Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention provides a broadband high-efficiency antenna unit, a serial-parallel feed array and a phased array. The invention has higher radiation efficiency and wider bandwidth, and can realize wider beam scanning range.
The broadband high-efficiency antenna unit adopts the following technical scheme:
a broadband high-efficiency antenna unit comprises a first dielectric substrate, a first metal floor, a second dielectric substrate, a third dielectric substrate and a second metal floor which are sequentially arranged, wherein a super-surface structure is arranged on the upper surface of the first dielectric substrate, a feed gap is etched in the first metal floor, and a strip-shaped feed line is arranged between the second dielectric substrate and the third dielectric substrate.
Further, the strip feeder is a graded feeder.
Furthermore, a metal grounding column is loaded around the strip feeder and bridged between the first metal floor and the second metal floor.
The series-parallel feed array adopts the following technical scheme:
a series-parallel feed subarray comprises two mirror-symmetrical series subarrays, the two series subarrays are spliced according to a mirror symmetry axis, and the series subarrays are formed by arranging a plurality of broadband high-efficiency antenna units in a series-feed mode in the subarray direction.
The first metal floor and the second metal floor are sequentially arranged below the first metal floor, and the first coupling gap and the second coupling gap are respectively etched at the center of the first metal floor and the center of the second metal floor.
The second coupling gap is connected with the coplanar waveguide wire, and sequentially excites the second coupling gap, the first coupling gap and the strip-shaped feeder line.
Furthermore, the upper and lower electric field signals of the first coupling gap are in equal-amplitude opposite phase, and the strip feeder line signals spliced by the mirror image and positioned above the first coupling gap are in equal-amplitude same phase, so that two serial sub-arrays placed by the mirror image can be excited by electromagnetic signals with equal-amplitude same phase, and the center parallel feeding of the serial and parallel feed sub-arrays is realized.
The phased array adopts the following technical scheme:
a phased array comprises a plurality of series-parallel feed sub-arrays which are periodically arranged along the vertical direction of the sub-arrays.
Further, the scanning range of the phased array is determined by the distance between adjacent series-parallel feed arrays, and the smaller the distance, the larger the scanning range.
And further, the metal phase perturbation branch knot is arranged on the same layer or different layers with the strip-shaped feed line, so that the isolation of the adjacent series-parallel feed line array is improved.
The invention has the beneficial effects that:
the antenna unit adopts a super-surface structure as a radiation unit and has wider bandwidth.
The subarray of the invention adopts a series-parallel feed mode, the feed network has simple structure and low loss, can realize higher antenna radiation efficiency, and has symmetrical directional diagram.
The phased array adopts the metal phase perturbation branch knot, can reduce the coupling among sub-arrays, improves the isolation degree, has array expansibility and can be widely applied to high-isolation arrays.
The phased array external connection shifter controls the phase difference of each input end, and can realize +/-58-degree beam scanning;
the invention has simple structure, easy processing and relatively low cost and weight. Thus, mass production is possible.
Drawings
Fig. 1 is a three-dimensional view of a broadband high efficiency antenna unit of the present invention.
Fig. 2(a) is a top view of the series feed sub array of the present invention.
Fig. 2(b) is a structural diagram of a strip feeder in the series-fed sub array of the present invention.
Fig. 2(c) is a side view of the series feed sub array of the present invention.
Fig. 3(a) is a three-dimensional exploded view of a series-parallel feed array of the present invention.
Fig. 3(b) is a side view of the series-parallel feed array of the present invention.
Fig. 3(c) is a structural diagram of a second metal ground plate and a first coupling gap etched thereon, a third metal ground plate and a second coupling gap etched thereon, and a coplanar waveguide line in a series-parallel feed array feeding structure of the present invention.
Fig. 4 is a top view of the wideband high-efficiency wide-angle scanning phased array proposed by the present invention.
Fig. 5(a) is an S parameter of a wideband high efficiency antenna unit proposed by the present invention;
FIG. 5(b) is a graph of gain of a broadband high efficiency antenna unit as a function of frequency;
fig. 5(c) is a graph of the radiation efficiency of a broadband high-efficiency antenna element as a function of frequency;
FIG. 6(a) is an S parameter of a series-parallel feed array of the present invention;
FIG. 6(b), FIG. 6(c) and FIG. 6(d) are H-plane directional diagrams of low frequency (24GHz), medium frequency (26.5GHz) and high frequency (29GHz), respectively;
FIG. 7(a) is an S parameter of a phased array of the present invention;
fig. 7(b), 7(c) and 7(d) show the H-plane scanning performance of the phased array at low frequency (24GHz), medium frequency (26.5GHz) and high frequency (29GHz), respectively, fig. 7(e) shows the change curve of the phased array radiation efficiency with frequency, and fig. 7(f) shows the change curve of the phased array gain with frequency.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited to these examples.
