WO2024093310A1 - Holographic antenna, communication device, and holographic antenna manufacturing method - Google Patents

Abstract

The present application relates to a holographic antenna, a communication device, and a holographic antenna manufacturing method. The method comprises: the holographic antenna comprises a control layer, a scattering unit, a substrate, and a feed network which are stacked in sequence; the control layer is used for controlling the radiation of the scattering unit; the scattering unit is disposed between the control layer and the feed network and is used for radiating energy; the feed network comprises a stripline waveguide and is used for generating and transmitting a transverse electromagnetic wave; and the substrate is disposed between the feed network and the scattering unit and is used for reducing the transmission speed of the transverse electromagnetic wave and outputting the decelerated transverse electromagnetic wave to the scattering unit so as to excite energy radiation of the scattering unit. By using the holographic antenna, the implementation difficulty of the holographic antenna can be reduced.

Description

Holographic antenna, communication device and method for preparing holographic antenna

Related Applications

This application claims priority to Chinese patent application number 2022113606743, filed on November 2, 2022, entitled “Holographic antenna, communication equipment and method for preparing holographic antenna”, the entire text of which is hereby incorporated by reference.

Technical Field

The present application relates to the field of wireless communication technology, and in particular to a holographic antenna, a communication device, and a method for preparing the holographic antenna.

Background technique

5G millimeter wave beamforming technology mainly includes active phased array antenna beamforming and holographic antenna beamforming. Due to the high implementation cost of active phased array antenna beamforming technology, most current technical research focuses on holographic antenna beamforming technology.

In the related technology, when studying holographic antennas, it is usually only based on knowledge-level research, and only conceptual solutions are proposed, that is, it is proposed to use beamforming technology to modify parameters such as the surface impedance of the holographic antenna structure to achieve beam scanning of the holographic antenna.

However, the above technology has the problem of being difficult to implement.

Summary of the invention

Based on this, it is necessary to provide a holographic antenna, communication equipment and a method for preparing a holographic antenna that can reduce the difficulty of implementation in order to solve the above-mentioned technical problems.

In a first aspect, the present application provides a holographic antenna, the holographic antenna comprising a control layer, a scattering unit, a substrate and a feeding network stacked in sequence;

The control layer is used to control the radiation of the scattering unit;

The scattering unit is arranged between the control layer and the feeding network to radiate energy;

The feeding network comprises a stripline waveguide for generating and transmitting transverse electromagnetic waves;

The substrate is arranged between the feeding network and the scattering unit, and is used to reduce the transmission speed of the transverse electromagnetic wave, and output the decelerated transverse electromagnetic wave to the scattering unit to stimulate the scattering unit to radiate energy.

In a second aspect, the present application also provides a communication device, comprising the holographic antenna of the first aspect.

In a third aspect, the present application further provides a method for preparing a holographic antenna, which is applied to the holographic antenna of the first aspect, and the method comprises:

Pressing the scattering unit and the feeding network and the substrate therebetween to obtain a formed intermediate layer, and making a third metallized via through the intermediate layer;

Laminating the control layer, the choke branch layer and the middle layer to obtain an initial holographic antenna;

A first metallized via hole is made through the control layer and the scattering unit of the initial holographic antenna, and a second metallized via hole is made through the initial holographic antenna to obtain a formed holographic antenna.

The above-mentioned holographic antenna, communication device and preparation method of the holographic antenna, the holographic antenna comprises a control layer, a scattering unit, a substrate and a feeding network which are stacked in sequence, wherein the control layer is used to control the radiation of the scattering unit, the scattering unit is arranged between the control layer and the feeding network, and is used to radiate energy, the feeding network comprises a stripline waveguide, which is used to generate and transmit transverse electromagnetic waves, the substrate is arranged between the feeding network and the scattering unit, and is used to reduce the transmission speed of the transverse electromagnetic wave, and output the decelerated transverse electromagnetic wave to the scattering unit to stimulate the scattering unit to radiate energy. With the holographic antenna, the transmission of the transverse electromagnetic wave in the holographic antenna can be realized by the control layer, the scattering unit, the substrate and the feeding network which are stacked in sequence, that is, the radiation and scanning functions of the holographic antenna are realized, and the structure is relatively simple, and can be realized relatively easily, that is, the difficulty of realizing the holographic antenna can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without paying any creative work.

