A four-port time domain antenna

Abstract

The present application belongs to the technical field of ultra-wideband antenna and time domain electromagnetism, and specifically provides a four-port time domain antenna, which simultaneously considers high amplitude radiation field, ultra-wideband, small physical size, high energy utilization rate and low failure risk. The present application mainly consists of an electric dipole bending plate, a feeding part, a parallel plate, an active magnetic dipole plate, a passive magnetic dipole plate and a grounding back plate, is based on an ultra-wideband electromagnetic combination antenna, is split and mirrored in horizontal and vertical directions to form a four-port structure, and can increase the radiation field of the antenna by more than 20% compared with power combination technology under the premise of unchanged input power and physical size, and does not need an additional combiner. In summary, the present application has the advantages of high radiation intensity, large bandwidth, small physical size, high energy utilization rate, low failure risk and the like, and has a wide application prospect in ground penetrating radar, ultra-wideband imaging, unmanned aerial vehicle countermeasures and long-range warning.

Description

Technical Field

[0001] This invention belongs to the field of ultra-wideband antenna technology and time-domain electromagnetics, and specifically provides a four-port time-domain antenna. Background Technology

[0002] With the rapid development of time-domain electromagnetics, time-domain antennas have attracted considerable attention due to their numerous advantages, including large bandwidth, low dispersion, simple structure, and high cost-effectiveness. They are widely used in high-power radiation sources, ground-penetrating radar, and other fields. In time-domain applications, to successfully perform tasks such as long-range detection and imaging, time-domain antennas must exhibit a sufficiently high radiation field.

[0003] Over the past decade, researchers have made significant progress in the development of time-domain antennas, including pulsed radiating antennas, Vivaldi antennas, and combined antennas, which have demonstrated excellent performance. However, despite these advances, single-antenna performance appears to face a bottleneck. Power combining has become a commonly used technique to further enhance the radiation field of time-domain antennas; however, this technique has an inherent characteristic: when the number of combining modules is n and the amplitude of a single module is U, the combined amplitude is only... Instead of nU; furthermore, combiners introduce insertion loss, which increases with the number of combined modules, affecting the overall system performance; therefore, the energy utilization of power combining is relatively low. In addition, combiners introduce additional size, and the increase in system modules leads to greater system complexity and a higher probability of system failure, which is undesirable in modern electronic systems. Based on this, multiport power combining antennas have been proposed to effectively achieve power combining without the need for combiners. Scholars have conducted extensive research on multiport power combining antennas, currently mainly applied to narrowband radiators such as patch antennas, with no relevant literature reporting applications of multiport antennas in the time domain; moreover, designing multiport antennas with direct power combining requires weighted driving signals to match the field distribution in the resonant modes, which undoubtedly increases the complexity of the design process. In addition, radiation field enhancement can also be achieved through spatial synthesis, which is essentially an excitation of the antenna array in the form of equal amplitude and phase. Since the synthesized amplitude of spatial synthesis is proportional to the amplitude of a single module by an integer multiple, it is a more effective method for enhancing the radiation field compared to power synthesis technology. However, the disadvantage of this method is that the physical aperture of the radiator also increases by an integer multiple with the increase of the radiation field.

[0004] It is evident that currently, no antenna in the time domain can simultaneously achieve a high amplitude radiation field, ultra-wide bandwidth, small physical size, high energy efficiency, and low failure risk. Therefore, this invention provides a four-port time-domain antenna to meet the above requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a four-port time-domain antenna that simultaneously achieves a high-amplitude radiation field, ultra-wide bandwidth, small physical size, high energy efficiency, and low failure risk. Under the premise of ensuring ultra-wide bandwidth, this invention utilizes four-port technology to break through the theoretical limit of power combining and improve the radiation field of the time-domain antenna.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A four-port time-domain antenna comprises an electric dipole plate 1, a feeding structure 2, a parallel plate 3, an active magnetic dipole plate 4, a passive magnetic dipole plate 5, and a grounding backplate 6; characterized in that:

[0008] With the center of the grounding backplate 6 as the origin of coordinates O, the grounding backplate 6 is arranged along the xOy plane, and the four-port time-domain antenna has a symmetrical structure about both the yOz plane and the xOz plane.

