A kind of wave groove quadruple ridged horn feed
Technical field
The present invention relates to the technical fields of compact feed antenna, and in particular to a kind of wave groove quadruple ridged horn feed.
Background technique
Feed is the important component of lens antenna or reflector antenna, wherein the feed system of high-quality wide frequency band
The working performance of antenna can effectively be improved, simultaneously because in recent years, in communication, national defence and radio astronomy field to ultra wide band
Feed proposes the demand being increasingly urgent to, and it is more steady to meet beam angle simultaneously in the bandwidth for requiring at least 3:1 even higher
Fixed and relatively better radiation characteristic, especially in Compact Range testing field, the design of such ultra wide band feed has very much is chosen
War property, so the research and application of ultra wide band feed antenna have highly important practical significance.
Quadruple ridged horn antenna has certain application space in Compact Range testing field as a kind of common broad-band antenna, but
It is that defect is also fairly obvious, directional diagram occurs asymmetry in high frequency, and beam angle is changed greatly with frequency, often
Sharply narrow with the raising of frequency, is also easier to the case where main lobe division occur in high frequency.Quadruple ridged horn antenna it is another
One limiting factor is that its cross-polarization levels is relatively high, this will lead to when doing electromagnetism test using quadruple ridged horn antenna,
Measuring accuracy is seriously affected at certain specific positions, so current ultra wide band feed and immature, needs to quadruple ridged horn
It improves and finer design.
Basic structure and optimization for quadruple ridged horn antenna have been achieved for much being in progress, mainly by loudspeaker wall
The parameter adjustment of the excipient and ridge piece of shape, the mode for radiate at opposite surface are controlled, and ideal radiance is reached.
Meanwhile some improved structures are also suggested the defect to solve quadruple ridged horn antenna, these, which improve structure, mainly has, and increases
Mouth face adapter, higher mode inhibit ring, and carry out the loudspeaker wall design of figuration.2006, Jacobs, which describes one kind, to be made
With the quadruple ridged horn antenna of the excipient loudspeaker wall of ellipse, having investigated can be by the variation of loudspeaker wall parameter, needed for obtaining
Directional diagram beam angle, 2013, Akgiray studied ridge plate shape and matching problem, specified ridge piece
The influence of spacing and ridge piece curve for loudspeaker radiation.The country for quadruple ridged horn antenna research there are also innovative point,
The methods of ridge piece thickness excipient and ridge piece extension are mainly used, improves the reflection at low frequency to a certain extent.At present with
On research it is still high without solving quadruple ridged horn antenna cross-polarization, beam angle changes excessive defect with frequency, low
Beam angle is excessive at frequency, and electromagnetic wave leakage resulting from is more serious, and these problems are particularly with Compact Range test macro
Application for, be the problem of comparing concern, and put forth effort problem to be solved.
Therefore, a novel ultra wide band feed antenna is designed, is to have to meet some test indexs requirement of Compact Range
Important practical usage.
Summary of the invention
The present invention designs a kind of wave groove quadruple ridged horn feed, which has return loss small, beam angle
More stable, cross polarization is low, outstanding advantages at low cost.
The technical solution adopted by the present invention are as follows: a kind of wave groove quadruple ridged horn feed, including four ridge of axial wave groove
Electromagnetic horn 1, supporting structure 2, ring flange 3 and absorbing material 4, electromagnetic horn include three section impedance matching structures 6, and use is specific
Four ridge pieces 5 of ridge curve, for connecting the cavity 7 of two orthogonal polarization direction top connections, a short board 8, one
The loudspeaker wall 9 of a corresponding size, the axial flute constructions 10 and two semi-rigids using sub-miniature A connector connection of four slots
Coaxial cable feed connector 11, electromagnetic horn 1 are connected by screw on supporting structure 2, and supporting structure 2 is fixed also by screw
Above ring flange 3;The stickup of absorbing material 4 is covered on ring flange 3;It is installed respectively using four ridge pieces 5 of particular ridge curve
On truncated cone-shaped loudspeaker wall 9, four burnishing surfaces of same size with ridge piece are cut out on loudspeaker wall 9, to install ridge piece;Two are adopted
Cavity 7 is sequentially passed through with the semi-rigid coaxial cable feed connector 11 that sub-miniature A connector connects and using four ridge pieces 5 of particular ridge curve
In one of them, the outer conductor of cable-fed connector and cavity 7 and the ridge passed through are electrically connected, and are led in cable-fed connector
Body and the ridge on opposite are electrically connected;The feed structure 6 of three section impedance matchings can be reduced back by adjusting the length and width of each section
The axial flute constructions 10 of wave loss, four slots obtain more stable beam angle by adjusting width and the depth of each slot.
