阅读说明：本技术 一种基于吸波材料的基片集成波导均衡器 (Substrate integrated waveguide equalizer based on wave-absorbing material ) 是由 彭浩 黄顺华 刘宇 周翼鸿 董俊 杨涛 于 2020-12-04 设计创作，主要内容包括：本发明涉及微波技术,具体涉及一种基于吸波材料的基片集成波导SIW均衡器。本发明实现在普通的PCB基板上,包括SIW本体,以及通过渐变过渡线与SIW本体两端相连的50Ω微带线；通过在SIW本体长边的一侧开设一条贯通SIW本体表面金属层的槽,并用吸波材料完全填覆该槽,引入损耗介质-吸波材料增加传播通道上的损耗,当电磁波在SIW本体中以TE-(10)模传播的时候,在槽中加入的吸波材料,就能在传播TE-(10)模的同时对信号进行一定程度的衰减,使均衡器的高低端插入损耗差值更大,从而达到更大的均衡值。本发明可以增加低频段损耗,降低高频段损耗,且成本较低廉；可用于微波、毫米波电路和系统中,对不同频率的信号进行不同的衰减,对信号进行幅度均衡。(The invention relates to a microwave technology, in particular to a substrate integrated waveguide SIW equalizer based on a wave-absorbing material. The invention is realized on a common PCB substrate, which comprises a SIW body and a 50 omega microstrip line connected with two ends of the SIW body through a gradual change transition line; a groove penetrating through a metal layer on the surface of the SIW body is formed in one side of the long edge of the SIW body, the groove is completely filled with a wave-absorbing material, a loss medium-wave-absorbing material is introduced to increase the loss on a propagation channel, and TE is used for TE of electromagnetic waves in the SIW body 10 When the mode is propagated, the wave-absorbing material added in the groove can propagate TE 10 And the mode simultaneously attenuates the signal to a certain degree, so that the insertion loss difference of the high end and the low end of the equalizer is larger, and a larger equalization value is achieved. The invention can increase the low-frequency band loss and reduce the high-frequency band loss, and has lower cost; it can be used in microwave and millimeter wave circuit and system to attenuate signals of different frequencies differentlyAnd subtracting, and carrying out amplitude equalization on the signals.)

1. A substrate integrated waveguide equalizer based on wave-absorbing materials is characterized in that: the circuit is realized on a PCB substrate and comprises a SIW body and a 50 omega microstrip line connected with two ends of the SIW body through a gradual change transition line;

the distance between the centers of two rows of metallized through holes on the wide side of the SIW body is W_sLong side length of L_sThe diameter of the metallized through hole is dvp, the distance between the centers of two adjacent through holes on one side of the long edge of the SIW is svp, and the length of the joint of the gradual transition line and the wide edge of the SIW body is W_tThe length of the connection part of the gradual transition line and the 50 omega microstrip is W;

respectively introducing a metalized through hole for matching at two sides of the connection part of the gradual transition line and the wide side of the SIW body, wherein the two metalized through holes for matching at the same side and the center line of the wide side of the SIW body form axial symmetry, one end of the SIW body is provided with two metalized through holes, and the two ends of the SIW body are totally 4 and are used for matching between the SIW body and the microstrip line;

one side of the long edge of the SIW body is provided with a groove which penetrates through the metal layer on the surface of the SIW body, the groove is completely filled with wave-absorbing materials to replace the excavated metal layer on the surface, the minimum distance between the groove and the central line of the wide edge of the SIW body is del, and the minimum distance between the groove and the central line of the wide edge of the SIW body is more than 0 and less than del and less than W_s2, and the slot is axisymmetrical with respect to the midline of the long side of the SIW body;

the product of the dielectric loss tangent tan delta epsilon and the real part of the dielectric constant epsilon' of the wave-absorbing material increases along with the increase of the frequency f.

2. The wave-absorbing material-based substrate integrated waveguide equalizer of claim 1, wherein: the shape of the groove is a shuttle shape with two thin ends and a thick middle.

