Super 40 octave directional radiation time domain pulse antenna

Abstract

The invention discloses an over 40 octave directional radiation time domain pulse antenna which is characterized by comprising an excitation plate, a grounding plate, a tuning plate, a left side plate, a right side plate, a reflecting plate, a radio frequency coaxial connector, a left side closing plate and a right side closing plate, all the plates are of metal structures, and the excitation plate is parallel to the lower plate of the grounding plate to form a section of air microstrip line. The intersecting curve of the upper portion and the XOZ face is an exponential gradual change curve, the opening size of the curve in the X direction is increased in an exponential gradual change mode along with increase of the height in the Z direction, an exponential gradual change opening horn is formed, the width of the excitation plate in the Y direction is increased in a linear gradual change mode along with increase of the height in the Z direction, and the width size of the grounding plate in the Y direction is not changed. The working bandwidth of the antenna unit and the array exceeds 40 octaves, and the antenna has the advantages of simple structure, small size, good radiation directionality, high time domain fidelity, good ultra-wideband performance and the like, can be independently used, and is also suitable for forming a large time domain array.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave antennas, and in particular to an ultra-40 octave directional radiation time-domain pulse antenna. Background Art

[0002] The time-domain pulse signal emitted by an impulse radar has an extremely narrow pulse width and its frequency spectrum is distributed in a very wide frequency band range. In order to efficiently radiate the narrow pulse signal, it is required that the operating frequency band of the antenna covers a very wide range and the low frequency is low enough. The time-domain characteristic is a unique parameter index of the impulse radar antenna. Because the impulse radar separates the information of the detected object in the time-domain waveform, the higher the waveform fidelity of the antenna, the smaller the time-domain waveform dispersion and distortion, and the lower the difficulty of the imaging algorithm, and the clearer the imaging. Due to the requirements of directional detection, high radiation efficiency, and device electromagnetic compatibility, the antenna is required to have directional radiation characteristics and array synthesis capabilities.

[0003] Currently, the research on time-domain antennas at home and abroad mostly focuses on the research of small unit antennas in short-distance low-power detection systems, and the requirements for antenna size, directivity, and waveform fidelity are not high. At present, there are few public achievements on directional radiation time-domain antennas and arrays. Conventional TEM horns or slotline antennas are usually used. Because the field mode in the structure of this type of antenna is maintained as the TEM main mode, and the current flow path is consistent with the transmission direction of the electric field, it has good phase linearity and the antenna has high waveform fidelity characteristics. However, the unit size of this type of antenna reaches 0.5 to 1 order of magnitude of the low-frequency wavelength, and the antenna size is large. If the low-frequency coverage is to reach 0.1 GHz, the aperture size of a single antenna reaches 1.5 meters, and the volume is too large and heavy, and it is more unsuitable for use in an array. When the array elements are simultaneously excited, due to the influence of common-mode resonance, cavity resonance, magnetic dipole resonance, etc., the operating bandwidth of the array is limited and is usually restricted within 10 octaves.

[0004] Since 2001, V.I. Koshelev et al. of the High Current Electronics Institute (HCEI) of the Russian Academy of Sciences have disclosed a combined antenna (CA) and array. For example, the nine-element array of the 5-octave combined antenna disclosed in "A Source of High-Power Pulses of Ultra-wideband Radiation with a Nine-Element Array of Combined Antennas" in 2017 uses a structure of a TEM horn combined with a magnetic dipole ring to realize a miniaturized TEM horn antenna. Subsequently, domestic research institutions such as the Northwest Institute of Nuclear Technology and universities such as the University of Electronic Science and Technology have carried out relevant research work on such antennas or tapered slotlines as time-domain antennas and arrays, and the working bandwidth is generally within 10 octaves. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a TEM horn antenna loaded with multiple types of tuning plates. The operating bandwidth of the antenna unit and the array exceeds 40 octaves. The antenna has the advantages of simple structure, small size, good radiation directivity, high time-domain fidelity, and good ultra-wideband performance. It can be used independently or is also suitable for forming a large-scale time-domain array.