FIG1 is a structural diagram of a holographic antenna according to an embodiment;

FIG2 is a structural diagram of a control layer in another embodiment;

FIG3 is a structural diagram of a scattering unit in another embodiment;

FIG4 is a structural diagram of a choke branch in conventional technology in another embodiment;

FIG5 is an effect diagram of the S parameter of the choke branch in the conventional technology in another embodiment;

FIG6 is a structural diagram of an improved choke branch in another embodiment;

FIG7 is a rendering of the S parameters of an improved choke branch in another embodiment;

FIG8 is a structural diagram of a choke branch layer in another embodiment;

FIG9 is a structural diagram of a first ground plane layer in another embodiment;

FIG10 is a structural diagram of a second ground plane layer in another embodiment;

FIG11 is a structural diagram of a conductive layer in another embodiment;

FIG12 is a diagram showing a specific structure of a holographic antenna in another embodiment;

FIG13 is a table showing the size of parameters involved in each layer of a holographic antenna in another embodiment;

FIG14 is a 2D radiation diagram of a holographic antenna operating at 25.5 GHz in another embodiment;

FIG15 is a 2D radiation diagram of a holographic antenna operating at 26 GHz in another embodiment;

FIG16 is a 2D radiation diagram of a holographic antenna operating at 26.5 GHz in another embodiment;

FIG17 is a 3D radiation diagram of a holographic antenna operating at 26 GHz in another embodiment;

FIG18 is a schematic flow chart of a method for preparing a holographic antenna in another embodiment;

Description of reference numerals:
Control layer: 11; PIN diode: 111; control line: 1111;
Scattering unit: 12; slot antenna: 121;
Feeding network: 13; first grounding plate layer: 131; conduction layer: 132; second grounding plate layer: 133; rectangular gap:
1311; Metal guide tape: 1321;
Substrate: 14; first dielectric substrate: 141; second dielectric substrate: 142; third dielectric substrate: 143;
Choke branch layer: 15; Choke branch: 151;
First metallized via: 16;
Second metallized via: 17; first circular groove: 171; second circular groove: 172;
Third metallized via: 18.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

The millimeter wave frequency bands for international mobile communications (IMT) determined by the World Radiocommunication Conference (WRC-19) of the International Telecommunication Union (ITU) are: 24.25~27.5GHz, 37-43.5GHz and 66-71GHz. At present, 5G millimeter wave beamforming technology mainly includes active phased array antenna beamforming and holographic antenna beamforming. Among them, the advantage of active phased array antenna beamforming is the use of small spacing (small spacing generally refers to the spacing between antennas is about half the wavelength corresponding to the high frequency band) to form a high-gain narrow beam with higher spatial resolution. The disadvantage is that the feeding network design of the phased array antenna is relatively complex and the cost of the entire equipment is relatively high. Holographic antenna beamforming refers to the control of the beam direction by changing the surface impedance of the holographic structure based on optical principles. The holographic antenna is composed of a feed source and a holographic structure. In terms of processing technology, it is similar to a microstrip antenna. It has the advantages of easy processing, easy integration, and light weight. Therefore, research and application of it are more important. At present, many enterprises and institutions have begun to study the holographic antenna beamforming antenna technology, but it is still only based on the knowledge level research, and only proposed a conceptual solution, that is, it is proposed to use the beamforming technology to modify the surface impedance and other parameters of the holographic antenna structure to achieve the beam scanning of the holographic antenna, but it has the problem of high difficulty in implementation. Based on this, the embodiment of the present application provides a holographic antenna, a communication device and a method for preparing a holographic antenna, which can solve the above technical problems.

It should be noted that the following embodiments of the present application are mainly described using the 25.5-26.5 GHz millimeter wave holographic antenna coverage frequency band as an example. It can be understood that the technical solutions of the embodiments of the present application can also be applied to other millimeter wave frequency bands.

