A kind of Novel planar transmission line
Technical field
The invention belongs to transmission line technology field, particularly relate to a kind of Novel planar transmission line.
Background technology
Microwave and millimeter wave parts, component internal widely use microstrip line, microstrip line on same dielectric substrate (as characteristic impedance 50 ohm) width under given impedance is fixing, in microwave component design process, sometimes need conduction band width increased mount the larger components and parts of volume when keeping line characteristic impedance constant or be connected with the coaxial inner conductor that diameter is greater than the microstrip line conduction band width of use.
Now often adopt traditionally and increase conduction band width with the following method: 1. adopt microstrip line, select dielectric constant identical but the dielectric substrate that thickness is larger; 2. adopt microstrip line, select thickness identical but the dielectric substrate that dielectric constant is less; 3. adopt sling line, dielectric substrate dielectric constant, thickness can remain unchanged, and obtain the conduction band width expected by selecting suitable suspension height; 4. adopting co-planar waveguide, obtaining the conduction band width expected by selecting the gap width between suitable conduction band and ground; 5. the comprehensive of said method is adopted, as: adopt microstrip line, select the dielectric substrate etc. that thickness is larger, dielectric constant is lower.
The co-planar waveguide of existing conventional several planar transmission line microstrip lines, sling line, co-planar waveguide and back-side ground as shown in Figures 1 to 4.In all diagrams, 1 represents conduction band, and 2 represent medium substrate, and 3 represent ground, and h represents dielectric substrate thickness, and w represents conduction band width, and s represents the gap width between conduction band and ground.
Microstrip line extensive use in microwave and millimeter wave parts, assembly, but other kind planar transmission lines existing and microstrip line are difficult to integrated use.Above-mentioned need increase transmission line conduction band width time, 1. method still adopts microstrip line, once dielectric substrate determine after under given characteristic impedance conduction band width be fixing, discontinuity is there is between the transmission line of two kinds of width, be unfavorable for obtaining good high frequency performance, and increase the dielectric substrate kind used in microwave circuits, increase cost.Meanwhile, for ensureing that two transmission line upper surfaces are in same level, the cavity placing two transmission line places needs to be processed into the different degree of depth, increases mechanical processing difficulty.2. method still adopts microstrip line, once dielectric substrate determine after under given characteristic impedance conduction band width be fixing, discontinuity is there is between the transmission of two kinds of width, be unfavorable for obtaining good high frequency performance, and increase the dielectric substrate kind used in microwave circuits, be more crucially difficult under normal circumstances find the dielectric substrate with certain dielectric constant.3. method adopts sling line, and after dielectric substrate and suspension height are determined, under given characteristic impedance, conduction band width is fixing, and suspension height is large on characteristic impedance impact, needs accurately to control, and increases mechanical processing difficulty.Meanwhile, although there is discontinuity between the transmission line of two kinds of width---in theory can conduction band width gradual change by gradual change suspension height thus under making specified impedance, mechanical processing difficulty is large, does not in fact almost apply.4. method adopts co-planar waveguide, can when retention performance impedance be constant, conduction band width is changed easily by the gap width changed between center conduction band and ground, conduction band width can continuous gradation as required, but because its center conduction band and ground are positioned at the same side (there is ground the co-planar waveguide dielectric substrate both sides of back-side ground) of dielectric substrate, microstrip line conduction band and ground are positioned at dielectric substrate both sides, ground between microwave and millimeter wave frequency range two kinds of transmission lines is difficult to good connection, thus causes two kinds of transmission lines not easily to integrate use.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of Novel planar transmission line, is intended to the problem solving microstrip line and other kind planar transmission lines existing use not easy of integration.
The present invention is achieved in that a kind of Novel planar transmission line, comprises conduction band and dielectric substrate, and described conduction band is positioned at the side of described dielectric substrate, and ground is positioned at the opposite side of dielectric substrate; Gap width between described conduction band and ground is adjustable.
Described Novel planar transmission line, wherein, described Novel planar transmission line adopts thick film technology to be made, and described thick film technology sinters by means of mask and formed described Novel planar transmission line with metal material on described dielectric substrate.
Described Novel planar transmission line, wherein, described Novel planar transmission line adopts thin film technique to be made, and described thin film technique adopts vacuum sputtering or vacuum evaporation to form metallic film on described dielectric substrate, then forms figure by photoetching corrosion.
Described Novel planar transmission line, wherein, photoetching corrosion continues after forming figure described Novel planar transmission line plating to increase conductor thickness.
Described Novel planar transmission line, wherein, the characteristic impedance of described Novel planar transmission line is determined by dielectric substrate thickness, dielectric substrate dielectric constant, conduction band width, gap width between conduction band and ground.
Described Novel planar transmission line, wherein, the gap width between described conduction band and ground be negative conduction band width two/for the moment, described Novel planar transmission line changes microstrip line into.
