A dual-polarized omnidirectional rectenna using a RF power combining scheme

Abstract

The present invention discloses a dual-polarization omnidirectional rectenna using a radio frequency power combining scheme. The antenna includes an orthogonally arranged horizontal polarization unit and a vertical polarization unit. The horizontal polarization unit includes a horizontal polarization group, which includes a tapered balun. The center point of the tapered balun is a feeding point. The tapered balun has a plurality of fan-shaped radiating branches evenly distributed circumferentially, and each of the radiating branches is connected to the tapered balun via a gradient microstrip line. The vertical polarization unit includes a reflective layer and a vertical polarization group parallel to the reflective layer. The vertical polarization group includes a connected gradient balun and a dipole, and the feeding point is located at the center of the gradient balun. The present invention provides a circumferentially arranged omnidirectional antenna array to receive horizontally polarized electromagnetic waves, and designs a four-dipole array to receive vertically polarized electromagnetic waves. This allows the antenna to operate in multiple polarization states and has good omnidirectional characteristics.

Description

Technical Field

[0001] The present invention relates to a dual-polarization omnidirectional rectenna adopting a radio frequency power combining solution, and belongs to the technical field of radio frequency rectennas. Background Art

[0002] In recent years, RF energy harvesting has garnered widespread attention and research to meet the energy needs of electronic devices in the Internet of Things (IoT). This forward-looking technology, which uses electromagnetic wave energy to power electronic devices, covers a wide range of fields, including information communications, power systems, medical equipment, and aerospace. Since RF energy is emitted by billions of radio transmitters worldwide, utilizing it to power low-power circuits has become a growing trend. The promotion and application of this technology presents new opportunities for innovative energy supply methods and the reuse of RF energy.

[0003] The core component of an RF energy harvesting system is the rectenna, which consists of an RF energy harvesting antenna and a rectifier circuit. After the RF energy in free space is received by the harvesting antenna, the rectifier circuit converts the RF energy into DC power for use by the load. For RF energy harvesting systems, RF-to-DC conversion efficiency is a key performance metric. During RF energy harvesting, the power of the incident electromagnetic wave is generally low, resulting in low RF power collected by the antenna, which in turn reduces the energy conversion efficiency of the rectifier circuit. Therefore, to increase the collected RF power, an array antenna is required to receive RF energy. When performing omnidirectional RF energy harvesting, multiple array antennas with different orientations can be used to cover a wider range of angles. If the RF energy harvesting antenna can receive electromagnetic waves with multiple polarizations, the system's collection dimensions can be effectively expanded. Because the direction of the incident electromagnetic wave is uncertain, the power received by each array antenna varies time-varyingly, resulting in a time-varying input power to the rectifier circuit behind the array antenna, reducing the system's energy conversion efficiency. Therefore, a rationally designed rectifier circuit integration structure is required to optimize power integration and achieve ideal reception. Patent No. CN114336030A proposes a multi-band omnidirectional rectifier antenna that uses an elliptical printed monopole antenna and a three-way broadband rectifier circuit design for RF energy harvesting. However, this solution cannot operate in scenarios where electromagnetic waves of different polarizations are incident in space. Patent No. CN108039591B proposes a dual-polarized rectifier antenna with harmonic suppression capability that uses a U-shaped slot-coupled dual-polarized antenna and a dual-branch rectifier circuit design to receive electromagnetic wave energy. However, this solution has certain limitations due to its narrow coverage range and inability to eliminate the energy loss caused by power mismatch in the input rectifier circuit. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a dual-polarized omnidirectional rectifying antenna adopting a radio frequency power combining scheme, which can achieve better radio frequency energy collection effect in various complex electromagnetic field environments.

[0005] To achieve the above-mentioned object, the present invention provides a dual-polarized omnidirectional rectifying antenna adopting a radio frequency power combining scheme, comprising an antenna and a rectifying circuit electrically connected, wherein the antenna comprises a horizontal polarization unit and a vertical polarization unit arranged orthogonally;

[0006] The horizontal polarization unit includes a horizontal polarization group, which includes a tapered balun. The center point of the tapered balun is a feeding point. The tapered balun has a plurality of fan-shaped radiation branches evenly distributed in a circumferential direction. Each of the radiation branches is connected to the tapered balun via a gradient microstrip line.

[0007] The vertical polarization unit includes a reflective layer and a vertical polarization group parallel to the reflective layer. The vertical polarization group includes a connected gradient balun and a dipole. The feeding point is located at the center of the gradient balun.

