Antipodal vivaldi antenna

Abstract

The utility model relates to an antipodal vivaldi antenna, and belongs to the technical field of antennas. Two opposite plate surfaces of a dielectric substrate of the antenna are respectively covered with a pair of balance radiation arms and antipodal radiation arms, and the balance radiation arms and the antipodal radiation arms on different plate surfaces are oppositely arranged and coincide in the direction perpendicular to the plate surfaces. A metal through hole is further formed in the three-layer plate structure composed of the balance radiation arm, the dielectric substrate and the antipodal radiation arm, the metal through hole is used for electrically connecting the balance radiation arm and the antipodal radiation arm which are opposite to each other, a metal pin is arranged in the metal through hole, and the outer circumferential face of the metal pin is attached to the inner wall of the metal through hole in the circumferential direction of the inner wall of the metal through hole. According to the antipodal vivaldi antenna, the metal pins are arranged in the metal through holes of the conventional antipodal vivaldi antenna, and the added metal pins can enhance the field intensity of an electric field opposite to the phase of the electric field in the vertical direction of the dielectric substrate, so that the degree of reducing the cross polarization level is further improved, and the signal receiving and transmitting quality of the antenna is further improved.

Description

Technical Field

[0001] This utility model relates to a Vivaldi antenna, belonging to the field of antenna technology. Background Technology

[0002] Vivaldi antennas are planar gradient slot antennas that propagate electromagnetic energy by etching gradient slot lines on a dielectric substrate. The minimum and maximum widths of the gradient lines determine the cutoff frequencies at high and low frequencies, respectively. Theoretically, Vivaldi antennas can have an infinitely large operating bandwidth, but the feed network limits the bandwidth of traditional Vivaldi antennas, such as microstrip-to-slot line structures, where the front of the dielectric substrate has short-circuited slot lines and the back of the dielectric substrate has open-circuited microstrip lines.

[0003] To address the bandwidth limitation caused by feeding, the TopVivaldi antenna was invented in 1988. Unlike traditional Vivaldi antennas, the TopVivaldi antenna uses microstrip line feeding directly, resulting in a significantly improved operating bandwidth. Furthermore, the TopVivaldi antenna offers advantages such as stable gain, good port matching, light weight, and ease of fabrication, making it widely applicable in fields such as ground-penetrating radar, ultra-wideband communication, microwave imaging, and measurement.

[0004] The Vivaldi antenna is a heterogeneous structure antenna, where the radiating structure is printed on both sides of a dielectric substrate and gradually expands to form gradient grooves. For example... Figure 1 As shown, in the prior art, the electric field direction of the Vivaldi antenna during operation points from the radiating arm 02 on one side of the substrate 01 to the radiating arm 02 on the other side of the substrate 01. This structure introduces unnecessary cross-polarization because the substrate 01 has thickness, and the electric field in the slot line forms an angle with the plane of the substrate 01, resulting in a normal electric field component perpendicular to the antenna plane, thus worsening the cross-polarization. Furthermore, the worsening of cross-polarization becomes more pronounced with increasing frequency. On the other hand, the size of the substrate limits the opening width of the antenna slot line, resulting in a smaller opening 03 in the Vivaldi antenna, which affects its low-frequency performance. Vivaldi antennas typically use thin dielectric substrates to print radiating patches, which reduces the angle between the electric field and the antenna plane, thereby reducing cross-polarization. A balanced topology structure can also be used, but this structure requires three layers of radiating patches on both sides of the dielectric substrate, making it complex and difficult to manufacture.

[0005] In the traditional Vivaldi antenna end-fire direction, because the electric field is not parallel to the antenna plane, an electric field component perpendicular to the antenna plane is generated, resulting in a relatively high level of cross-polarization of the Vivaldi antenna. Excessive cross-polarization will interfere with the main polarization, thereby affecting the quality of the antenna's transmit and receive signals.