Example 1
As shown in fig. 1, a broadband high-efficiency antenna unit adopts a multilayer PCB process, and the whole antenna adopts Roger5880 as a dielectric substrate. The super-surface structure comprises a first dielectric substrate 2, a first metal floor 3, a second dielectric substrate 5, a third dielectric substrate 8 and a second metal floor 9 which are sequentially attached from top to bottom, wherein a super-surface structure 1 is arranged on the upper surface of the first dielectric substrate, a feed gap 4 is etched in the first metal floor 3, and a strip-shaped feed line 7 is arranged between the third dielectric substrate 8 and the second dielectric substrate 5.
As the radiating part of the antenna: the super-surface structure 1 is formed by arranging M × N super-surface units in a centrosymmetric and periodic manner, and the super-surface structure in this embodiment 1 is formed by arranging 2 × 2 super-surface units in a centrosymmetric and periodic manner. The super surface unit comprises a metal patch.
The shape of the metal patch is not limited to rectangle, and can be square, parallelogram, trapezoid, rhombus and the like; the shape of the feed gap can be H-shaped, pi-shaped, I-shaped or M-shaped, and the metal grounding column can be a cylinder or a cuboid.
As a feeding portion of the antenna: the central position of the first metal floor 3 is etched with a feed gap 4 for exciting the upper radiating section. The feed gap is one, and the shape of the feed gap is not limited. The feed slot in this embodiment 1 is two connected cross-shaped.
The strip feeder is a graded feeder used for broadband impedance matching adjustment, and the grading can be arc cutting or step cutting; the strip feeder is perpendicular to the feed gap, a plurality of metal grounding posts 6 are loaded around the strip feeder 7 and bridged between two layers of metal floors to inhibit the outward diffusion of feeder signals.
The metal patches are rectangular patches with a size a of 2.6mm, a size b of 0.8mm, a spacing c between adjacent metal patches of 0.3mm, and a gradual change in length sl of the strip-shaped feed line312.7mm, transition R1Is [0.6 lambda, 0.8 lambda ]]Transition section R2Is [0.5 lambda, 0.7 lambda ]]Where λ is the free-space wavelength at the center frequency. The length sl of the H-shaped gap is 3.2mm2Is 1.4 mm. The dielectric constant of the adopted dielectric substrate is 2.2, the loss angle is 0.0009, the thickness of the first dielectric substrate is 0.508mm, and the thicknesses of the second dielectric substrate and the third dielectric substrate are 0.254 mm.
With reference to fig. 5(a) to 5(c), the operating frequency band of the antenna unit is 26.5 ± 2.5GHz, the impedance bandwidth is about 20%, the array efficiency in the operating frequency band is greater than 90%, the antenna directional diagram is symmetrical, the cross polarization is lower than-30 dB, and the gain fluctuation is less than 2 dB.
Example 2
As shown in fig. 3(a), 3(b), and 3(c), a series-parallel feed sub-array includes two mirror-symmetric series sub-arrays, the two series sub-arrays are spliced according to a mirror-symmetric axis, and the series sub-array D is formed by arranging a plurality of broadband high-efficiency antenna units in series-feed along a sub-array direction as described in embodiment 1.
As shown in fig. 2(a), 2(b) and 2(c), the series sub-array D is formed by expanding two broadband high-efficiency antenna units in the sub-array direction, and the two feed gaps are symmetrical.
Each broadband high-efficiency antenna unit is further provided with a fourth dielectric substrate 11 and a third metal floor 12 in sequence below the second metal floor 9, a first coupling gap 10 is etched in the center of the second metal plate 9, a second coupling gap 13 is etched in the third metal floor 12, and the second coupling gap is located below the first coupling gap. The second coupling gap is connected with the coplanar waveguide line 14; the second coupling slot 13, the first coupling slot 10 and the strip feed line 7 are excited in this order by the coplanar waveguide line 14.