[0006] The object of the present invention is achieved through the following technical solutions.

[0007] An ultra-40-octave directional radiation time-domain pulse antenna includes an excitation plate, a ground plate, tuning plates, a left side plate, a right side plate, a reflector, a radio frequency coaxial connector, a left closed plate, and a right closed plate. All the above plates are metal structures. The excitation plate and the ground plate are parallel between the lower plates, forming a section of air microstrip line. The intersection curve with the XOZ plane above is an exponential gradient curve. The opening size of the curve along the X direction increases exponentially with the increase of the Z-direction height, forming an exponential gradient opening horn. The width of the excitation plate in the Y direction increases linearly with the increase of the Z-direction height, and the width dimension of the ground plate in the Y direction remains unchanged.

[0008] The tuning plates include an exponential gradient tuning plate, an upward-tilting tuning plate, a downward-tilting tuning plate, and a vertical tuning plate. The exponential gradient tuning plate, the upward-tilting tuning plate, the downward-tilting tuning plate, the vertical tuning plate, the right side plate, and the left side plate together form a multi-stage magnetic dipole structure to load the TEM horn. The multi-stage different tuning plates are jointly loaded and tuned. By adjusting the positions, sizes, and tilt angles of the tuning plates, the antenna operates in a port matching state across multiple octaves, achieving good port matching, directional radiation performance, and high waveform fidelity over 40 octaves.

[0009] The structure below the excitation plate is an exponential gradient tuning plate, an upward-tilting tuning plate, a downward-tilting tuning plate, and a vertical tuning plate. The intersection curve of the exponential gradient tuning plate with the XOZ plane is an exponential gradient curve. The opening size of the curve in the X direction increases exponentially with the increase of the Z-direction height. The width of the exponential gradient tuning plate in the Y direction increases linearly with the increase of the Z-direction height.

[0010] The upward-tilting tuning plate connects the excitation plate and the right side plate, and is assembled in a left-low and right-high tilt. The width of the upward-tilting tuning plate in the Y direction increases linearly with the increase of the Z-direction height.

[0011] The downward-tilting tuning plate connects the excitation plate and the right side plate, and is assembled in a left-high and right-low tilt. The width of the downward-tilting tuning plate in the Y direction increases linearly with the increase of the Z-direction height.

[0012] The vertical tuning plate is a vertically installed rectangular metal sheet, connecting the exponential gradient tuning plate, the upward-tilting tuning plate, the downward-tilting tuning plate, and the reflector.

[0013] The outer conductor of the radio frequency coaxial connector is installed on the reflector, and the inner conductor pin is connected to the bottom of the excitation plate to feed the antenna; the left closed plate encloses the annular space formed by the ground plate, the left plate and the reflector, and the right closed plate encloses the annular space formed by the excitation plate, the right plate and the tapered tuning plate.

[0014] The radio frequency signal feeds the TEM horn with an exponentially tapered aperture formed by the excitation plate and the ground plate, and the electrical signal is converted from the coaxial electrical signal into free-space electromagnetic signal and radiated outward.

[0015] The lengths, widths and heights of the 40-octave time-domain pulse antenna unit with directional radiation along the X, Y and Z directions are 0.276λ L ×0.16λ L ×0.267λ L , λ L is the electromagnetic wave wavelength corresponding to the low-frequency edge frequency of the operating frequency band of the antenna in air medium.

[0016] When forming an array of units, the two ring structures inside the closed unit are closed and the side plates between adjacent units are electrically continuously assembled.

[0017] Compared with the prior art, the advantages of the present invention are as follows: the present invention overcomes the problems of limited matching and radiation bandwidth existing in the conventional TEM horn antenna and its improved forms (combined antennas), and the further limitation of the operating bandwidth caused by various resonance problems when used in array synthesis.

