CN104078733A - SIW circulator - Google Patents

Abstract

A SIW circulator relates to microwave and millimeter wave technology. The invention comprises a substrate integrated waveguide and a microstrip line, and is characterized in that the connection part of the substrate integrated waveguide and the microstrip line is a circular arc, the width a of the substrate integrated waveguide and the radius R of a circular ferrite_fChamfer radius R of arc connecting microstrip line and SIW_cWhile satisfying the following relationship: r is more than or equal to 0.162_c/a≤0.2160.769≤R_c/R_fThe invention adopts a novel matching technology of SIW to microstrip lines, realizes good impedance matching and realizes miniaturization and broadband of devices.

Description

A kind of SIW circulator

Technical field

The present invention relates to microwave, millimeter-wave technology.

Background technology

Along with the fast development of modern microwave, millimeter-wave technology, microwave, millimeter-wave systems be rapidly to miniaturization, lightness, high reliability, multi-functional, low cost future development, and traditional transmission line can not meet these requirements completely as rectangular waveguide and microstrip line.Substrate integration wave-guide (SIW) is as a kind of emerging transmission line, it had both had rectangular waveguide high quality factor, low-loss and relatively high power capacity, have advantages of that again microstrip line volume is little, it is integrated to be easy to, thereby SIW transmission line can be used widely in microwave, millimeter wave equipment.

At present, SIW transmission line has started the design for filter, circulator, isolator, antenna etc., and integrated for convenient and other circuit will adopt microstrip line to transfer to SIW conventionally, and this has just existed the problem of a coupling.Conventional matching process has microstrip line and Chebyshev's gradual change microstrip line coupling of linear gradient microstrip line, single-unit or more piece 1/4 wavelength, when the shortcoming of these methods is to obtain low return loss, micro-band transition line can be generally partially long, contradicts with the miniaturization that realizes device.In the design of SIW circulator and being connected for Bandwidth and realization and external circuit, generally can adopt the outer microstrip line coupling of knot, conventional is linear gradient microstrip line coupling at present, and for the reflection that reduces to cause due to change in the instantaneous impedance, the microstrip line of gradual change is generally all longer.

Summary of the invention

Technical problem to be solved by this invention is, a kind of SIW circulator with low return loss and short microstrip line length feature is provided.

The technical scheme that the present invention solve the technical problem employing is, SIW circulator, comprises substrate integration wave-guide and microstrip line, it is characterized in that, the junction of substrate integration wave-guide and microstrip line is circular arc, substrate integration wave-guide width a, circular ferrite radius R _fthe chamfer radius Rc that is connected circular arc with microstrip line with SIW meets following relation simultaneously:

0.162≤R _c/a≤0.216

0.769≤R _c/R _f≤1.026

Further, a=3.70mm, R _f=0.78mm, R _c=0.70mm.

The invention has the beneficial effects as follows, adopted new SIW to turn the matching technique of microstrip line, realized the matched well of impedance, and realized miniaturization and the wideband of device.

Brief description of the drawings

Fig. 1 is SIW simulation model figure.

Fig. 2 is S (1, the 1) curve chart that SIW different in width a is corresponding.

Fig. 3 is the SIW circulator structure chart that has microstrip line coupling.

Fig. 4 is circulator S parametric plot.

Fig. 5 is the output impedance curve chart of 3 ports.

Fig. 6 is the different chamfer radius R of circulator _ccorresponding S (1,1) curve chart.

Embodiment

Work in the circulator design of ka wave band and be prepared as example with one, present embodiment meets following index request: centre frequency is at 37.5GHz, the bandwidth of return loss in the time of-20dB is not less than 5GHz, and Insertion Loss is less than 0.5dB, and the output impedance of three ports is 50 Ω.

Design and preparation process are:

The selection of step 1, circulator design material, mainly comprises the selection of medium substrate and Ferrite Material.

Step 2, determine the parameter of SIW transmission line, the plated-through hole of stamping periodic arrangement on medium substrate forms SIW transmission line, the structure of SIW is by the width a of through-hole diameter d, pitch of holes s (pitch of holes in distance of center circle from), substrate thickness h and SIW and determine, they meet relational expression: s/d<2, d/a<0.2, and formula below

$a_{\mathrm{eff}}=a-1.08\frac{d^2}{s}+0.1\frac{d^2}{a}---\left(1\right)$

Wherein a _efffor filling the width of rectangular waveguide of medium of the same race, a _effdesirable 0.8 λ of initial value _g(λ _gfor operation wavelength).