3. The wave-absorbing material-based substrate integrated waveguide equalizer of claim 1, wherein:

the shape of the groove is formed by splicing a rectangle, two semicircles and two isosceles trapezoids in a matching way; the rectangle is arranged in the middle by the coincidence of the central line of the wide side and the central line of the long side of the SIW, and the long bottom sides of the two isosceles trapezoids are equal to and correspondingly spliced with the long side of the rectangleThe diameters of the two semicircles at the two long edges of the rectangle are equal to the diameters of the short bottom edges of the isosceles trapezoids and are spliced at the wide bottom edges of the two isosceles trapezoids in a matching manner respectively; the length of the rectangular wide side, i.e. the side parallel to the propagation direction of the electromagnetic wave, is L_srThe length of the long side of the rectangle is W_sr，W_sr<W_s2, the radiuses of the two semicircles are both rvp, and the heights of the two isosceles trapezoids are both L_srt，L_sr+2*L_srt+2*rvp<L_s。

Technical Field

The invention relates to microwave technology, in particular to a Substrate Integrated Waveguide (SIW) equalizer based on a wave-absorbing material.

Background

Equalizers play an important role in both wireless transmitting and receiving ends, and in various new power components such as microwave power modules. The development of electronic systems today requires the equalizer to be lighter in weight, lower loss, smaller in size, and easier to integrate. The Substrate Integrated Waveguide (SIW) technology, which has been emerging in recent years, is a new microwave transmission line technology. Has the advantages of small volume, light weight, high Q value, small insertion loss and the like. At present, SIW has been widely used in the development of microwave devices such as power splitters, directional couplers, resonators, antennas, and filters due to its excellent structural characteristics, but equalizers implemented on SIW are still rare.

Reference 1: in 2000, J.Kampa et al introduced a wideband equalizer model operating in the frequency band of 6-18 GHz, where the attenuation of the equalizer decreased with the increase of frequency, and the frequency characteristics of the system could be equalized by connecting the equalizer to the microwave system, with an equalization amount of approximately 8 dB. See J.Kampa and K.Petrus, "Microwave amplitude equalizer,"13th International Conference on Microwaves, radio and Wireless communications, MIKON-2000.Conference Proceedings (IEEE Cat. No.00EX428), Wroclaw, Poland,2000, vol.1, pp.37-40

Reference 2: in 2010, s.tang et al designed an equalizer of a new structure using a spiral resonator. The test result at 4-8GHz shows that the equilibrium value is close to 7dB, and the return loss is better than-14 dB. For details, see S.Tang, Y.Zhang and J.Zhang, "A novel compact size microstrip equalizer based on spectral detectors," 2010International Conference on Microwave and Millimeter Wave Technology, Chengdu, China,2010, pp.730-733

Reference 3: in 2015, H.He and the like simulate an equalizer working at 2-6 GHz by using an LTCC process design, and can provide 12dB of maximum attenuation, and the minimum insertion loss is 1.25 dB. For details, see H.He and L.Xia, "Microwave LTCC equalized based composite right/left-enhanced structure,"2015IEEE International Conference on Communication Proble-solving (ICCP), Guilin,2015, pp.274-277

Reference 4: recently, a novel SIW equalizer based on a surface resistive material is designed, simulated and tested, the equalizer works in a Ka frequency band (26-40GHz), the measurement results of the equalization values are respectively 2.8dB, 5.6dB and 9dB, and the return loss is better than-18.8 dB. See H.Peng et al, "Substrate Integrated waveform oscillators and actuators With Surface Resistance," in IEEE Transactions on Microwave Theory and Techniques, vol.68, No.4, pp.1487-1495, April 2020, doi:10.1109/TMTT.2019.2958267 for details.

In the above reference reports, the design theory and design flow of most equalizers in the microwave and millimeter wave frequency band are similar to those of filters. Equalizers implemented in SIW are not common, while SIW equalizers used in the millimeter wave band have only one reference. The equalizer in this study has two implicit drawbacks: high cost and large high-end insertion loss.

Disclosure of Invention

In order to overcome the defects of the SIW equalizer, the invention provides a Substrate Integrated Waveguide (SIW) equalizer based on a wave-absorbing material, which is implemented on a common PCB Substrate, has controllable cost and relatively low insertion loss (especially, has obvious advantages when the equalization amount is large).

A Substrate Integrated Waveguide (SIW) equalizer based on wave-absorbing materials is realized on a PCB Substrate and comprises an SIW body and a 50 omega microstrip line connected with two ends of the SIW body through gradual change transition lines; and the surface of the SIW body is provided with a groove which penetrates through the metal layer on the surface of the SIW body, and wave-absorbing materials are filled to replace the excavated metal layer on the surface.

