Terahertz wave band circularly polarized antenna based on sequential rotation feeding

Abstract

The invention discloses a terahertz wave band circularly polarized antenna based on sequential rotation feeding, and belongs to the field of radio frequency front-end devices. The circularly polarized antenna is composed of four microstrip patches, chamfers located on a radiation patch, a microstrip line, a microstrip line feed port, a sequential rotation feed network, a dielectric substrate, a metal ground backboard and a microstrip line matching structure. A 90-degree phase difference is generated by strictly designing the electrical length from each port to the feed network to realize circular polarization performance, right-handed circularly polarized waves are radiated, the radiation gain is 10.47 dB, the 3dB axial ratio bandwidth is greater than 8GHZ, the 3dB axial ratio range exceeds 90 degrees, and the complete half-power beam width is covered. The antenna adopts the microstrip line for feeding, the loss of the microstrip line is small, the microwave transmission characteristic is good, and the antenna radiation efficiency is high. The antenna adopts a single-layer board design, has no complex feed network, and is simple in structure and convenient to manufacture.

Description

Technical Field

[0001] The invention relates to a terahertz band circularly polarized antenna based on sequential rotation feeding, which is mainly used in a communication system in the terahertz frequency band and belongs to the field of radio frequency front-end devices. Background Art

[0002] Sequential rotation feeding technology is widely used in radio frequency identification systems (RFID), fifth-generation mobile communication (5G) systems, satellite communications, and millimeter wave communication systems because it is simple to implement and can effectively improve the bandwidth, gain, and radiation symmetry of circularly polarized antennas without any additional cost. Compared with single-feed port multi-layer circularly polarized antennas and dual-port multi-layer circularly polarized antennas that use perturbation, circularly polarized antennas based on sequential rotation feeding use a single-layer dielectric substrate and have a simple structural design. They do not require a large number of antenna units to form an array, nor do they require the design of a complex array feeding network. They are often used to realize high-gain planar circularly polarized antenna arrays. As RF front-end devices, they can achieve more efficient electromagnetic wave transmission and reception performance.

[0003] The working principle of the circularly polarized antenna based on sequential rotation feeding is based on the output phase of each port being connected in series at 0°, 90°, 180°, and 270° to form a 2*2 unit to excite different current directions, thereby achieving circular polarization performance. The circularly polarized antenna with sequential rotation feeding has the advantages of flexibility, high efficiency, and adaptability, and can reduce hardware costs. Through reasonable feeding network design, it can achieve good matching and radiation characteristics within a specific frequency band. In the future, it is expected to be widely used in millimeter wave communication fields such as wireless communication, satellite communication, Internet of Things, and radar.

[0004] Antenna polarization refers to the direction of the electric field vector when the antenna transmits or receives electromagnetic waves. In communication systems, antenna polarization affects the propagation characteristics and reception effect of the signal. Choosing the right polarization method can improve the transmission efficiency of the signal and reduce interference. For example, satellite communications often use circular polarization to resist signal attenuation caused by multipath propagation, while in some terrestrial wireless communications, linear polarization may be selected to adapt to specific environmental conditions. Reconfigurable technology enables the antenna to switch between multiple polarization radiation modes to meet the application requirements of different scenarios. At present, circularly polarized antennas usually use a single feed port in the form of perturbation, dual-port feeding, and sequential rotation feeding to achieve circular polarization performance.

[0005] At present, conventional circularly polarized antennas are mostly used in low-frequency bands below 10 GHz or satellite communication bands such as Ku / Ka. In the millimeter wave bands above 100 GHz, it is usually difficult to achieve large-scale production due to the complexity of high-frequency design and the difficulty of processing technology. Common circularly polarized antennas usually use single-port feeding or dual-port feeding of multi-layer dielectrics to achieve circular polarization, but in the terahertz band of 300 GHz and above, the circular polarization performance achieved by such antennas is poor, and the feeding network is usually more complex, requiring the design of a multi-layer board structure to carry the power distribution and impedance matching network, which also increases the overall size of the antenna and is difficult to apply to the reconfigurable demand scenarios of future terahertz communications. Summary of the invention

[0006] In order to solve the problems existing in the background technology, the present invention designs a terahertz band circularly polarized antenna based on sequential rotation feeding, which can achieve good circular polarization performance in the millimeter wave band of 140GHz. The designed antenna unit has a low profile, and uses a single-layer quartz glass dielectric plate as a substrate. The feeding method is simple, the process difficulty is low, and it is easy to process and test. The unit used for sequential rotation feeding is a low-profile microstrip antenna with small size, light weight, low cost, easy integration and easy design. The designed terahertz band circularly polarized antenna based on sequential rotation feeding has the characteristics of good circular polarization performance, high gain, and wide circular polarization axis ratio.

