A dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots

Abstract

The present invention discloses a dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots, comprising an upper dielectric plate and a lower dielectric plate. One side of the upper dielectric plate is provided with a radiating conductor patch, a first U-shaped slot and a second U-shaped slot, and respectively provided with a first switching device, a second switching device, a third switching device, and a fourth switching device. Each switching device passes through the arm where it is located and connects the radiating conductor patches on both sides of the arm where it is located. One side of the lower dielectric plate is provided with a microstrip line, one end of the microstrip line is connected to the radiating conductor patch through a conductor column, and the other end serves as an external terminal. The dual-frequency circularly polarized reconfigurable microstrip antenna of the present invention only needs to change the voltage applied to certain circuit modules therein to achieve simultaneous switching of polarization directions in two frequency bands. The antenna has a simple structure and is easy to process, making it easy to switch the polarization direction of the antenna. It is a flexible dual-frequency circularly polarized antenna. The present invention is widely used in the field of antenna technology.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, in particular to a dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots. Background Art

[0002] Circularly polarized antennas, due to their resistance to multipath interference, attenuation, and lack of polarization mismatch, have found widespread application in mobile communications, satellite communications, and radio frequency identification. As frequency resources become increasingly congested, the demand for device integration is also increasing. Antennas capable of receiving and transmitting electromagnetic waves in dual or even multi-bands can replace multiple antennas operating independently, reducing mutual interference while shrinking the antenna size and achieving miniaturization. Combining the advantages of circularly polarized waves has led to the development of dual-band circularly polarized antennas.

[0003] Compared with antennas with fixed polarization direction, polarization reconfigurable antennas have higher degrees of freedom and flexibility in application. Currently, there is a demand for dual-band circularly polarized antennas. Summary of the Invention

[0004] In response to current technical requirements for dual-frequency circularly polarized antennas, an embodiment of the present invention includes a dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots, comprising:

[0005] A dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots, the dual-frequency circularly polarized reconfigurable microstrip antenna comprising:

[0006] An upper dielectric plate; a radiating conductor patch is provided on one side of the upper dielectric plate, the radiating conductor patch having a first U-shaped slot and a second U-shaped slot, the first U-shaped slot surrounding the second U-shaped slot, the opening of the first U-shaped slot and the opening of the second U-shaped slot being in opposite directions; a first switching device is provided on one arm of the first U-shaped slot, and a second switching device is provided on the other arm; a third switching device is provided on one arm of the second U-shaped slot, and a fourth switching device is provided on the other arm; each switching device passes through its respective arm and connects to the radiating conductor patches on both sides of its respective arm, and each switching device can be controlled to be turned on or off;

[0007] A lower dielectric plate; a microstrip line is provided on one side of the lower dielectric plate, one end of the microstrip line is connected to the radiation conductor patch through a conductor column, and the other end of the microstrip line serves as an external connection end.

[0008] Furthermore, the radiating conductor patch is further provided with a first DC-isolating gap and a second DC-isolating gap; the first DC-isolating gap is used for performing DC isolation between the inside and outside of the first U-shaped gap, and the second DC-isolating gap is used for performing DC isolation between the inside and outside of the second U-shaped gap.

[0009] Furthermore, the first DC-isolating gap and the second DC-isolating gap are respectively provided with a plurality of capacitors; each capacitor is respectively connected to the radiation conductor patches on both sides of the DC-isolating gap.

[0010] Furthermore, the lower dielectric plate is provided with an SMA connector, which is connected to the other end of the microstrip line; the other side of the lower dielectric plate is provided with a conductor floor, and the conductor floor is insulated from the conductor column; the other side of the lower dielectric plate is the side opposite to the upper dielectric plate; the conductor column penetrates the upper dielectric plate and the lower dielectric plate, and the connection point between the conductor column and the radiating conductor patch is surrounded by the second U-shaped gap; the upper dielectric plate and the lower dielectric plate are fixed by a nylon column.

[0011] Furthermore, the first switching device, the second switching device, the third switching device and the fourth switching device are all diodes; the positive electrode of the first switching device is connected to the inside of the first U-shaped gap, and the negative electrode is connected to the outside of the first U-shaped gap; the positive electrode of the second switching device is connected to the outside of the first U-shaped gap, and the negative electrode is connected to the inside of the first U-shaped gap; the positive electrode of the third switching device is connected to the inside of the second U-shaped gap, and the negative electrode is connected to the outside of the second U-shaped gap; the positive electrode of the fourth switching device is connected to the outside of the second U-shaped gap, and the negative electrode is connected to the inside of the second U-shaped gap.

[0012] Further, the arm where the first switching device is located and the arm where the third switching device is located are located on the same side of the radiating conductor patch, and the arm where the second switching device is located and the arm where the fourth switching device is located are located on another same side of the radiating conductor patch;

[0013] The switching status of each switching device includes:

[0014] The first switching device and the fourth switching device are turned on, and the second switching device and the third switching device are turned off;

[0015] or

[0016] The first switching device and the fourth switching device are turned off, and the second switching device and the third switching device are turned on;

[0017] When each switching device is in one of the switching states, the antenna has two orthogonal modes in the low-frequency operating band, and these two orthogonal modes work together alternately to excite circularly polarized waves. In the high-frequency band, there are three orthogonal modes, and these three orthogonal modes work together alternately to excite circularly polarized waves.

[0018] Furthermore, the two orthogonal modes of the dual-frequency circularly polarized reconfigurable microstrip antenna in the low-frequency working band are TM 10Patterns and TMs 01 Mode, TM 10 Patterns and TMs 01 When working alone, the modes are linearly polarized and unidirectionally radiate; among them, TM 10 The current of the mode is distributed outside the first U-shaped gap along the x-axis, TM 01 The current of the TM mode is distributed outside the first U-shaped gap along the y-axis; 10 Patterns and TMs 01 The mode polarizations are orthogonal and are 90 degrees out of phase in time under the influence of the first U-shaped slot, TM 10 Patterns and TMs 01 The two modes work together alternately, thereby exciting left-handed / right-handed circularly polarized waves in the low frequency band.

