A kind of micro-band flat plate array antenna of multilayer of wave beam symmetryTechnical field
The invention belongs to antenna technical field, be specifically related to a kind of micro-band flat plate array antenna of multilayer of wave beam symmetry, in the time of design, the secondary lobe of one dimension serial feed planar array antenna wave beam is realized symmetrical by the design of feed.
Technical background
At present, micro-strip array antenna is widely used at aspects such as radar, remote sensing, communications.The features such as single layer microstrip antenna is lightweight with it, and thickness is little, easy syntype are paid attention to, but compared with common microwave antenna, the general frequency band of microstrip antenna is narrow, lossy, thereby gain is not high.When frequency one timing, broader bandwidth, the gain of thick substrate are higher, and the substrate broader bandwidth gain that dielectric constant is less is higher.Due to the representative value of the microstrip antenna bandwidth magnitude that is a few percent, so Bandwidth-Constrained system is one of shortcoming of microstrip antenna.
For desirable planar array antenna, different feeding classifications directly affects antenna different directions diagram shape.According to Pattern Synthesis theory, the Antenna Far Field directional diagram that the equiphase feeding classification of amplitude symmetry obtains is also symmetrical.But in the practical application of micro-strip array antenna, normally feeding network and array element are all in the same side.Due to microstrip line, this will produce certain radiation in radio frequency band, the radiation field of its feeder line and the radiation field of radiating element mutually superpose produce mutual coupling, not only can affect cross polarization and the isolation of antenna, and affecting the gain of main lobe, the secondary lobe of Antenna Far Field directional diagram also can irregularly be arranged simultaneously.Particularly when bay number is less, wave beam is when wider, the directional diagram main beam that micro-strip paster antenna forms can be out of shape deterioration, thereby can not meet the symmetrical practical application of some required direction figure.About the problem of array antenna feed, forefathers have done a large amount of work.General feeding network is all wiring around radiation fin, the mutual coupling problem of keeping away so unavoidable feeder line and radiating element.Add the method for mating shielding conductor can make single microstrip line radiant power be significantly less than the power while not adding shielding conductor, but be often difficult to realize because the restriction of microstrip array radiating element spacing makes this method in actual engineering design.
Summary of the invention
The technical problem to be solved in the present invention is: overcome the deficiency of existing micro-strip array antenna Bandwidth-Constrained system and feeding classification technology, design the micro-band flat plate array antenna of the symmetrical multilayer of a kind of wave beam, this aerial loss is little, simple in structure, processing is simple.
Realizing technical scheme of the present invention is: the micro-band flat plate array antenna of multilayer of wave beam symmetry is designed to three layers, formed by radiating layer, feed layer and reflecting plate, and symmetrical radiation patch on the inner surface of radiating layer, radiation patch array is 3 × 6 totally 18 unit, described feed layer is between radiating layer and reflecting plate, every interlamellar spacing is quarter-wave, feed layer is ground plane towards the one side of radiating layer, be microstrip feed line face towards the one side of reflecting plate, on ground plane, offer 3 × 6 coupling gaps of totally 18 H shapes, arrange microstrip feed line at feeder line face, microstrip feed line network is by distributing point, first order power splitter, two second level power splitters, serial feed terminated line and transmission line composition, distributing point is used for welding semi-flexible cable, energy is distributed to two second level power splitters and is made two second level power splitter single spin-echos through first order power splitter, give each radiating element finally by mistake serial impedance matching circuit by energy distribution, described reflecting plate is metallic plate, form the inner surface of antenna housing, described radiating layer possesses the function of radome simultaneously, whole antenna is complete among an airtight housing except a connector.
Feed layer design of the present invention adopts symmetric form, reduces the impact of feed transmission line pair array directional diagram, forms symmetrical beam pattern, and the geometric center of the radiating slot adhering on ground plane overlaps with the center of gravity of the radiation patch of adhering on radiating layer; Make the microstrip feed line energy in feeder line layer be coupled to radiation patch and then radiate by coupling gap, eliminated the coupling influence between feeder line self radiation and radiating element.
Feeding classification at microstrip feed line face azimuth dimension feeder line is serial feed, by regulating the size of 1/4 impedance matching line of each joint to realize the distribution of amplitude, wherein distribute with axial symmetry near two row's azimuth dimension and the pitching fibrillar center feeder line of top edge and lower limb, this two rows feeder line feed opposite direction, the feed opposite direction of middle row's feeder line the right and left, tie up in pitching, regulate power splitter by two second level, realize amplitude distribution, power splitter is by not isometric asymmetric double port network and two second level power splitter cascades, realize between two second level power splitters 180 ° of phase phasic differences, thereby the phase difference that the symmetrical feeder line of collocation structure produces.Because the energy of the microstrip feed line in feeder line layer is be coupled to radiation patch and then radiate by coupling gap, the radiation field of microstrip feed line itself does not affect radiation patch, and microstrip feed line itself is also symmetry arrangement, therefore this structure has just been eliminated the coupling influence between feeder line self radiation and radiating element, thereby directional diagram is also symmetrical.
The micro-band flat plate array antenna of multilayer of the wave beam symmetry of the present invention being made up of technique scheme is compared with the prior art, and the beneficial effect having is:
Prior art is conventionally by radiation patch with feeder line is placed in same plane and feeder line is arranged as unsymmetric structure, and often symmetry is bad for the antenna actual measurement directional diagram of this structure, and gain is also because radiation patch and feeder line mutual coupling reduce.The present invention, by unique feed design, can reduce the mutual coupling between radiation patch and feeder line, realizes the symmetry that wave beam is good.
