CN113690637B

CN113690637B - 5G millimeter wave LTCC shunt-feed wide-angle scanning phased array

Info

Publication number: CN113690637B
Application number: CN202110814667.5A
Authority: CN
Inventors: 靳贵平; 孙毅; 廖绍伟
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-07-19
Filing date: 2021-07-19
Publication date: 2022-06-10
Anticipated expiration: 2041-07-19
Also published as: CN113690637A

Abstract

The invention provides a 5G millimeter wave LTCC (low temperature co-fired ceramic) parallel-feed wide-angle scanning phased array which comprises a plurality of areas, wherein a plurality of dielectric resonant cavities are formed on the inner side surrounded by metalized through holes on a first area, and extra metal covering type metal layers are arranged in the areas between the metalized through holes and the dielectric resonant cavities on the uppermost substrate layer in the first area; at least two radiation units are arranged on the substrate layer positioned on the uppermost layer in the second area, each radiation unit comprises a plurality of radiation gaps, two corresponding radiation gaps of adjacent radiation units are positioned in the same space surrounded by the metalized through holes, the two radiation gaps are not on the same straight line, and metal matching holes used for disturbing the distribution of the field are arranged on the other side of each radiation gap in the space. Through the I-shaped gap and the metal matching hole structure, the matching of a common gap antenna is improved, and the extra metal covering type metal layer is arranged to change the aperture field distribution, so that the wide-angle scanning is realized while the gain is ensured.

Description

5G millimeter wave LTCC shunt-feed wide-angle scanning phased array

Technical Field

The invention relates to the field of antennas of electronic communication technology, and provides a 5G millimeter wave LTCC shunt-fed wide-angle scanning phased array.

Background

The millimeter wave technology increasingly shows great application value in military, civil and industrial fields in recent years, and particularly for emerging fifth/sixth generation mobile communication (5G/6G) and vehicle-mounted millimeter wave radar technology, the millimeter wave technology becomes an important direction for the development of wireless technology. Antennas are essential components of wireless systems, and scanning phased array antennas (phased arrays for short) are an important type of antenna. The phased array can change the direction of a high-gain wave beam or form a specific wave beam shape according to requirements, and has important values for millimeter wave communication (including 5G/6G), radar, imaging, detection and other systems. Phased arrays are divided into one-dimensional and two-dimensional scans according to the dimensions of the beam scan. Although only one-way scanning can be realized, the required phase/amplitude control channels are few, the cost is lower, and therefore, the one-dimensional scanning phased array is more suitable for most millimeter wave wireless applications, such as 5G/6G millimeter wave terminals, small base stations and vehicle-mounted millimeter wave radars. In addition, future millimeter wave antennas/antenna arrays will be implemented primarily in the form of packaged Antennas (AiP) (e.g., LTCC, HDI, and FOWLP technologies) using packaging processes to improve system integration, reduce cost, and reduce interconnect losses.

The most important index of the phased array is the wide-angle beam scanning capability in the working bandwidth, and meanwhile, the beam gain in the scanning range is required to be high, the fluctuation is small, the side lobe level is low, the loss is low, and the matching is good, so that the coverage range of a millimeter wave wireless system is ensured. Generally, to meet the above requirements, the scanning phased array must have a wide array element beam, a sufficiently small array element spacing, and a high inter-array element isolation. In addition, increasing the number of scan direction array elements can also effectively increase the scan range, but this results in higher cost and larger volume. The general antenna (such as a patch antenna) is used as a phased array element, and if the special design is not adopted, the half-power wave beam width is narrow, so that the requirement of wide wave beams cannot be met. On the other hand, the requirement of a small array element interval and a wide beam array element can cause serious coupling among the array elements. Therefore, most of the wide-angle scanning phased array research is developed from widening array element beams and improving the isolation between array elements.