[0018] 1. Ultra-wideband characteristics: multi-order magnetic dipole loaded and tuned exponentially tapered aperture TEM horn, with an operating bandwidth exceeding 40 octaves, more than 1 time or more than the same type of antenna.

[0019] 2. Simple and compact structure: all-metal structure, which can be realized by welding metal plates. The unit size is only 0.277λL×0.16λL×0.267λL, where λL is the electromagnetic wave wavelength corresponding to the low-frequency edge frequency of the operating frequency band of the antenna in air medium, and the size is reduced by more than 50% compared with the conventional TEM horn antenna.

[0020] 3. Good directional radiation performance: the ratio of the radiation energy in the front and back of the antenna unit reaches 20.1 dB.

[0021] 4. High waveform fidelity: efficiently transmit and receive extremely narrow zero-order Gaussian pulses, and the antenna waveform fidelity reaches 0.9.

[0022] 5. Can be used as a large array unit for array formation: the two ring structures inside the closed unit are closed and the side plates between adjacent units are electrically continuously assembled, and an ultra-wideband time-domain array exceeding 40 octaves can be realized. Description of the Drawings

[0023] Figure 1 Schematic diagram of the antenna structure in Embodiment 1 of the present invention.

[0024] Figure 2 Side view of the antenna structure in Embodiment 1 of the present invention.

[0025] Figure 3 Top view of the antenna structure in Embodiment 1 of the present invention.

[0026] Figure 4 Schematic diagram of the structure where the antenna elements in Embodiment 1 of the present invention form a 4×4 array.

[0027] Figure 5 Excitation signal waveform diagram of the antenna element ports in Embodiment 1 of the present invention.

[0028] Figure 6 Standing wave curve of the antenna element ports in Embodiment 1 of the present invention.

[0029] Figure 7 Time-domain signal waveform at 5 meters in front of and behind the antenna element in Embodiment 1 of the present invention.

[0030] Figure 8 Normalized radiation energy pattern of the E and H main cut planes of the antenna element in Embodiment 1 of the present invention.

[0031] Figure 9 Active standing wave curve of the 4×4 array antenna in Embodiment 1 of the present invention. Detailed implementation manners

[0032] The present invention will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0033] The ultra-wideband time-domain antenna element and array of the present invention are realized by loading multi-order magnetic dipoles on a TEM horn antenna with an exponentially tapered aperture. The TEM horn with an exponentially tapered aperture ensures the TEM main mode working mode, and realizes a stable radiation beam and high waveform fidelity within the working frequency band; multiple types of tuning plates and side plates together constitute a multi-stage magnetic dipole structure to load and tune the TEM horn. The tuning plates include an exponentially tapered tuning plate, an upward-tilting tuning plate, a downward-tilting tuning plate, and a vertical tuning plate, realizing antenna miniaturization and good port impedance matching and directional radiation characteristics over a bandwidth of more than 40 octaves; when forming an array of units, two loop structures inside the closed unit are closed and the side plates between adjacent units are electrically continuously assembled, avoiding the damage to the array performance caused by various malignant resonance problems, and realizing an ultra-wideband time-domain array with a bandwidth of more than 40 octaves.

[0034] An ultra-wideband time-domain pulse antenna element with a radiation direction of more than 40 octaves is shown in the appendix Figures 1 to 3As shown, the specific structure includes: excitation plate 1, ground plate 2, exponentially tapered tuning plate 3, upward-tilting tuning plate 4, downward-tilting tuning plate 5, vertical tuning plate 6, left side plate 7, right side plate 8, reflector 9, RF coaxial connector 10, left closing plate 11 and right closing plate 12. All the above plates are of metal structure.