[0007] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0008] A terahertz band circularly polarized antenna based on sequential rotation feeding, comprising a dielectric substrate 10 and a metal ground backplane 11, wherein a microstrip patch 4, a microstrip line 7 and a sequential rotation feeding network 9 are arranged on the upper surface of the dielectric substrate 10;

[0009] The microstrip patch is a rectangular metal patch, and there are four of them in total; one of the two corners of each microstrip patch is provided with a cut corner defect, and one of the edges between the two cut corners is connected to a microstrip line 7; the microstrip lines on two adjacent microstrip patches are connected through four branches of a sequentially rotating feeding network 9;

[0010] The sequential rotation feeding network is connected to the feeding port 8 via a microstrip line matching structure 12 .

[0011] Furthermore, the sequential rotation feeding network includes a two-branch node and a four-branch node; the four-branch node is provided with two, respectively connected to the two ends of the two-branch node; the two-branch node is connected to the middle position of the four-branch node; the microstrip line matching structure is connected to the two-branch node.

[0012] Furthermore, the microstrip line, the four branches of the sequential rotation feeding network 9 and the microstrip patch with the cut-corner defect are all rotationally symmetric about the center of the dielectric substrate.

[0013] Furthermore, the four-branch node includes four folding branch nodes connected in sequence; the four folding branch nodes have three 90° bending angles, wherein the direction of the middle bending angle is opposite to the direction of the bending angles at both ends.

[0014] Furthermore, the ends of the four branch sections are provided with extensions for connecting to microstrip lines.

[0015] Furthermore, on the four-branch node, defective cut angles are provided on the back sides of the bending angles at both ends.

[0016] Furthermore, the four microstrip patches have a phase difference of 90°, and the four microstrip lines have a phase difference of 90°.

[0017] Compared with the background technology, the present invention has the following advantages:

[0018] a) The terahertz band circular polarization performance is good and the gain is high. The terahertz band circular polarization antenna based on sequential rotation feeding is used as an integral structure. The bandwidth of the unit on the microwave transmission line is S11<-10dB>12GHZ, and the gain is>10dBi. When feeding through the microstrip line, the loss of the microstrip line is small, the microwave transmission characteristics are good, and the antenna radiation efficiency is high.

[0019] b) The circular polarization axial ratio range is wide, the axial ratio bandwidth is high, and the standing wave ratio is small. The terahertz band circularly polarized antenna based on sequential rotation feeding radiates right-hand circularly polarized waves, with a 3dB axial ratio bandwidth of > 8GHZ and a 3dB axial ratio range of more than 90°, covering the full half-power beam width.

[0020] c) Low profile, small size, easy to manufacture. 1um gold is etched on the quartz glass substrate as the radiation unit and the feeding network. The reflective backplane is a complete layer of gold. The dielectric thickness is 50um. The single-layer board processing is easier to achieve, and does not involve the substrate through-hole process. The gold layer can be realized through the surface process. The feeding structure is simple and can be quickly printed and manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a top view schematic diagram of the complete structure of a terahertz band circularly polarized antenna based on sequential rotation feeding;

[0022] Figure 2 It is a top view schematic diagram of a single microstrip patch structure;

[0023] Figure 3 It is a top view schematic diagram of the microstrip line matching structure;

[0024] Figure 4 It is the front view of the microstrip line matching structure;

[0025] Figure 5 It is a structural front view of the sequential rotating feeding network;

[0026] Figure 6 is the return loss S11 of a single microstrip patch

[0027] Figure 7 It is the 3dB axial ratio bandwidth curve of a single microstrip patch;

[0028] Figure 8 is the gain plot of a single microstrip patch;

[0029] Fig. 9 The return loss S11 of the antenna using a sequential rotating feed network

[0030] Fig.10 It is the 3dB axial ratio bandwidth curve of the antenna using the sequential rotation feeding network;

[0031] Fig.11 is the gain diagram of the antenna using a sequential rotating feed network; DETAILED DESCRIPTION

[0032] The following is combined with Figure 1-11 The specific implementation modes of the present invention are further described in detail with examples.

[0033] A terahertz band circularly polarized antenna based on sequential rotation feeding comprises four microstrip patches 1-4, cut corners 5 and 6 on the radiation patch, a microstrip line 7, a microstrip line feeding port 8, a sequential rotation feeding network 9, a dielectric substrate 10, a metal ground backplane 11 and a microstrip line matching structure 12. The invention is characterized in that it also comprises cut corners 15-20 on the feeding network.