[0006] Patent application CN116487878A discloses a low-cross-polarization Vivaldi antenna. The antenna includes a dielectric substrate with two pairs of topological arms and two balanced arms on it. The topological arms and balanced arms on different surfaces of the substrate are arranged opposite each other. Metal vias are formed in the substrate, through which the topological arms and balanced arms are electrically connected. A dielectric director is located on one side of the substrate, and a reflector is located on the other side. The dielectric director is used to adjust the phase difference of electromagnetic waves at the opening of the Vivaldi antenna. The reflector is used to improve the front-to-back ratio of the electromagnetic waves. Electromagnetic waves radiate from the reflector towards the dielectric director. When the antenna is at a high frequency, the second pair of topological arms couples with the second balanced arm on the other side, generating an electric field in the opposite direction to the first pair of topological arms. This cancels out some of the cross-polarized electromagnetic waves, further reducing the cross-polarization level of the Vivaldi antenna. This antenna can be applied to satellite communications, ground-penetrating radar, microwave imaging, and UWB ultra-wideband communications. This scheme electrically connects the topological radiating arm and the balanced radiating arm through metal vias. When the antenna is excited, the two will generate an electric field that is out of phase with the electric field in the direction perpendicular to the substrate. Therefore, it can reduce the cross-polarization level of the antenna to a certain extent. However, the degree of reduction in cross-polarization level is relatively low, which makes the cross-polarization level of the pair of topological Vivaldi antennas still relatively high, resulting in relatively low quality of antenna transmission and reception signals. Utility Model Content

[0007] The purpose of this invention is to provide a Vivaldi antenna to solve the problem of relatively low signal quality caused by the relatively high cross-polarization level of existing Vivaldi antennas.

[0008] To achieve the above objectives, the solution of this utility model includes:

[0009] This utility model discloses a Vivaldi antenna with a dielectric substrate. Each of the two opposing surfaces of the dielectric substrate is covered with a pair of balanced radiating arms and a pair of opposing radiating arms. The balanced radiating arms and the pair of opposing radiating arms on different surfaces are arranged opposite to each other and coincide in a direction perpendicular to the surface. A metal through hole is also provided on the three-layer plate structure composed of the balanced radiating arms, the dielectric substrate and the pair of opposing radiating arms. The metal through hole is used to electrically connect the opposing balanced radiating arms and the pair of opposing radiating arms. A metal pin is provided in the metal through hole, and the outer peripheral surface of the metal pin is attached to the inner wall of the metal through hole along the circumferential direction of the inner wall of the metal through hole.

[0010] Furthermore, the length of the bonding is less than or equal to the length of the metal through hole.

[0011] Furthermore, the diameter of the metal through-hole ranges from 0.1 mm to 0.5 mm.

[0012] Furthermore, the metal through holes are evenly distributed on the three-layer plate structure.

[0013] Furthermore, the spacing between adjacent metal through holes is less than or equal to 1 mm.

[0014] Furthermore, the surfaces of any one or any combination of the balancing radiating arm, the top radiating arm, the inner wall of the metal through hole, and the metal pin are also coated with copper.

[0015] Furthermore, the dielectric substrate is selected to be 90 mm long, 70 mm wide, and 1 mm high.

[0016] The beneficial effects of this utility model are:

[0017] This invention is an improved version of the Vivaldi antenna, which provides a Vivaldi antenna by setting a metal pin in the metal through hole of the existing Vivaldi antenna. The added metal pin can enhance the field strength of the electric field that is opposite to the phase of the electric field in the direction perpendicular to the dielectric substrate, so as to further improve the degree of reduction of cross polarization level and further improve the quality of antenna signal transmission and reception. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the existing Vivaldi antenna structure.

[0019] Figure 2 This is a schematic diagram of a low-cross-polarization ultrawideband pair topology Vivaldi antenna structure;

[0020] Figure 3 This is a front view of a low cross-polarization ultrawideband pair topology Vivaldi antenna;

[0021] Figure 4 This is a diagram of the back structure of a low cross-polarization ultrawideband pair topology Vivaldi antenna;

[0022] Figure 5 This is a schematic diagram of the voltage standing wave ratio (VSWR) of a Vivaldi antenna based on existing technology.

[0023] Figure 6 This is a schematic diagram of the main polarization and cross-polarization gain of the existing Vivaldi antenna.

[0024] Figure 7 This is a schematic diagram of the voltage standing wave ratio (VSWR) of a low cross-polarization ultrawideband topologically polarized Vivaldi antenna.