[0009] The parallel plate 3 is composed of an upper parallel plate 31 and a lower parallel plate 32. The electric dipole plate 1 is composed of first to fourth electric dipole units 11 to 14. The feeding structure 2 is composed of first to fourth feeding units 21 to 24. The active magnetic dipole plate 4 is composed of first to fourth active magnetic dipole units 41 to 44. The passive magnetic dipole plate 5 is composed of first to fourth passive magnetic dipole units 51 to 54. The upper parallel plate 31 and the lower parallel plate 32 are arranged parallel to the xOz plane. The first electric dipole unit 11 and the second electric dipole unit 12 are connected to the grounding back plate 6 through the upper parallel plate 31. The third electric dipole unit 13 and the fourth electric dipole unit 14 are connected to the grounding back plate 6 through the lower parallel plate 32.

[0010] The first to fourth thermocouple units 11 to 14 all adopt a TEM horn structure. For any thermocouple unit, a passive magnetic coupler unit is connected between the thermocouple unit and the parallel plate and is set parallel to the xOy plane. A passive magnetic coupler unit is connected to the passive magnetic coupler unit and points towards the ground back plate and is set parallel to the xOz plane. The power supply unit is connected to the end of the thermocouple unit and is set parallel to the xOz plane.

[0011] Furthermore, in the electric dipole plate 1, the electric dipole unit adopts a gradient structure along both the x-axis and y-axis directions. The gradient methods include: exponential gradient, linear gradient, elliptical gradient, Chebyshev gradient, and Klopfenstein gradient.

[0012] Furthermore, in the power supply structure 2, the power supply unit adopts a rectangular plate structure or a gradient plate structure, and its starting end (the contact end connected to the coaxial connector) has an impedance of 50 ohms.

[0013] Furthermore, in the four-port time-domain antenna, the excitation pulses of a set of electrical couplers symmetrical about the xOz plane adopt opposite polarities.

[0014] It should also be noted that:

[0015] This invention is based on an ultra-wideband electromagnetic combined antenna and has been optimized and improved. The feed unit adopts a planar structure, and its impedance at the contact end with the coaxial connector is 50 ohms. The specific parameters are obtained by theoretical calculation of parallel double lines. The current on the parallel plate is mainly concentrated at the edge. Therefore, without affecting the current distribution at the edge of the parallel plate, any form of hollowing out can be carried out in the middle part of the parallel plate to achieve the purpose of weight reduction. Active magnetic dipole plates and passive magnetic dipole plates are used to adjust the matching degree of the low frequency band of the antenna. Their optimal positions can be determined by simulation according to the application frequency band. Furthermore, based on the four-port structure proposed in this invention, the antenna can be extended to any even number of ports and is not limited to four ports.

[0016] In terms of working principle:

[0017] For four-port power combining, let the unit voltage amplitude be U, and the corresponding antenna radiation field amplitude be m. Under ideal conditions (i.e., the combiner combining efficiency is 100%), the theoretical limit of four-port power combining is 2U, and correspondingly, the limit of the antenna radiation field amplitude is 2m. However, in this invention, with the antenna aperture and total input remaining unchanged, the antenna radiation field amplitude can be increased to about 2.5m, an increase of about 25%, breaking through the limit of power combining technology.

[0018] Based on the above technical solution, the beneficial effects of the present invention are as follows: It provides a four-port time-domain antenna with the following advantages:

[0019] 1. Compared to simply improving the radiation intensity of a time-domain antenna by optimizing the pulse source or the antenna itself, the antenna proposed in this invention can reduce the difficulty of optimizing a single module.

[0020] 2. Compared with power combining technology, the antenna proposed in this invention can break through the theoretical limit of power combining and increase the radiation field by more than 20% on the basis of its theoretical limit.

[0021] 3. Compared with conventional four-port power combining antennas, the antenna proposed in this invention can achieve a relative bandwidth of over 180%;

[0022] 4. This invention has a high degree of freedom; theoretically, any even number of ports can be designed within the same limited range.