[0019] Furthermore, the three orthogonal modes of the dual-frequency circularly polarized reconfigurable microstrip antenna in the high-frequency operating band are all hybrid modes, and the characteristics of the hybrid mode are dominated by the mode with stronger radiation;

[0020] Among the three orthogonal modes, the first mode is a strong TM distributed inside the second U-shaped gap. 10 Mode and weak TM distribution outside the first U-shaped gap 20 The second mode is a strong TM distributed inside the second U-shaped gap. 10 Mode and weak TM distribution outside the first U-shaped gap 11 The third mode is a strong TM distributed inside the second U-shaped gap. 01 Mode and weak TM distribution outside the first U-shaped gap 02 superposition of patterns;

[0021] The first mode and the second mode have the same current distribution inside the second U-shaped gap, so the first mode and the second mode can be excited at the same time, further generating a new hybrid mode; the new hybrid mode is orthogonal to the polarization of the third mode, and under the influence of the second U-shaped gap, the phase difference in time is 90 degrees; the new hybrid mode and the third mode work alternately together, thereby exciting right-handed / left-handed circularly polarized waves in the high frequency band.

[0022] Furthermore, the switching devices of the first U-shaped slot and the second U-shaped slot have opposite switching states in the two arms, and the switching states affect the rotation direction of the circularly polarized wave;

[0023] The first U-shaped slot works in the low frequency band, and the second U-shaped slot works in the high frequency band. The dual-frequency circularly polarized reconfigurable microstrip antenna radiates circularly polarized waves of different rotation directions in the low frequency band and the high frequency band, respectively, to achieve the function of polarization isolation in different frequency bands.

[0024] Furthermore, the dual-frequency circularly polarized reconfigurable microstrip antenna further includes a 2×2 reconfigurable array;

[0025] The 2×2 reconfigurable array includes four unit radiation patches, and the geometric structure of each unit radiation patch is rotated counterclockwise around the unit center by 0°, 90°, 180° and 270° respectively;

[0026] Among the four unit radiation patches, the feeding phase state of a pair of unit radiation patches at diagonal positions is designed to be ±90° phase flipped, and the feeding phase state of another pair of unit radiation patches at diagonal positions is designed to be fixed at 0° and 180° phases;

[0027] When the feeding phase states of the four unit radiation patches are 0°, +90°, 180° and -90° respectively, the right-hand circularly polarized wave will be strengthened, while the left-hand circularly polarized wave will be weakened, and a radiation null point will be formed at the center, and the radiation pattern will be split into four beams;

[0028] When the feeding phase states of the four unit radiation patches are 0°, -90°, 180° and +90° respectively, the left-hand circularly polarized wave will be strengthened, while the right-hand circularly polarized wave will be weakened. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A three-dimensional view of a dual-frequency circularly polarized reconfigurable microstrip antenna in an embodiment;

[0030] Figure 2 A top view of a dual-frequency circularly polarized reconfigurable microstrip antenna according to an embodiment;

[0031] Figure 3 Schematic diagram of device distribution on the radiating conductor patch in the embodiment;

[0032] Figure 4 A bottom view of a dual-frequency circularly polarized reconfigurable microstrip antenna in an embodiment;

[0033] Figure 5 A side view of a dual-frequency circularly polarized reconfigurable microstrip antenna in an embodiment;

[0034] Figure 6 Schematic diagram of the evolution of the equivalent model of the dual-frequency circularly polarized reconfigurable microstrip antenna in the embodiment;

[0035] Figure 7 Schematic diagram of the reflection coefficient and central axis ratio performance of different forms of double U-shaped slot radiating conductor patches in the embodiment;

[0036] Figure 8 (a) is an equivalent circuit diagram of the radiating conductor patch when the first and fourth switching devices are turned on and the second and third switching devices are turned off in the embodiment;

[0037] Figure 8 (b) is an equivalent circuit diagram of the radiating conductor patch when the first and fourth switching devices are turned off and the second and third switching devices are turned on in the embodiment;

[0038] Figure 9 Schematic diagram of the reflection coefficient and central axis ratio of the antenna in state 1 in the embodiment;

[0039] Figure 10 (a) is a schematic diagram of the radiation field of the antenna in state 1 when operating at 2.45 GHz in the embodiment;

[0040] Figure 10 (b) is a schematic diagram of the radiation field of the antenna in state 1 when operating at 4.05 GHz in the embodiment;

[0041] Figure 11 Schematic diagram of the principle of a 2×2 reconfigurable array using sequential rotation technology in an embodiment;

[0042] Figure 12 Schematic diagram of the feeding network design of the 2×2 reconfigurable array antenna in an embodiment;

[0043] Figure 13 (a) is a front view of a 2×2 reconfigurable array in an embodiment;

[0044] Figure 13 (b) is a back view of the 2×2 reconfigurable array in an embodiment;

[0045] Figure 14 Schematic diagram of the axial ratio performance of a 2×2 reconfigurable array in an embodiment;

[0046] Figure 15 Schematic diagram of the gain performance of a 2×2 reconfigurable array in an embodiment. DETAILED DESCRIPTION

[0047] In this embodiment, refer to Figure 1 The dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots includes an upper dielectric plate 104 and a lower dielectric plate 103. The upper dielectric plate 104 and the lower dielectric plate 103 are fixed together by nylon columns 106, so that the upper dielectric plate 104 and the lower dielectric plate 103 are parallel and maintained at a distance.

[0048] Reference Figure 1A radiating conductor patch 100 is provided on the side of the upper dielectric plate 104 that is not facing the lower dielectric plate 103. Radiating conductor patch 100 can be a metal patch produced through a printing process. A portion of the metal is removed from radiating conductor patch 100 by etching or other means, exposing the upper dielectric plate 104 to form a first U-shaped gap 107 and a second U-shaped gap 109.