[0008] Furthermore, the antenna further includes a first dielectric substrate and a second dielectric substrate;

[0009] Two horizontal polarization groups are respectively provided on both sides of the first dielectric substrate, and the feeding points of the tapered baluns in the two horizontal polarization groups are coaxially arranged;

[0010] The second dielectric substrate includes an inner cylindrical dielectric substrate and an outer cylindrical dielectric substrate that are nested. A reflective layer is provided on the outer wall of the inner cylindrical dielectric substrate. A vertical polarization unit is provided on the inner and outer walls of the outer cylindrical dielectric substrate respectively. The projection centers of the two vertical polarization units are symmetrically arranged, and the symmetry center is coaxially arranged with the two feeding points.

[0011] Furthermore, first dielectric substrates are provided at both ends of the inner cylinder dielectric substrate in the axial direction, and the feeding points on the two first dielectric substrates are coaxially arranged;

[0012] On the second dielectric substrate, four groups of two centrally symmetrically arranged vertical polarization units are evenly distributed with the axis of the inner cylindrical dielectric substrate as the center.

[0013] Furthermore, a power combining network is provided between the antenna and the rectifier circuit, and the power combining network comprises: a power divider group and a coupler electrically connected;

[0014] The power splitter group includes two power splitters respectively connected to the horizontal polarization unit and the vertical polarization unit. Each power splitter is a one-to-n power splitter, where n is the number of polarization units, and each port of the power splitter is connected to a polarization unit.

[0015] Furthermore, two groups of the rectifier circuits are arranged in parallel and connected to a coupler.

[0016] Furthermore, the rectifier circuit includes a T-junction and a cross junction connected in series, and a diode with a current flow direction from the T-junction to the cross junction is provided between the T-junction and the cross junction;

[0017] Furthermore, each port of the T-junction and the cross junction is connected in series with a microstrip line.

[0018] Furthermore, the power divider is a Wilkinson power divider.

[0019] Furthermore, the center of the fan-shaped circle of the radiation branch is the feeding point.

[0020] Furthermore, the reflective layer is a metal reflective layer.

[0021] The beneficial effects achieved by the present invention are:

[0022] The present invention provides a dual-polarization omnidirectional rectenna using a radio frequency power combining scheme. The present invention provides a circumferentially arranged omnidirectional antenna array to receive horizontally polarized electromagnetic waves, and designs a quad-dipole array to receive vertically polarized electromagnetic waves, so that the antenna can operate in multiple polarization states and has good omnidirectional characteristics.

[0023] The present invention provides an RF power combining network. When performing RF energy collection, a one-to-many power splitter is used to collect RF energy from each polarization unit, thereby reducing the impact of energy differences collected by each unit on rectification efficiency. High and stable energy conversion efficiency can be achieved in different polarization reception test scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a three-dimensional diagram of an antenna in a dual-polarized omnidirectional rectenna using a radio frequency power combining solution provided by an embodiment of the present invention;

[0025] Figure 2 This is a physical diagram of the antenna in the present invention;

[0026] Figure 3 Figure 1 is a diagram showing the S-parameter and isolation simulation and test results of the antenna unit in the present invention;

[0027] Figure 4 The radiation patterns of the antenna in the present invention are simulated and tested on the xoy and yoz planes in the horizontal polarization state;

[0028] Figure 5 The radiation patterns of the antenna in the present invention are simulated and tested on the xoy and yoz planes in the vertical polarization state;

[0029] Figure 6 Schematic diagram of the rectifier circuit in the present invention;

[0030] Figure 7 This is a physical diagram of the rectifier circuit in the present invention;

[0031] Figure 8 1 is a diagram showing simulation and test results of the rectifier circuit efficiency in the present invention;

[0032] Figure 9 Schematic diagram of the structure of the radio frequency power combining network in the present invention;

[0033] Figure 10 A physical diagram of the radio frequency power combining network in the present invention;

[0034] Figure 11 Figure 4 is a diagram showing the S-parameter simulation and test results of the RF power combining network in the present invention;

[0035] Figure 12 This is a graph showing the insertion loss and isolation test results of the RF power combining network in the present invention;

[0036] Figure 13 This is a schematic diagram of the dual-polarized omnidirectional rectifying antenna using the RF power combining solution of the present invention;