In the wave groove quadruple ridged horn feed, in the axial wave groove quadruple ridged horn antenna, loudspeaker wall 9 is circle
Taper, length is between 210~230mm, and electric size is in 1.4 λc~1.6 λcBetween (λcFor the corresponding wavelength of cutoff frequency), mouth
Face diameter is between 115~125mm, and mouth face electric size is in 0.75 λc~0.85 λcBetween.
In the wave groove quadruple ridged horn feed, in the axial wave groove quadruple ridged horn antenna, using particular ridge
The thickness of four ridge pieces 5 of curve is between 5~5.5mm, and the spacing of two ridge of loudspeaker ridge waveguide part is between 2~2.15mm;
60 ° of corner cuts are used at position close to each other using four ridge pieces 5 of particular ridge curve, make the main mould characteristic impedance of four ridge waveguides
Match with coaxial line;Distance of the semi-rigid coaxial cable feed connector 11 apart from short board 8 of two sub-miniature A connectors connection be respectively
23.4mm and 24.4mm.
In the wave groove quadruple ridged horn feed, in the axial wave groove quadruple ridged horn antenna, loudspeaker feed section
Using three section impedance matching structures 6, the open width of three sections is followed successively by 0.55~0.65mm (0.0037 λ of electric sizec~
0.0043λc), 0.85~0.95mm (0.0057 λ of electric sizec~0.0063 λc), 1~1.1mm (0.0067 λ of electric sizec~
0.0073λc), the length of three sections is followed successively by 4.1~4.3mm (0.027 λ of electric sizec~0.029 λc), 2~2.2mm (electric size
0.0137λc~0.015 λc), 4.1~4.3mm (0.027 λ of electric sizec~0.029 λc);Connect the length of first segment and the second section
For 7.3mm (0.049 λ of electric sizecLeft and right), connecting the length between the second section and third section is 10.4mm (0.069 λ of electric sizec
Left and right);Third section is connected with the ridge piece of particular ridge curve, constitutes complete ridge piece.
In the wave groove quadruple ridged horn feed, in the axial wave groove quadruple ridged horn antenna, the ridge of ridge piece is bent
For line according to fixed amendment type exponential curve gradual change, exponential curve equation is y=2.192*e0.0167*x+ 0.057*x, use are specific
Four ridge pieces 5 of ridge curve use 60 ° of corner cuts at position close to each other.
In the wave groove quadruple ridged horn feed, in the axial wave groove quadruple ridged horn antenna, bell mouth surface position
The place of setting is loaded with the axial flute constructions 10 of four slots, and the width of four slots is between 10~11mm, and electric size is in 0.06 λc~
0.07λcBetween, 37.6,37.6,36.5,36.5mm are followed successively by by the groove depth of internal layer to outer layer, electric size is in 0.2 λc~0.3 λc
Between, the wall thickness of slot about 1mm.
In the wave groove quadruple ridged horn feed, in the axial wave groove quadruple ridged horn antenna, using particular ridge
Four ridge pieces 5 of curve apart from short board 8 close to the plane of ridge piece side distance between 20.9~21.9mm;Using specific
Four ridge pieces 5 of ridge curve conducting resinl is connect with cavity 7, and is fixed with screw, is realized and is used the four of particular ridge curve
The excellent electric contact of a ridge piece 5 and cavity 7.
In the wave groove quadruple ridged horn feed, the antenna body consists of metal, and metal is selected from: aluminium, iron,
Tin, copper, silver, gold, the alloy of platinum and above-mentioned metal.
In the wave groove quadruple ridged horn feed, the support column of supporting structure 2 is between ring flange 3 and electromagnetic horn 1
Length between 150mm~300mm;The absorbing material thickness on ring flange 3 is covered between 30mm~80mm.
