of fluctuating input signal power, thus ensuring the overall reliability of the energy harvesting system. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0028] Figure 1 This is a three-dimensional structural diagram of the high-order folded dipole antenna of Embodiment 1 of the present invention.

[0029] Figure 2 This is a diagram of the upper structure of the dielectric substrate in the high-order folded dipole antenna of Embodiment 1 of the present invention.

[0030] Figure 3 This is a diagram of the lower layer structure of the dielectric substrate in the high-order folded dipole antenna of Embodiment 1 of the present invention.

[0031] Figure 4 The image shows the reflection coefficient data of the high-order folded dipole antenna of Embodiment 1 of the present invention.

[0032] Figure 5 This is the gain pattern of the high-order folded dipole antenna of Embodiment 1 of the present invention when it operates at 5 GHz.

[0033] Figure 6 This is a structural block diagram of the wide power dynamic range energy harvesting system of Embodiment 2 of the present invention.

[0034] Figure 7 This is a structural diagram of the wide power dynamic range rectifier circuit of Embodiment 2 of the present invention.

[0035] Figure 8 This is the layout of the wide power dynamic range rectifier circuit in Embodiment 2 of the present invention.

[0036] Figure 9 This is a frequency / efficiency data diagram of the wide power dynamic range rectifier circuit of Embodiment 2 of the present invention.

[0037] Figure 10 This is a power / efficiency data diagram of the wide power dynamic range rectifier circuit of Embodiment 2 of the present invention.

[0038] Figure 11 This is a graph showing the output voltage data of the wide power dynamic range rectifier circuit of Embodiment 2 of the present invention at different input powers when it operates at 5GHz.

[0039] Wherein, 1-first bend, 2-second bend, 3-third bend, 4-junction, 5-dielectric plate, 6-H-shaped gap, 7-port, 8-metal ground, 9-metal reflector, 10-first microstrip line, 11-first DC blocking capacitor, 12-first rectifier diode, 13-first filter capacitor, 14-first load resistor, 15-second microstrip line, 16-second DC blocking capacitor, 17-second rectifier diode, 18-second filter capacitor, 19-second load resistor, 20-open circuit microstrip line, 21-gradient microstrip line, 22-ground terminal. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] Example 1:

[0042] like Figures 1-3 As shown, this embodiment provides a high-order folded dipole antenna, which includes folded dipole arms, a dielectric substrate 5, a metal ground 8, a metal reflector 9, and coaxial lines. The four folded dipole arms form two sets of folded dipoles, which are symmetrically arranged on the upper layer of the dielectric substrate 5. The two folded dipole arms of each set are symmetrical to each other and fold in a direction perpendicular to themselves after a certain length. The metal ground 8 is arranged on the lower layer of the dielectric substrate 5, and the metal reflector 9 is located below the dielectric substrate 5. There are two coaxial lines, and the outer metal shielding layers of the two coaxial lines are respectively welded to the metal ground 8. The inner cores of the two coaxial lines pass through the dielectric substrate 5 and are connected to the two sets of folded dipoles one by one.

[0043] Furthermore, the two folded dipole arms of each group of folded dipoles are connected by a junction 4. Each folded dipole arm includes a first bending portion 1, a second bending portion 2, and a third bending portion 3. The first bending portion 1, the second bending portion 2, and the third bending portion 3 are sequentially disposed between the center and the edge of the dielectric plate, and the lengths of the first bending portion 1, the second bending portion 2, and the third bending portion 3 increase sequentially.

[0044] Specifically, the first bending part 1 is formed by bending three times along the direction perpendicular to the folded dipole arm, with a length of 5.4 mm; the second bending part 2 is formed by bending three times along the direction perpendicular to the folded dipole arm, with a length of 7.8 mm; and the third bending part 3 is formed by bending four times along the direction perpendicular to the folded dipole arm, with a length of 11.2 mm.

[0045] Furthermore, the metal ground 8 has an H-shaped slit 6 engraved in the middle and two ports 7 are provided. Each port 7 is connected to a via. The two coaxial outer metal shielding layers are respectively welded to the two ports 7 through the vias. Specifically, the distance between the H-shaped slit 6 and the edge of the metal ground 8 is 2mm. The H-shaped slit 6 can be used to adjust the matching.

[0046] Furthermore, holes are drilled at the four corners of the dielectric plate 5, and it is fixedly connected to the metal reflector 9 through nylon pillars; specifically, the dielectric plate 5 is a square dielectric plate with a side length of 160mm, and the metal reflector 9 is a square reflector with a side length of 200mm.

