Tapered beam antenna based on Fabry-Perot resonant cavityTechnical Field
The invention relates to the technical field of antennas, in particular to a Fabry-Perot (FP) -based high-gain cone beam antenna.
Technical Field
A cone beam antenna is a special antenna with a pattern different from the normal pattern. The direction of maximum gain of the pattern is not on the normal line of the antenna, but has a certain angle with the normal line of the antenna, and is axially symmetrical around the normal line, and presents a circular ring shape, so that the pattern has the characteristic of axial symmetry. In engineering systems such as radio communication, electronic countermeasure, radar, television, remote sensing, navigation, broadcasting, radio astronomy, etc., antennas are required to transmit or receive electromagnetic waves. For different application scenes, corresponding antennas are needed to better exert the device performance. The cone beam antenna is used as an important antenna, the maximum radiation direction of the directional diagram of the cone beam antenna forms a certain included angle with the zenith direction, and 360-degree coverage can be realized on the azimuth plane, so that the cone beam antenna has important application value in systems such as vehicle-mounted communication, unmanned aerial vehicle remote control, missile-borne fuze, large airspace detection and the like. In mobile communications, it is required to use cone beams with different frequencies corresponding to different inclinations.
In order to realize high-gain cone beams, the cone beam antenna of the present technology selects a spiral antenna and a slot array antenna engraved on a three-dimensional object, but has the defects of heavy weight, difficult installation of a common spiral antenna, low gain of a patch antenna and complex array antenna array.
Disclosure of Invention
The invention aims to provide a cone beam antenna based on a Fabry-Perot resonant cavity.
The cone-shaped wave beam antenna based on the Fabry-Perot resonant cavity comprises a first medium substrate, a second medium substrate, a first metal layer, a second metal layer and a single-port feed source, wherein the first medium substrate and the second medium substrate are arranged in parallel, a first metal printed circuit is printed on one surface of the first medium substrate facing the second medium substrate, a second metal printed circuit is printed on one surface of the second medium substrate facing the first medium substrate, the first metal layer is arranged between a part of the first medium substrate, which is not printed with the first metal printed circuit, and the second metal printed circuit, which is not printed with the second medium substrate, to form an FP cavity, the second metal layer is arranged on one surface of the second medium substrate, which is far away from the second metal printed circuit, a part of metal is cut away between the second metal layer and the second medium substrate to form a metal E-shaped cavity, and the single-port feed source is arranged at the bottom center of the second medium substrate, and penetrates through the metal E-shaped cavity and the second metal layer.
Preferably, the single-port feed source comprises a horn radial waveguide and an SMA connector, wherein the horn radial waveguide is arranged at the center of the metal E-shaped cavity, and the SMA connector is arranged on the second metal layer and is connected with the horn radial waveguide.
Preferably, the first metal printed circuit comprises 8 circles of metal circular ring bull's eye patterns, the pattern arrangement rule is that a circle is arranged at the center, n circles of circular rings are added along the radial direction with the length of P as a period, the width of each circular ring is W, the outer circle radius of the nth circular ring from the center to the outside satisfies the formula that R=W+n is equal to P, and n is an integer.
Preferably, the second dielectric substrate comprises a disc and a ring, the ring is arranged around the disc, and the disc is connected with the ring through 30 branches arranged at equal intervals.
Preferably, the second metal printed circuit is printed on a disc of the second dielectric substrate, covering the entire circle.
Preferably, every 120 degrees of the 30 knots is provided with a knot with a width 3 times the width of the rest knots.
Preferably, the cavity edge of the FP cavity is inclined towards the second dielectric substrate.
Preferably, the cavity edge of the metal E-shaped cavity is inclined towards the second dielectric substrate.
Compared with the prior art, the invention has the remarkable advantages that:
The invention utilizes the Fabry-Perot cavity antenna to construct the low-profile high-gain cone-shaped wave beam antenna with simple structure. The structure is relatively simple, and the production and processing cost is lower;
The invention adopts the structural design of the metal E-shaped cavity in the radial line slot antenna, a double-layer structure of radial line waveguide is formed by the second medium substrate at intervals, the center of the metal E-shaped cavity is fed by the horn radial waveguide and the SMA joint, a radial outward TEM mode is generated, the metal E-shaped cavity is converted into a radial inward traveling wave mode in the FP cavity, and part of energy is radiated from the first medium substrate, so that the process of feeding from the peripheral edge to the center is realized.
