CN104091993A - Double-frequency stub coupler based on substrate integrated coaxial line technology - Google Patents

Abstract

The invention discloses a double-frequency stub coupler based on the substrate integrated coaxial line (SICL) technology. The double-frequency stub coupler comprises a dielectric substrate, an upper surface metal layer, a lower surface metal layer, a main body of the coupler and a grounded co-planar waveguide. The main body of the coupler is composed of SICL transmission lines. The main body of the coupler comprises four quarter-wave-electrical-length stubs, four half-wavelength-electrical-length stubs and four port lines. The port lines of the coupler are connected with the grounded co-planar waveguide through metal through holes. According to the double-frequency stub coupler based on the SICL technology, a high return loss performance is achieved on an input port at the working frequency point, high isolation is achieved on an isolation port, two output ports have the same amplitude and a 90-degree phase difference, and the coupler can work at different double frequency points by changing the size.

Description

A kind of double frequency minor matters line coupler that adopts substrate integrated coaxial line technology

Technical field

The present invention relates to a kind of double frequency 3-dB minor matters line coupler based on substrate integrated coaxial line (Substrate Integrated Coaxial Line, SICL) technology, belong to Films In Passive Microwave Devices field.

Background technology

Microwave and millimeter wave passive device is the important component part of wireless communication system.Along with the fast development of wireless communication system, little to volume, cost is low, performance is high and be easy to integrated passive device has produced urgent demand.In microwave and millimeter wave system, in order to realize at output port, amplitude equates, 90 ° of phase differences, meets the performance requirements such as low return loss, as the various forms of passive devices such as Wilkinson power divider, coupler arise at the historic moment at input port.Traditional minor matters line coupler uses microstrip line or strip line as transmission line conventionally, has the shortcomings such as narrow bandwidth, loss be large when high frequency, cannot be applicable to the scenes such as two-frequency operation.Therefore need to design a kind of low-loss, and be operated in the minor matters line coupler of double frequency, meet the demand of microwave and millimeter wave system.

In the last few years, a kind of Novel transmission line: substrate integrated coaxial line SICL is suggested and is widely applied.SICL is a kind of plane coaxial line structure, arranges metal throuth holes be comprised of two of a signal conduction band between upper and lower two-layer ground connection dielectric layer and its both sides.Be similar to common strip line, what in SICL, transmit is TEM mould.The metal throuth hole of conduction band both sides, center has been avoided the transmission of the plate mode that may cause due to discontinuity, therefore reduced energy leakage and and other wire between mutual coupling.SICL can realize by PCB technique, is therefore easy to the planar circuit structure assembly with other.

Summary of the invention

Goal of the invention: equate in order to realize amplitude at two frequencies, the power splitting/synthesis network of 90 ° of phase phasic differences, reduce the energy loss when high frequency, at input port, realize good return loss performance, the invention provides a kind of novel double frequency 3-dB minor matters line coupler based on SICL technology.

Technical scheme: in order to realize foregoing invention object, the technical solution used in the present invention is as follows:

A kind of double frequency minor matters line coupler that adopts substrate integrated coaxial line SICL technology, the main part and ground connection co-planar waveguide (the Grounded Co-Planar Waveguide that comprise dielectric substrate, upper surface metal level, lower surface metal layer, coupler, GCPW), the main part of described coupler comprises the minor matters line of four quarter-wave electrical length, minor matters line and four port lines of four 1/2nd wavelength electrical length, and minor matters line and the port lines of the minor matters line of quarter-wave electrical length, 1/2nd wavelength electrical length form by SICL transmission line.

SICL transmission line comprises inner wire holding wire and outer conductor screen, and outer conductor screen consists of some metal throuth holes, upper surface metal level and the lower surface metal layer of inner wire holding wire both sides.In order further to reduce energy leakage, on the metal throuth hole of the inner wire holding wire both sides of SICL transmission line, shielded metal layer can be set, described shielded metal layer and metal throuth hole radial parallel, and with inner wire holding wire in same layer.

The inner wire holding wire of the minor matters line of four quarter-wave electrical length of the main part of the coupler composition rectangular configuration that joins end to end, article four, one end of the inner wire holding wire of the minor matters line of 1/2nd wavelength electrical length is connected with four angles of rectangular configuration respectively, the other end is provided with grounded metal through hole, article four, one end of the inner wire holding wire of port lines is connected with four angles of rectangular configuration respectively, and the other end is connected with a GCPW by metal connecting hole respectively.

Beneficial effect: total of the present invention can adopt traditional printing circuit board (Printed circuit board, PCB) multilayer technology to realize, and is easy to design and integrated.Compare with traditional minor matters line coupler, tool of the present invention has the following advantages: the amplitude that 1, can realize on two frequencies of microwave and millimeter wave frequency range equates, the power splitting/synthesis network of 90 ° of phase phasic differences.2, utilize SICL technology and in metal throuth hole, added shielded metal layer, having reduced energy leakage, having improved the isolation between standing wave performance and port.