[0049] In this embodiment, the structure of the side of the upper dielectric plate 104 where the radiation conductor patch 100 is printed is as follows: Figure 2 and Figure 3 As shown. Figure 2 and Figure 3 The first U-shaped slit 107 and the second U-shaped slit 109 have the same shape. Taking the first U-shaped slit 107 as an example, the first U-shaped slit 107 is formed by connecting three slits into a U-shaped slit, wherein each slit is rectangular when viewed individually. Two slits in the first U-shaped slit 107 are parallel, and the other slit is perpendicular to the two slits. The two parallel slits are not connected end to end to form an opening.

[0050] Reference Figure 2 and Figure 3 The first U-shaped gap 107 and the second U-shaped gap 109 are of different sizes, that is, the lengths of the individual gaps that make up the first U-shaped gap 107 are different from the lengths of the individual gaps that make up the second U-shaped gap 109. The individual gaps that make up the first U-shaped gap 107 are longer, so the first U-shaped gap 107 is larger. The first U-shaped gap 107 can be called a "large U-shaped gap" and the second U-shaped gap 109 can be called a "small U-shaped gap".

[0051] Reference Figure 2 and Figure 3 The second U-shaped slot 109 is surrounded by the first U-shaped slot 107 , and the opening direction of the second U-shaped slot 109 is opposite to the opening direction of the first U-shaped slot 107 .

[0052] Reference Figure 2 and Figure 3 One arm of the first U-shaped slot 107 (one of the two parallel slots) is provided with a first switching device, and the other arm (the other of the two parallel slots) is provided with a second switching device. One arm of the second U-shaped slot 109 is provided with a third switching device, and the other arm is provided with a fourth switching device.

[0053] Reference Figure 2 and Figure 3 Each switching device passes through the arm where it is located and connects the radiation conductor patches 100 on both sides of the arm where it is located. Each switching device can be turned on or off in a controlled manner.

[0054] Taking the first switching device as an example, when the first switching device is turned on, the first switching device can be regarded as an ideal conductor. The radiating conductor patches 100 on both sides of one arm of the first U-shaped slot 107 where the first switching device is located are connected at the location of the first switching device. Since one arm of the first U-shaped slot 107 is a dielectric, when the first switching device is turned on, one arm of the first U-shaped slot 107 is equivalent to being "cut off" at the first switching device, and the equivalent length of one arm of the first U-shaped slot 107 is reduced. Compared with when the first switching device is turned off, the equivalent length of this arm is reduced. When the first switching device is turned off, the first switching device can be regarded as an ideal insulator, and the radiating conductor patches 100 on both sides of one arm of the first U-shaped slot 107 where the first switching device is located are disconnected at the location of the first switching device. Since one arm of the first U-shaped slot 107 is a dielectric, one arm of the first U-shaped slot 107 is equivalent to being "connected" at the first switching device, and the equivalent length of one arm of the first U-shaped slot 107 is restored to the length of the arm itself. Compared with when the first switching device is turned on, the equivalent length of this arm is longer.

[0055] In this embodiment, the structure of the side of the lower dielectric plate 103 where the microstrip line 300 is located is as follows: Figure 4 shown. Figure 4 The side of the lower dielectric plate 103 shown is not opposite to the upper dielectric plate 104. Figure 4 One end of the microstrip line 300 extends to the center of the lower dielectric plate 103 and is connected to one end of the conductor column 101. The other end of the microstrip line 300 extends to the edge of the lower dielectric plate 103 and serves as an external connection end for connection to an excitation source, etc.

[0056] Reference Figure 4 An SMA connector 105 is provided at the edge of the lower dielectric plate 103 and is connected to the other end of the microstrip line 300. The SMA connector 105 can be connected to an excitation source or the like.

[0057] Figure 1 The side view of the dual-frequency circularly polarized reconfigurable microstrip antenna is shown in Figure 5 As shown. Figure 5 The upper dielectric plate 104 is provided with a metallized via 400, and the lower dielectric plate 103 is provided with a metallized via 401. One end of the conductor post 101 passes through the metallized via 400 and reaches the side of the upper dielectric plate 104 provided with the radiation conductor patch 100. One end of the conductor post 101 is connected to the radiation conductor patch 100. Figure 1 The connection point between the conductor post 101 and the radiation conductor patch 100 is surrounded by a second U-shaped slot 109 .

[0058] Reference Figure 5One end of the conductor post 101 passes through the metallized via 401 to reach the side of the lower dielectric board 103 where the microstrip line 300 is provided, and is connected to one end of the microstrip line 300.

[0059] In this embodiment, the conductive post 101 may be made of metal, such as copper.

[0060] In this embodiment, refer to Figure 5 The other side of the lower dielectric plate 103 (the side opposite to the upper dielectric plate 104) is provided with a conductor ground 102. Specifically, the conductor ground 102 can be a metal layer covering the other side of the lower dielectric plate 103. Figure 5 The conductor ground 102 and the conductor post 101 are insulated by an insulating region 402 .

[0061] In this embodiment, refer to Figure 3 A first DC-isolating slot 108 can be provided on the radiating conductor patch 100. One end of the first DC-isolating slot 108 is connected to the end of one arm of the first U-shaped slot 107, and the other end of the first DC-isolating slot 108 is connected to the end of the other arm of the first U-shaped slot 107. In other words, the first DC-isolating slot 108 effectively "seals" the opening of the first U-shaped slot 107. Due to the provision of the first DC-isolating slot 108, the radiating conductor patch 100 within the first U-shaped slot 107 is insulated from the radiating conductor patch 100 outside the first U-shaped slot 107. In other words, the radiating conductor patch 100 within the first U-shaped slot 107 and the radiating conductor patch 100 outside the first U-shaped slot 107 can be at different potentials.

[0062] Reference Figure 3 The first straight-isolating slit 108 “seals” the opening of the first U-shaped slit 107 . The first straight-isolating slit 108 and the first U-shaped slit 107 form a closed figure, and this closed figure encloses the second U-shaped slit 109 .

[0063] When the first DC blocking gap 108 is provided, diodes may be used as the first switching device and the second switching device.