The width and side length of the SIW body is W_s(i.e., the distance between the centers of the two rows of metallized through holes) and a long side length of L_sThe diameter of the metallized through hole is dvp, the distance between the centers of two adjacent through holes on the long side of the SIW is svp, and the transition is gradually changedThe length of the joint of the line and the broadside of the SIW body is W_tThe length of the connection part of the gradual transition line and the 50 omega microstrip is W;

and two metallized through holes for matching are respectively introduced into two sides of the connection part of the gradual transition line and the wide side of the SIW body, the two metallized through holes for matching on the same side and the central line of the wide side of the SIW body form axial symmetry, one end of the SIW body is provided with two metallized through holes, and the number of the two metallized through holes is 4 in total, so that the SIW body and the microstrip line can be matched more accurately. L is_tFor the length of the gradual change line, dvp is the diameter of the metallized through hole, svp is the distance between the centers of two adjacent through holes on one side of the long edge of the SIW and is svp, W_sIs the distance between the centers of the two rows of metallized through holes, L_xFor matching the longitudinal (electromagnetic wave propagation direction) distance, L, of a metallized via from an adjacent metallized via on the same side_yThe distance between the metalized via for matching and the adjacent metalized via on the same side is perpendicular (the perpendicular direction is perpendicular to the propagation direction of the electromagnetic wave).

The wave-absorbing material has the following properties: the product of the dielectric loss tangent tan δ ∈ and the real part of permittivity ∈' increases with increasing frequency f. Through theoretical derivation, the wave-absorbing material meeting the property can enable the insertion loss difference value of the high end and the low end of the equalizer to be larger, and therefore a larger equalization value is achieved.

One side of the long edge of the SIW body is provided with a groove which penetrates through the metal layer on the surface of the SIW body and is completely filled with a wave-absorbing material, and the minimum distance between the groove and the central line of the wide edge of the SIW body is del (0 < del < W)_s2) and the slot is axisymmetrical about the center line of the long side of the SIW body.

Furthermore, in order to optimize standing waves, the groove is in a shuttle shape (two ends are thin and the middle is thick), and is formed by splicing a rectangle, two semicircles and two isosceles trapezoids in a matching way; the rectangle is placed in the middle and is set up with the coincidence of its broadside central line and the long limit central line of SIW, and the long base of two isosceles trapezoids equals and the concatenation that suits with the long limit of rectangle in two long limits departments of rectangle, and the diameter of two semicircles is equal and the concatenation that suits respectively in two isosceles trapezoid's broadside departments with the short base of isosceles trapezoid. The length of the wide side (the side parallel to the propagation direction of the electromagnetic wave) of the rectangle is L_srRectangularLength of long side is W_sr(W_sr<W_s2), the radius of the two semi-circles is rvp, the height of the two isosceles trapezoids is L_srt(L_sr+2*L_srt+2*rvp<L_s)。

The working principle of the equalizer in the invention is as follows: electromagnetic waves in the SIW body with TE₁₀The modes are propagated, and front and back metal layer covers in the transmission structure and two rows of metallized through holes of the SIW are used for restraining the propagation boundary of the electromagnetic wave. In the conventional SIW structure, the loss is mostly from the loss of the dielectric substrate itself. In order to increase the loss on the propagation channel, the invention introduces a loss medium-wave absorbing material. When electromagnetic wave is in SIW body with TE₁₀When the mode is propagated, the wave-absorbing material added in the groove can propagate TE₁₀The mode simultaneously attenuates the signal to a certain degree, and the attenuation is closely related to the working frequency. Compared with reference 4, the introduced loss medium (wave-absorbing material) can increase the low-frequency loss and reduce the high-frequency loss, and the cost is lower.

In summary, the present invention provides a new SIW equalizer structure in consideration of cost and insertion loss at high frequency, which can be used in microwave and millimeter wave circuits and systems to perform different attenuations and amplitude equalization on signals at different frequencies.

Drawings

Fig. 1 is a top view of an equalizer structure according to an embodiment of the present invention.

FIG. 2 is a schematic view of wave-absorbing material area of an equalizer according to an embodiment of the invention.

Fig. 3 shows the areas of lossy material attached to the top surface of a RW in accordance with an embodiment of the present invention.

FIG. 4 is a graph of simulated attenuation values for different k values according to an embodiment of the present invention.

FIG. 5 is a simulation plot of normalized attenuation values for differences between k and k + Δ k in accordance with an embodiment of the present invention.

FIG. 6 shows values of dielectric loss tangent tan delta epsilon and relative dielectric constant epsilon' of the wave-absorbing material of the embodiment of the invention at different frequencies.

Fig. 7 is a comparison of normalized attenuation values corresponding to different values of a with the variation of operating frequency when k is 0.8 in the embodiment of the present invention.