[0035] Below the excitation plate 1 and the ground plate 2, the plates are parallel to each other, forming a section of air microstrip line. The intersection curve with the XOZ plane above is an exponentially tapered curve. The opening size of the curve along the X direction increases exponentially with the increase of the height in the Z direction, forming an exponentially tapered open-mouth horn. The width of the excitation plate 1 in the Y direction increases linearly with the increase of the height in the Z direction, and the width dimension of the ground plate 2 in the Y direction remains unchanged. The structure below the excitation plate 1 is the exponentially tapered tuning plate 3, upward-tilting tuning plate 4, downward-tilting tuning plate 5 and vertical tuning plate 6. The intersection curve of the exponentially tapered tuning plate 3 with the XOZ plane is an exponentially tapered curve. The opening size of the curve in the X direction increases exponentially with the increase of the height in the Z direction, and the width of the exponentially tapered tuning plate 3 in the Y direction increases linearly with the increase of the height in the Z direction. The upward-tilting tuning plate 4 connects the excitation plate 1 and the right side plate 8, and is assembled in an inclined manner with the left side lower and the right side higher. The width of the upward-tilting tuning plate 4 in the Y direction increases linearly with the increase of the height in the Z direction. The downward-tilting tuning plate 5 connects the excitation plate 1 and the right side plate 8, and is assembled in an inclined manner with the left side higher and the right side lower. The width of the downward-tilting tuning plate 5 in the Y direction increases linearly with the increase of the height in the Z direction. The vertical tuning plate 6 is a vertically installed rectangular metal sheet, connecting the exponentially tapered tuning plate 3, upward-tilting tuning plate 4, downward-tilting tuning plate 5 and the reflector 9. The outer conductor of the RF coaxial connector 10 is installed on the reflector, and the inner conductor pin is connected to the bottom of the excitation plate 1 to feed the antenna. The left closing plate 11 closes the annular space surrounded by the ground plate 2, left side plate 7 and reflector 9, and the right closing plate 12 closes the annular space surrounded by the excitation plate 1, right side plate 8 and tapered tuning plate 3.

[0036] During operation, the RF signal feeds the exponentially tapered open-mouth TEM horn formed by the excitation plate 1 and the ground plate 2 through the RF coaxial connector 10, and the electrical signal is converted from the coaxial electrical signal into free-space electromagnetic signal and radiated outward. The exponentially tapered tuning plate 3, upward-tilting tuning plate 4, downward-tilting tuning plate 5, vertical tuning plate 6, right side plate 7 and left side plate 8 together form a multi-stage magnetic dipole loop to load the TEM horn. By adjusting the positions, sizes and tilt angles of the respective tuning plates, the antenna operates in a port-matched state across multiple octaves and obtains good radiation performance. The lengths, widths and heights of the directional radiation 40-octave time-domain pulse antenna unit along the X, Y and Z directions are 0.276λ L ×0.16λ L ×0.267λ L ,λ Lis the electromagnetic wave wavelength corresponding to the low-frequency edge frequency of the operating frequency band of the antenna in the air medium. Multiple different tuning plates are jointly loaded for tuning to realize the miniaturization of the antenna, and achieve good port matching, directional radiation performance, and high waveform fidelity with an ultra-40 octave bandwidth.

[0037] When forming an array of units, the two loop structures inside the closed unit are electrically continuous with the side plates between adjacent units, avoiding the damage to the array performance caused by various malignant resonance problems, and realizing an ultra-40 octave broadband time-domain array.

[0038] The following gives specific embodiments in accordance with the above design, assembly and fixing methods, and dimensional requirements.