[0064] Reference Figure 3Taking the first switching device as an example, the anode of the diode 200_A, serving as the first switching device, is connected to the radiating conductor patch 100 located within the first U-shaped gap 107, and the cathode of the diode 200_A, serving as the first switching device, is connected to the radiating conductor patch 100 located outside the first U-shaped gap 107. When a higher voltage is applied to the radiating conductor patch 100 located within the first U-shaped gap 107 and a higher voltage is applied to the radiating conductor patch 100 located outside the first U-shaped gap 107, the diode 200_A, serving as the first switching device, is turned off. When a lower voltage is applied to the radiating conductor patch 100 located within the first U-shaped gap 107 and a higher voltage is applied to the radiating conductor patch 100 located outside the first U-shaped gap 107, the diode 200_A, serving as the first switching device, is turned on.

[0065] Similar to the principle of the first isolating gap 108, in this embodiment, referring to Figure 3 A second DC-isolating slot 110 can be provided on the radiating conductor patch 100. One end of the second DC-isolating slot 110 is connected to the end of one arm of the second U-shaped slot 109, and the other end of the second DC-isolating slot 110 is connected to the end of the other arm of the second U-shaped slot 109. In other words, the second DC-isolating slot 110 effectively "seals" the opening of the second U-shaped slot 109. Due to the provision of the second DC-isolating slot 110, the radiating conductor patch 100 within the first U-shaped slot 107 is further divided into two parts: the radiating conductor patch 100 within the second U-shaped slot 109 and the radiating conductor patch 100 outside the second U-shaped slot 109. Furthermore, the radiating conductor patch 100 within the second U-shaped slot 109 is insulated from the radiating conductor patch 100 outside the second U-shaped slot 109, meaning that the radiating conductor patch 100 within the second U-shaped slot 109 and the radiating conductor patch 100 outside the second U-shaped slot 109 can be at different potentials.

[0066] In this embodiment, refer to Figure 3 The first DC-isolating slot is equipped with capacitors such as 201_A, 201_B, and 201_C, while the second DC-isolating slot is equipped with capacitors such as 201_D, 201_E, and 201_F. These capacitors block DC current while allowing AC current to pass through. Taking the first DC-isolating slot as an example, since DC current cannot pass through the first DC-isolating slot, the radiating conductor patches inside and outside the first U-shaped slot can be maintained at different potentials, thereby providing bias voltages for diode 200_A, the first switching device, and diode 200_B, the second switching device. AC current can pass through the first DC-isolating slot via capacitors such as 201_A. Therefore, the radiation pattern of the dual-band circularly polarized reconfigurable microstrip antenna is not affected by the first DC-isolating slot.

[0067] In this embodiment, refer to Figure 3The first switching device is diode 200_A, the second switching device is diode 200_B, the third switching device is diode 200_C, and the fourth switching device is diode 200_D. The first switching device, diode 200_A, and the third switching device, diode 200_C, are located on the same side (right side), while the second switching device, diode 200_B, and the fourth switching device, diode 200_D, are located on the same side (left side).

[0068] In this embodiment, refer to Figure 3 The positive electrode of the first switching device diode 200_A is connected to the inside 500 of the first U-shaped gap, and the negative electrode is connected to the outside 501 of the first U-shaped gap; the positive electrode of the second switching device diode 200_B is connected to the outside 501 of the first U-shaped gap, and the negative electrode is connected to the inside 500 of the first U-shaped gap; the positive electrode of the third switching device diode 200_C is connected to the inside 502 of the second U-shaped gap, and the negative electrode is connected to the outside 500 of the second U-shaped gap; the positive electrode of the fourth switching device diode 200_D is connected to the outside 500 of the second U-shaped gap, and the negative electrode is connected to the inside 502 of the second U-shaped gap.

[0069] In this embodiment, the principle of the dual-frequency circularly polarized reconfigurable microstrip antenna is as follows:

[0070] (1)Reference Figure 6 In the dual-frequency circularly polarized reconfigurable microstrip antenna of this embodiment, the radiating conductor patch with the first U-shaped slot and the second U-shaped slot can be regarded as evolved from a single U-shaped slot patch; Figure 6 In the first image from the left, a single symmetrical U-shaped slotted radiating conductor patch can radiate a single-frequency linearly polarized wave, and the frequency of the radiation is determined by the size of the U-shaped slot and the radiating conductor patch. The larger the U-shaped slot, the lower the radiation frequency. Therefore, referring to Figure 6 In the second image from the left, two symmetrical U-shaped slots of different sizes are opened on the radiating conductor patch. The radiating conductor patch can radiate dual-frequency linear polarization waves. Among them, the first U-shaped slot (the large U-shaped slot) works at low frequency, and the second U-shaped slot (the small U-shaped slot) works at high frequency; while a single asymmetric U-shaped slot can radiate single-frequency circular polarization waves. Therefore, referring to Figure 6 In the third image from the left, the first U-shaped slot is designed to be asymmetric, that is, one arm of the first U-shaped slot is shorter than the other arm, so that the radiating conductor patch can radiate circularly polarized waves in the low frequency band and still radiate linearly polarized waves in the high frequency end band; similarly, referring to Figure 6 In the fourth image from the left, the second U-shaped slot is designed to be asymmetric, so that the radiating conductor patch can radiate circularly polarized waves in the high-frequency band and still radiate linearly polarized waves in the low-frequency band. In summary, referring to Figure 6In the fifth image from the left, if both U-shaped slots are designed to be asymmetric, the radiating conductor patch can radiate circularly polarized waves in two frequency bands at the same time, and the rotation direction of the radiated circularly polarized waves depends on the length of the two arms of the U-shaped slot.

[0071] (2)Reference Figure 6 In the fifth image from the left, the radiating conductive patch has two orthogonal modes in the low-frequency operating band. These two orthogonal modes work together alternately to excite circularly polarized waves. In the high-frequency band, there are three orthogonal modes. These three orthogonal modes work together alternately to excite circularly polarized waves.