Xu et al, in Bandwidth Enhancement for a 60GHz Substrate Integrated Waveguide Array Antenna on LTCC, in IEEE Transactions on Antennas and Propagation, vol.59, No.3, pp.826-832, March 2011, doi:10.1109/TAP.2010.2103018, propose a parallel feed multilayer SIW slot Antenna based on LTCC process, which is designed based on a parallel feed scheme and has good beam stability and wider Bandwidth; but at the same time the number of layers of such an antenna is too high, the number of elements is too high, and only one array of fixed beams is made.

At present, three methods are mainly used for improving the scanning capability of a phased array: 1. increasing the unit beam width: a wider beam covering capability is realized by improving the beam width of the antenna unit; 2. reducing the cell pitch: wide angle scanning is achieved by reducing the spacing between the column elements to at least half a wavelength; 3. reducing cell mutual coupling: mutual coupling among the units can greatly influence the directional diagram of the array, and the stability of the directional diagram is maintained by reducing the mutual coupling of the units, so that a high scanning angle is obtained; the above method for improving the scanning capability of the scanning phased array is mainly applied to the microwave frequency band, but is difficult to apply to the millimeter wave frequency band, because: (1) the millimeter wave wavelength is short, part of the structure requires high processing precision, and the current packaging process cannot be guaranteed; (2) the packaging process is basically a planar circuit process, and the processing freedom is limited.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a 5G millimeter wave LTCC parallel-feed wide-angle scanning phased array.

In order to achieve the purpose of the invention, the 5G millimeter wave LTCC parallel-feed wide-angle scanning phased array provided by the invention comprises a plurality of regions which are respectively defined as a first region, a second region, a third region, a fourth region and a fifth region from top to bottom, wherein the first region and the second region are radiation structures of the phased array, the third region, the fourth region and the fifth region are feed structures of the phased array, each region comprises a plurality of laminated substrate layers, and each region is respectively provided with a metalized through hole penetrating through all the substrate layers of the region;

a plurality of medium resonant cavities are formed on the first area at the inner side surrounded by the metalized through holes, and extra metal covering type metal layers are arranged on the uppermost layer of the substrate layer in the first area in the area between the metalized through holes and the medium resonant cavities; at least one column unit is arranged on the substrate layer positioned on the uppermost layer in the second area, each column unit is provided with two radiation units, each radiation unit comprises a plurality of radiation gaps, the two corresponding radiation gaps of the adjacent radiation units are positioned in the same space surrounded by the metalized through holes, the two radiation gaps are not on the same straight line, and metal matching holes for disturbing the distribution of the field are arranged on the other side of each radiation gap in the space;

the uppermost substrate layers of the third area and the fourth area are respectively provided with an I-shaped gap for increasing the resonance length, the I-shaped gaps are all positioned in a space surrounded by the metalized via holes, and second metal matching holes are arranged at positions close to the I-shaped gaps; the lowermost substrate layer of the fifth region is provided with a grounded coplanar waveguide and a first metal matching hole.

Further, the phased array is manufactured by adopting an LTCC process.

Further, the material of the substrate layer of each area adopts FerrooA 6M.

Further, the substrate layers of the first area and the second area have 8 layers respectively.

Further, the substrate layer of the third area has 7 layers, the substrate layer of the fourth area has 2 layers, and the substrate layer of the third area has 3 layers.

Further, a fifth region feeds the grounded coplanar waveguide with an SMPM connector, and then converts the coplanar waveguide into a SIW structure.

Further, there are 4 radiating elements.

Further, 4 radiation slits are provided in each radiation unit.

Furthermore, two corresponding radiation gaps of adjacent radiation units are located in the same rectangular space surrounded by the metalized via holes, and the two radiation gaps are distributed in a diagonal manner.