[0037] Figure 14 This is a physical picture of the dual-polarization omnidirectional rectifying antenna using the RF power combining solution of the present invention;

[0038] Figure 15 This is a test scenario diagram of a dual-polarized omnidirectional rectenna using the RF power combining solution of the present invention;

[0039] Figure 16 This is a diagram showing the efficiency simulation and test results of the dual-polarization omnidirectional rectifying antenna using the RF power combining solution in the horizontal polarization reception mode of the present invention;

[0040] Figure 17 This is a diagram showing the efficiency simulation and test results of the dual-polarization omnidirectional rectifying antenna using the RF power combining solution in vertical polarization reception;

[0041] Figure 18 This is a diagram showing the efficiency simulation and test results of the dual-polarization omnidirectional rectifying antenna using the RF power combining solution of the present invention when receiving both horizontal and vertical polarizations;

[0042] Figure 19 This is a structural dimension diagram of the dual-polarized omnidirectional rectifying antenna using the RF power combining solution of the present invention;

[0043] In the figure: 100, first dielectric substrate; 110, tapered balun; 120, radiating branch; 130, gradient microstrip line; 200, second dielectric substrate; 210, outer cylindrical dielectric substrate; 220, dipole; 230, gradient balun; 240, reflective layer; 250, inner cylindrical dielectric substrate. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0045] An embodiment of the present invention provides a dual-polarized omnidirectional rectifying antenna adopting a radio frequency power combining scheme, including an electrically connected antenna, a power combining network and a rectifying circuit. In the antenna design part, the embodiment of the present invention adopts two circularly arranged omnidirectional antenna arrays to receive horizontally polarized electromagnetic waves, and adopts a four-dipole 220 array to receive vertically polarized electromagnetic waves, and realizes the dual-polarized omnidirectional antenna array design through reasonable layout; in the rectifying circuit design part, the embodiment of the present invention adopts a half-wave rectification structure to convert radio frequency energy into direct current energy. Considering the power density of radio frequency energy in space, the Schottky diode HSMS-2850 with a low turn-on voltage threshold is selected; in order to reduce the impact of the energy difference collected by each unit on the rectification efficiency, the embodiment of the present invention adopts a power combining network to combine the antenna and the rectifying circuit, and redistributes the energy collected by the antenna, thereby realizing the dual-polarized omnidirectional rectifying antenna array design based on the radio frequency power combining principle.

[0046] In a specific design, the antenna includes a horizontally polarized array and a vertically polarized array. The horizontally polarized array includes two concentrically arranged first dielectric substrates 100. Each first dielectric substrate 100 is a Rogers RO4350B circular dielectric substrate with a relative dielectric constant of 3.66, a loss tangent of 0.0037, and a thickness of 30 mils. The axes of the two first dielectric substrates 100 are located on the same straight line. A horizontally polarized unit is provided on each first dielectric substrate 100. Each horizontally polarized unit includes two horizontally polarized groups, which are located on two surfaces of the first dielectric substrate 100.

[0047] In the specific design, each of the horizontal polarization groups includes a balun, a radiating branch 120 and a microstrip line. The balun is located at the center of the first dielectric substrate 100, and the feeding point coincides with the center of the circle. Several radiating branches 120 are circumferentially uniformly distributed with the balun as the center, and the radiating branches 120 and the balun are connected through a microstrip line. In the design of the present invention, a conical balun 110 is selected, and fan-shaped radiating branches 120 are circumferentially uniformly distributed with the conical balun 110 as the center. The center point of the fan-shaped radiating branch 120 is the center point of the conical balun 110 and the center point of the first dielectric substrate 100. Each radiating branch 120 is connected to the conical balun 110 through a gradient microstrip line 130.

[0048] In a specific design, in the two horizontal polarization groups of the first dielectric substrate 100, the feeding points of the tapered balun 110 are coaxially arranged, and the projections of the radiation branches 120 in the two horizontal polarization groups overlap. However, the projections of the tapered microstrip lines 130 corresponding to the two radiation branches 120 with overlapping projections are symmetrically arranged.

[0049] When designing the horizontal polarization unit on the first dielectric substrate 100 , metal layers are printed on both sides of the first dielectric substrate 100 , and horizontal polarization groups are arranged in the metal layers to complete the horizontal polarization setting.