Fig. 8 shows the distribution of the wave-absorbing material areas on the top surface of a RW in an embodiment of the invention.

Fig. 9 is a schematic view of a covering method of the wave-absorbing material.

FIG. 10 is a simulation and test plot of an embodiment of the present invention with an equalization of 3 dB.

FIG. 11 is a simulation and test plot of an embodiment of the present invention with an average of 6 dB.

FIG. 12 is a 10dB equalization simulation and test chart for an embodiment of the present invention.

FIG. 13 is a simulation and test plot of an embodiment of the present invention with an equalization of 15 dB.

FIG. 14 is a graph of 20dB equalization for simulation and test in accordance with an embodiment of the present invention.

FIG. 15 is a 25dB equalization simulation and test chart for an embodiment of the present invention.

Reference numerals: the chip comprises a SIW body-1, a groove-2, a metalized through hole-3, a gradual transition line-4, a matched metalized through hole-5 and a microstrip line-6.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Since the EM field distribution characteristics in SIW and Rectangular Waveguide (RW) are similar, we can derive an expression for the attenuation constant α at this time by first analyzing the equalizer in RW for simplicity. The distribution of the wave-absorbing material on the side wall part of the equalizer body is shown in figure 3.

In the + z direction, the electric field amplitude is set to α as the attenuation constant in RW, and the electric field propagates as a wave, TE₁₀The modal transmit power may be expressed as

P＝P₀e^-2αz (1)

Defining a power loss per unit length of

The power loss per unit length caused by the limited wall conductivity is

Rs'＝1/Lσ (6)

Wherein R is_s、R_s'、L、σ、Andthe surface resistance of the wall of RW, the surface resistance of the wave-absorbing material, the surface current density of RW, the length of the wave-absorbing material, the resistivity (unit: Siemens/m) of the wave-absorbing material, the normal unit vector pointing to the ideal metal conductor and the loss material, and the magnetic field intensity in RW are shown. The integration path C encloses the perimeter of the waveguide wall and, for simplicity, the power loss introduced by the RW metal wall can be considered to be 0.

Then, the surface magnetic field intensity of the RW tip (y ═ b)

η、Z_TEAnd f_cIntrinsic resistance of RW fill material respectivelyAnti, TE₁₀The wave impedance of the mode and the cut-off frequency.

For the wave-absorbing material, the relative dielectric constant is:

ε＝ε'-jε”＝ε'(1-jtanδε) (9)

ε”＝ε'tanδε＝σ/ω＝σ/(2πf) (10)

wherein epsilon, epsilon' and tan delta epsilon are respectively the complex dielectric constant of the wave-absorbing material, the real part and the imaginary part of the complex dielectric constant of the wave-absorbing material and the dielectric loss tangent.

Substitution of formulae (6), (7), (8) and (10) for formula (5) can give:

TE₁₀the power flow of the modulus through RW is calculated as:

thus, the attenuation constant α is given by:

let c be k.a (k is 0. ltoreq. k.ltoreq.1), F be F_cf(0.5<F<0.85), from equation (15), the attenuation constant α can be rewritten as

We can orderThe rewrite decay constant α is:

assuming that a does not vary with frequency, the attenuation values corresponding to different values of k and the variation of the difference of the attenuation values of k to k + Δ k with frequency can be made according to equation (16).

As can be seen from fig. 4, all insertion losses and operating frequencies have a negative slope in the range of k 0 to k 1. Fig. 5 shows that the difference in attenuation values k to k + Δ k is also inversely related to the operating frequency in the range of k 0 to k 1; furthermore, as k increases, the amount of equalization within the band becomes larger.

FIG. 6 shows values of dielectric loss tangent tan δ ε and relative dielectric constant ε' of the wave-absorbing material (Chengdahi electronic technology Co., Ltd., JCXB-S-120 type) at different frequencies according to the embodiment of the present invention. It is to be noted that, in fig. 6, as the frequency becomes larger, the dielectric loss tangent tan δ ∈ shows an upward tendency, and the real part of permittivity ∈' shows a downward tendency. In the range of 26-40GHz, tan delta epsilon becomes larger by about 82.5%, while the change in the real part of permittivity epsilon' is almost negligible (about 2.7% reduction), and the total product of the two becomes larger by about 77.5%. Therefore, we cannot directly refer to equation (16)When constants are processed, the expression for α is rewritten:

α＝A*B (17)

wherein the content of the first and second substances,

when f is increased, α ↓ B ↓, both a and B present a descending trend, and α as a whole also presents a descending trend.