Step 3, utilize the transmission line after optimizing above to carry out the design of circulator, and carry out impedance matching and switching with microstrip line.Ferritic radius can be obtained according to formula below

$R_f=\frac{1.84\mathrm{\&lambda;}}{2\mathrm{\&pi;}\sqrt{{\mathrm{\&epsiv;}}_f{\mathrm{\&mu;}}_e}}---\left(2\right)$

Wherein λ is the wavelength in vacuum under this frequency, ε _ffor ferritic relative dielectric constant, μ _efor ferrite effective permeability.

Step 4, the major parameter in circulator is optimized, comprises chamfer radius R _c, ferrite radius R _f, SIW width a, and obtain R _cspan.

Step 5, the definite parameter value of the above each step of foundation are made the SIW circulator with circular arc microstrip line.

As an embodiment, step is more specifically:

Step 1, select a kind of relative dielectric constant ε of double-sided copper-clad _rbe 3, the pcb board that substrate thickness h is 0.508mm is as medium substrate.Ferritic saturation magnetization 4πms=5200Gauss, effective line width Δ H=100Oe, relative dielectric constant ε _fbe 13.

Step 2, the plated-through hole of stamping periodic arrangement on medium substrate form SIW transmission line, and the diameter d of through hole is 0.4mm, and pitch of holes s is 0.75mm, and the width a of SIW is calculated as 3.7mm according to formula.Fig. 1 is SIW model structure figure, and Fig. 2 is return loss plot figure when width a is optimized.

Step 3, by simulation result above, selecting one preferably the corresponding SIW transmission line of a value carry out the design of circulator, three arms of circulator are made up of three sections of SIW transmission lines, and carry out impedance matching with 1/4 wavelength microstrip line, adopt circular arc chamfering at microstrip line and SIW junction.Ferritic radius R _fobtain as 0.76mm according to formula.Now the structure of circulator as shown in Figure 3.

Step 4, the structural parameters that circulator centre frequency and bandwidth of operation are had the greatest impact have a, R _f, R _c, as a, R _fby formula primary Calculation out after, R _cshould meet relational expression below with a, Rf:

0.162≤R _c/a≤0.216(3)

0.769≤R _c/R _f≤1.026(4)

Determine chamfer radius R with this _c.

Further, prove a=3.70mm, R through test _f=0.78mm, R _c=0.70mm, pitch of holes s=0.75mm, through-hole diameter d=0.4mm, 50 Europe micro belt line width w _{_ 50 Ω}=1.31mm, substrate width w _{_ sub}=6mm, when microstrip line length l=1.39mm, has splendid performance.As shown in Figure 4, the centre frequency of circulator is at 37.5GHz, and the bandwidth of the corresponding return loss of-20dB and isolation has all reached 6.5GH, exceeded the 5GHz bandwidth of index request, and Insertion Loss is all less than 0.5dB.Fig. 5 has provided the output impedance of three ports, all in 50 Ω left and right.Fig. 6 has provided different R _con the impact of return loss, work as R _cwhen=0.7mm, curve occurs significantly bimodal, and bandwidth of operation has maximum, on this basis, and R _cincrease or reduce all to make Double-peak Phenomenon weaken, gradually to unimodal development, bandwidth of operation is corresponding to be reduced.R _cequal 0.6mm and 0.8mm, be respectively the minimum and the maximum that meet design objective, i.e. R in design _cspan should be 0.6mm～0.8mm.

Claims (2)

1. a SIW circulator, comprises substrate integration wave-guide and microstrip line, it is characterized in that, the junction of substrate integration wave-guide and microstrip line is circular arc, substrate integration wave-guide width a, circular ferrite radius R _fbe connected the chamfer radius R of circular arc with SIW with microstrip line _cmeet following relation simultaneously:

0.162≤R _c/a≤0.216

0.769≤R _c/R _f≤1.026。

2. SIW circulator as claimed in claim 1, is characterized in that, a=3.70mm, R _f=0.78mm, R _c=0.70mm, pitch of holes s=0.75mm, through-hole diameter d=0.4mm, 50 Ω micro belt line width w _{_ 50 Ω}=1.31mm, substrate width w _{_ sub}=6mm, microstrip line length l=1.39mm.