[0034] The four microstrip patches have the same shape and size, with a phase difference of 90°, and are designed with the same size and the same cutting angle. The four microstrip lines have the same size and structure, with a phase difference of 90°, and are located at the end of the microstrip antenna and the beginning of the T-type power divider feeding network.

[0035] The feeding network is designed with impedance matching, and the microstrip line lumped port can be fed through a radio frequency probe. The feeding port is located at the end of the feeding network, and the feeding port is connected to the sequential rotation feeding network 9 through a microstrip line matching structure 12.

[0036] Attach Figure 1 Taking a terahertz band circularly polarized antenna based on sequential rotation feeding as an example, a terahertz band circularly polarized antenna based on sequential rotation feeding includes four microstrip patches 1-4, cut corners 5 and 6 located on the radiation patch, a microstrip line 7, a feeding port 8, a sequential rotation feeding network 9, a dielectric substrate 10, a metal ground backplane 11 and a microstrip line matching structure 12, and is fed by a lumped port of the microstrip line.

[0037] The microstrip patch is directly connected to the microstrip line as the antenna body, and the resonant point can be fine-tuned by adjusting the size of the patch. The cut angle on the sequential rotation feed network is to reduce radiation loss, and the circular polarization performance is achieved by controlling the electrical length from each port to the feed network to produce a 90° phase difference. The different widths of the microstrip lines on the sequential rotation feed network are to better match the patch, and the microstrip line width on the sequential rotation feed network can be adjusted to achieve a good match with the microstrip line feed port.

[0038] The size of the sequential rotary feeding network has been strictly designed, which includes long lines with larger cutting angles and short lines with smaller cutting angles. By exciting currents in different directions at four microstrip patches, circularly polarized waves are synthesized. At the same time, the circular polarization performance can be controlled by adjusting the microstrip line matching structure, which can achieve circularly polarized beam radiation with a 3dB axial ratio bandwidth of 10GHz.

[0039] Attached Figure 2 The single microstrip patch structure shown is a rectangular microstrip antenna, which consists of a dielectric substrate, a ground plane and a microstrip line. The dielectric substrate is made of quartz, which has a large dielectric constant and ensures its structural strength and stability. The cut angles 5 and 6 are used to increase the circular polarization performance of the single microstrip patch.

[0040] Attached Figure 3 The top view of the microstrip line matching structure is shown. In order to achieve a good match with the 50Ω feeding port, the width of the microstrip line needs to be continuously optimized.

[0041] Attached Figure 4 The front view of the microstrip line matching structure is shown. Side feeding is used here to achieve the circular polarization performance of the antenna.

[0042] Attached Figure 5 The sequential rotation feeding network structure is shown. The cut angles 15, 16, 17, 18, 19 and 20 on the sequential rotation feeding network are to reduce radiation loss. The electrical length from each microstrip patch through the side feeding port to the feeding network is controlled to generate a 90° phase difference to synthesize the original planned wave to achieve circular polarization performance. A 1-micron thick metal floor is printed on the lower surface of the dielectric substrate. Without the metal ground, the antenna will radiate to the back lobe and leak a lot of energy. The metal ground is used to reflect the beam and point it to the space in the upper half plane. In order to reduce losses, the metal materials of all structures generally use metals with low resistivity, such as aluminum, copper, gold, etc. The dielectric substrate 10 uses materials with low loss, such as high-resistance silicon, Rogers5880, etc. In this example, the metal material is gold, the dielectric substrate is quartz glass, the dielectric constant is 3.78, and the loss tangent is 0.0008.

[0043] The structure of a terahertz band circularly polarized antenna based on sequential rotation feeding is described in an embodiment by selecting a size combination (the following data units are micrometers):

[0044] when Figure 1 The dimensions of the structure are:

[0045] Microstrip patch 1-4 length × width = 525 × 522, cut corner defect 5-6 length × width = 82, microstrip line 7 length × width = 32 × 294.5, feeding port 8 length × width = 180 × 50, four-branch node 9 line width = 122, dielectric substrate 10 length × width = 2800 × 2800;

[0046] when Figure 2 The dimensions of the structure are:

[0047] Microstrip patch 1-4 length × width = 525 × 522, corner defect 5-6 length × width = 82;

[0048] when Figure 3 The dimensions of the structure are:

[0049] The long narrow section 13 of the microstrip matching structure has a length×width=1242×107, and the short wide section 14 of the microstrip matching structure has a length×width=229.05×157;

[0050] when Figure 4 The dimensions of the structure are:

[0051] The dielectric substrate 10 has a thickness of 50 and the metal back plate 11 has a thickness of 1.

