CN105048051A - Tunable substrate integrated waveguide circular resonant cavity filter - Google Patents

Abstract

The present invention discloses a tunable substrate integrated waveguide circular resonant cavity filter. A symmetric circular SIW resonant cavity structure is used as a basic unit, and the middle dielectric substrate of the circular SIW resonant cavity structure is provided with an air slot in the diameter direction of the middle dielectric substrate. The air slot is internally provided with a metal column capable of moving along the diameter direction of the middle dielectric substrate, and a turning unit is formed by the air slot and the metal column. The main mold resonance frequency of the circular SIW resonant cavity structure is adjusted through adjusting the circle center distance between the metal column and the middle dielectric substrate. The filter provided by the invention has the advantages of simple structure and easy processing, a frequency band is in a Ku band, the tuning range of the filter reaches 18%, the main mold frequency can be adjusted continuously, and the estimated tuning can be carried out.

Description

A kind of tunable substrate integration wave-guide circular resonant cavity filter

Technical field

The present invention relates to a kind of tunable substrate integration wave-guide circular resonant cavity filter, belong to millimeter-wave technology.

Background technology

Along with the high speed development of modern microwave millimetre-wave circuit system, its function becomes increasingly complex, electrical performance indexes requirement is more and more higher, requires that its volume is more and more less, weight is more and more lighter simultaneously; Whole system is rapidly to miniaturization, lightweight, high reliability, multifunctionality and low cost future development.The microwave and millimeter wave technology of low cost, high-performance, high finished product rate is very crucial for the business-like low cost microwave and millimeter wave broadband system of exploitation.Therefore, in the urgent need to developing new microwave and millimeter wave integrated technology.Substrate integration wave-guide (SubstrateIntegratedWaveguide, SIW) be a kind of periodic structure of solid, it can make by integrated technique, limited to extraradial electromagnetic wave by metal throuth hole or air via hole, thus replace traditional rectangular metal waveguide or non-radiative dielectric waveguide.

High quality factor resonator is a typical index of the superior function of many active and passive circuits.Total institute is known, and SIW has higher quality factor in plane microwave device.SIW technology has been applied to many microwave devices, maintains the advantage of traditional metal waveguide: 1, low-loss and high quality factor with the device that SIW realizes; 2, permanent electric isolation; 3, high power handling capability 4, high integration with other various active and passive circuits.

Be generally acknowledged to the important need of the dynamic management of frequency spectrum, software radio adds the demand of radio frequency/microwave device process different frequency range.Microwave filter becomes the main restricting factor of design said system, needs to cover more frequency range.This just needs to make SIW filter tunable, has higher tuning range, keeps high quality factor simultaneously.Existing tuning methods mainly contains: the electric tuning of variable capacitance diode sideband coupling, by PN diode or variable capacitance diode to the electric tuning of the disturbance of via hole, and the electric tuning under iron oxygen Kiev helps, and the mechanical tuning to industry control.Although relatively good based on the prior art linearity of mechanical tuning, complex process, manufacture difficulty is comparatively large, and simultaneous tuning scope is narrow.

Summary of the invention

Goal of the invention: in order to overcome the deficiencies in the prior art, the invention provides a kind of tunable substrate integration wave-guide circular resonant cavity filter, and technique is simple, while realizing tunable frequency, has the predictable characteristic of tuned frequency; Solve the defect that existing complex process, manufacture difficulty are comparatively large, tuning range is narrow.

Technical scheme: for achieving the above object, the technical solution used in the present invention is:

A kind of tunable substrate integration wave-guide circular resonant cavity filter, this filter adopts symmetrical circular SIW cavity resonator structure as elementary cell, circular SIW cavity resonator structure bag intermediate medium substrate, the upper surface of intermediate medium substrate is provided with top layer metallic layer, the lower surface of intermediate medium substrate is provided with bottom metal layer, on intermediate medium substrate, be along the circumferential direction provided with the plated-through hole of cycle arrangement, plated-through hole electrical connection top layer metallic layer and bottom metal layer; It is characterized in that: the intermediate medium substrate of circular SIW cavity resonator structure is also provided with an air groove, the through top layer metallic layer of air groove, intermediate medium substrate and bottom metal layer, air groove is on the radial direction of intermediate medium substrate, air groove one end is positioned at the home position of intermediate medium substrate, and the other end of air groove is no more than plated-through hole; In air groove, arrange one can along the metal column of the radial direction movement of intermediate medium substrate, air groove and metal column form tuned cell jointly, by regulating the main mould resonance frequency of the circular SIW cavity resonator structure of the center of circle distance adjustment of metal column and intermediate medium substrate; The input and output of circular SIW cavity resonator structure adopt microstrip line-coplanar waveguide structure, and first the input and output terminal impedance of circular SIW cavity resonator structure matches 50 Ω, and then connects external devices with 50 Ω microstrip lines.