Furthermore, the number of the grounded coplanar waveguides arranged in the fifth region, the number of the third metal matching holes, the number of the i-shaped slots arranged in the third region and the fourth region, and the number of the radiation slots of each radiation unit in the second region are all equal to the number of the dielectric resonant cavities in the first region

Compared with the prior art, the invention can at least realize the following beneficial effects:

1. the invention uses the multilayer shunt feed network to feed the radiation network, and ensures the matching of the structure, thereby ensuring the coverage of the whole 5G millimeter wave frequency band (24.25GHz-29.5GHz), and simultaneously ensuring that the antenna structure keeps good beam stability in the edge radiation direction in the whole 5G millimeter wave frequency band.

2. The novel I-shaped gap is used, so that the transverse length of the gap can be effectively reduced, and the novel I-shaped gap is very important for a high dielectric constant material adopted by the LTCC. And the matching of the common slot antenna is improved through the I-shaped slot and the metal matching hole structure.

3. According to the invention, the additional metal covering type metal layer is used at the top of the resonant cavity, and the LTCC process only can adopt Ferro A6M material with high dielectric constant, but the high dielectric constant material has strong constraint capability on electromagnetic waves and is difficult to radiate, so that the application of the LTCC process in a relatively low-frequency millimeter wave frequency band of 5G millimeter wave frequency band becomes possible by loading the additional metal covering type metal layer.

5. According to the invention, the extra metal covering type metal layer is arranged on the radiation structure to change the aperture field distribution, so that a wide-angle scanning is realized while the gain is ensured.

6. According to the novel LTCC-based antenna design idea, a multilayer shunt feed network is used for feeding each gap of the substrate integrated waveguide, so that the amplitude and the phase of an electric field fed to each gap are close to the same value, and the stability of matching and directional diagrams is guaranteed.

7. Because the number of layers required by the LTCC process at a relatively low frequency is large, an extra metal covering resonant cavity is formed by loading an extra metal covering type metal layer above a medium resonant area, the number of layers can be effectively reduced by the extra metal covering resonant cavity and a radiation structure, and radiation characteristics are guaranteed at the same time.

Drawings

Fig. 1 is a schematic structural diagram of a 5G millimeter wave LTCC parallel-feed wide-angle scanning phased array provided in an embodiment of the present invention.

FIG. 2 is a top view of the Region of Region I of FIG. 1.

FIG. 3 is a top view of the Region II of FIG. 1.

Fig. 4 is a top view of the Region iii of fig. 1.

FIG. 5 is a top view of the Region IV of FIG. 1.

FIG. 6 is a top view of the Region V of FIG. 1.

Fig. 7 is a diagram illustrating the relationship between the column unit S11 and the S parameter.

Fig. 8 is a diagram showing the relationship between the degree of isolation and the degree of coupling between column cells.

Fig. 9 is the lowest scan angle and gain pattern across the band.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The 5G millimeter wave LTCC parallel-feed wide-angle scanning phased array provided by the invention consists of two basic parts, and the structural sketch of the phased array is shown in figure 1; the first basic part is a feeding structure, corresponding to the Layer17-Layer28 part of fig. 1, i.e. the third, fourth and fifth regions: feeding power to the coplanar waveguide through a back-connected SMPM joint, then switching into an SIW structure, and then feeding energy to a radiation network through a multilayer shunt-feed feeding network; the second essential part is the radiating structure, corresponding to the Layer1-Layer16 part of fig. 1, i.e. the first and second regions: a high-gain and wide-beam-width column unit structure is formed by a medium resonant cavity and an extra metal covering type resonant cavity structure in the form of an SIW slot antenna.

1) Feed structure at bottom

The feed structure corresponds to regions iii, iv, v in fig. 1, that is, a third Region, a fourth Region, and a fifth Region, each Region is distributed in a stacked manner in a longitudinal space, the third Region, the fourth Region, and the fifth Region each include a plurality of substrate layers, each layer in each Region is completely the same, and each Region is provided with a metalized via penetrating through all the substrate layers in the Region. In one embodiment of the present invention, the third area of the substrate layer has 7 layers, the fourth area of the substrate layer has 2 layers, and the fifth area of the substrate layer has 3 layers. It is understood that in other embodiments, other numbers of layers may be provided as desired.