[0052] when Figure 5 The dimensions of the structure are:

[0053] The line width of the four-branch node 9 is 122, the length × width of the defective cutting angles 15, 18 and 20 is 120 × 120, and the length × width of the defective cutting angles 16, 17 and 19 is 91 × 91;

[0054] When the microstrip line is fed, the center frequency is solved to be 140 GHz, which belongs to the terahertz frequency band.

[0055] At this time, a simulation diagram of the reflection coefficient of a terahertz band circularly polarized antenna based on sequential rotation feeding is as follows:

[0056] Figure 6 and Figure 7 This is a graph of return loss S11 and 3dB axial ratio bandwidth of a single microstrip patch, showing that the S11 of the microstrip patch is significantly less than -10dB in the frequency range of 136.34GHz-143.29GHz, and the 3dB axial ratio bandwidth of the microstrip patch is 1.92GHz (138.79GHz-140.71GHz)

[0057] Figure 8 It is the gain diagram of a single microstrip patch, which shows that the microstrip patch achieves good hemispherical circular polarization radiation at the required frequency, and the right-hand circular polarization gain reaches 6.2dBi.

[0058] Fig. 9 and Fig.10 The return loss S11 and 3dB axial ratio bandwidth curve of the sequential rotation feed network antenna shows that the S11 of the unit is significantly less than -10dB in the frequency range of 133.34GHz-145.16GHz, and the 3dB axial ratio bandwidth of the microstrip patch is 8.20GHz (142.40GHz-134.20GHz)

[0059] Fig.11 It is the gain diagram of the sequential rotation feed network antenna, which shows that the unit achieves good hemispherical circular polarization radiation at the required frequency, and the right-hand circular polarization gain reaches 10.47dBi.

[0060] The antenna unit can achieve broadband circular polarization bandwidth when operating in the terahertz frequency band, has high gain, and has a simple structural design. It is composed of only a single-layer board with a low profile. The microstrip line feeding method has a good impedance matching bandwidth and is easy to process and implement.

[0061] The above is only an example. If one wants to obtain a terahertz band circularly polarized antenna based on sequential rotation feeding at different center frequencies, different parameters can be adjusted according to the specific implementation method to achieve different working frequency bands and circular polarization effects.

Claims

1. A terahertz band circularly polarized antenna based on sequential rotation feeding, comprising a dielectric substrate (10) and a metal backplane (11), characterized in that: The upper surface of the dielectric substrate (10) is provided with a microstrip patch (4), a microstrip line (7) and a sequential rotation feeding network (9); The microstrip patch is a rectangular metal patch, and there are four of them in total; one of the two corners of each microstrip patch is provided with a cut corner defect, and one of the edges between the two cut corners is connected to a microstrip line (7); the microstrip lines on two adjacent microstrip patches are connected through four branches of a sequentially rotating feeding network (9); The sequential rotation feeding network is connected to the feeding port (8) via a microstrip line matching structure (12).

2. A terahertz band circularly polarized antenna based on sequential rotation feeding according to claim 1, characterized in that: The sequential rotation feeding network includes a two-branch node and a four-branch node; the four-branch node is provided with two and is respectively connected to the two ends of the two-branch node; the two-branch node is connected to the middle position of the four-branch node; the microstrip line matching structure is connected to the two-branch node.

3. The terahertz band circularly polarized antenna based on sequential rotation feeding according to claim 1, characterized in that: The microstrip line, the four branches of the sequential rotation feeding network (9) and the microstrip patch with the cut-angle defect are all rotationally symmetrical about the center of the dielectric substrate.

4. The terahertz band circularly polarized antenna based on sequential rotation feeding according to claim 2, characterized in that: The four-branch node includes four folding nodes connected in sequence; the four folding nodes have three 90° bending angles, wherein the direction of the middle bending angle is opposite to the direction of the bending angles at both ends.

5. The terahertz band circularly polarized antenna based on sequential rotation feeding according to claim 1, characterized in that: The ends of the four branches are provided with extensions for connecting to microstrip lines.

6. The terahertz band circularly polarized antenna based on sequential rotation feeding according to claim 1, characterized in that: On the four-branch node, defective cut angles are provided on the back sides of the bending angles at both ends.

7. The terahertz band circularly polarized antenna based on sequential rotation feeding according to claim 1, characterized in that: The four microstrip patches have a phase difference of 90°, and the four microstrip lines have a phase difference of 90°.

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