Fig. 1 is a schematic diagram of the structure of a holographic antenna provided in an embodiment. As shown in Fig. 1, the holographic antenna includes a control layer 11, a scattering unit 12, a substrate 14 and a feeding network 13 which are stacked in sequence; the control layer 11 is used to control the radiation of the scattering unit 12; the scattering unit 12 is arranged between the control layer 11 and the feeding network 13, and is used to radiate energy; the feeding network 13 includes a stripline waveguide, and is used to generate and transmit transverse electromagnetic waves; the substrate 14 is arranged between the feeding network 13 and the scattering unit 12, and is used to reduce the transmission speed of the transverse electromagnetic waves, and output the decelerated transverse electromagnetic waves to the scattering unit 12, so as to stimulate the scattering unit 12 to radiate energy.

Among them, the control layer 11 can be a control layer 11 including a control circuit, which can be electrically connected to the scattering unit 12, and is used to control the radiation of the scattering unit 12, specifically, it can be used to control whether the scattering unit 12 participates in the radiation. In addition, the control layer 11 can also discretize the situation of whether the scattering unit 12 participates in the radiation, that is, the scattering unit 12 is divided into participating in the radiation and not participating in the radiation, which can simplify the radiation control process of the scattering unit 12 by the control layer 11.

Here, the control layer 11 can be arranged on the top layer, and the scattering units 12 can be stacked in sequence below the control layer 11 and above the feed network 13. The number of the scattering units 12 can be one or more, generally multiple. The scattering units 12 are mainly used to radiate energy to the outside to achieve signal transmission and reception.

The feeding network 13 can be stacked in sequence below the scattering unit 12, which can include a stripline waveguide, which can be used to generate a transverse electromagnetic wave, which can be a TEM wave. The full name of TEM wave in English is: Transverse Electromagnetic Wave. TEM wave is an electromagnetic wave in which the electric field component and the magnetic field component are perpendicular to each other and perpendicular to the propagation direction. The stripline waveguide can be a waveguide composed of one or more striplines, and the specific material can be metal, such as copper. At the same time, the stripline waveguide can also transmit the generated TEM wave to the inside of the feeding network 13 and the scattering unit 12.

The substrate 14 can be a dielectric substrate with a high dielectric constant. As an optional embodiment, the substrate 14 uses RO4360G2TM with a dielectric constant of 6.4, a dielectric loss of 0.0038, and a thickness of 1.524 mm. The RO4360G2TM laminate is a low-loss, glass-fiber-reinforced hydrocarbon resin ceramic-filled thermosetting material that can better balance the performance of the holographic antenna and the machinability of the substrate. The substrate can include one or more dielectric substrates, which can be stacked in sequence below the scattering unit 12 and above the feed network 13, that is, between the scattering unit 12 and the feed network 13. When the feed network 13 generates and transmits TEM waves, the substrate can increase the reflectivity of the stripline waveguide in the feed network 13, and at the same time can receive the transmitted TEM waves and reduce the transmission speed of the TEM waves, weaken the frequency scanning characteristics of the holographic structure, and realize broadband scanning characteristics. In addition, the substrate 14 can also output the decelerated TEM waves to the scattering unit 12 through the reflection characteristics, so that the scattering unit 12 can be stimulated to participate in the radiation and radiate energy, so as to realize the signal transmission and reception of the holographic antenna.

In addition, the holographic antenna may further include some other layers and substrates between the control layer 11, the scattering unit 12, the feeding network 13 and the substrate 14, and the specific number and type of the layers and substrates are not specifically limited here.

Furthermore, the actual sizes of the control layer 11, the scattering unit 12, the feeding network 13 and the substrate 14 in the above-mentioned holographic antenna can be the same, which can facilitate the processing and assembly of the holographic antenna and further reduce the difficulty of realizing the holographic antenna.

In order to more clearly explain the control principle of the control layer 11, the following takes the scattering unit 12 as a plurality of examples, and the amplitude weighting theory of the holographic antenna including the scattering unit 12 can be first explained:

Taking a one-dimensional uniform linear array as an example, the scattering unit 12 is located in the y-axis direction (the y-axis represents the extension direction of the scattering unit 12, the side direction of the substrate is the x-axis, and the direction perpendicular to the side of the substrate is the z-axis). Based on the basic idea of amplitude weighting in the holographic antenna theory, an amplitude function can be used to represent the amplitude weighting principle of the holographic antenna, as shown in the following formula (1):

Wherein, m( _yn , _θ0 ) represents the excitation amplitude value of the antenna at _yn when the desired beam points to _θ0 ; _θ0 represents the beam pointing angle; _yn represents the position information of the nth scattering unit 12 on the holographic antenna structure; _kr represents the propagation constant of the reference wave; and _k0 represents the propagation constant of the object wave.