The invention selects the annular bullseye structure frequency selection surface printed on the dielectric plate, can effectively improve the directivity and gain of cone-shaped wave beams, and can further improve the angle direction of a directional diagram by changing the period and the ring width of the ring.
The invention is described in further detail below with reference to the drawings and the detailed description.
Drawings
Fig. 1 is a front view of a cone-beam antenna based on a Fabry-Perot resonator of the present invention.
Fig. 2 is a top view of a Fabry-Perot resonator based cone beam antenna of the present invention.
FIG. 3 is a schematic illustration of the dimensions of the first dielectric substrate of FIG. 1 according to the present invention.
FIG. 4 is a schematic illustration of the dimensions of the second dielectric substrate of FIG. 1 according to the present invention.
Fig. 5 is a schematic diagram of the FP cavity and metal E-shaped cavity dimensions of fig. 1 in accordance with the present invention.
FIG. 6 is a cross-sectional view of the horn radial waveguide and SMA joint of FIG. 1 according to the present invention.
Fig. 7 is an E-plane and H-plane pattern at 12.5GHz for an embodiment of the invention.
Fig. 8 is a plot of cone beam antenna return loss versus frequency in accordance with an embodiment of the present invention.
Detailed Description
As shown in fig. 1, the tapered beam antenna based on the Fabry-Perot resonant cavity includes a first dielectric substrate 6, a second dielectric substrate 8, a first metal layer, a second metal layer and a single-port feed source 2, where the first dielectric substrate 6 and the second dielectric substrate 8 are arranged in parallel, a first metal printed circuit 7 is printed on a surface of the first dielectric substrate 6 facing the second dielectric substrate 8, a second metal printed circuit 9 is printed on a surface of the second dielectric substrate 8 facing the first dielectric substrate 6, the first metal layer is disposed between a portion of the first dielectric substrate 6 where the first metal printed circuit is not printed and the second metal printed circuit 9 where the second metal printed circuit 8 is not printed, the first metal printed circuit 7, the second metal printed circuit 9 and the first metal layer form an FP cavity 1, the second metal layer is disposed on a surface of the second dielectric substrate 8 far from the second metal printed circuit 9, a portion of the split metal is formed between the second metal layer and the second dielectric substrate 8, and the single-port feed source 8 is disposed at a bottom of the second dielectric substrate 8, and the FP cavity 3 is formed by passing through the second metal printed circuit 8. The single-port feed source 2 feeds power from the center to the periphery. The emitted electromagnetic wave is reflected twice through the metal E-shaped cavity 3 and the FP cavity 1 to form a wave beam forming network, and finally cone-shaped wave beams are formed.
Specifically, the first dielectric substrate 6 is Rogers RO4350, and the dielectric constant thereof is 3.66.
Specifically, the second dielectric substrate 8 is Rogers RO4003, and the dielectric constant thereof is 3.55.
In a further embodiment, the single-port feed 2 includes a horn radial waveguide 4 and an SMA connector 5, where the horn radial waveguide 4 is disposed at the center of the metal E-shaped cavity 3, and the SMA connector 5 is disposed on the second metal layer and connected to the horn radial waveguide 4. The single-port feed source 2 radiates electromagnetic waves in the horizontal direction outwards through the horn radial waveguide 4, and the electromagnetic waves reach the FP cavity 1 under the action of twice reflection of the metal E-shaped cavity 3.
In a further embodiment, the first metal printed circuit 7 includes an 8-ring metal bullseye pattern, the pattern is arranged by arranging a circle at the center, adding n rings with the length of P as a period along the radial direction, wherein the width of each ring is W, and the radius of the outer circle of the n-th ring from the center to the outside satisfies the formula that r=w+n×p, and n is an integer. By changing the period and the ring width of the ring, the angular orientation of the pattern can be improved.