[0023] In summary, this invention is based on an ultra-wideband electromagnetic combined antenna, which is segmented and mirrored in both horizontal and vertical directions to form a four-port structure. Simultaneously, in the feeding mode, the polarity of the excitation pulses for the ports corresponding to the upper electrocoupler units 11 and 12 and the lower electrocoupler units 13 and 14 is set to be opposite. Based on this, the invention has advantages such as high radiation intensity, large bandwidth, small physical size, high energy utilization, and low failure risk, and has broad application prospects in applications such as ground-penetrating radar, ultra-wideband imaging, UAV countermeasures, and long-range surveillance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of an existing ultra-wideband electromagnetic combined antenna.

[0025] Figure 2 This is a schematic diagram of the structure of a four-port time-domain antenna in an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the size parameters of a four-port time-domain antenna in an embodiment of the present invention.

[0027] Figure 4 This is a comparison diagram of the excitation modes of the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combination antenna.

[0028] Figure 5 This is a comparison diagram of S11 between the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combination antenna.

[0029] Figure 6 This is a gain comparison diagram between the four-port time-domain antenna in this embodiment of the invention and an existing ultra-wideband electromagnetic combination antenna.

[0030] Figure 7 This is a comparison diagram of the low-frequency radiation pattern (0.2GHz) of the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combined antenna.

[0031] Figure 8 This is a comparison diagram of the intermediate frequency (1.5GHz) radiation pattern of the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combination antenna.

[0032] Figure 9 This is a comparison diagram of the high-frequency domain radiation pattern (3.5GHz) of the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combination antenna.

[0033] Figure 10 This is an excitation waveform diagram of a four-port time-domain antenna and an existing ultra-wideband electromagnetic combination antenna in an embodiment of the present invention.

[0034] Figure 11This is a comparison diagram of the radiation field waveforms of the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combination antenna.

[0035] Figure 12 This is a spectral comparison diagram of the radiation field waveforms of the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combined antenna.

[0036] Figure 13 This is a comparison diagram of the time-domain radiation patterns of the four-port time-domain antenna in this embodiment of the invention and the existing ultra-wideband electromagnetic combined antenna.

[0037] Figure 14 This is a comparison diagram of the radiation field waveforms of a four-port time-domain antenna and an existing ultra-wideband electromagnetic combination antenna under single-port excitation in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] This embodiment provides a four-port time-domain antenna, which is as follows: Figure 1 The ultra-wideband electromagnetic combined antenna shown (hereinafter referred to as the comparative example) is improved by deforming the positive pole part (gradual part) on the basis of the comparative example, so that its width becomes half of the original. At the same time, it is copied and translated in the horizontal direction to form a two-port structure in the positive pole part. Finally, the positive pole part of the two-port structure is symmetrical in the vertical direction to form this embodiment.

[0040] In this embodiment, the four-port time-domain antenna is as follows: Figure 2 As shown, the antenna consists of six parts: an electric dipole plate 1 serving as the electric radiation structure; a feed section 2 connected to the radio frequency coaxial connector; a parallel plate 3, an active magnetic dipole plate 4, and a passive magnetic dipole plate 5 that together with the electric dipole plate 1 form the magnetic radiation structure; and a grounding backplate 6 serving as the common grounding terminal. The entire antenna is made of metal, and in principle, any type of metal material can be selected. Considering rigidity, weight, and conductivity, in this embodiment, 6061 aluminum is selected as the metal used to make the antenna.

[0041] The electric dipole plate 1 of the above-mentioned antenna adopts a gradient structure in both the lateral and longitudinal directions. The lateral gradient is linear, and the longitudinal gradient is exponential. The electric dipole plate can be equivalent to an electric dipole, radiating the electric part. The impedance of the beginning end (the contact end with the coaxial connector) of the feed structure 2 is 50 ohms. The specific parameters are calculated theoretically by parallel double lines. The feed structure 2 can be a rectangular structure or a gradient structure. The specific structure is determined by the width of the beginning end of the electric dipole plate 1. If the width of the beginning end of the electric dipole plate 1 is equal to the width of the end of the feed structure 2 (the contact end with the beginning end of the electric dipole plate 1), then the feed structure 2 is a rectangular structure. If it is not equal, then it is a gradient structure. In this embodiment, the feed structure 2 is a rectangular structure.