Specifically, when the phase shift value at y _n is equal to the target value, m(y _n ,θ ₀ ) takes the value of 1, indicating that the energy radiated by the antenna at this location is the largest; when the phase shift value at y _n is opposite to the target phase, m(y _n ,θ ₀ ) takes the value of 0, indicating that the energy radiated by the antenna at this location is the smallest; when the phase shift value at y _n differs from the target value by a certain value, m(y _n ,θ ₀ ) takes the value between 0 and 1.

Based on the above amplitude weighting principle, assuming that the number of scattering elements 12 in the holographic antenna of this embodiment is 64, i.e., a 1*64 holographic antenna, when the beam pointing angle is θ ₀ and is 0°, and the operating frequency of the holographic antenna is 26 GHz, the excitation amplitudes of the 64 scattering elements 12 after being excited by the feeding network 13 can be shown in the following Table 1:

Table 1

In order to facilitate the control layer 11 to better control the radiation of each scattering unit 12, the amplitude of each scattering unit 12 in the above Table 1 can be discretized by the control layer 11. Assuming that the discretization threshold M is set to 0.7, the above amplitude is greater than or equal to 0.7, which can be considered that the scattering unit 12 participates in the radiation, and the amplitude can be discretized to 1. The amplitude is less than 0.7, which can be considered that no scattering unit 12 participates in the radiation, and the amplitude can be discretized to 0. In this way, the amplitude in the above Table 1 can be discretized into the corresponding amplitude in the following Table 2. For details, see the following Table 2:

Table 2

The control layer 11 discretizes the radiation amplitude of the scattering unit 12, so that it is easier to control whether the scattering unit 12 participates in the radiation, thereby reducing the difficulty of radiation control. The stripline waveguide in the feeding network 13 can generate and transmit TEM waves. At the same time, the speed of the transmitted TEM waves can be reduced through the substrate and transmitted to the scattering unit 12 to stimulate the scattering unit 12 to participate in radiation, thereby realizing the scanning characteristics of the holographic antenna.

In this embodiment, the holographic antenna includes a control layer 11, a scattering unit 12, a substrate 14 and a feeding network 13 which are stacked in sequence, wherein the control layer 11 is used to control the radiation of the scattering unit 12, the scattering unit 12 is arranged between the control layer 11 and the feeding network 13, and is used to radiate energy, the feeding network 13 includes a stripline waveguide, and is used to generate and transmit transverse electromagnetic waves, and the substrate 14 is arranged between the feeding network 13 and the scattering unit 12, and is used to reduce the transmission speed of the transverse electromagnetic waves, and output the decelerated transverse electromagnetic waves to the scattering unit 12, so as to stimulate the scattering unit 12 to radiate energy. With the holographic antenna, the transmission of transverse electromagnetic waves in the holographic antenna can be realized by stacking the control layer 11, the scattering unit 12, the substrate 14 and the feeding network 13 in sequence, that is, the radiation and scanning functions of the holographic antenna can be realized, and the structure is relatively simple, and it can be relatively easy to realize, that is, the difficulty of realizing the holographic antenna can be reduced.

The above embodiment roughly describes the composition structure of the holographic antenna. The following further describes the detailed composition of each composition structure of the holographic antenna. FIG2 is a schematic diagram of the specific structure of the control layer 11 provided in another embodiment. As shown in FIG2, the control layer 11 includes a first dielectric substrate 141 and a plurality of control units arranged on the first dielectric substrate 141. The plurality of control units are arranged in two rows and correspond to each other one by one. Each control unit includes a PIN diode 111. The switching state of the PIN diode 111 corresponds to whether the scattering unit 12 radiates energy.

Among them, the number of control units arranged on the first dielectric substrate 141 can be set according to actual conditions. As an optional embodiment, the embodiment of the present application is for a 1*64 holographic antenna, so for the two rows of control units arranged on the first dielectric substrate 141, each row can be arranged with 64 control units, that is, the control layer 11 includes 2*64 control units. As an optional embodiment, the material of the first dielectric substrate is RO4450F, the dielectric constant is 3.52, the dielectric loss is 0.004, and the substrate thickness is 4mil.