[0050] In a specific design, the vertical polarization array includes a second dielectric substrate 200, which comprises two nested inner cylindrical dielectric substrates 250 and an outer cylindrical dielectric substrate 210. The second dielectric substrate 200 is made of a C-UV 9400E dielectric substrate with a relative dielectric constant of 3, a loss tangent of 0.05, and a thickness of 0.8 mm. The inner cylindrical substrate and the outer cylindrical dielectric substrate 210 are coaxially arranged, with the inner cylindrical dielectric substrate 250 connected to the two first dielectric substrates 100 at both ends along its axis. The axis of the inner cylindrical dielectric substrate 250 coincides with the axes of the two first dielectric substrates 100. Eight connecting columns are provided between the outer wall of the inner cylindrical dielectric substrate 250 and the inner wall of the outer cylindrical dielectric substrate 210. The ends of the connecting columns connect the outer wall of the inner cylindrical dielectric substrate 250 to the inner wall of the outer cylindrical dielectric substrate 210. A vertical polarization unit is provided on the second dielectric substrate 200.

[0051] In a specific design, the vertical polarization unit includes several vertical polarization groups, each of which includes a metal reflective layer 240 and a vertical polarization unit. The vertical polarization unit is parallel to the metal reflective layer 240, and the metal reflective layer 240 is printed on the outer wall of the inner cylinder dielectric substrate 250. The vertical polarization unit is arranged on the outer cylinder dielectric substrate 210. In the present invention, a vertical polarization unit is respectively arranged on the inner and outer walls of the outer cylinder dielectric substrate 210, and the projection centers of the two vertical polarization units are symmetrically arranged, and the center of symmetry is coaxially arranged with the feeding point of the two vertical polarization units.

[0052] In the specific design, four groups of vertical polarization units symmetrically arranged with two projection centers are evenly distributed with the axis of the inner cylindrical dielectric substrate 250 as the center.

[0053] When designing the vertical polarization group, a rectangular strip dipole 220 and a gradient balun 230 are selected. The invention introduces the gradient balun 230 to effectively improve the impedance matching. The dipole 220 and the gradient balun 230 are made in one piece and printed on a 45 μ m thin film circuit.

[0054] When designing the vertical polarization units on the second dielectric substrate 200 , a metal reflective layer 240 is printed on the outer wall of the inner cylindrical dielectric substrate 250 . The four groups of vertical polarization units share this metal reflective layer 240 .

[0055] When designing the rectifier circuit, the present invention adopts a half-wave rectifier structure to convert radio frequency energy into direct current energy. A T-junction, a diode, and a cross junction are connected in series. The flow direction of the diode is from the T-junction to the cross junction. Considering the power density of radio frequency energy in space, the Schottky diode HSMS-2850 with a low conduction voltage threshold is selected. Microstrip lines are connected in series at each port of the T-junction and the cross junction. The numbers and dimensions of each microstrip line are shown in the figure.

[0056] A power combining network is set between the antenna and the rectifier circuit to combine the antenna and the rectifier circuit to redistribute the collected energy, which can effectively reduce the impact of the energy difference between each unit on the rectification efficiency; in the specific design, the power combining network includes an electrically connected power divider and a coupler, the coupler is connected to two groups of rectifier circuits in parallel, the power divider is used to integrate the energy collected by the polarization unit, including two groups of power dividers connected to the horizontal polarization unit and the vertical polarization unit respectively, the power divider uses a Wilkinson power divider, each of the power dividers is a one-to-n power divider, n is the number of polarization units, and each port of the power divider is connected to a polarization unit. In the present invention, one power divider is divided into two, respectively connected to two horizontal polarization units, and the other power divider is divided into four, respectively connected to four vertical polarization units.

[0057] The size of the specific antenna is combined Figure 19 , see Table 1:

[0058]

[0059] Figure 2 shows a physical image of the antenna in an embodiment of the present invention. It can be seen that to facilitate signal input, each polarization unit of the antenna is soldered to a 50Ω SMA RF cable. To facilitate spatial layout, multiple non-metallized through-holes are machined on the inner cylindrical dielectric substrate. Both the inner and outer cylindrical dielectric substrates are processed using 3D printing, and the vertical polarization unit is printed on a 45mm thick substrate. μ During assembly, the corresponding through holes of different dielectric substrates and the positions of each polarization unit need to be calibrated.

[0060] Figure 3 The simulation and test results of the S parameters and isolation of the antenna in the embodiment of the present invention are provided.