In the following, we plot and analyze the influence of the change of a on the attenuation constant by using the measured data by taking k equal to 0.8 as an example, and fig. 7 shows the relationship between the normalized attenuation value and the operating frequency when formula (14) in document [4], formula (16) in the invention assume that a is constant, dielectric loss tangent tan δ ∈ in a is taken as variable, and dielectric loss tangent tan δ ∈ and real dielectric constant ∈' in a are taken as variables, respectively.

Apparently, it is compared with the document [4]]Compared with equation (14), the normalized equalization value (i.e. the insertion loss difference value of the high-low end frequency) of the invention is obviously increased; in addition, when we consider the electromagnetic properties (dielectric loss tangent tan delta epsilon and relative dielectric constant epsilon) of the wave-absorbing material_rEtc.) the amplitude of the attenuation constant change with the operating frequency is larger as the frequency changes; further, as is clear from FIG. 6, the influence of the change in the dielectric loss tangent tan. delta. epsilon. is dominant, and the change in the real part of permittivity. epsilon ` hardly influences. That is, the introduction of the wave-absorbing material effectively increases the equalization value of the SIW equalizer, so that the insertion loss value of the equalizer in a high frequency band can be obviously reduced.

Based on the theoretical derivation of the electromagnetic property and the RW attenuation property of the wave-absorbing material, a slender wave-absorbing material can be introduced into a surface metal layer of the SIW to form an equalizer. It should be noted that in order to achieve a larger amount of equalization, the absorbing material may be placed as far away from the center line as possible, and in order to achieve the maximum slope and to be workable, k is 0.8 or so, as shown in fig. 8.

The method for covering the wave-absorbing material is shown in fig. 9, the wave-absorbing material is placed between a PCB (printed circuit board) and an insulating rubber plate and is fixed by screws and upper and lower metal plates, so that the wave-absorbing material is uniformly covered in a groove, and the influence of a clamp on an experimental result can be effectively avoided.

And (3) digging surface metal from one side near the boundary line of k-0.8 to form a gap and covering the gap with the wave-absorbing material. The SIW equalizer is shown in top view in fig. 1.

According to the SIW equalizer based on the wave-absorbing material, which is operated in a Ka frequency band and is realized on a Rogers 5880 medium substrate, the thickness is 0.254mm, the dielectric constant is 2.2, and the tangent loss is 0.0009.

After simulation and optimization are performed by an electromagnetic simulation software Ansoft HFSS, the optimal parameter size is obtained, as shown in table 1 (note: in order to achieve a small balance, the gap needs to be close to the center):

TABLE 1

Simulation results of the equalization values of 3dB, 6dB, 10dB, 15dB, 20dB and 25dB are shown in fig. 10, 11, 12, 13, 14 and 15, respectively, and specific analysis results are shown in table 2. The test result is basically consistent with the simulation result, and the S11 measured value is better than-14.8 dB in the whole Ka frequency band. The equalization values of the SIW equalizer, which are defined as different values of the transmission loss S21 at the frequency points of 26Ghz and 40Ghz, are actually 2.94dB, 6.55dB, 9.74dB, 14.9dB, 20.39dB, and 24.01dB, respectively, and the equalization errors are 0.06dB, 0.55dB, 0.26dB, 0.1dB, 0.39dB, and 0.99dB, respectively, as compared with the simulation results of 3dB, 6dB, 10dB, 15dB, 20dB, and 25 dB.

The simulation and concrete experiment results show that the slot penetrating through the metal layer on the surface of the SIW body is formed in one side of the long side of the SIW body, the slot is completely filled with the wave-absorbing material, the loss medium-wave-absorbing material is introduced to increase the loss on the propagation channel, and when electromagnetic waves are in the SIW body by TE₁₀When the mode is propagated, the wave-absorbing material added in the groove can propagate TE₁₀And the mode simultaneously attenuates the signal to a certain degree, so that the insertion loss difference of the high end and the low end of the equalizer is larger, and a larger equalization value is achieved. The SIW equalizer provided by the invention can perform different attenuations on signals with different frequencies, and the attenuation is smaller when the frequency is higher; the low-frequency band loss can be increased, the high-frequency band loss can be reduced, and the cost is lower. The method can be used in microwave and millimeter wave circuits and systems to perform different attenuation on signals with different frequencies and perform amplitude equalization on the signals. In addition, the equalizer using the wave-absorbing material has the advantages of low cost and low insertion loss value at high frequency.