Described Novel planar transmission line, wherein, described dielectric substrate is rigid substrate.
Described Novel planar transmission line, wherein, described rigid substrate is Al
2o
3, quartz or artificial white stone.
Described Novel planar transmission line, wherein, described dielectric substrate is flexible substrate.
Described Novel planar transmission line, wherein, described flexible substrate is polytetrafluoroethylene, polyimides.
Novel planar transmission line of the present invention has the advantage of microstrip line and co-planar waveguide concurrently, is particularly suitable for using with microstrip line hybrid integrated.Its feature makes the conduction band width dimensions gradual change when keeping line characteristic impedance constant become possibility, eliminates size and to suddenly change the discontinuity brought; Meanwhile, the transmission line described in employing will reduce the kind of the dielectric substrate used in microwave designing, reduces design cost, and reduces mechanical processing difficulty.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of the planar transmission line microstrip line that prior art provides;
Fig. 2 is the schematic diagram of the planar transmission line sling line that prior art provides;
Fig. 3 is the schematic diagram of the planar transmission line co-planar waveguide that prior art provides;
Fig. 4 is the schematic diagram of the co-planar waveguide of the planar transmission line back-side ground that prior art provides;
Fig. 5 is the Novel planar transmission line structural representation that the embodiment of the present invention provides;
Fig. 6 is the structural representation that Novel planar transmission line that the embodiment of the present invention provides is arranged in metallic cavity;
Fig. 7 is that the Novel planar transmission line that the embodiment of the present invention provides is keeping, under particular characteristics impedance permanence condition, changing conduction band width indication figure as required.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
The present invention has put forward a kind of Novel planar transmission line, and this transmission line has some advantage of microstrip line and co-planar waveguide concurrently.This transmission line is as microstrip line, and conduction band and ground are positioned at dielectric substrate both sides, makes it be applicable to using with microstrip line hybrid integrated.Meanwhile, this transmission line and co-planar waveguide similar, during given characteristic impedance, the conduction band width expected can be obtained conveniently by the gap width changed between conduction band and ground, thus make when maintenance specified impedance conduction band width can continuous gradation as required; During given conduction band width, the characteristic impedance expected can be obtained conveniently by the gap width changed between conduction band and ground.Described Novel planar transmission line can reduce the kind of the dielectric substrate used in microwave designing and then reduce costs, simultaneously, due to can conduction band width can continuous gradation as required under maintenance particular characteristics impedance, reduce discontinuity when changing between different conduction band width transmission lines.
As shown in Figure 5, a kind of Novel planar transmission line, by dielectric substrate 2 and be positioned at the conduction band 1 of described dielectric substrate about 2 both sides and ground 3 is formed, described Novel planar transmission line can adopt thick film technology or thin film technique to realize.When adopting thick film technology, sinter on dielectric substrate 2 by means of mask and formed transmission line with metal material.When adopting thin film technique, adopt vacuum sputtering or vacuum evaporation to form metallic film on dielectric substrate 2, then form figure by photoetching corrosion.Preferably, need to continue to described Novel planar transmission line plating to increase conductor thickness, reduction conductor losses.Described dielectric substrate 2 Material selec-tion and microstrip line require similar, both can be Al
2o
3, quartz, the rigid substrate such as artificial white stone, also can be the flexible substrate such as polytetrafluoroethylene, polyimides.
Further, Novel planar transmission line described in practical application is the same with traditional co-planar waveguide needs suspension, as shown in Figure 6, with make metallic cavity 4 avoid ground 3 above conductive portion.Because described Novel planar transmission line electrical property is to the height h of suspension
0and width W
0insensitive, reduce the required precision to machining.
Further, the dielectric constant of the thickness h of dielectric substrate 2, dielectric substrate 2, conduction band 1 width w, gap width s between conduction band 1 and ground 3 are depended in described Novel planar transmission line characteristic impedance.After dielectric substrate 2 is determined, conduction band 1 width and the gap width s between conduction band 1 and ground 3 are only depended in characteristic impedance.From co-planar waveguide s only can get be greater than zero on the occasion of different, in the present invention s value can be on the occasion of, also can be zero or negative value, its minimum value be-w/2.When s gets-w/2, this transmission line changes microstrip line into.
Further, the calculating of described Novel planar transmission line characteristic impedance can adopt commercial microwave simulation software HFSS, ADS, CST etc. to carry out.
Further, described Novel planar transmission line makes the conduction band width dimensions gradual change when keeping line characteristic impedance constant become possibility, eliminate size to suddenly change the discontinuity brought, as shown in Figure 7, simultaneously, adopt described Novel planar transmission line to reduce the kind of the dielectric substrate used in microwave designing, reduce design cost, and reduce mechanical processing difficulty.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.