The principle of the invention lies in:
The invention is a kind of invention of ultra wide band feed for being directed to Compact Range test.The frequency coverage of the feed exists
More than 3 octaves, such as 2-6GHz.The whole series invention includes axial wave groove electromagnetic horn 1, supporting structure 2, ring flange 3, suction wave material
Material 4.The invention uses the matched feed structure of three sections, by adjusting the open width and length of each section, can make ridge waveguide
Main mould characteristic impedance and the characteristic impedance of coaxial line reach extraordinary matching effect, the return loss of loudspeaker is subtracted significantly
It is small, the standing wave performance of loudspeaker is improved, while cooperating specific ridge curve, the bandwidth of operation of loudspeaker is greatly opened up
Exhibition.Four axial wave grooves are loaded at the aperture position of loudspeaker.In a quarter λ c, (λ c is cutoff frequency to the depth of wave groove
The corresponding wavelength of rate) left and right, it can be very good the beam angle for inhibiting low-frequency range, simultaneously as the presence of wave groove, mouth face
Field distribution is by central compressed, it is suppressed that is present in the field distribution of existing circumferential direction between ridge piece, to reduce loudspeaker
Cross-polarization levels, over the entire frequency band, cross polarization averagely reduces 5dB or more.Certain length is configured after electromagnetic horn
Supporting structure, the upper and lower ends of supporting structure configure certain connection attachment connection electromagnetic horn and ring flange, and in bracket
Structural base is laid with specific absorbing material, and inhibition is repeatedly radiated due to caused by supporting structure.
The advantages of the present invention over the prior art are that:
(1), the axial flute constructions of the invention by loading four slots at aperture position, by low-frequency range directional diagram
Beam angle reduce 20 degree or more, more stable beam angle is obtained over the entire frequency band, thus in ultra wide band feed
Field has stronger practicability.
(2), the present invention passes through the compression of wave groove opposite surface electric field, reduces the opposite electric size of bell mouth surface,
The circumferential electric field generated between ridge piece is inhibited, cross-polarization levels are greatly reduced in working band, improve testing efficiency
And precision.
(3), the present invention uses three section impedance matching structures at the feed of ridge waveguide, hinders the main mould characteristic of ridge waveguide
The anti-characteristic impedance with coaxial line reaches extraordinary matching effect, and the return loss of loudspeaker is greatly reduced, loudspeaker are improved
Standing wave performance.
Detailed description of the invention
Fig. 1 is a kind of structural schematic diagram of wave groove quadruple ridged horn feed of the present invention;
Fig. 2 is axial wave groove quadruple ridged horn antenna structure view;
Fig. 3 is supporting structure and ring flange and connected mode schematic diagram;
Fig. 4 is three section impedance matching structure schematic diagrames;
Appended drawing reference meaning in figure are as follows: 1 is axial wave groove quadruple ridged horn antenna, and 2 be supporting structure, and 3 be ring flange,
4 be absorbing material, and 5 is, using four ridge pieces of particular ridge curve, 6 are three section impedance matching structures, and 7 be cavity, and 8 be short circuit
Plate, 9 be loudspeaker wall, and 10 be the axial flute constructions of four slots, and 11 be that the semi-rigid coaxial cable feed connected using sub-miniature A connector is connect
Head.
Specific embodiment
Specific design of the invention is as follows: since quadruple ridged horn antenna has the characteristics that bandwidth, so with quadruple ridged horn
More piece matching technique and wave groove technology are introduced based on antenna, the return loss and beam angle of Lai Gaishan loudspeaker can
It is applied in Compact Range testing field.Increase a more piece impedance matching structure at the feed of ridge waveguide, tune can be passed through
The size of section multi-section structure largely reduces return loss.Wave groove technology is utilized simultaneously, and four are loaded at aperture position
A axial groove, axial groove can reduce the beam angle of low-frequency range, to stablize the beam angle on entire frequency band, while ripple
The presence of slot can compress the field distribution of bell mouth surface, inhibit the field distribution for being present in existing circumferential direction between ridge piece, from
And the cross-polarization levels of loudspeaker can be reduced.
According to the design of foregoing invention, the present invention adopts the following technical scheme:
First determine the mouth face size and horn length of quadruple ridged horn antenna, mouth face size is determined by cutoff frequency, traditional
Quadruple ridged horn mouth face need to be greater than the half of lowest operating frequency, corresponding 2GHz, and the selection of mouth face should be greater than 75mm, finally remove ripple
The mouth face diameter of slot part loudspeaker between 115~125mm, the length of electromagnetic horn should according to the principle of optimal horn designs,
It is as small as possible to combine mouthful face phase difference, horn length is selected as between 1.4 λ of λ c~1.6 c.
According to magnetic field integral equation method, determines the thickness of four ridge waveguides and ridge waveguide spacing is respectively 5~5.5mm and 2
~2.15mm.Four ridges of four ridge waveguides use 60 ° of corner cuts at position close to each other, make the main mould characteristic impedance of four ridge waveguides
With coaxial lines matching.Principle to the design of the corner cut of ridge is that four ridge pieces cannot be overlapped, while should be to standing wave performance
It has greatly improved.