[0025] Figure 8 This is a schematic diagram of the main polarization and cross-polarization gain of a low cross-polarization ultrawideband topology Vivaldi antenna;

[0026] Figure 9 This is a schematic diagram of the current distribution of a conventional topological Vivaldi antenna (left) and a low cross-polarization ultrawideband topological Vivaldi antenna (right) at 14.8 GHz.

[0027] Figure 10 This is the E / H plane main polarization cross-polarization pattern of the low cross-polarization ultrawideband pair topology Vivaldi antenna at 6 GHz;

[0028] Figure 11 This is the E / H plane main polarization cross-polarization pattern of the low cross-polarization ultrawideband pair topology Vivaldi antenna at 12 GHz;

[0029] Figure 12 This is the E / H plane main polarization cross-polarization pattern of the low cross-polarization ultrawideband paired topology Vivaldi antenna at 18 GHz.

[0030] Explanation of reference numerals in the attached figures:

[0031] 01. Substrate; 02. Radiation arm; 03. Opening; 1. Dielectric substrate; 2. First pair of topological radiation arms; 3. Second pair of topological radiation arms; 4. First balanced radiation arm; 5. Second balanced radiation arm; 6. Metal pin; 7. Metal microstrip line; 8. Metal reflector. Detailed Implementation

[0032] To address the problems in the prior art, this invention provides a metal pin in the metal through-hole of an existing Vivaldi antenna. The added metal pin enhances the field strength of the electric field that is out of phase with the electric field in the direction perpendicular to the dielectric substrate, thereby further reducing the cross-polarization level.

[0033] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] One implementation method for a Vivaldi antenna:

[0035] A type of Vivaldi antenna, such as Figure 2 As shown, it includes a dielectric substrate 1, two balanced radiating arms and two paired radiating arms. On the two opposite surfaces of the dielectric substrate 1, there is a pair of balanced radiating arms and a pair of paired radiating arms. The two balanced radiating arms are the first balanced radiating arm 4 and the second balanced radiating arm 5, and the two paired radiating arms are the first paired radiating arm 2 and the second paired radiating arm 3.

[0036] Balanced radiating arms and opposing radiating arms on different plates are arranged opposite to each other on the dielectric substrate 1, and coincide in a direction perpendicular to the plate surface of the dielectric substrate 1. That is, the first pair of radiating arms 2 and the second balanced radiating arms 5 are arranged opposite to each other on the dielectric substrate 1, and the second pair of radiating arms 3 and the first balanced radiating arms 4 are arranged opposite to each other on the dielectric substrate 1. The two balanced radiating arms and their opposing opposing radiating arms coincide in a direction perpendicular to the plate surface where the balanced radiating arms are located. Gradual grooves are formed between the balanced radiating arms and the opposing radiating arms. The three-layer plate structure composed of the second balanced radiating arm 5, the dielectric substrate 1, and the first pair of radiating arms 2, and the first balanced radiating arm 4, the dielectric substrate 1, and the first pair of radiating arms 2 are arranged opposite to each other on the plate surface. The three-layer plate structure composed of the second pair of topographic radiating arms 3 also has metal through holes (not shown in the figure). The metal through holes are used to electrically connect the opposing balanced radiating arms and the topographic radiating arms. A metal pin 6 is set in the metal through hole. The outer peripheral surface of the metal pin 6 is attached to the inner wall of the metal through hole along the circumferential direction of the inner wall of the metal through hole. That is, the first pair of topographic radiating arms 2 and the second balanced radiating arm 5, the second pair of topographic radiating arms 3 and the first balanced radiating arm 4 are electrically connected through the metal through holes and the metal pin 6. The metal pin 6 can enhance the field strength of the electric field that is opposite to the phase of the electric field in the direction perpendicular to the dielectric substrate 1, further improving the degree of reduction of cross polarization level and the quality of antenna transmission and reception signals.