[0042] The electric dipole plate 1, the parallel plate 3, and the grounding back plate 6 of the antenna together form a current loop, which forms the magnetic part of the antenna, thereby achieving the purpose of optimizing the low-frequency radiation performance. Since the magnetic dipole moment formed by the current loop formed by the electric dipole plate 1, the parallel plate 3, and the grounding back plate 6 alone is insufficient to achieve a good match with the electric dipole moment formed by the electric dipole bending plate, it is necessary to add an active magnetic dipole plate 4 and a passive magnetic dipole plate 5 to form more current loops, thereby forming more magnetic dipole moments, so as to further match the electric dipole moments.

[0043] The positive radiator of the antenna is composed of a first electric dipole unit 11, a second electric dipole unit 12, a first feed unit 21, a second feed unit 22, an upper parallel plate 31, a first active magnetic dipole unit 41, a second active magnetic dipole unit 42, a first passive magnetic dipole unit 51, a second passive magnetic dipole unit 52, and a grounding backplate 6, corresponding to the two ports of the antenna above the xOz plane.

[0044] The negative radiator of the antenna is composed of a third electric dipole unit 13, a fourth electric dipole unit 14, a third feed unit 23, a fourth feed unit 24, a lower parallel plate 32, a third active magnetic dipole unit 43, a fourth active magnetic dipole unit 44, a third passive magnetic dipole unit 53, a fourth passive magnetic dipole unit 54, and a grounding backplate 6, corresponding to the two ports of the antenna below the xOz plane.

[0045] Referring to the accompanying drawings, specific data for a preferred embodiment of a multi-port time-domain antenna are now provided; such as... Figure 3As shown, the multi-port antenna has a length L of 400mm, a width W of 225mm, and a height H of 300mm; the width W1 of the contact end between the feed section and the RF connector is 26.5mm, and the distance W2 between the first feed unit 21 and the second feed unit 22 is 86mm; the width W3 of the passive magnetic dipole unit is 53.2mm; the length L1 of the feed section 2 is 35mm, and the length L2 of the passive magnetic dipole plate 5 is 85.4mm; the distance L3 between the passive magnetic dipole plate 5 and the parallel plate 3 is 73mm, the distance G1 between the first feed section 21 and the third feed section 23 is 12mm, and the distance G2 between the feed section 2 and the grounding backplate 6 is 2mm; the thickness t of the metal plate is 3mm, and the exponential curve gradient factor r of the electric dipole plate is 0.01.

[0046] like Figure 4 The diagram shows the antenna's excitation modes; the comparative example is excited by a positive excitation, in... Figure 4 The symbol "+" indicates the polarity of the antenna. To maintain the symmetry of the positive and negative currents on the antenna, the electric dipole plates 11, 12 and 13, 14 in this embodiment need to be excited by excitations of different polarities. Figure 4 The middle part is represented by "-".

[0047] like Figure 5 The diagram shows a comparison of S11 between this embodiment and the comparative example. It can be seen that the operating frequency bands of both the comparative example and this embodiment are approximately 0.16–4.5 GHz. This indicates that, as a preferred embodiment of the present invention, the impedance characteristics of this embodiment do not deteriorate after using multi-port technology. Using the wavelength corresponding to the starting frequency as the standard, the electrical lengths corresponding to the comparative example and this embodiment are only 0.21λ(L)×0.12λ(W)×0.16λ(H).

[0048] like Figure 6 The figure shows a comparison of the full-band gain of this embodiment and the comparative example. Obviously, compared with the comparative example, the gain of this embodiment is almost unchanged in the low-frequency band (0.2~0.5GHz), but shows a certain improvement in the high-frequency band (0.5~4GHz). The gains of the comparative example and this embodiment at 0.2GHz are -1.35dBi and -1.2dBi, respectively. When the frequency increases to 3.5GHz, the gains of the comparative example and this embodiment are 9.27dBi and 14.80dBi, respectively.