The ridge curve of ridge piece generally uses the form of amendment type exponential function: y=a*eR*x+ b*x, wherein R is essentially dictated
The opening speed of ridge curve, R is bigger, and opening speed is faster, and respective antenna axial length is shorter, and R is smaller, and opening speed is slower, antenna
Axial length is longer.R is bigger, and reflection is bigger, it is contemplated that needing stable phase center as feed antenna, cannot be selected with this
Excessive antenna axial length is selected, simultaneity factor a, b also can control the subtended angle of loudspeaker, the subtended angle and beam angle and return loss of loudspeaker
There is relationship, so should weigh two results takes optimal value, the present invention passes through a obtained after optimization, b, and R value is respectively
2.192,0.057,0.0167.
There are certain errors for antenna processing in practical projects, need to provide corresponding processing tolerance in the design, due to
Mismachining tolerance exists, using four ridge pieces 5 and the cavity 7 of particular ridge curve it is difficult to ensure that good electrical contact, emulation and experiment
It proves, if the four ridge pieces 5 and cavity 7 using particular ridge curve will produce the standing wave of ridged horn without good electrical contact
Raw very big influence.Therefore conductive glue connection ridge piece and cavity are added in the design, meanwhile, it is reinforced using four M2 screws,
Ridge piece is mechanically fixed with cavity.
The processing of modified quadruple ridged horn antenna can use aluminium, and the metal of the well conductings such as copper is preferred real as one
Example is applied, using duralumin as rapidoprint.
In order to reduce the return loss of loudspeaker to the full extent, good standing wave performance is obtained, three section impedances are introduced
Distribution structure 6, by design three sections of progressive structures of ridge waveguide part, improve the characteristic impedance of main mould in ridge waveguide, make its with it is same
The characteristic impedance of axis is easier to match, while can also widen the bandwidth of operation of electromagnetic horn.After optimizing and revising, three sections
Open width be followed successively by 0.55~0.65mm (0.0037 λ of electric sizec~0.0043 λc), 0.85~0.95mm (electric size
0.0057λc~0.0063 λc), 1~1.1mm (0.0067 λ of electric sizec~0.0073 λc), the length of three sections is followed successively by 4.1~
4.3mm (0.027 λ of electric sizec~0.029 λc), 2~2.2mm (0.0137 λ of electric sizec~0.015 λc), 4.1~4.3mm (electricity
0.027 λ of sizec~0.029 λc).The length for connecting first segment and the second section is 7.3mm (0.049 λ of electric sizecLeft and right), connection
Length between second section and third section is 10.4mm (0.069 λ of electric sizecLeft and right).The ridge piece of third section and particular ridge curve
It is connected, constitutes complete ridge piece.With this structure, voltage standing wave ratio reduces 0.3 or so, has reached voltage standing wave ratio and has existed
Both less than 1.5 level in working band.
In order to which the beam angle to low-frequency range antenna pattern carries out certain control, to reach the wave beam in entire frequency range
Width is all relatively stable, introduces axial flute constructions, by the axis for increasing by four slots at quadruple ridged horn Antenna aperture position
To flute constructions 10, the mouth face of axial wave groove and loudspeaker keeps horizontal, and wave groove inhibits the beam angle of low-frequency range, increases
After adding wave groove, the 3dB beam angle at low frequency 2GHz is reduced to 55 degree from original 80 degree, the 3dB wave beam in entire frequency band
Width is stablized between 20~55 degree, simultaneously as the presence of wave groove, the field distribution in mouth face is pressed down by central compressed
The field distribution for being present in existing circumferential direction between ridge piece is made, so that the cross-polarization levels of loudspeaker are reduced, in entire frequency
It takes, cross polarization averagely reduces 5dB or more.
In actual Compact Range test macro, generally there is support fixed structure behind feed, which may generate
Some scatterings, influence measuring accuracy.The present invention devises supporting structure 2, and electromagnetic horn is erected, and makes itself and Compact Range reflecting surface
Focus is overlapped, while absorbing material 4 is laid between the ring flange of support construction and bottom 3, inhibits the support knot due to metal
Reflection caused by structure.
A kind of wave groove quadruple ridged horn feed of the present invention, the feed can be used for conduct in Compact Range test macro
Emit or receive antenna.It can also be used as Compact Range dead zone scanning head, realize higher measuring accuracy.Meanwhile the feed is also
The feed in radio astronomy field, as large-scale reflector antenna can be applied to use.