[0037] The bonding length refers to the length extending in the direction perpendicular to the radial direction of the metal via. The bonding length is less than or equal to the length of the metal via. When the bonding length is less than the length of the metal via, there is a portion of the inner wall of the metal via that is not in contact with the outer peripheral surface of the metal pin. When the bonding length is equal to the length of the metal via, the inner wall of the metal via is completely in contact with the outer peripheral surface of the metal pin. When the inner wall of the metal via is completely in contact with the outer peripheral surface of the metal pin, the electric field strength, which is opposite to the phase of the electric field in the direction perpendicular to the dielectric substrate 1, is greater than the electric field strength when there is no complete contact. This can further improve the degree of reduction in cross-polarization level and the quality of antenna transmission and reception signals.

[0038] The diameter of the metal via ranges from 0.1 mm to 0.5 mm. As the preferred embodiment, the diameter of the metal via is 0.3 mm, which has the best effect on reducing the cross-polarization level.

[0039] Among them, the number of metal vias is greater than or equal to 1. The more metal vias there are, the greater the field strength of the electric field that is opposite to the phase of the electric field in the direction perpendicular to the dielectric substrate 1, which can further improve the degree of reduction of cross polarization level and the quality of antenna transmission and reception signals.

[0040] The diameter of the metal through holes is consistent.

[0041] Among them, the metal vias are evenly distributed on the three-layer plate structure. The evenly distributed metal vias provide a more continuous current when the antenna is excited, so that the antenna will not generate additional cross-polarization components, thereby further improving the degree of reduction of cross-polarization level and the quality of antenna signal transmission and reception.

[0042] More specifically, the metal vias are closely arranged on the three-layer plate structure, that is, there are as many metal vias as possible on the three-layer plate structure. The number of metal pins 6 is less than or equal to the number of metal vias. When the number of metal pins 6 is equal to the number of metal vias, the metal pins 6 can also be closely distributed in the closely arranged metal vias on the three-layer plate structure. This can maximize the enhancement of the electric field strength that is opposite to the phase of the electric field in the direction perpendicular to the dielectric substrate 1, and further improve the degree of reduction of cross polarization level and the quality of antenna transmission and reception signals.

[0043] Among them, the spacing between adjacent metal vias is less than or equal to 1 mm. When the spacing between metal vias is small, it can be ensured that the current path between the radiating arms on both sides of the dielectric substrate will not be destroyed when the antenna is excited, thereby generating electric fields with opposite phases and the same amplitude between the two connected arms, which can further cancel cross-polarization.

[0044] Among them, the surfaces of any one or any combination of the balanced radiating arm, the topological radiating arm, the inner wall of the metal through hole, and the metal pin are also coated with copper to further strengthen the electrical connection between the balanced radiating arm and the topological radiating arm, improve the degree of reduction of cross polarization level, and further improve the quality of antenna signal transmission and reception.

[0045] The dielectric substrate is selected as having a length of 90 mm, a width of 70 mm, and a height of 1 mm, i.e., dielectric substrate 1 is an F4BM-2 dielectric substrate with dimensions of 90 mm × 70 mm × 1 mm. The dielectric constant of this dielectric substrate is 2.65, and the loss tangent is 0.002.

[0046] Among them, such as Figure 3 As shown on the front of the antenna, the metal microstrip line 7 connects to the first pair of topographic radiating arms 2, as... Figure 4On the back of the antenna shown, the metal reflector 8 is connected to the second pair of topological arms 3. The metal microstrip line 7 is provided with an SMA radio frequency dedicated interface, which is connected to the signal input to the antenna. The electrical signal enters the first pair of topological arms 2 and the second pair of topological arms 3 through the metal microstrip line 7 and the metal reflector 8, respectively.

[0047] The electromagnetic radiation principle of the low cross-polarization ultra-wideband Vivaldi antenna provided by this invention is as follows: A coaxial microstrip line connects the antenna's metal microstrip line and a metal reflector to excite the antenna's radiating arms, thereby radiating electromagnetic waves in the antenna's end-firing direction. The paired and balanced radiating arms in this antenna are arranged opposite each other to increase the current path at low frequencies and reduce cross-polarization at high frequencies. Specifically, the second pair of paired radiating arms 3 is connected to the first balanced radiating arm 4 via a metal pin 6. Therefore, when current reaches the second pair of paired radiating arms 3, it flows along the metal pin 6 into the first balanced radiating arm 4, thus greatly increasing the antenna's low-frequency bandwidth. Furthermore, the radiation of the first pair of paired radiating arms 2 and the second balanced radiating arm 5 is similar. When the antenna is at high frequencies, the second pair of paired radiating arms 3, through coupling with the first balanced radiating arm 4, generates an electric field in the opposite direction to that between the second pair of paired radiating arms 3 and the first pair of paired radiating arms 2, canceling out some of the cross-polarized electromagnetic waves, thus giving the antenna low cross-polarization performance.