Accompanying drawing explanation

Fig. 1 is the circuit model of the main part of coupler of the present invention;

Fig. 2 is top cross-sectional view of the present invention;

Fig. 3 is that master of the present invention looks generalized section;

Fig. 4 is that SICL master used in the present invention looks generalized section;

Fig. 5 is SICL top cross-sectional view used in the present invention;

Fig. 6 is that the present invention is at emulation and the measured result of the S at low frequency place parameter;

Fig. 7 is that the present invention is at emulation and the measured result of the S of high frequency treatment parameter;

Fig. 8 is that the present invention is at emulation and the measured result of the phase difference at low frequency place;

Fig. 9 is that the present invention is at emulation and the measured result of the phase difference of high frequency treatment.

Embodiment

Below in conjunction with specific embodiment, further illustrate the present invention, should understand these embodiment is only not used in and limits the scope of the invention for the present invention is described, after having read the present invention, those skilled in the art all fall within the application's claims limited range to the modification of the various equivalent form of values of the present invention.

As shown in Figure 2 and Figure 3, the embodiment of the present invention discloses a kind of double frequency minor matters line coupler of employing SICL technology of the PCB of utilization technique realization, the main part and the GCPW6 (co-planar waveguide that has metal backing) that comprise dielectric substrate 12, upper surface metal level 10, lower surface metal layer 11, coupler, wherein the circuit model of the main part of coupler as shown in Figure 1.Z ₀for the normalized characteristic impedance of feeding network input, Z ₁, Z ₂and Z ₃be respectively the characteristic impedance of specific minor matters line in coupler.If required dual-frequency point is f ₁and f ₂, the parameter of the circuit model of double frequency minor matters line coupler is followed following formula:

$Z_1=\frac{Z_0}{\sqrt{2}}\·\frac{1}{\cos \left(\frac{\mathrm{\δ\π}}{2}\right)}$ (formula 1)

$Z_2=Z_0\·\frac{1}{\cos \left(\frac{\mathrm{\δ\π}}{2}\right)}$ (formula 2)

$Z_3=\frac{Z_0}{1+\sqrt{2}}\·\frac{1}{\sin \left(\frac{\mathrm{\δ\π}}{2}\right)+\tan \left(\frac{\mathrm{\δ\π}}{2}\right)}$ (formula 3)

Wherein

$\mathrm{\δ}=\frac{f_2-f_1}{f_2+f_1}$ (formula 4)

The main part of the coupler based on foregoing circuit modelling comprises the minor matters line of four quarter-wave electrical length that consist of SICL transmission line, the minor matters line of four 1/2nd wavelength electrical length and four port lines.As shown in the structural representation of the SICL transmission line of Fig. 4 and Fig. 5 middle port line, SICL transmission line comprises inner wire holding wire 3 and the outer conductor screen in dielectric substrate 12, and outer conductor screen comprises the metal throuth hole 7 (being illustrated by Dark grey lines in Fig. 2) of upper surface metal level 10, lower surface metal layer 11 and inner wire holding wire 3 both sides.The structure of the structure of the SICL transmission line of the minor matters line of the minor matters line of quarter-wave electrical length and 1/2nd wavelength electrical length and the SICL transmission line of port lines is variant on the width of inner wire holding wire, and outer conductor shielding layer structure is identical.In order further to reduce the energy leakage on SICL transmission line, can set up the shielded metal layer 8 in same layer with metal throuth hole 7 radial parallel and inner wire holding wire.

In Fig. 2, the monnolithic case of coupler design squaring circuit plate, the vertical view of coupler is square, L ₀for the foursquare length of side.The holding wire 1 of the minor matters line of four quarter-wave electrical length of the main part of the coupler composition rectangular configuration that joins end to end, article four, the minor matters line of quarter-wave electrical length is divided into two pairs, the minor matters line of every pair of quarter-wave electrical length is parallel to each other, and the width of holding wire is identical, L ₁, L ₂for the length of the corresponding holding wire of the minor matters line of two pairs of quarter-wave electrical length of coupler, W ₁, W ₂it is the width of corresponding holding wire of the minor matters line of two pairs of quarter-wave electrical length.Article four, the shape of the holding wire 2 of the minor matters line of 1/2nd wavelength electrical length is identical, be symmetrically distributed in the outside of rectangular configuration, one end of the holding wire 2 of the minor matters line of every 1/2nd wavelength electrical length is connected with four angles of rectangular configuration respectively, the other end is provided with grounded metal through hole 5, for compact in design is dwindled overall dimensions, the minor matters line of 1/2nd wavelength electrical length is bending shape, L ₄, L ₅, L ₆be the length of corresponding bending part of holding wire 2 of the minor matters line of 1/2nd wavelength electrical length, W ₃it is the width of holding wire of the minor matters line of 1/2nd wavelength electrical length.Article four, one end of the holding wire 3 of port lines is connected with four angles of rectangular configuration respectively, and the other end is connected with a GCPW6 by metal connecting hole 4 respectively.L ₃for the length of the holding wire 3 of port lines, W ₀width for the holding wire 3 of port lines.GCPW6 holding wire is positioned at the upper surface of dielectric substrate 12, is provided with groove around, separates W with upper surface metal level 10 ₄width for GCPW6 holding wire.In Fig. 3, h ₁thickness for dielectric substrate 12.