[0061] like Figure 3As shown in (a), the horizontally polarized unit and the vertically polarized unit have good impedance matching at the center frequency of 2.45GHz, and the simulated and tested S parameters are both lower than -30dB. The test impedance bandwidth of the horizontally polarized unit is 2.16GHz~2.77GHz, while the S parameter test results of the vertically polarized unit are less than -10dB in the range of 2.17GHz~2.58GHz; the simulated impedance bandwidth is slightly narrower than the test value. In the range of 2.22GHz~2.66GHz, the S parameter simulation value of the horizontally polarized unit is less than -10dB, while the simulated impedance bandwidth of the vertically polarized unit is 2.31GHz~2.62GHz. Figure 3 As shown in (b), the isolation test and simulation results between the internal ports of the horizontal polarization unit and the vertical polarization unit are both better than 18dB, while the isolation test and simulation results between the ports of the horizontal polarization and vertical polarization units are both better than 55dB.

[0062] Figure 4 The radiation patterns of the antenna in the horizontal polarization state in the xoy and yoz planes, as simulated and tested, are presented for this embodiment of the present invention. The results show that in the xoy plane, the antenna exhibits good omnidirectional radiation characteristics, with maximum actual gains of 5.31 dBi and 5.01 dBi in simulation and testing, respectively. The simulated gain fluctuation is 0.38 dB, while the gain fluctuation in testing is 0.85 dB. In the yoz plane, the antenna's radiation pattern exhibits good symmetry. The cross-polarization of the antenna in both the xoy and yoz planes is less than -30 dB in simulation and testing.

[0063] Figure 5 The radiation patterns of the antenna in the vertical polarization state in the Xoy and Yoz planes of the embodiment of the present invention are provided. It can be found that in the Xoy plane, the simulated value of the antenna gain fluctuation is 0.9dB, corresponding to the gain fluctuation of 1.36dB during testing; the maximum simulated gain reaches 2.25dBi, and the maximum gain value during testing is 1.83dBi. The radiation pattern of the Yoz plane antenna is also symmetrical. In the Xoy plane, the cross-polarization of the antenna is less than -30dB in both simulation and test, while the cross-polarization in the Yoz plane is less than -40dB in both simulation and test.

[0064] Figure 6 shows the principle structure of the rectifier circuit in the embodiment of the present invention. The rectifier circuit uses a Rogers RO4350B dielectric substrate with a thickness of 30 mil, a relative dielectric constant of 3.66, and a loss tangent of 0.0037, and an HSMS-2850 Schottky diode. Its optimal output load is 1900Ω. The circuit structure is simple and the size is small. It has the same operating frequency as the antenna in the embodiment of the present invention. Table 2 provides Figure 6 Dimensional parameters of the rectifier circuit:

[0065]

[0066] Figure 7 A physical diagram of the rectifier circuit in an embodiment of the present invention is shown. An SMA connector is welded to the microstrip line at one end of the rectifier circuit for energy input, and a wire is welded to the other end of the microstrip line to facilitate connection to the load. The front microstrip structure is connected to the metal layer on the back through a circular metallized via for grounding.

[0067] Figure 8 Simulation and test results for the efficiency of the rectifier circuits of the present invention are provided. It is clear that when the input power range of a single rectifier circuit is -8dBm to 9dBm, the actual measured energy conversion efficiency of the rectifier circuit exceeds 50%. This corresponds to a simulated input power range of -7dBm to 4dBm. The maximum rectification efficiency in simulation and test is 70.48% and 71.9%, respectively, both achieved at an input power of 2dBm.

[0068] Figure 9 A schematic diagram of the structure of the RF power combining network in an embodiment of the present invention is given. The RF power combining network also uses a Rogers RO4350B dielectric substrate with a relative dielectric constant of 3.66, a loss tangent of 0.0037, and a thickness of 30 mils. The power combining network includes a one-to-two and a one-to-four Wilkinson power divider and a 3dB directional coupler. The introduction of isolation resistors facilitates the realization of high isolation between ports and reduces energy coupling between branches. Ports 1, 2, 3, 4 and ports 5, 6 of the power combining network correspond to the output ports of the vertically polarized antenna unit and the horizontally polarized antenna unit, respectively. Table 3 provides Figure 9 Structural dimensions of the medium RF power combining network:

[0069]

[0070] Figure 10 shows a physical diagram of the RF power combining network in an embodiment of the present invention. To facilitate energy input and output, the network's ports are soldered with 50Ω SMA connectors. The front of the network is a microstrip structure, with a metal ground on the back. The isolation resistor is an 1812 chip resistor with a resistance of 100Ω.