The uppermost substrate layers of the third area and the fourth area are respectively provided with an I-shaped gap 5 used for increasing the resonance length, the I-shaped gaps are located in a space surrounded by the metalized through holes, second metal matching holes 6 are loaded at positions close to the I-shaped gaps 5, and high-order modes are excited near the gaps through the second metal matching holes to improve matching. The top views corresponding to the respective regions correspond to fig. 4, 5, and 6, respectively.

The uppermost substrate layer of the fifth area is provided with a grounded coplanar waveguide 7 and a first metallic matching hole 8 for feeding through a feeding port 9. And the grounded coplanar waveguide (GCPW) is fed through a back-connected SMPM connector at the lowest layer of the fifth region, and then the coplanar waveguide is converted into an SIW structure, so that the conversion from a TEM mode to a TE10 mode is realized. The structure realizes a broadband feed network structure through a multilayer shunt feed network. The structure of the first metal matching hole is loaded through the I-shaped seam to feed the upper layer. Although the shunt feed structure increases the number of layers and loss, this structure ensures in-band impedance matching and pattern stability,

in one embodiment of the present invention, the phased array is made by LTCC process, and all substrate layer materials are selected from FerroA6M, dielectric constant is 5.9, and loss tangent is 0.002. Because the substrate layer is made of FerroA6M, the width of SIW corresponding to FerroA6M is narrower on the premise of having the same cut-off frequency, and the length of the slot is limited, so that the bandwidth is also limited. Therefore, the present invention ensures matching while reducing the slot length by providing the structure of the drum slot to increase the resonance length and the structure of the metal matching hole to form an additional resonance region.

2) Radiation structure on top

The first area and the second area are radiation structures of a phased array, each area comprises a plurality of substrate layers which are arranged in a stacked mode, and each area is provided with metalized through holes penetrating through all the substrate layers in the area. The substrate layer adopts FerrooA 6M, the dielectric constant is 5.9, the loss tangent is 0.002, the number of layers is 16, the upper 8 (first area) is a dielectric resonant cavity, the lower 8 (second area) layers are basic radiating elements of the antenna, and the used radiating structure is in the form of a substrate integrated waveguide slot antenna assisted by the dielectric resonant cavity.

A plurality of dielectric resonators 1 are formed on the first area inside the periphery of the metalized vias, and the uppermost substrate layers in the first area are provided with additional metal-clad metal layers in the area between the metalized vias and the dielectric resonators.

The second area is composed of 8 FerrooA 6M substrate layers, at least one column unit is arranged on the uppermost substrate layer in the second area, each column unit comprises two radiation units 2, each radiation unit comprises a plurality of radiation slits 3, the two corresponding radiation slits of the adjacent radiation units are located in the same space surrounded by the metalized through holes, the two radiation slits are not on the same straight line, and a first metal matching hole 4 for disturbing the distribution of the field is arranged on the other side of each radiation slit in the space. In one embodiment of the present invention, two corresponding radiation slots of adjacent radiation units are located in the same rectangular space surrounded by the metalized via, and the two radiation slots are distributed diagonally. The first metal matching holes 4 are added on the other side of the radiation gap to disturb the field distribution so that higher order modes are excited at the radiation gap to form a resonance region with a denser field, thereby improving matching, as shown in fig. 3 in a top view.

In the invention, the number of the grounded coplanar waveguides arranged in the fifth region, the number of the third metal matching holes, the number of the I-shaped gaps arranged in the third region and the fourth region, and the number of the radiation gaps of each radiation unit in the second region are equal to the number of the dielectric resonant cavities in the first region. More specifically, in one embodiment of the present invention, there are 4 dielectric resonators formed in the first region.