[0039] The operating frequency band of an ultra-40 octave directional radiation time-domain pulse antenna in this embodiment covers 0.1 - 4 GHz. As Figure 1 shown, the length × width × height of the antenna unit in the X, Y, and Z directions = 830 mm × 480 mm × 800 mm. The exponential gradient rates of the excitation plate 1, the ground plate 2, and the exponential gradient tuning plate 3 are all 0.005. The starting Z coordinate of the gradient curves of the excitation plate 1 and the ground plate 2 is 30 mm, and the distance between the bottom parallel plates is 3 mm. The starting and ending Z coordinates of the gradient curve of the exponential gradient tuning plate 3 are 216 mm and 552 mm respectively. The starting and ending Z coordinates of the upward-tilting tuning plate 4 are 216 mm and 300 mm respectively, and the width at the end along the y direction is 300 mm. The starting and ending Z coordinates of the downward-tilting tuning plate 5 are 216 mm and 150 mm respectively, and the width at the end along the Y direction is 240 mm. The vertical tuning plate 6 is 250 mm away from the RF coaxial connector 10 in the X direction, and the width in the Y direction is 160 mm.

[0040] Figure 5 is the zero-order Gaussian pulse signal used to excite the antenna in the embodiment of the present invention. The abscissa represents time, the ordinate represents signal intensity, the pulse width is only 200 ps, and the pulse energy is mainly distributed in the 0.1 - 4 GHz frequency band.

[0041] Figure 6 is the port standing wave curve of a single antenna in the embodiment of the present invention. The abscissa represents the operating frequency, the ordinate represents the standing wave value, and the standing wave of the antenna is less than 3 within the observed 0.1 - 5.3 GHz range, and the matching bandwidth exceeds 40 octaves.

[0042] Figure 7 is the antenna in the embodiment of the present invention being Figure 5After being excited by the signal, the waveform diagram of the time-domain signal received at the far field 5 meters in front of and behind the antenna. The forward direction refers to the +Z direction, and the backward direction refers to the -Z direction. The abscissa in the figure represents time, and the ordinate represents the signal electric field strength. It can be seen that the Gaussian pulse is converted into a bipolar pulse after passing through the antenna of the embodiment, which conforms to the physical law of the first-order differential action of the time-domain antenna with high waveform fidelity on the pulse signal. The signal tail continues weakly. From this, the waveform fidelity of the antenna can be calculated to reach 0.9. This value is in the range of 0 to 1, and the closer it is to 1, the higher the waveform fidelity. In addition, it can be seen that the intensity of the backward radiation signal of the antenna is very weak, and the antenna has very good directivity.

[0043] Figure 8 After the antenna of the embodiment of the present invention is Figure 5 After being excited by the signal, the polar coordinate normalized energy pattern of the two main sections at the far field 5 meters away from the antenna. It can be seen that the energy ratio of the forward and backward radiation of the antenna is very large, and the front-to-back ratio reaches 20.1 dB, which more specifically shows that the antenna has good directivity.

[0044] Figure 9 The antenna unit array of the embodiment of the present invention is Figure 4 After all the units of the antenna array shown Figure 5 The active standing wave curve graph of the units in the array when the pulse signals shown are equally amplitude and simultaneously excited. The abscissa represents the operating frequency, and the ordinate represents the standing wave value. Without considering the inherent singularities introduced by the first grating lobe, the active standing wave of the units in the array covers 0.1 - 4 GHz, and the in-band standing wave is less than 3.7. The ultra-wideband characteristic is maintained after the array formation.

[0045] Although the present invention has been described herein with reference to its illustrative embodiments, it should be understood that these embodiments are presented only by way of example and not with any limiting effect. Therefore, various forms and details may be changed without departing from the spirit and scope of the present invention. Any design that adopts the design structure and concept of the present invention and makes some simple transformations or modifications falls within the scope of protection of the present invention.

Claims

1. A super 40 - octave - band directional - radiation time - domain pulse antenna, characterized in that it includes an excitation plate, a ground plate, a tuning plate, a left - hand side plate, a right - hand side plate, a reflector, a radio - frequency coaxial connector, a left - hand closed plate and a right - hand closed plate. All the above - mentioned plates are of metal structure. The excitation plate and the ground plate are parallel between the lower plates, forming a section of air microstrip line. The intersection curve of the upper part with the XOZ plane is an exponential - gradient curve. The opening size of the curve along the X - direction increases exponentially with the increase of the Z - direction height, forming an exponential - gradient open - mouth horn. The width of the excitation plate in the Y - direction increases linearly with the increase of the Z - direction height, and the width size of the ground plate in the Y - direction remains unchanged.