[0071] Figure 11 The S-parameter simulation and test results of the RF power combining network in the embodiment of the present invention are given.

[0072] It can be found that at the center frequency of 2.45 GHz, the simulated and tested S parameters of each port of the RF power combining network are less than -20 dB, and the corresponding S parameter simulation and test values ​​within the antenna operating bandwidth are both lower than -12 dB.

[0073] Figure 12 The insertion loss and isolation test results of the RF power combining network in accordance with an embodiment of the present invention are provided. The results show that the isolation between each port in the network at 2.45 GHz is better than 25 dB. The insertion loss from the input port of a one-to-four Wilkinson power splitter to the output port of the coupler in the network is 9.2 dB, and the insertion loss from the input port of a one-to-two Wilkinson power splitter to the output port of the coupler is 6.4 dB.

[0074] Figure 13 The schematic diagram of a dual-polarized omnidirectional rectenna using an RF power combining scheme in an embodiment of the present invention is provided. The output ports of the vertically polarized antenna array and the horizontally polarized antenna array are combined by a one-to-four and one-to-two Wilkinson power splitter in the RF power combining network, respectively. A 3dB coupler then evenly distributes the two polarized RF energies before feeding them into two identical rectifier circuits. The load resistance is half that of a single rectifier circuit, at 950Ω.

[0075] Figure 14 shows a physical image of a dual-polarized omnidirectional rectenna using an RF power combining solution, according to an embodiment of the present invention. The RF cables at each unit port of the dual-polarized omnidirectional antenna are connected to the SMA connectors of the RF power combining network, and then to the rectifier circuit via an SMA two-way adapter. The wires on the front and back sides of the two identical rectifier circuits are then connected separately and then to the load terminals.

[0076] Figure 15 The diagram shows the test scenario of the dual-polarized omnidirectional rectifying antenna using the RF power combining solution in the embodiment of the present invention. During the test, an RF signal generator is connected to a power amplifier, and power is transmitted through a horn antenna. The distance between the horn antenna and the present invention is set to 2m. An antenna with a known gain is placed at the receiving position, and the received power is measured using a spectrum analyzer to calculate the incident electromagnetic wave power density at the receiving position. The present invention is then placed on a turntable at the receiving position, and the control of the turntable can adjust the incident angle. The voltage value on the rectifying antenna load is measured by a multimeter to calculate the acquired DC power.

[0077] Figure 16 The efficiency simulation and test results of the dual-polarization omnidirectional rectenna using the RF power combining scheme in horizontal polarization reception are provided. The results show that when the received electromagnetic wave power density is 100.3 μ W / cm 2 The simulation and test results are quite close. Under different incident angles, the rectification efficiency of the present invention simulation is higher than 59%, and the energy conversion efficiency can be maintained above 61% during the test; when the power density of the received electromagnetic wave increases to 251.9 μ W / cm 2When the power is 100W, the efficiency of both simulation and test decreases. At this time, the simulated values ​​of rectification efficiency at all incident angles are greater than 28%, while the tested energy conversion efficiency is greater than 45%. The embodiment of the present invention has good stability during horizontal polarization reception, and the fluctuation of simulation and test efficiency under different power densities and different angles of electromagnetic wave incidence does not exceed 5%.

[0078] Figure 17 The efficiency simulation and test results of the dual-polarization omnidirectional rectenna using the RF power combining scheme in the vertical polarization reception are given. It can be found that when the power density of the incident electromagnetic wave is 287.2 μ W / cm 2 The efficiency simulation of the present invention is in good agreement with the test results. Within the 360° range of the horizontal plane, the rectification efficiency simulation values ​​are all greater than 44%, and the energy conversion efficiency of the actual test is slightly higher and is above 45%; and at the maximum power density of 555.1 μ W / cm 2 When subjected to electromagnetic waves, the present invention achieved minimum simulation and test efficiencies greater than 25% and 35% at various incident angles, respectively. During vertical polarization reception, the present invention exhibited some stability, with fluctuations in simulation efficiency under various conditions less than 6%, and in test efficiency less than 10%.