Above-mentioned circular SIW cavity resonator structure, design air groove only through intermediate medium substrate, retains top layer metallic layer above air groove in theory, and below retains bottom metal layer, to avoid leakage signal; But consider and conveniently regulate metal column, at this design air groove through top layer metallic layer, intermediate medium substrate and bottom metal layer simultaneously, but in actual use, after having regulated the position of metal column, covering metal sheet above and below air groove, to avoid leakage signal.

Above-mentioned circular SIW cavity resonator structure, the plated-through hole of loading cycle on intermediate medium substrate, can be enclosed in electromagnetic field in the intermediate medium substrate of the cavity that plated-through hole surrounds, form the structure of similar waveguide; Above-mentioned tuned cell is made up of jointly air groove and metal column, the distance of center circle of metal column and intermediate medium substrate is from the main mould resonance frequency determining circular SIW cavity resonator structure, main mould resonance frequency can regulate continuously, and the distance of center circle of metal column and intermediate medium substrate forms relation one to one from mould resonance frequency.

Preferably, the angle of the input and output microstrip line of circular SIW cavity resonator structure is 60 ° ~ 90 °, and theoretic optimum angle is 75 °.

Preferably, in this filter, the circular SIW cavity resonator structure position of arbitrary neighborhood two meets Central Symmetry, to facilitate theory analysis and research.

Beneficial effect: tunable substrate integration wave-guide circular resonant cavity filter provided by the invention, compared with prior art, there is following features: 1, filter adopts symmetrical circular SIW cavity resonator structure as elementary cell, global design meets Central Symmetry, be convenient to theory analysis and calculating, the design cycle is short; 2, the tuned cell structure of filter is simple, and tuning range is wide, and tuner parameters is unique; 3, filter does not need to adopt extra components and parts to realize tuber function, and cost is low; 4, the resonance frequency of filter uniquely can be determined by the tuner parameters of tuned cell, and main mould frequency to regulate continuously, and becomes one-to-one relationship with metal column with the distance in the circular SIW cavity resonator structure center of circle.

Accompanying drawing explanation

Fig. 1 is single tunable circular SIW resonant cavity plan structure schematic diagram of the present invention;

Fig. 2 is the tuned cell side-looking structural representation of tunable circular SIW resonant cavity of the present invention;

Fig. 3 is tuned frequency and the tuned cell distance home position relation schematic diagram of single tunable circular SIW resonant cavity of the present invention;

Fig. 4 is tunable circular SIW resonant cavity filter plan structure schematic diagram of the present invention;

Fig. 5 is the different corresponding filter insertion loss of tuned cell of the present invention distance home position;

Fig. 6 is the different corresponding filter return loss of tuned cell of the present invention distance home position.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described.

A kind of tunable substrate integration wave-guide circular resonant cavity filter, this filter adopts symmetrical circular SIW cavity resonator structure as elementary cell; As shown in Figure 1 and Figure 2, circular SIW cavity resonator structure bag intermediate medium substrate 6, the upper surface of intermediate medium substrate 6 is provided with top layer metallic layer 1, the lower surface of intermediate medium substrate 6 is provided with bottom metal layer 3, on intermediate medium substrate 6, be along the circumferential direction provided with the plated-through hole 5 of cycle arrangement, plated-through hole 5 is electrically connected top layer metallic layer 1 and bottom metal layer 3; The intermediate medium substrate 6 of circular SIW cavity resonator structure is also provided with an air groove 4, the through top layer metallic layer 1 of air groove 4, intermediate medium substrate 6 and bottom metal layer 3, air groove 4 is on the radial direction of intermediate medium substrate 6, air groove 4 one end is positioned at the home position of intermediate medium substrate 6, and the other end of air groove 4 is no more than plated-through hole 5; In air groove 4, arrange one can along the metal column 2 of the radial direction movement of intermediate medium substrate 6, air groove 4 and metal column 2 form tuned cell jointly, by regulating the main mould resonance frequency of the circular SIW cavity resonator structure of the center of circle distance adjustment of metal column 2 and intermediate medium substrate 6; The input and output of circular SIW cavity resonator structure adopt microstrip line-coplanar waveguide structure, and first the input and output terminal impedance of circular SIW cavity resonator structure matches 50 Ω, and then connects external devices with 50 Ω microstrip lines.