[0072] The two orthogonal modes of the radiating conductive patch in the low frequency working band are TM 10 Patterns and TMs 01 mode, these two modes are linearly polarized and unidirectional when working alone. 10 The current of the mode is distributed outside the first U-shaped gap along the x-axis. 01 The current in the two modes is distributed along the y-axis outside the first U-shaped slot. The two modes have orthogonal polarizations and, under the influence of the first U-shaped slot, are 90 degrees out of phase in time. Therefore, the two modes work together alternately, exciting left-handed and right-handed circularly polarized waves in the low-frequency band.

[0073] The three orthogonal modes of the radiating conductive patch in the high-frequency operating band are all mixed modes, and the characteristics of the mixed mode are dominated by the mode with stronger radiation. Among them, the first mode is a strong TM distributed inside the second U-shaped gap. 10 Mode and weak TM distribution outside the first U-shaped gap 20 The second mode is a strong TM distributed inside the second U-shaped gap. 10 Mode and weak TM distribution outside the first U-shaped gap 11 The third mode is a strong TM distributed inside the second U-shaped gap. 01 Mode and weak TM distribution outside the first U-shaped gap 02 Overlay of patterns.

[0074] Because the current distribution within the second U-shaped slot is identical for the first and second modes, they can be excited simultaneously, generating a new hybrid mode. This new hybrid mode is orthogonal to the third mode and, under the influence of the second U-shaped slot, is 90 degrees out of phase in time. Thus, the first and second modes operate alternately, exciting right-handed and left-handed circularly polarized waves at high frequencies.

[0075] (3)Reference Figure 6In the fifth figure from the left, the first U-shaped slot in the radiating conductor patch has a longer left arm and a shorter right arm, while the second U-shaped slot has a shorter left arm and a longer right arm. The two U-shaped slots have opposite arms, and the direction of rotation of the radiated circularly polarized wave depends on the length of the two arms. Since the first U-shaped slot operates in the low-frequency band and the second U-shaped slot operates in the high-frequency band, the antenna radiates left-handed circularly polarized waves in the low-frequency band and right-handed circularly polarized waves in the high-frequency band, respectively, achieving polarization isolation between different frequency bands. Similarly, if the first U-shaped slot in the radiating conductor patch has a shorter left arm and a longer right arm, while the second U-shaped slot has a longer left arm and a shorter right arm, the antenna can radiate left-handed circularly polarized waves in the low-frequency band and right-handed circularly polarized waves in the high-frequency band.

[0076] (4) The reflection coefficient and central axis ratio performance of different types of double U-shaped slot radiating conductor patches are as follows: Figure 7 As shown. The reflection coefficient of the radiating conductor patch with four double U-shaped slots operates in two frequency bands. The axial ratio of the radiating conductor patch with double symmetric U-shaped slots is greater than 3dB in both frequency bands, so it radiates dual-frequency linearly polarized waves. The axial ratio of the radiating conductor patch with an asymmetric first U-shaped slot is less than 3dB in the low frequency band and greater than 3dB in the high frequency band. Therefore, it radiates circularly polarized waves in the low frequency band and linearly polarized waves in the high frequency band. The axial ratio of the radiating conductor patch with an asymmetric second U-shaped slot is greater than 3dB in the low frequency band and less than 3dB in the high frequency band. Therefore, it radiates linearly polarized waves in the low frequency band and circularly polarized waves in the high frequency band. The axial ratio of the radiating conductor patch with double asymmetric U-shaped slots is less than 3dB in both frequency bands, so it radiates dual-frequency circularly polarized waves.

[0077] (5) Since the rotation direction of the radiated circularly polarized wave depends on the length of the two arms of the U-shaped slot, in order to achieve polarization reconfiguration, that is, the antenna can switch between two working states (state 1: radiating left-hand circularly polarized waves in the low frequency band and right-hand circularly polarized waves in the high frequency band; state 2: radiating right-hand circularly polarized waves in the low frequency band and left-hand circularly polarized waves in the high frequency band), four diodes are placed on the two arms of the two U-shaped slots to control the length of the arms of the U-shaped slot. Figure 3 As shown in the figure, when the diode is turned on, the current flowing along the U-shaped gap will flow directly through the diode instead of through the top of the arm, so the arm of the U-shaped gap is equivalently shortened; when the diode is turned off, the current flowing along the U-shaped gap will not flow through the diode, but through the top of the arm, so the arm of the U-shaped gap is equivalently lengthened.

[0078] Based on the above principles (1)-(5), refer to Figure 3, the first U-shaped slot outer portion 500 and the second U-shaped slot inner portion 502 are grounded to 0V, and a voltage of +1.3V is applied to the first U-shaped slot inner portion (second U-shaped slot outer portion) 501. Then, the first switching device diode 200_A and the fourth switching device diode 200_D are turned on, and the second switching device diode 200_B and the third switching device diode 200_C are turned off. At this time, the equivalent circuit of the radiating conductor patch is as follows: Figure 8 As shown in Figure (a), the first U-shaped slot (large U-shaped slot) is equivalent to a long left arm and a short right arm, while the second U-shaped slot (small U-shaped slot) is equivalent to a short left arm and a long right arm. The state of the radiating conductor patch in this state is called State 1. In State 1, the antenna radiates left-handed circularly polarized waves at low frequencies and right-handed circularly polarized waves at high frequencies.

[0079] Based on the above principles (1)-(5), refer to Figure 3 , the first U-shaped slot outer portion 500 and the second U-shaped slot inner portion 502 are grounded to 0V, and a voltage of -1.3V is applied to the first U-shaped slot inner portion (second U-shaped slot outer portion) 501. Then, the first switching device diode 200_A and the fourth switching device diode 200_D are cut off (off), and the second switching device diode 200_B and the third switching device diode 200_C are turned on. At this time, the equivalent circuit of the radiating conductor patch is as follows: Figure 8 As shown in Figure (b), the first U-shaped slot (large U-shaped slot) is equivalent to a short left arm and a long right arm, while the second U-shaped slot (small U-shaped slot) is equivalent to a long left arm and a short right arm. The state of the radiating conductor patch in this state is called State 2. In State 2, the antenna radiates right-handed circularly polarized waves in the low-frequency band and left-handed circularly polarized waves in the high-frequency band.