[0049] like Figure 7 , 8Figures 9 and 10 show a comparison of the E- / H-plane frequency domain radiation patterns of this embodiment and the comparative example at three frequency points: 0.2, 1.5, and 3.5 GHz. Clearly, at 0.2 GHz, the H-plane patterns of both antennas are typical cardioid patterns, demonstrating good low-frequency radiation performance. It is also noteworthy that the E-plane radiation pattern of the antenna exhibits a consistent shape across all frequency points, with the only significant change being gain. Conversely, the H-plane radiation pattern is slightly different. At 0.2 and 1.5 GHz, the shapes of the H-plane radiation patterns of the comparative example and this embodiment are essentially consistent. However, as the frequency increases, the main lobe of the H-plane radiation pattern of this embodiment becomes narrower, and grating lobes begin to appear. Obviously, this embodiment can be represented by a 2-element H-plane array, thus its H-plane beam is narrower than that of the comparative example. Furthermore, as the frequency increases, the close spacing between array elements leads to the appearance of grating lobes. Regarding the E-plane radiation pattern, although this embodiment is excited by two ports in the vertical direction, the current direction is essentially the same as that of the comparative example; therefore, the shapes of the E-plane radiation patterns of the comparative example and this embodiment are almost identical.

[0050] The above description explains the radiation characteristics of the antenna involved in this invention from the frequency domain. Another key aspect of this invention is the time domain characteristics of the antenna. Considering the realism of the design, the positive and negative pulses used for excitation are actual test pulses, rather than ideal pulses provided in the simulation software.

[0051] like Figure 10 The diagram shows the time-domain excitation pulses of this embodiment and the comparative example. The positive pulse is used as the excitation for the comparative example, while the positive and negative pulses are used as the excitations for this embodiment. Both pulses exhibit similar shapes and have no delay. Their peak voltages differ slightly, with the positive pulse at 3.52kV and the negative pulse at 3.49kV. This slight difference has a negligible impact on antenna performance.

[0052] like Figure 11 The diagram shows a comparison of the radiation field waveforms of this embodiment and the comparative example. For ease of comparison, all amplitudes are normalized based on the radiation field amplitude of the comparative example. It can be seen that the amplitude of the comparative example is normalized to 1V / m, corresponding to a radiation field amplitude of 2.52V / m in this embodiment. From a power combining perspective, when the unit amplitude is 1V and the voltage and efficiency of the combiner are 100%, the limit of the quaternary combined circuit pulse amplitude is 2V. When using its excitation antennas, their corresponding radiation field amplitudes should also follow the same proportion; however, it can be seen that the radiation field amplitude of this embodiment exceeds the theoretical limit of power combining. Figure 12 As shown Figure 11 The normalized spectrum of the waveforms shown in the figure shows that, compared with the comparative example, the spectrum of the radiation field corresponding to this embodiment exhibits a significant combination effect. In addition, they show a certain degree of consistency.

[0053] To more intuitively describe the time-domain radiative performance of the comparative model and this embodiment, such as... Figure 13 The figure shows a comparison of the time-domain radiation patterns of this embodiment and the comparative example, similar to... Figure 11 The amplitude of the time-domain radiation pattern is normalized based on the comparative example; since the time-domain radiation pattern is characterized by amplitude, its half-power beamwidth (HPBW) should be limited to 70.7% of the maximum amplitude; therefore, the E-plane HPBW of the comparative example and this embodiment is approximately 41° and 39°, respectively, and the H-plane HPBW is 44° and 34°, respectively; in addition, the time-domain radiation patterns of the comparative example and this embodiment are almost identical, which proves that using multi-port technology does not cause drastic changes in the time-domain radiation characteristics of the antenna.