2. The super 40 - octave - band directional - radiation time - domain pulse antenna according to claim 1, wherein The tuning plate includes an exponential - gradient tuning plate, an upward - tilted tuning plate, a downward - tilted tuning plate, and a vertical tuning plate. The exponential - gradient tuning plate, the upward - tilted tuning plate, the downward - tilted tuning plate, the vertical tuning plate, the right - hand side plate and the left - hand side plate together form a multi - stage magnetic - dipole structure to load the TEM horn. The multi - stage different tuning plates are loaded and tuned together. By adjusting the positions, sizes and tilt angles of each tuning plate, the antenna operates in a port - matching state across multiple octave bands, achieving good port - matching, directional - radiation performance and high waveform fidelity in the super 40 - octave band.

3. The super 40-octave directive radiation time-domain pulse antenna according to claim 2, wherein The structure under the excitation plate is an exponential - gradient tuning plate, an upward - tilted tuning plate, a downward - tilted tuning plate and a vertical tuning plate. The intersection curve of the exponential - gradient tuning plate with the XOZ plane is an exponential - gradient curve. The opening size of the curve in the X - direction increases exponentially with the increase of the Z - direction height. The width of the exponential - gradient tuning plate in the Y - direction increases linearly with the increase of the Z - direction height.

4. A super 40 - octave directional radiation time - domain pulse antenna according to claim 3, wherein The upward - tilted tuning plate connects the excitation plate and the right - hand side plate, and is assembled in a left - low - right - high tilted manner. The width of the upward - tilted tuning plate in the Y - direction increases linearly with the increase of the Z - direction height.

5. The super 40 - octave directive - radiation time - domain pulse antenna according to claim 3, characterized in that The downward - tilted tuning plate connects the excitation plate and the right - hand side plate, and is assembled in a left - high - right - low tilted manner. The width of the downward - tilted tuning plate in the Y - direction increases linearly with the increase of the Z - direction height.

6. The super 40-octave directive radiation time-domain pulse antenna according to claim 3, wherein The vertical tuning plate is a vertically - installed rectangular metal sheet, connecting the exponential - gradient tuning plate, the upward - tilted tuning plate, the downward - tilted tuning plate and the reflector.

7. The super 40 - octave - band directional radiation time - domain pulse antenna according to claim 1, characterized in that The outer conductor of the radio - frequency coaxial connector is installed on the reflector, and the inner - conductor pin is connected to the bottom of the excitation plate to feed the antenna. The left - hand closed plate closes the annular space surrounded by the ground plate, the left - hand side plate and the reflector. The right - hand closed plate closes the annular space surrounded by the excitation plate, the right - hand side plate and the gradient tuning plate.

8. The ultra-40 octave directional radiation time-domain pulse antenna according to claim 1, wherein The radio - frequency signal feeds the exponential - gradient open - mouth TEM horn formed by the excitation plate and the ground plate through the radio - frequency coaxial connector, and the electrical signal is converted into free - space electromagnetic signal and radiated outward.

9. A super 40 - octave directive radiation time - domain pulse antenna according to claim 1, characterized in that the directivity The length, width, and height dimensions of the radiation 40-octave time-domain pulse antenna element along the X, Y, and Z directions are 0.276λ L ×0.16λ L ×0.267λ L , λ L is the electromagnetic wave wavelength corresponding to the low-frequency side frequency of the operating frequency band of the antenna in the air medium.

10. The super 40 - octave directive - radiation time - domain pulse antenna according to claim 1, characterized in that When forming a unit array, the two ring structures inside the closed unit are closed and the side plates between adjacent units are electrically continuously assembled.

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