In all kinds of planar waveguiding structure, circular SIW cavity resonator structure has best quality factor, has best performance when the angle of the input and output microstrip line of circular SIW cavity resonator structure is 75 ° in theory; The angle designing the input and output microstrip line of circular SIW cavity resonator structure in this example is 72 °.The resonance frequency f of the circular SIW cavity resonator structure surrounded with solid wall _mnpfor:

$f_{mnp}=\left\{\begin{array}{cc}\frac{c}{2\mathrm{\π}\sqrt{{\mathrm{\μ}}_r{\mathrm{\ϵ}}_r}}\sqrt{{\left(\frac{{\mathrm{\μ}}_{mn}^{\′}}{R}\right)}^2+{\left(\frac{p\mathrm{\π}}{\mathrm{\Δ}h}\right)}^2}& {\mathrm{TE}}_{mnp}\\ \frac{c}{2\mathrm{\π}\sqrt{{\mathrm{\μ}}_r{\mathrm{\ϵ}}_r}}\sqrt{{\left(\frac{{\mathrm{\μ}}_{mn}}{R}\right)}^2+{\left(\frac{p\mathrm{\π}}{\mathrm{\Δ}h}\right)}^2}& {\mathrm{TM}}_{mnp}\end{array}\right.$

Wherein: μ _rand ε _rbe respectively relative permeability and the relative dielectric constant of filled media material, μ _mnwith μ ' _mnbe respectively m root of m root of n rank Bessel function of the first kind and the derivative of n rank Bessel function of the first kind, R is the radius (intermediate medium substrate center and plated-through hole center distance) of circular SIW cavity resonator structure, △ h is the thickness of the intermediate medium substrate of circular SIW cavity resonator structure, c is the light velocity in vacuum, main mould TE _mnprepresent the resonance frequency of rectangular cavity, main mould TM _mnprepresent the resonance frequency calculating formula in circular resonant chamber.In this example, TM ₁₀₁being main mould, is also mode of operation, so the 1st of 0 rank Bessel function of the first kind the root μ ₁₀be 2.4048, TM ₁₀₁corresponding resonance frequency f is:

$f=\frac{c}{2\mathrm{\π}\sqrt{{\mathrm{\μ}}_r{\mathrm{\ϵ}}_r}}\frac{2.4048}{R}=\frac{0.383c}{R\sqrt{{\mathrm{\μ}}_r{\mathrm{\ϵ}}_r}}$

Replace solid wall with plated-through hole, the equivalent redius of circular SIW cavity resonator structure can be modified to:

$r=R-a/2+0.268{\left(\frac{dx}{a}\right)}^{0.326}$

Wherein: a is the diameter of plated-through hole, dx is the distance in the center of circle of adjacent two plated-through holes.

Therefore, the main mould frequency of circular SIW cavity resonator structure is:

$f=\frac{0.383c}{(R-a/2+0.268{\left(\frac{dx}{a}\right)}^{0.326})\sqrt{{\mathrm{\μ}}_r{\mathrm{\ϵ}}_r}}$

Metal column 2 in mobile air groove 4, corresponding resonance frequency can change, and works as R=6mm, when the corresponding central angle of two plated-through holes 5 is 8 °, can calculate corresponding main mould resonance frequency f=11.86GHz by above formula.Prismatic in Fig. 3 selects resonance frequency f corresponding to the length d of the distance in metal column 2 centre distance intermediate medium substrate 6 center of circle representing practical adjustments, these prismatic points of matching, best fitting function formula quadratic function:

f(d)＝p ₁d ²+p ₂d+p ₃

In this case, parameter is:

p ₁＝0.06468(0.06088,0.06847)

p ₂＝-1.224(-1.246,-1.201)

p ₃＝16.82(16.79,16.85)

Wherein, the confidential interval of bracket content representation 95%.