[0054] Based on the above analysis, compared with the comparative example, the multi-port antenna proposed in this embodiment has the characteristic of exceeding the power combination limit. The following will explain the basic principle behind this phenomenon using simulation methods. Both the comparative example and this embodiment will operate under the same excitation conditions. This means that in this embodiment, only one of the four ports is excited, while the other ports are simulated as external matched loads; for example... Figure 14 The figure shows the normalized radiation waveforms of the comparative example and this embodiment under single-port excitation. In order to maintain consistency with... Figure 11 To maintain consistency, all amplitudes are still normalized based on the comparative model; the radiation field amplitude of the comparative model is set as a reference, corresponding to an amplitude of 0.63 V / m in this embodiment; comparison Figure 14 and Figure 11 As can be seen, the amplitude of the single-port excitation in this embodiment is 0.63V / m, while the amplitude increases to 2.52V / m when fully excited. The amplitude of the fully excited amplitude is exactly an integer multiple of the amplitude of the single-port excitation. Therefore, it can be concluded that in the four-port time-domain antenna proposed in this invention, the behavior between different ports is not power combining, but field combining.

[0055] Based on the above description, combined with Figures 5-14 The results show that this invention has a smaller size (0.21λ(L) × 0.12λ(W) × 0.16λ(H)), a relative bandwidth of 186%, and a radiation field that is more than 25% higher than that of power combining techniques. Furthermore, this invention eliminates the need for an additional combiner, avoiding the insertion loss introduced by combiners. It also simplifies the system composition, significantly reducing the risk of system failure. Therefore, this invention simultaneously achieves a high-amplitude radiation field, ultra-wide bandwidth, small physical size, high energy efficiency, and low failure risk, making it a preferred option for designing high-power time-domain antennas.

[0056] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A four-port time-domain antenna, comprising an electric dipole plate (1), a feeding structure (2), a parallel plate (3), an active magnetic dipole plate (4), a passive magnetic dipole plate (5), and a grounding backplate (6); characterized in that: With the center of the grounding backplate (6) as the origin O, the grounding backplate (6) is set along the xOy plane, and the four-port time-domain antenna has a symmetrical structure about both the yOz plane and the xOz plane; The parallel plate (3) is composed of an upper parallel plate (31) and a lower parallel plate (32). The electric dipole plate (1) is composed of first to fourth electric dipole units (11 to 14). The power supply structure (2) is composed of first to fourth power supply units (21 to 24). The active magnetic dipole plate (4) is composed of first to fourth active magnetic dipole units (41 to 44). The passive magnetic dipole plate (5) is composed of first to fourth passive magnetic dipole units (51 to 54). The upper parallel plate (31) and the lower parallel plate (32) are arranged parallel to the xOz plane. The first electric dipole unit (11) and the second electric dipole unit (12) are connected to the grounding back plate (6) through the upper parallel plate (31). The third electric dipole unit (13) and the fourth electric dipole unit (14) are connected to the grounding back plate (6) through the lower parallel plate (32). The first to fourth thermocouple units (11 to 14) all adopt a TEM horn structure. For any thermocouple unit, a passive magnetic coupler unit is connected between the thermocouple unit and the parallel plate and is set parallel to the xOy plane. A passive magnetic coupler unit is connected to the passive magnetic coupler unit and points towards the ground back plate and is set parallel to the xOz plane. A power supply unit is connected to the end of the thermocouple unit and is set parallel to the xOz plane.

2. The four-port time-domain antenna according to claim 1, characterized in that, In the electric dipole plate (1), the electric dipole unit adopts a gradient structure along both the x-axis and y-axis directions. The gradient methods include: exponential gradient, linear gradient, elliptical gradient, Chebyshev gradient and Klopfenstein gradient.

3. The four-port time-domain antenna according to claim 1, characterized in that, In the power supply structure (2), the power supply unit adopts a rectangular plate structure or a gradient plate structure, and its starting end (the contact end connected to the coaxial connector) has an impedance of 50 ohms.

4. The four-port time-domain antenna according to claim 1, characterized in that, In the four-port time-domain antenna, the excitation pulses of a set of electrocouple elements symmetrical about the xOz plane have opposite polarities.

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