The structure can effectively improve the matching and the gain of the structure by loading the medium resonant cavity in the first region, the structure surrounds a larger resonant region above a radiation gap through the metalized through holes, so as to assist energy radiation, the top view is shown in figure 2, and meanwhile, an extra metal covering type metal layer is used at the topmost part of the medium resonant cavity, the structure effectively changes the distribution of the caliber field of radiation surface, obtains relatively higher gain while reducing the number of layers required by the resonant cavity, and greatly relieves the pressure caused by the limitation of the number of processing layers.

In one embodiment of the present invention, 4 radiation elements are disposed in the second region, which are defined as 1 element, 2 elements, 3 elements and 4 elements, and each of the elements has 4 radiation slits disposed therein. In this embodiment, the passive reflection coefficients of each row of units of the formed phased array in the 5G frequency band are shown in fig. 4, and it can be seen that the structure can ensure that the passive reflection coefficient is < -10dB in the whole 5G frequency band; FIG. 8 shows the mutual coupling of the phased array, with adjacent element coupling < -12dB in the frequency band; fig. 9 shows the scanning condition of the lowest scanning angle frequency point in the whole frequency band, and the structure can realize the scanning capability of a 3dB roll-off scanning angle larger than 56 ° in the whole 5G frequency band.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The 5G millimeter wave LTCC parallel-feed wide-angle scanning phased array is characterized by comprising a plurality of areas which are respectively defined as a first area, a second area, a third area, a fourth area and a fifth area from top to bottom, wherein the first area and the second area are radiation structures of the phased array, the third area, the fourth area and the fifth area are feed structures of the phased array, each area comprises a plurality of laminated substrate layers, and each area is provided with a metalized through hole penetrating through all the substrate layers of the area;

a plurality of medium resonant cavities are formed on the first area at the inner side surrounded by the metalized through holes, and extra metal covering type metal layers are arranged on the uppermost layer of the substrate layer in the first area in the area between the metalized through holes and the medium resonant cavities; at least two radiation units are arranged on the substrate layer positioned on the uppermost layer in the second area, each radiation unit comprises a plurality of radiation gaps, two corresponding radiation gaps of adjacent radiation units are positioned in the same space surrounded by the metalized through holes, the two radiation gaps are not on the same straight line, and metal matching holes for disturbing the distribution of the field are arranged on the other side of each radiation gap in the space;

2. The 5G millimeter wave LTCC parallel-feed wide angle scanning phased array of claim 1, wherein the phased array is made by LTCC process.

3. The 5G millimeter wave LTCC parallel-fed wide angle scanning phased array of claim 1, wherein the material of the substrate layer of each region is FerrooA 6M.

4. A 5G millimeter wave LTCC parallel feed wide angle scanning phased array as claimed in claim 1 wherein the substrate layers of the first region and the second region each have 8 layers.

5. A 5G mm wave LTCC parallel feed wide angle scanning phased array as claimed in claim 1 wherein the third region has 7 layers of substrate, the fourth region has 2 layers of substrate and the fifth region has 3 layers of substrate.

6. A 5G mm wave LTCC parallel-fed wide angle scanning phased array as claimed in claim 1 wherein a fifth region feeds the grounded coplanar waveguide with SMPM junctions before converting the coplanar waveguide into a SIW structure.

7. A 5G millimeter wave LTCC parallel feed wide angle scanning phased array as claimed in claim 1 wherein there are 4 radiating elements.

8. The 5G millimeter wave LTCC parallel feed wide angle scanning phased array of claim 1, wherein 4 radiating apertures are provided in each radiating element.

9. The 5G millimeter wave LTCC parallel-feed wide-angle scanning phased array of claim 1, wherein two corresponding radiation slots of adjacent radiation elements are located in a same rectangular space surrounded by metalized vias, and the two radiation slots are distributed diagonally.

10. The 5G millimeter wave LTCC parallel-fed wide angle scanning phased array as claimed in any one of claims 1 to 9, wherein the number of grounded coplanar waveguides provided in the fifth region, the number of third metal matching holes, the number of i-shaped slots provided in the third region and the fourth region, and the number of radiating slots per radiating element in the second region are equal to the number of dielectric resonators in the first region.