[0047] Figure 4 The image shows the reflection coefficient (return loss) data of the high-order folded dipole antenna in this embodiment. The overall return loss is less than -10 dB in the 4.6-5.4 GHz range, covering the target 5 GHz frequency band.

[0048] Figure 5 This diagram shows the gain pattern of the XOZ plane of the high-order folded dipole antenna in this embodiment when operating at 5 GHz. The horizontal axis represents the scanning angle of the antenna's far-field pattern, ranging from -180° to 180°. The vertical axis represents the actual gain of the antenna, in dBi. The antenna's peak gain is 7.95 dBi, and its 3 dB beamwidth is 98° (-46° - 52°). Within the angular range of -38° to 45°, the antenna exhibits gain fluctuation of less than 1 dB and high gain flatness. Simultaneously, it ensures a significant gain roll-off outside the coverage area.

[0049] Therefore, the high-order folded dipole antenna in this embodiment adopts a folded dipole method on the upper layer of the dielectric substrate. By changing the size of the bending point, the radiation pattern is shaped, and a flat radiation gain can be achieved without the need for array weighting methods. At the same time, adding a metal reflector on the lower layer of the dielectric substrate can suppress back radiation, improve forward gain, and increase gain roll-off outside the target direction, thereby improving the overall performance of the system.

[0050] Example 2:

[0051] like Figure 6 As shown, this embodiment provides a wide power dynamic range energy harvesting system. The system includes a wide power dynamic range rectifier circuit and a high-order folded dipole antenna as described in Embodiment 1 above. The high-order folded dipole antenna is connected to the wide power dynamic range rectifier circuit through a power divider phase shifter. The power divider phase shifter is a 0° / 180° phase shifter that combines the two differential signals output from the two sets of folded dipoles into one signal, which is then input into the wide power dynamic range rectifier circuit.

[0052] like Figure 7 and Figure 8 As shown, the wide power dynamic range rectifier circuit can be called a rectifier. It consists of two rectifier branches connected in parallel, namely the first rectifier branch and the second rectifier branch.

[0053] The first rectifier branch includes a first microstrip line 10, a first DC blocking capacitor 11, a first rectifier diode 12, a first filter capacitor 13, and a first load resistor 14. The first microstrip line 10, the first DC blocking capacitor 11, and the first rectifier diode 12 are connected in series, then connected in parallel with the first filter capacitor 13, and then connected in series with the first load resistor 14.

[0054] The second rectifier branch includes a second microstrip line 15, a second DC blocking capacitor 16, a second rectifier diode 17, a second filter capacitor 18, and a second load resistor 19. The second microstrip line 15, the second DC blocking capacitor 16, and the second rectifier diode 17 are connected in series, then connected in parallel with the second filter capacitor 18, and finally connected in series with the second load resistor 19.

[0055] The first and second rectifier branches are connected in parallel via an open-circuit microstrip line 20 and a tapered microstrip line 21. The open-circuit microstrip line 19 is a matching structure, and the tapered microstrip line 20 is an RF input port. The ends of both the first and second rectifier branches are ground terminals 22, which are designed with vias. In this embodiment, the vias are circular. The length of the first microstrip line 10 is less than the length of the second microstrip line 15, i.e., the first microstrip line 10 is a short microstrip line, and the second microstrip line 15 is a long microstrip line. The first rectifier diode 12 and the second rectifier diode 17 are HSMS2862. The back of the wide power dynamic range rectifier circuit is printed with a metal ground, and the ground terminal 22 is connected to this metal ground.

[0056] All vias in the above embodiments are metallized vias.

[0057] Figure 9 The curve of efficiency versus frequency for the wide power dynamic range rectifier circuit in this embodiment at an input power of 13dBm shows that the efficiency exceeds 60% and the fluctuation is less than 5% in the range of 4.95-5.85 GHz, covering the target antenna operating frequency band.

[0058] Figure 10 The curve showing the efficiency of the wide power dynamic range rectifier circuit in this embodiment as a function of input power at 5 GHz is shown. The efficiency reaches a maximum of 65% when the input power is 13 dBm. When the input power is 3 dBm and 16.8 dBm, the efficiency drops to 60% of the peak value, reaching the dynamic range boundary. Therefore, the power dynamic range is 13.8 dB.