Brief description of the drawings
Fig. 1 is radiating layer radiating element distribution map
Fig. 2 is feed layer ground plane coupling gap figure
Fig. 3 is feed layer microstrip feed line distribution map
Fig. 4 is radiating layer feed layer and reflecting plate assembly schematic diagram
Fig. 5 is pitching dimension actual measurement directional diagram
Fig. 6 is azimuth dimension actual measurement directional diagram
Embodiment
Below in conjunction with accompanying drawing, content of the present invention is clearly and detailedly illustrated.
Fig. 1 is the radiating element distribution map of radiating layer 11.In Fig. 1, radiation patch 1 is arranged in the inner surface of radiating layer according to the result of calculation of Pattern Synthesis theory, is symmetric.Radiation patch array is 3 × 6 totally 18 unit.Screw hole 2 is distributed in radiating layer edge.
Fig. 2 is feed layer 15 ground plane coupling gap figure.This layer is printed on the one side of centre feed layer, and the ground plane 14 of feed layer 15 is positioned at the below place of radiating layer.The gap 6 that is wherein coupled is shaped as " H " shape, and coupling gap array is 3 × 6 totally 18, and the center of gravity of the center in each gap 6 and radiation patch 1 overlaps.What arrow 3 was indicated is the polarised direction of antenna.The welding that via hole 4 and via hole 5 are cable is reserved.In figure, 3 pointing directions are antenna pitching dimension, are vertically azimuth dimension with it at same plane.
Fig. 3 is feed layer microstrip feed line distribution map.The microstrip feed line of feed layer is by distributing point 7, first order power splitter 8, and the second level the first power splitter 9, the second level the second power splitter 10, serial impedance matching circuit 12 and transmission line 13 form.The semi-flexible cable of distributing point 7 welding diameter 2.2mm, energy passes through first order power splitter 8 and distributes to the second level the first power splitter 9 and the second level the second power splitter 10 and make the second level the first power splitter 9 and the second level the second power splitter 10 single spin-echos, gives each radiating element finally by mistake serial impedance matching circuit 12 by energy distribution.
In Fig. 3, numbering 3 pointing directions is antenna pitching dimension, is vertically azimuth dimension with it at same plane.Microstrip feed line is serial feed in the feeding classification of azimuth dimension, by regulating the size of 1/4 serial impedance matching line 12 of each joint to realize the distribution of amplitude, wherein distribute with axial symmetry near two row's azimuth dimension and the pitching fibrillar center feeder line of top edge and lower limb, this two rows feeder line feed opposite direction, the feed opposite direction of middle row's feeder line the right and left, tie up in pitching, by regulating first order power splitter 8, the second level the first power splitter 9 is realized amplitude distribution with the second level the second power splitter 10, first order power splitter 8 is by not isometric asymmetric double port network and the second level the first power splitter 9, the second level the second power splitter 10 cascades, realize the second level the first power splitter 9 and 180 ° of the second level the second power splitter 10 phase phasic differences, thereby the phase difference that the symmetrical feeder line of collocation structure produces.
Fig. 4 is radiating layer, feed layer and reflecting plate assembly schematic diagram.Shown in figure, antenna separation structure is three layers, is respectively radiating layer 11, feed layer 15 and reflecting plate 17.Feed layer 15 is between radiating layer 11 and reflecting plate 17, and every interlamellar spacing is quarter-wave.The material of radiating layer 11 is chosen as the epoxy resin bonded fiber (one side covers copper thickness 0.035mm) of the thick dielectric constant 4.3 of 1mm, the polytetrafluoroethylene (all thick 0.035mm of copper are covered on two sides) of the thick dielectric constant 2.65 of feed layer 15 material selection 1mm, reflecting plate 17 is Glabrous thorn metallic plate.Radiation patch 1 dress is affixed on the inner surface of radiating layer 11.Radiating layer 11 also possesses the function of radome simultaneously.Ground plane 14 and feeder line face 16 lay respectively at the upper and lower surface of feed layer 15.Reflecting surface 17 is inner surfaces of antenna housing, and support column 19 supports feed layer 15.SMA connector 18 is fixed on reflector 17 outer surfaces, and the semi-flexible cable 20 being attached thereto passes via hole 4 around to via hole 5 (avoiding radiating element in space), and cable inner core is soldered to solder joint 7 places.Whole antenna except connector 18 all among an airtight housing.
According to Pattern Synthesis theory, consider practical structures size, beamwidth is that 15 ° of azimuth dimension can realize by 6 × 3 microstrip array with the radiation beam of 30 ° of pitching dimensions, unit interval is 48mm × 50mm.According to micro strip theory of radiation, through calculating, to adopt thickness be that 1mm dielectric constant is that the radiation patch that 4.3 epoxy resin bonded fiber is substrate is of a size of 26.4mm × 24mm.Adopting thickness is that 1mm dielectric constant is that the width of 2.65 polytetrafluoroethylene, the 50 ohm of serial impedance matching lines that are substrate is 2.75mm.
Be symmetric in frequency band through actual measurement directional diagram, wherein Figure 5 shows that the pitching dimension directional diagram of a certain frequency.Figure 6 shows that the azimuth dimension directional diagram of a certain frequency.Pitching wave beam and orientation wave beam are symmetrical in respectively antenna array normal, and beamwidth, actual measurement gain meet design requirement.
The invention provides in sum a kind of wave beam symmetrical antenna execution mode, provided concrete implementing method and accompanying drawing is illustrated for the method.Also feasibility and the correctness of the feed design of this uniqueness have been verified by concrete emulation experiment and the actual measurement of test exemplar.