[0080] The dual-frequency circularly polarized reconfigurable microstrip antenna in this embodiment only needs to change some circuit modules (such as Figure 3 By controlling the voltage inside the first U-shaped slot 501), the polarization direction can be switched simultaneously in two frequency bands. The antenna has a simple structure and is easy to process, and it is easy to switch the polarization direction of the antenna. It is a flexible dual-frequency circularly polarized antenna.

[0081] The simulation results of this antenna in state 1 are as follows Figure 9 and 10 As shown, Figure 9 Schematic diagram of the antenna's reflection coefficient and central axis ratio. The -10dB reflection coefficient bandwidth of the antenna at low and high frequencies are 11.8% and 12.3% respectively, and the 3dB axial ratio bandwidth is 2% and 3.9% respectively. Figure 10 (a) and Figure 10(b) Schematic diagrams of the radiation field when the antenna operates at 2.45 GHz and 4.05 GHz, respectively. The dotted circle represents the radiation field of left-hand circular polarization, and the solid circle represents the radiation field of right-hand circular polarization. Figure 10 From the radiation field diagram of (a), we can see that the dotted coil is in the outer circle and the solid coil is in the inner circle, which means that when the antenna works at 2.45 GHz, the left-hand circular polarization field can be effectively excited. Figure 10 The radiation field diagram in (b) shows the dotted coil in the inner circle and the solid coil in the outer circle, indicating that the antenna can effectively generate a right-handed circularly polarized field when operating at 4.05 GHz. When the antenna switches to State 2, due to the symmetry of the structure, the simulation results for State 1 are essentially the same, with only the polarization direction being reversed.

[0082] In summary, the dual-frequency circularly polarized reconfigurable microstrip patch antenna in this embodiment is designed based on the microstrip patch antenna structure. Since the radiation frequency of the U-shaped slot patch depends on the size of the U-shaped slot, two U-shaped slot patches, one large and one small, can operate in both low-frequency and high-frequency bands. At the same time, the patch formed by the asymmetric U-shaped slot can radiate circularly polarized waves. Based on this, a patch with two asymmetric U-shaped slots of different sizes is proposed. The patch can operate in two frequency bands and radiate circularly polarized waves in both frequency bands at the same time. In order to realize the reconfigurable polarization direction of the circularly polarized wave, a diode is introduced as a switch to control the on and off of the two arms of the U-shaped slot. The two diodes are placed at appropriate positions on the left and right arms of the U-shaped slot, respectively. The right arm diode is turned on and the left arm diode is turned off. In this way, the right arm of the U-shaped slot becomes shorter and the length of the left arm remains unchanged, thus realizing the asymmetry of the U-shaped slot and radiating left-handed circularly polarized waves. When the states of the two diodes switch simultaneously, the asymmetry of the U-shaped slot is reversed, resulting in the radiation of right-handed circularly polarized waves. Therefore, when both U-shaped slots are designed in this way, the antenna can radiate circularly polarized waves at two frequencies simultaneously, with the directions of rotation of the circularly polarized waves being opposite in the two different states. The antenna of this embodiment can be used in fields such as MIMO wireless communication systems and multi-target communications.

[0083] In order to expand the axial ratio bandwidth and make the antenna more practical, the sequential rotation feeding technology is introduced and a 2×2 reconfigurable array is designed.

[0084] Reference Figure 11The four element radiating patches in the 2×2 reconfigurable array all have the same structure and function as the antenna described above, and the geometric structure is rotated counterclockwise around the element center by 0°, 90°, 180°, and 270°, respectively. When the feeding phase states of the four elements of the 2×2 reconfigurable array are 0°, +90°, 180°, and -90°, right-hand circularly polarized waves are enhanced, while left-hand circularly polarized waves are weakened. At the same time, a radiation null is formed at the center, and the radiation pattern is split into four beams. Similarly, when the feeding phase states of the four elements of the 2×2 reconfigurable array are 0°, -90°, 180°, and +90°, left-hand circularly polarized waves are enhanced, while right-hand circularly polarized waves are weakened.

[0085] Based on this principle, refer to Figure 11 The feeding phase state of a pair of diagonally opposite unit radiation patches (unit 2 and unit 4) is designed to be ±90° phase flipped, and the feeding phase state of another pair of diagonally opposite unit radiation patches (unit 1 and unit 3) is designed to be fixed at 0° and 180° phases.

[0086] Table 1 shows the four states of a 2×2 reconfigurable array based on the feeding phase and unit state. To ensure consistency with the unit state definition and facilitate differentiation of array states, the 2×2 reconfigurable array is defined as state 1, where it radiates left-hand circularly polarized waves in the low-frequency band and right-hand circularly polarized waves in the high-frequency band. State 2, where it radiates right-hand circularly polarized waves in the low-frequency band and left-hand circularly polarized waves in the high-frequency band, is defined as state 2. The feeding phases for the low and high frequencies are different for the same state.

[0087] Reference Figure 11 From Table 1, there is a 180° constant phase difference between unit 1 and unit 3, so the phase shifter of unit 3 is designed as a 180° microstrip transmission line. Compared with unit 1, units 2 and 4 need to have a variable ±90° phase difference, so a reconfigurable phase shifter needs to be designed. Based on the above analysis, Figure 12 (a) and (b) show two sets of phase shift networks for low and high frequency bands. In order to achieve antenna reuse and improve the integration of the feeding network, a single-pole double-throw RF switch is used to connect the phase shift networks of the two frequency bands to the antenna. Two one-to-four power dividers are used to feed the phase shifters of the two frequency bands respectively. The complete 2×2 array antenna structure is shown in Figure 2. Figure 12 (c) shown.