[0059] Figure 11 The output voltage data diagram shows the output voltage of the wide power dynamic range rectifier circuit at different input powers when it operates at 5GHz. When the circuit input power reaches 2.5dBm (that is, when the power reaching the antenna exceeds -5dBm), the output voltage can exceed 1V, and it will always maintain a high-efficiency operating state until the diode exceeds its power capacity and breaks down.

[0060] In summary, the flat radiation gain of this invention ensures that the energy harvesting system can collect radio frequency energy over a wider range, and the significant out-of-band gain roll-off avoids interference with signals outside the target area. Simultaneously, the power range of the rectifier circuit is also broadened, preventing efficiency degradation caused by received power fluctuations. The designed high-order folded dipole antenna has better adaptability to energy harvesting systems and can meet the functional requirements of small and medium-sized nodes in passive IoT.

[0061] Although the invention has been described herein with reference to embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the drawings themselves. In this specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple components. While different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0062] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications fall within the scope of the invention and its equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A high-order folded dipole antenna, characterized in that, The device includes folded dipole arms, a dielectric plate, a metal ground, a metal reflector, and coaxial lines. There are four folded dipole arms, which form two sets of folded dipoles. The two sets of folded dipoles are symmetrically arranged on the upper layer of the dielectric plate, and the two folded dipole arms of each set are symmetrical to each other. The metal ground is located on the lower layer of the dielectric plate, and the metal reflector is located below the dielectric plate. There are two coaxial lines, and the outer metal shielding layers of the two coaxial lines are respectively welded to the metal ground. The inner cores of the two coaxial lines pass through the dielectric plate and are connected to the two sets of folded dipoles one by one. The two folded dipole arms of each set of folded dipoles are connected by a junction. Each folded dipole arm includes a first bend, a second bend, and a third bend. The first bend, the second bend, and the third bend are sequentially disposed between the center and the edge of the dielectric plate, and the lengths of the first bend, the second bend, and the third bend increase sequentially.

2. The high-order folded dipole antenna according to claim 1, characterized in that, The first bending portion is formed by bending three times along the direction perpendicular to the folded dipole arm, with a length of 5mm-6mm; the second bending portion is formed by bending three times along the direction perpendicular to the folded dipole arm, with a length of 7mm-8mm; and the third bending portion is formed by bending four times along the direction perpendicular to the folded dipole arm, with a length of 11mm-12mm.

3. The high-order folded dipole antenna according to claim 1, characterized in that, The metal ground has an H-shaped slit engraved in the middle and two ports for welding coaxial lines. The four corners of the dielectric plate are perforated and fixedly connected to the metal reflector through nylon pillars.

4. The high-order folded dipole antenna according to claim 3, characterized in that, The distance between the H-shaped gap and the edge of the metal ground is 1mm-3mm.

5. The high-order folded dipole antenna according to claim 1, characterized in that, The four corners of the dielectric plate are fixedly connected to the metal reflector via nylon pillars.

6. The high-order folded dipole antenna according to any one of claims 1-5, characterized in that, The dielectric substrate is a square dielectric substrate with a side length of 150mm-170mm.

7. The high-order folded dipole antenna according to any one of claims 1-5, characterized in that, The metal reflector is a square reflector with a side length of 190mm-210mm.

8. A wide power dynamic range energy harvesting system, characterized in that, It includes a wide power dynamic range rectifier circuit and a high-order folded dipole antenna as described in any one of claims 1-7, wherein the high-order folded dipole antenna is connected to the wide power dynamic range rectifier circuit via a power divider phase shifter.

9. The wide power dynamic range energy harvesting system according to claim 8, characterized in that, The wide power dynamic range rectifier circuit is composed of two rectifier branches connected in parallel, namely the first rectifier branch and the second rectifier branch. The first rectifier branch includes a first microstrip line, a first DC blocking capacitor, a first rectifier diode, a first filter capacitor, and a first load resistor. The first microstrip line, the first DC blocking capacitor, and the first rectifier diode are connected in series in sequence, then connected in parallel with the first filter capacitor, and then connected in series with the first load resistor. The second rectifier branch includes a second microstrip line, a second DC blocking capacitor, a second rectifier diode, a second filter capacitor, and a second load resistor. The second microstrip line, the second DC blocking capacitor, and the second rectifier diode are connected in series in sequence, then connected in parallel with the second filter capacitor, and then connected in series with the second load resistor. The first rectifier branch and the second rectifier branch are connected in parallel through an open-circuit microstrip line and a tapered microstrip line, and the ends of the first rectifier branch and the second rectifier branch are both grounded. The length of the first microstrip line is less than the length of the second microstrip line.

Images