[0048] The inner and outer sides of the topological radiating arm are composed of exponentially gradient curves y1 and y2, which can be used to adjust the impedance matching of the Vivaldi antenna. The outer curves of both the topological and balanced radiating arms are exponential curves with a curvature greater than that of the inner curves.

[0049] Vertical electric field components with opposite phases and the same amplitude are generated on the top and balanced radiating arms; a dielectric director is provided on one side of the dielectric substrate, and a reflective ground plane is provided on the other side. The dielectric director is used to adjust the phase difference of the electromagnetic wave at the opening of the Vivaldi antenna; the reflective ground plane is used to improve the front-to-back ratio of the electromagnetic wave; the electromagnetic wave is radiated from the reflective ground plane towards the dielectric director.

[0050] This invention employs a microstrip tapered balun feed, which is simple and easy to manufacture, suitable for printing on a single-layer dielectric substrate, and can achieve impedance transformation over a wide bandwidth. The antenna feed design method includes: printing a metal microstrip line and a metal reflector on both sides of the dielectric substrate, with the metal microstrip line and the metal reflector at the same height, and the curves on both sides of the metal reflector being determined by elliptical curves.

[0051] The beneficial effects of this utility model are as follows:

[0052] 1) It overcomes the unnecessary cross-polarization caused by thicker dielectric substrates. The thickness of the dielectric substrate of the antenna design does not affect the vertical component of the electric field, making the antenna more widely used.

[0053] 2) The antenna uses a single-layer dielectric substrate, which is more convenient to process and manufacture. The double-layer radiation structure solves the shortcomings of the balanced pair topology Vivaldi antenna, such as complex structure and difficult processing.

[0054] 3) The topological and balanced radiating arms are connected by metal pins. When the antenna is excited, the topological and balanced radiating arms on different sides of the dielectric substrate couple with each other, generating electric fields in opposite directions along the antenna normal. This reduces the component of the electric field in the normal direction of the antenna plane, thereby canceling out some of the cross-polarized electromagnetic waves and improving the cross-polarization level of the antenna at high frequencies. The antenna designed in this scheme can be applied to satellite communications, ground-penetrating radar, microwave imaging, and UWB ultra-wideband communications.

[0055] like Figure 3 and Figure 4 As shown, the antenna radiating part, i.e., the radiating arm, has a length L = 9 mm and a width W = 7 mm. The metal microstrip line has a length Ls = 9.87 mm and a width Ws = 2.2 mm. The metal microstrip line 7 (dielectric director) is 10 mm from the boundary G2. The radiating arm is composed of two exponentially gradient curves y1 and y2, which are obtained by the following formula:

[0056]

[0057]

[0058] In the formula, y1 and y2 represent exponentially gradient groove structure curves, R1 and R2 represent groove curvatures, and (x1,y1) and (x2,y2) represent the starting and ending points of the y1 exponentially gradient groove structure curve, respectively. By using the known (x1,y1), (x2,y2), and R1, the variables C1 and C2 of the y1 exponentially gradient groove structure curve can be determined, and thus the y1 curve can be determined. Similarly, the y2 curve can be obtained.

[0059] like Figure 5 As shown, the existing technology provides a voltage standing wave ratio (VSWR) of less than 2 for the Vivaldi topology; as... Figure 6 As shown in the diagram of the Vivaldi antenna gain, the antenna gain is up to 11 dBi in the frequency band. Due to the influence of the dielectric substrate thickness, an electric field component perpendicular to the dielectric substrate appears, which increases the antenna cross-polarization level.