[0079] Figure 18 The present invention provides the efficiency simulation and test results of the dual-polarization omnidirectional rectenna using the RF power combining scheme when receiving both horizontal and vertical polarizations. The results show that the present invention can achieve the desired reception efficiency when receiving a power density of 133.5 μ W / cm 2 When the electromagnetic wave is applied, the energy conversion efficiency of the simulation and test is very stable at all angles, with the efficiency fluctuation being only 2%; the simulation values ​​of the energy conversion efficiency are all greater than 57%, and the rectification efficiency of the test is better than 58%. μ W / cm 2 The simulated energy conversion efficiency during omnidirectional reception was higher than 29%, while the tested rectification efficiency remained above 45%. The efficiency fluctuations of simulation and test at different angles did not exceed 5%.

[0080] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual-polarized omnidirectional rectenna using a radio frequency power combining scheme, comprising an antenna and a rectifier circuit electrically connected, characterized in that: The antenna includes a horizontal polarization unit and a vertical polarization unit that are orthogonally arranged; The horizontal polarization unit includes a horizontal polarization group, the horizontal polarization group includes a tapered balun (110), the center point of the tapered balun (110) is a feeding point, the tapered balun (110) is uniformly distributed with a plurality of fan-shaped radiation branches (120) in a circumferential direction, and each of the radiation branches (120) is connected to the tapered balun (110) via a gradient microstrip line (130); The vertical polarization unit comprises a reflection layer (240) and a vertical polarization group parallel to the reflection layer (240), the vertical polarization group comprises a connected gradient balun (230) and a dipole (220), and the feeding point is located at the center of the gradient balun (230).

2. The dual-polarization omnidirectional rectenna using the RF power combining scheme according to claim 1, characterized in that: The antenna further comprises a first dielectric substrate (100) and a second dielectric substrate (200); Two horizontal polarization groups are respectively arranged on both sides of the first dielectric substrate (100), and the feeding points of the tapered baluns (110) in the two horizontal polarization groups are coaxially arranged; The second dielectric substrate (200) comprises an inner cylindrical dielectric substrate (250) and an outer cylindrical dielectric substrate (210) which are nested, a reflection layer (240) being provided on the outer wall of the inner cylindrical dielectric substrate (250), and two vertical polarization units being provided on the inner and outer walls of the outer cylindrical dielectric substrate (210), respectively, the projection centers of the two vertical polarization units being symmetrically arranged, and the symmetry centers being coaxially arranged with the two feeding points.

3. The dual-polarization omnidirectional rectenna using the RF power combining scheme according to claim 2, characterized in that: First dielectric substrates (100) are provided at both ends of the inner cylinder dielectric substrate (250) in the axial direction, and the feeding points on the two first dielectric substrates (100) are coaxially arranged; On the second dielectric substrate (200), four groups of two centrally symmetrically arranged vertical polarization units are evenly distributed with the axis of the inner cylindrical dielectric substrate (250) as the center.

4. The dual-polarization omnidirectional rectenna using a radio frequency power combining scheme according to claim 1, characterized in that: A power combining network is provided between the antenna and the rectifier circuit, the power combining network comprising: a power divider group and a coupler electrically connected; The power splitter group includes two power splitters respectively connected to the horizontal polarization unit and the vertical polarization unit. Each power splitter is a one-to-n power splitter, where n is the number of polarization units, and each port of the power splitter is connected to a polarization unit.

5. The dual-polarization omnidirectional rectenna using the RF power combining solution according to claim 4, characterized in that: The rectifier circuits are arranged in two groups in parallel and connected to a coupler.

6. The dual-polarization omnidirectional rectenna using the RF power combining solution according to claim 4, characterized in that: The rectifier circuit includes a T-junction and a cross junction connected in series, and a diode with a current flow direction from the T-junction to the cross junction is arranged between the T-junction and the cross junction.

7. The dual-polarization omnidirectional rectenna using the RF power combining scheme according to claim 6, characterized in that: Each port of the T-junction and the cross junction is connected in series with a microstrip line.

8. The dual-polarization omnidirectional rectenna using the RF power combining solution according to claim 4, characterized in that: The power divider is a Wilkinson power divider.

9. The dual-polarization omnidirectional rectenna using a radio frequency power combining scheme according to claim 2, characterized in that: The center of the fan-shaped circle of the radiation branch (120) is the feeding point.

10. The dual-polarization omnidirectional rectenna using a radio frequency power combining solution according to claim 1, characterized in that: The reflective layer (240) is a metal reflective layer.

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