[0088] Table 1 2×2 array status

[0089]

[0090] Figure 13An example of implementing this 2×2 reconfigurable array is presented. Each of the four element radiating patches in the array antenna has the same structure and function as the single dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots, with the geometric structure rotated counterclockwise around the element center by 0°, 90°, 180°, and 270°, respectively.

[0091] Reference Figure 13 In order to achieve ±90° wideband phase switching, a microstrip line-slot line-microstrip line structure reconfigurable phase shifter is used. Unit 2 and unit 4 are respectively connected to the reconfigurable phase shifters of two frequency bands, and the phase difference between the two units is 180°, which is determined by the direction of the diode on the reconfigurable phase shifter. Unit 1 and unit 3 are respectively connected to the 0° and 180° microstrip transmission line phase shifters of the two frequency bands. Each unit has two feed signal inputs of low frequency and high frequency, and relies on a single-pole double-throw RF switch to control which signal needs to be input. Each phase shifter uses an SMA connector to input the signal, and eight SMA connectors are externally connected to two one-to-four power dividers for feeding. The performance achieved by the array antenna is as follows Figure 14 and Figure 15 As shown, in state 1, the axial ratio bandwidths for low and high frequencies are 22% and 19%, respectively, and the 3dB gain bandwidths are 17.2% and 18%, respectively. In state 2, the axial ratio bandwidths for low and high frequencies are 19% and 25%, respectively, and the 3dB gain bandwidths are 17.2% and 18%, respectively. The array antenna's bandwidth is more than five times greater than that of a single unit, making it suitable for a wider range of communication scenarios.

[0092] It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly fixed or connected to the other feature, or it may be indirectly fixed or connected to the other feature. In addition, the descriptions of up, down, left, right, etc. used in this disclosure are only relative to the relative positional relationship of the components of the present disclosure in the accompanying drawings. The singular forms of "a", "said" and "the" used in this disclosure are also intended to include the plural forms, unless the context clearly indicates otherwise. In addition, unless otherwise defined, all technical and scientific terms used in this embodiment have the same meaning as those generally understood by those skilled in the art. The terms used in the description of this embodiment are only for describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this embodiment includes any combination of one or more related listed items.

[0093] It should be understood that, although the present disclosure may adopt the term first, second, third etc. to describe various elements, these elements should not be limited to these terms.These terms are only used to distinguish the elements of the same type from each other.For example, without departing from the scope of the present disclosure, the first element may also be referred to as the second element, and similarly, the second element may also be referred to as the first element.The use of any and all examples or exemplary language ("for example", "such as" etc.) provided by the present embodiment is only intended to better illustrate embodiments of the present invention, and unless otherwise required, the scope of the present invention will not be limited.

[0094] It should be appreciated that embodiments of the present invention can be implemented or practiced by computer hardware, a combination of hardware and software, or by computer instructions stored in a non-transitory computer-readable memory. The methods can be implemented in a computer program using standard programming techniques, including a non-transitory computer-readable storage medium configured with a computer program, wherein the storage medium so configured causes the computer to operate in a specific and predefined manner, according to the methods and figures described in the specific embodiments. Each program can be implemented in a high-level procedural or object-oriented programming language to communicate with the computer system. However, if desired, the program can be implemented in assembly or machine language. In any case, the language can be a compiled or interpreted language. In addition, the program can be run on a programmed application-specific integrated circuit for this purpose.

[0095] In addition, the operations of the processes described in this embodiment may be performed in any suitable order, unless otherwise indicated in this embodiment or otherwise clearly contradicted by the context. The processes described in this embodiment (or variations and / or combinations thereof) may be performed under the control of one or more computer systems configured with executable instructions, and may be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) that is executed collectively on one or more processors, by hardware, or a combination thereof. The computer program includes a plurality of instructions that can be executed by one or more processors.

[0096] Furthermore, the methods can be implemented in any type of computing platform that is operably connected to a suitable computer, including but not limited to a personal computer, a minicomputer, a mainframe, a workstation, a network or distributed computing environment, a separate or integrated computer platform, or in communication with a charged particle tool or other imaging device, etc. Various aspects of the present invention can be implemented as machine-readable code stored on a non-transitory storage medium or device, whether removable or integrated into a computing platform, such as a hard disk, an optical read and / or write storage medium, RAM, ROM, etc., so that it can be read by a programmable computer, and when the storage medium or device is read by the computer, it can be used to configure and operate the computer to perform the processes described herein. In addition, the machine-readable code, or portions thereof, can be transmitted over a wired or wireless network. When such media includes instructions or programs that implement the steps described above in conjunction with a microprocessor or other data processor, the invention described in this embodiment includes these and other different types of non-transitory computer-readable storage media. When programmed according to the methods and techniques of the present invention, the present invention also includes the computer itself.

[0097] The computer program can be applied to input data to perform the functions described in the present embodiment, thereby converting the input data to generate output data that is stored in a non-volatile memory. The output information can also be applied to one or more output devices such as a display. In a preferred embodiment of the present invention, the converted data represents a physical and tangible object, including a specific visual depiction of the physical and tangible object produced on the display.

[0098] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the aforementioned embodiments. As long as the technical effects of the present invention are achieved by the same means, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention. Within the scope of protection of the present invention, various modifications and variations of the technical solutions and / or implementation methods are possible.

Claims

1. A dual-frequency circularly polarized reconfigurable microstrip antenna loaded with dual asymmetric U-shaped slots, characterized in that: The dual-frequency circularly polarized reconfigurable microstrip antenna comprises: An upper dielectric plate; a radiating conductor patch is provided on one side of the upper dielectric plate, the radiating conductor patch having a first U-shaped slot and a second U-shaped slot, the first U-shaped slot surrounding the second U-shaped slot, the opening of the first U-shaped slot and the opening of the second U-shaped slot being in opposite directions; a first switching device is provided on one arm of the first U-shaped slot, and a second switching device is provided on the other arm; a third switching device is provided on one arm of the second U-shaped slot, and a fourth switching device is provided on the other arm; each switching device passes through its respective arm and connects to the radiating conductor patches on both sides of its respective arm, and each switching device can be controlled to be turned on or off; A lower dielectric plate; a microstrip line is provided on one side of the lower dielectric plate, one end of the microstrip line is connected to the radiation conductor patch through a conductor column, and the other end of the microstrip line serves as an external connection end.

2. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The radiating conductor patch further has a first DC isolation gap and a second DC isolation gap; the first DC isolation gap is used to perform DC isolation between the inside and outside of the first U-shaped gap, and the second DC isolation gap is used to perform DC isolation between the inside and outside of the second U-shaped gap.

3. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 2, characterized in that: The first DC-isolating gap and the second DC-isolating gap are respectively provided with a plurality of capacitors; each capacitor is respectively connected to the radiation conductor patches on both sides of the DC-isolating gap.

4. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The lower dielectric plate is provided with an SMA connector, which is connected to the other end of the microstrip line; the other side of the lower dielectric plate is provided with a conductor floor, which is insulated from the conductor column; the other side of the lower dielectric plate is the side opposite to the upper dielectric plate; the conductor column penetrates the upper dielectric plate and the lower dielectric plate, and the connection point between the conductor column and the radiating conductor patch is surrounded by the second U-shaped gap; the upper dielectric plate and the lower dielectric plate are fixed by a nylon column.

5. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The first switching device, the second switching device, the third switching device and the fourth switching device are all diodes; the positive electrode of the first switching device is connected to the inside of the first U-shaped gap, and the negative electrode is connected to the outside of the first U-shaped gap; the positive electrode of the second switching device is connected to the outside of the first U-shaped gap, and the negative electrode is connected to the inside of the first U-shaped gap; the positive electrode of the third switching device is connected to the inside of the second U-shaped gap, and the negative electrode is connected to the outside of the second U-shaped gap; the positive electrode of the fourth switching device is connected to the outside of the second U-shaped gap, and the negative electrode is connected to the inside of the second U-shaped gap.

6. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The arm where the first switching device is located and the arm where the third switching device is located are located on the same side of the radiating conductor patch, and the arm where the second switching device is located and the arm where the fourth switching device is located are located on another same side of the radiating conductor patch; The switching status of each switching device includes: The first switching device and the fourth switching device are turned on, and the second switching device and the third switching device are turned off; or The first switching device and the fourth switching device are turned off, and the second switching device and the third switching device are turned on; When each switching device is in one of the switching states, the antenna has two orthogonal modes in the low-frequency operating band, and these two orthogonal modes work together alternately to excite circularly polarized waves. In the high-frequency band, there are three orthogonal modes, and these three orthogonal modes work together alternately to excite circularly polarized waves.

7. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The two orthogonal modes of the dual-frequency circularly polarized reconfigurable microstrip antenna in the low-frequency working band are TM 10 Patterns and TMs 01 Mode, TM 10 Patterns and TMs 01 When working alone, the modes are linearly polarized and unidirectionally radiate; among them, TM 10 The current of the mode is distributed outside the first U-shaped gap along the x-axis, TM 01 The current of the TM mode is distributed outside the first U-shaped gap along the y-axis; 10 Patterns and TMs 01 The mode polarizations are orthogonal and are 90 degrees out of phase in time under the influence of the first U-shaped slot, TM 10 Patterns and TMs 01 The two modes work together alternately, thereby exciting left-handed / right-handed circularly polarized waves in the low frequency band.

8. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The three orthogonal modes of the dual-frequency circularly polarized reconfigurable microstrip antenna in the high-frequency operating band are all hybrid modes, and the characteristics of the hybrid mode are dominated by the mode with stronger radiation; Among the three orthogonal modes, the first mode is a strong TM distributed inside the second U-shaped gap. 10 Mode and weak TM distribution outside the first U-shaped gap 20 The second mode is a strong TM distributed inside the second U-shaped gap. 10 Mode and weak TM distribution outside the first U-shaped gap 11 The third mode is a strong TM distributed inside the second U-shaped gap. 01 Mode and weak TM distribution outside the first U-shaped gap 02 superposition of patterns; The first mode and the second mode have the same current distribution inside the second U-shaped gap, so the first mode and the second mode can be excited at the same time, further generating a new hybrid mode; the new hybrid mode is orthogonal to the polarization of the third mode, and under the influence of the second U-shaped gap, the phase difference in time is 90 degrees; the first mode and the second mode work together alternately, thereby exciting right-handed / left-handed circularly polarized waves in the high frequency band.

9. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The switching devices of the first U-shaped slot and the second U-shaped slot have opposite switching states in the two arms, and the switching states affect the rotation direction of the circularly polarized wave; The first U-shaped slot works in the low frequency band, and the second U-shaped slot works in the high frequency band. The dual-frequency circularly polarized reconfigurable microstrip antenna radiates circularly polarized waves of different rotation directions in the low frequency band and the high frequency band, respectively, to achieve the function of polarization isolation in different frequency bands.

10. The dual-frequency circularly polarized reconfigurable microstrip antenna according to claim 1, characterized in that: The dual-frequency circularly polarized reconfigurable microstrip antenna also includes a 2×2 reconfigurable array; The 2×2 reconfigurable array includes four unit radiation patches, and the geometric structure of each unit radiation patch is rotated counterclockwise around the unit center by 0°, 90°, 180° and 270° respectively; Among the four unit radiation patches, the feeding phase state of a pair of unit radiation patches at diagonal positions is designed to be ±90° phase flipped, and the feeding phase state of another pair of unit radiation patches at diagonal positions is designed to be fixed at 0° and 180° phases; When the feeding phase states of the four unit radiation patches are 0°, +90°, 180° and -90° respectively, the right-hand circularly polarized wave will be strengthened, while the left-hand circularly polarized wave will be weakened, and a radiation null point will be formed at the center, and the radiation pattern will be split into four beams; When the feeding phase states of the four unit radiation patches are 0°, -90°, 180° and +90° respectively, the left-hand circularly polarized wave will be strengthened, while the right-hand circularly polarized wave will be weakened.

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