The size of SICL and GCPW is relevant with the applied frequency of coupler.Wherein, the size of GCPW can calculate and carry out simulation optimization acquisition by common approximate formula, and the size of SICL can calculate and carry out simulation optimization acquisition by the approximate formula of common strip line size.The thickness of its inner wire holding wire is equal to the thickness that metal applies copper.

Adopt Electromagnetic Simulation software to be optimized coupler size, obtain coupler dimensional parameters as shown in table 1.The meaning of each parameter representative is in explanation above.

Tested object is the minor matters line coupler that is operated in 1.62GHz and two frequency bands of 2.50GHz that utilizes PCB technology to realize.What dielectric material adopted is that dielectric constant is 4.4 FR-4 dielectric-slab.Fig. 6 is that the present invention is at simulation result and the measured result of the amplitude of the S at low frequency place parameter.Fig. 7 is that the present invention is at simulation result and the measured result of the amplitude of the S of high frequency treatment parameter.Fig. 8 is that the present invention is at simulation result and the measured result of the phase difference of the S at low frequency place parameter.Fig. 9 is that the present invention is at simulation result and the measured result of the phase difference of the S of high frequency treatment parameter.

The result of emulation and actual measurement is as shown in table 2.Measured result and simulation result coincide well.Measured result has reached respectively 9.3% and 12% bandwidth at two frequencies.

Double frequency coupler of the present invention can be used in the feeding network of microwave passive and active system, particularly antenna of microwave and millimeter wave frequency range.Can adjust operating frequency by length and the width parameter of change holding wire, be applied in different frequent points.

Table 1 coupler dimensional parameters

Parameter	Numerical value (mm)	Parameter	Numerical value (mm)
				L 0	55	W 0	0.74
L 1	18	W 1	1.3
				L 2	18	W 2	0.63
L 3	7.7	W 3	0.23
				L 4	7.7	W 4	4
L 5	10	h 1	1.75
				L 6	14	?	?

The result contrast of table 2 emulation and actual measurement

Claims (5)

1. a double frequency minor matters line coupler that adopts substrate integrated coaxial line technology, it is characterized in that: the main part and the ground connection co-planar waveguide GCPW that comprise dielectric substrate, upper surface metal level, lower surface metal layer, coupler, the main part of described coupler comprises the minor matters line of four quarter-wave electrical length, minor matters line and four port lines of four 1/2nd wavelength electrical length, and minor matters line and the port lines of the minor matters line of described quarter-wave electrical length, 1/2nd wavelength electrical length form by SICL transmission line.

2. the double frequency minor matters line coupler of employing substrate integrated coaxial line technology according to claim 1, it is characterized in that: the structure of described SICL transmission line comprises inner wire holding wire and outer conductor screen, outer conductor screen consists of some metal throuth holes, upper surface metal level and the lower surface metal layer of being located at inner wire holding wire both sides.

3. the double frequency minor matters line coupler of employing substrate integrated coaxial line technology according to claim 2, it is characterized in that: the inner wire holding wire of the minor matters line of four quarter-wave electrical length of the main part of the coupler composition rectangular configuration that joins end to end, article four, one end of the inner wire holding wire of the minor matters line of 1/2nd wavelength electrical length is connected with four angles of rectangular configuration respectively, the other end is provided with grounded metal through hole, article four, one end of the inner wire holding wire of port lines is connected with four angles of rectangular configuration respectively, the other end is connected with a GCPW by metal connecting hole respectively.

4. the double frequency minor matters line coupler of employing substrate integrated coaxial line technology according to claim 2, it is characterized in that: the structure of described SICL transmission line also comprises the shielded metal layer on the metal throuth hole that is arranged on inner wire holding wire both sides, described shielded metal layer and metal throuth hole radial parallel, and with inner wire holding wire in same layer.

5. according to the double frequency minor matters line coupler of the employing substrate integrated coaxial line technology described in claim 1-4 any one, it is characterized in that: the minor matters line of described 1/2nd wavelength electrical length is bending shape.