[0060] like Figure 7 As shown, the voltage standing wave ratio (VSWR) of the low cross-polarization ultrawideband Vivaldi antenna of this invention is less than 2.2; Figure 8As shown, due to the addition of a balanced radiating arm structure and the short circuit to the topological radiating arm via metal pins, a longer current loop can be easily formed in the low-frequency band, thus widening the low-frequency bandwidth. At the same time, a vertical electric field component with the same amplitude but opposite phase as that on the topological radiating arm is generated on the balanced radiating arm, and the two cancel each other out. As a result, the Vivaldi antenna in this invention has a lower cross-polarization value, and the electromagnetic waves radiated by the antenna are radiated horizontally, which is beneficial for subsequent antenna array formation.

[0061] like Figure 9 As shown, the current distribution diagrams of the existing topological Vivaldi antenna (left) and the low cross-polarization ultra-wideband topological Vivaldi antenna (right) proposed in this invention are presented at 14.8 GHz. The current distribution is more uniform on the balanced radiating arm and the topological radiating arm of the low cross-polarization ultra-wideband topological Vivaldi antenna, and the antenna gain reaches 10 dBi.

[0062] like Figure 10 As shown, the low cross-polarization ultra-wideband Vivaldi antenna exhibits a cross-polarization pattern in the E / H planes at 6 GHz. The E plane is a parallel electric field plane, which in this case is a radiation plane parallel to the substrate; the H plane is a perpendicular electric field plane, which in this case is a plane perpendicular to the substrate. At 6 GHz, the Vivaldi antenna pattern is symmetrical, exhibits uniform radiation, and has a low level of cross-polarization. Figure 11 As shown, at a frequency of 12 GHz, the Vivaldi antenna pattern is generally symmetrical and has uniform radiation. Due to the presence of balanced radiating arms, cross-polarization is also suppressed. Figure 12 As shown, when the frequency is 18 GHz, the peak gain of the Vivaldi antenna can reach 11.8 dBi, and the gain is uniform throughout the frequency band.

[0063] This invention relates to a low-cross-polarization ultra-wideband Vivaldi antenna. By setting a pair of topological radiating arms and a pair of balanced radiating arms on a dielectric substrate, the current path of the antenna at low frequencies is increased, and the cross-polarization generated at high frequencies is reduced. This results in an impedance bandwidth of 3GHz to 18GHz and a maximum gain of 11.2dBi within the frequency band. It can be applied to satellite communications, ground penetrating radar, microwave imaging, UWB ultra-wideband communications, and other fields, further improving the gain level of the Vivaldi antenna.

Claims

1. A Vivaldi antenna with opposing topologies, comprising a dielectric substrate, wherein a pair of balanced radiating arms and a pair of opposing radiating arms are each covered on two opposing surfaces of the dielectric substrate, the balanced radiating arms and the pair of opposing radiating arms on different surfaces are arranged opposite to each other and coincide in a direction perpendicular to the surfaces, and a metal through-hole is further formed on the three-layer plate structure composed of the balanced radiating arms, the dielectric substrate and the pair of opposing radiating arms, the metal through-hole being used for electrically connecting the opposing balanced radiating arms and the pair of opposing radiating arms, characterized in that... A metal pin is provided inside the metal through hole, and the outer peripheral surface of the metal pin is in circumferential contact with the inner wall of the metal through hole.

2. The Vivaldi antenna according to claim 1, characterized in that, The length of the bonding is less than or equal to the length of the metal through hole.

3. The Vivaldi antenna according to claim 1, characterized in that, The diameter of the metal through-hole ranges from 0.1 mm to 0.5 mm.

4. The Vivaldi antenna according to any one of claims 1 to 3, characterized in that, The metal through holes are evenly distributed on the three-layer plate structure.

5. The Vivaldi antenna according to claim 1, characterized in that, The spacing between adjacent metal through holes is less than or equal to 1 mm.

6. The Vivaldi antenna according to claim 1, characterized in that, The surfaces of any one or any combination of the balancing radiating arm, the top radiating arm, the inner wall of the metal through hole, and the metal pin are also coated with copper.

7. The Vivaldi antenna according to claim 1, characterized in that, The dielectric substrate is selected to be 90 mm long, 70 mm wide and 1 mm high.

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