What the little * point expression in Fig. 3 calculated does not have the main mould frequency f=11.86GHz of the resonant cavity of air groove.As can be seen from the figure the main mould frequency of tuning distance d and resonant cavity has quadratic function relation, one_to_one corresponding.

Fig. 4 is an embodiment of tunable circular SIW resonant cavity filter, is coupled to form by two of Fig. 1 symmetrical circular SIW resonant cavitys.Distance between adjacent resonators is adjustable to obtain best coupling

The medium of this embodiment is TaconicTLT (tm), and dielectric thickness is 0.5mm, and the dielectric constant of medium is 2.55.Top layer metallic layer, bottom metal layer and metal column all adopt copper, as follows according to the size that Fig. 1 and Fig. 4 indicates: W ₁=2.2mm, W ₂=1.4mm, R=6mm, dx=0.84mm, a=0.5mm, g=1.9mm, b=1.0mm, e=10mm, α=72 °.

Fig. 5 and Fig. 6 is the simulation result of the embodiment of filter of the present invention, and the abscissa of Fig. 5 and Fig. 6 represents frequency (unit GHz), and ordinate represents filter return loss (unit dB); In Figure 5, filter return loss is more better close to 0, and in figure 6, it is basic demand that filter return loss is less than-10dB, and this value is the smaller the better.

Above simulation result result shows: filter centre frequency changes to 15.15GHz from 12.6GHz, is equivalent to 18% corresponding to 13.875GHz tunable range.The reflection coefficient of the heart is lower than-15dB in the pass-band, insertion loss 0.5dB-1dB.

A kind of novel tunable substrate integration wave-guide circular resonant cavity filter embodiment tunable range 12.6GHz to 15.15GHz provided by the invention.Tuned unit is the copper post based on moving radially in SIW chamber.Embodiment filter only needs traditional PCB manufacturing process, and production cost reduces greatly.The major advantage of the structure proposed is continuously adjustabe, tuning range can calculate, and can calculate in advance and adjusting position.

The above is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (3)

1. a tunable substrate integration wave-guide circular resonant cavity filter, this filter adopts symmetrical circular SIW cavity resonator structure as elementary cell, circular SIW cavity resonator structure bag intermediate medium substrate (6), the upper surface of intermediate medium substrate (6) is provided with top layer metallic layer (1), the lower surface of intermediate medium substrate (6) is provided with bottom metal layer (3), on intermediate medium substrate (6), be along the circumferential direction provided with the plated-through hole (5) of cycle arrangement, plated-through hole (5) electrical connection top layer metallic layer (1) and bottom metal layer (3), it is characterized in that: the intermediate medium substrate (6) of circular SIW cavity resonator structure is also provided with an air groove (4), air groove (4) through top layer metallic layer (1), intermediate medium substrate (6) and bottom metal layer (3), air groove (4) is on the radial direction of intermediate medium substrate (6), air groove (4) one end is positioned at the home position of intermediate medium substrate (6), and the other end of air groove (4) is no more than plated-through hole (5), in air groove (4), arrange one can along the metal column (2) of the radial direction movement of intermediate medium substrate (6), air groove (4) and metal column (2) form tuned cell jointly, by regulating the main mould resonance frequency of the circular SIW cavity resonator structure of the center of circle distance adjustment of metal column (2) and intermediate medium substrate (6), the input and output of circular SIW cavity resonator structure adopt microstrip line-co-planar waveguide knot, and first the input and output terminal impedance of circular SIW cavity resonator structure matches 50 Ω, and then connects external devices with 50 Ω microstrip lines.

2. tunable substrate integration wave-guide circular resonant cavity filter according to claim 1, is characterized in that: the angle of the input and output microstrip line of described circular SIW cavity resonator structure is 60 ° ~ 90 °.

3. tunable substrate integration wave-guide circular resonant cavity filter according to claim 1, is characterized in that: in this filter, and the circular SIW cavity resonator structure position of arbitrary neighborhood two meets Central Symmetry.