In a further embodiment, the second dielectric substrate 8 includes a disc 16 and a ring 12, the ring 12 is disposed around the disc 16, and the disc 16 is connected to the ring 12 by 30 branches 13 disposed at equal intervals. The finer the 30 equally spaced knots 13, the more radiation passes, the better the directivity and transmission properties.
In a further embodiment, the second metal printed circuit 9 is printed on the disc 21 of the second dielectric substrate 8, covering the whole circle.
In a further embodiment, every 120 degrees of the 30 knots 13 is provided with a knot 14 having a width 3 times the width of the remaining knots 15. From the stability of the invention, the branches with different widths are arranged, so that the possibility of insufficient supporting force in application is prevented.
In a further embodiment, the cavity edge of the FP cavity 1 is inclined towards the second dielectric substrate, so as to form a beam radiating towards the center of the FP cavity 1.
In a further embodiment, the cavity edge of the metal E-shaped cavity 3 is inclined towards the direction of the second dielectric substrate, so as to form a beam radiating towards the edge of the FP cavity 1.
The invention provides a frequency selective surface of an annular bullseye structure printed on a dielectric plate, which can effectively improve the directivity and gain of cone beams by utilizing the structure of an FP cavity, and can further improve the angle direction of a directional diagram by changing the period and the ring width of a ring. The invention adopts the structural design of the metal E-shaped cavity in the radial line slot antenna, and realizes a novel feeding mode of feeding from the peripheral edge to the center. The invention has higher application value in mobile communication.
Examples
Referring to fig. 3, a schematic size diagram of the first dielectric substrate 6 is shown, wherein the radius of the first dielectric substrate 6 is RF =106 mm, the radius of the first metal printed circuit 7 is Rs =100 mm, n circles of circles are added along the radial direction with the length of p=13.35 mm as a period, and the width of each circle is w=11.65 mm. Referring to fig. 1, t=0.1 mm is the thickness of the first dielectric substrate 6.
Referring to fig. 4, a schematic size diagram of the second dielectric substrate 8 is shown, wherein the radius of the second dielectric substrate 8 is Rp =120 mm, the radius of the second metal printed circuit 9 is Rs =100 mm, the length of 30 branches 13 connecting the disc 16 and the ring 12 is Ws =5.8 mm, one branch 14 having a width 3 times as wide as the rest of the branches 15 is Ls =1.1 mm, the rest of the branches 15 have a width Lp =0.36 mm, and the thickness of the second dielectric substrate 8 is h=0.5 mm.
Referring to fig. 5, the sizes of the FP cavity 1 and the metal E-shaped cavity 3 are schematically shown, the diameter of the connection surface between the FP cavity 1 and the first dielectric substrate 6 is Ds＝2*Rs =200 mm, the height of the FP cavity 1 is h1=14.5 mm, the height of the second metal layer is h2=10 mm, the height of the metal E-shaped cavity 3 is hh=6mm, and the length of the FP cavity 1 and the metal E-shaped cavity 3 from the edge is Ws =5.8 mm, which is the same as the length of the 30 branches 13 of the second dielectric substrate 8.
Referring to fig. 6, the horn radial waveguide 6 and SMA joint 5 are shown in cross section in the shape of a trapezoid, the upper base 17 of the trapezoid has a length Da =5.4mm, the lower base 18 has a length Dr =0.8mm, the height hh=6mm, the diameter of the probe in the SMA joint 5 is Dr =0.8mm, and the diameter of the teflon layer (19) is Dt =4mm.
Referring to fig. 7, using HFSS simulation software, at 12.5GHz, the highest gain of the antenna can reach 14.3dB, and a cone beam with a directional angle of 30 degrees is formed, and the two patterns are consistent.
Referring to fig. 8, using HFSS simulation software, the reflection coefficient is-19.7 dB at the center frequency of 12.5GHz, and the bandwidth is between 12.42GHz and 12.69GHz, which is about 2.2%, based on the graph of the return loss versus frequency of the Fabry-Perot resonator cone beam antenna.