The first coupling slot and the second coupling slot are identical, and the condition that the H-shaped slot with the circular end needs to meet is that the overall size is about 1/2 medium wavelength of central frequency. Other shapes are also possible, such as a straight line shape or a double M shape, etc., and the shape of the end portion may be circular, square, triangular, etc.
The upper and lower electric field signals of the first coupling gap are in equal-amplitude opposite phase, and the strip feeder line signals spliced by the mirror image and positioned above the first coupling gap are in equal-amplitude same phase, so that two serial sub-arrays placed by the mirror image can be excited by electromagnetic signals with equal-amplitude and same phase, and the center parallel feeding of the serial and parallel feed sub-arrays is realized.
Dimension sl of coupling slot4Is 2.6mm, sl54.4mm, the overall antenna array size is 30.8mm x 20 mm. The distance between the serial and parallel feeder arrays is 4.5 mm; the dielectric constant of the adopted dielectric substrate is 2.2, the loss angle is 0.0009, the thickness of the first dielectric substrate is 0.508mm, and the thicknesses of the second dielectric substrate and the third dielectric substrate are 0.254 mm. The thickness of the fourth dielectric substrate 11 is 0.127 mm.
With reference to fig. 6(a) to 6(d), the operating frequency band of the series-parallel fed sub-array is 26.5 ± 2.5GHz, the impedance bandwidth is about 20%, the antenna directional diagram is symmetrical, and the cross polarization is lower than-30 dB.
Example 3
As shown in fig. 4, in a phased array, a plurality of serial-parallel feed sub-arrays are periodically arranged in the vertical direction of the sub-arrays, and in this embodiment 3, the phased array is composed of 1 × 4 serial-parallel feed sub-arrays, and metal phase perturbation branches 15 are loaded around the head and tail ends of the strip-shaped feed lines 7 of the serial-parallel feed sub-arrays, so as to improve the isolation between adjacent serial-parallel feed sub-arrays.
And the metal phase perturbation branches are arranged on the same layer or different layers with the strip-shaped feeder line, so that the isolation of the adjacent serial-parallel feeder arrays is improved, and the metal phase perturbation branches of the phased array are symmetrical according to a mirror symmetry axis.
The scanning range of the phased array is determined by the distance between adjacent series-parallel feed arrays, and the smaller the distance, the larger the scanning range. Typically less than half a wavelength, and therefore the size of the broadband high efficiency antenna element in the beam scanning direction should also be as small as possible.
The phase perturbation branch knot 15 can be in a U shape, a parallel line shape, an M shape, a pi shape and the like, and the corner can be an arc corner cut, a line corner cut or no corner cut. The antenna array can be applied to high-isolation antenna arrays, including microstrip patch antennas, slot antennas, super-surface antenna arrays and the like.
Size sl of phase perturbation branch section 156Is 1.8mm, sl7Is 2.6 mm; the array pitch was 4.5 mm.
With reference to fig. 7(a) to 7(f), the working frequency band of the phased array is 26.5 ± 2.5GHz, the impedance bandwidth is about 20%, the isolation between units in the array is greater than 20dB, the phased array has high isolation characteristics, the efficiency in the working frequency band is greater than 80%, the antenna directional diagram is symmetrical, the cross polarization is lower than-30 dB, and the gain fluctuation is less than 2 dB. The array scanning performance can be represented by low-frequency (24GHz), medium-frequency (26.5GHz) and high-frequency (29GHz) points, the amplitude of an excitation signal is kept unchanged, the phase of each feed port is changed, phase-controlled scanning can be achieved, the scanning angle of the low-frequency point can reach 60 degrees, the gain loss is less than 5dB, the scanning angle of the central frequency point can reach 60 degrees, the gain loss is less than 4dB, the scanning of the high-frequency point can reach 58 degrees, and the gain loss is less than 3 dB.
The design of the series-parallel feed network reduces the energy loss in the feed process, and the antenna array can obtain higher radiation efficiency; the metal phase perturbation branch knot is positioned on the same layer of the strip-shaped feeder line, can realize broadband decoupling and has better array expansibility. The invention can realize high-efficiency wide-angle scanning performance in a wider frequency band. The invention is suitable for the design of plane antenna array and is applied to large-scale production because of easy processing, low cost and low section.
The invention can change the beam direction by changing the phase of the input signal, has wide prospect in 5G communication equipment, and has the advantages of small size, high integration level, high antenna efficiency and less system energy consumption.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.