Each control unit may include a PIN diode 111, and the PIN diode 111 of each control unit may be packaged in a 0201 package size to achieve miniaturized packaging of the control unit. Here, each PIN diode 111 includes two states, namely, on and off, to achieve two states similar to the on and off states of a switch, wherein the off state of the PIN diode 111 indicates that the scattering unit 12 participates in radiation, and the on state of the PIN diode 111 indicates that the scattering unit 12 does not participate in radiation, that is, the switch state of the PIN diode 111 corresponds to whether the scattering unit 12 radiates energy.

In addition, each control unit may also include a first metallized via 16, wherein the first metallized via 16 is used to electrically connect to the scattering unit 12 below the control layer 11, so as to control whether the scattering unit 12 participates in radiation through the first metallized via 16. The shape of the first metallized via 16 is generally circular; the size of the first metallized via 16 can be set according to actual conditions. Here, a circular first metallized via 16 is taken as an example, and its radius can be set according to actual conditions, for example, it can be between 0.1-0.2mm, assuming it can be 0.1mm. The boundary of the first metallized via 16 can be a square whose side length can be recorded as PL1, wherein the length and width of the space occupied by the PIN diode 111 in each control unit can also be PL1 (its size can be set according to actual conditions). Of course, the pins of the PIN diode 111 can also be welded on the first metallized via 16 to achieve electrical connection between the first metallized via 16 and the PIN diode 111.

Further, as an optional embodiment, the width W1 of the first dielectric substrate 141 may be W1=8.0 mm; as an optional embodiment, the length L1 of the first dielectric substrate 141 may be L1=80.0 mm; as for the two rows of control units arranged on the first dielectric substrate 141, they may be arranged in parallel, and the distance between the two rows of control units is D1, as an optional embodiment, D1=4.0 mm; when arranging each row of control units, they may be arranged at equal intervals, and the interval between any two adjacent control units in the two rows of control units is also equal, for example, the interval between any two adjacent control units in each row in the y-axis direction is recorded as D2, as an optional embodiment, D2=1.13 mm; as for the control units at the head and the end of the two rows of control units, the distance from the edge of the first dielectric substrate 141 may be equal, and may be recorded as D3, as an optional embodiment, D3=3.76 mm. As for the numbers 0 and 1 in the middle of the two rows of control units in FIG. 2, they correspond to the amplitudes in the above Table 2, which are the amplitudes corresponding to each control unit.

As an optional embodiment, Fig. 3 is a schematic diagram of the specific structure of the scattering unit 12 provided in another embodiment. As shown in Fig. 3, the scattering unit 12 includes a second dielectric substrate 142 and a plurality of slot antennas 121 arranged on the second dielectric substrate 142, wherein the plurality of slot antennas 121 are arranged in two rows and correspond to each other; the slot antennas 121 in each row on the scattering unit 12 are electrically connected to the control units in each row on the control layer 11 in a one-to-one correspondence.

For the scattering unit 12, similar to the above-mentioned control layer 11, this is also for a 1*64 holographic antenna. Then, for the two rows of slot antennas 121 arranged on the second dielectric substrate 142, each row may be arranged with 64 slot antennas 121, that is, the second dielectric substrate 142 includes 2*64 slot antennas 121.

For the slot antenna 121, a slot may be etched on the metal layer (for example, copper foil) on the second dielectric substrate 142, and the slot is used as the slot antenna 121. In addition, as an optional embodiment, the spacing between the slot antennas on the y-axis in the extension direction of the scattering unit is 1.13 mm. That is to say, for the two rows of slot antennas 121 on the second dielectric substrate 142, the spacing between these slot antennas 121 in the y-axis direction is recorded as D2, D2 = 1.13 mm, which is the same/consistent with the spacing between each adjacent two control units in the y-axis direction mentioned above, so that each control unit can achieve precise control of the corresponding slot antenna 121. Each slot antenna 121 corresponds to the PIN diode 111 in the control unit at the corresponding position on the first dielectric plate 141 and is electrically connected one by one, and the corresponding PIN diode 111 controls the slot antenna 121 to achieve the purpose of whether the slot antenna 121 participates in radiation. When the PIN diode 111 is working/conducting, the corresponding slot antenna 121 controlled by it does not participate in radiation, and when the PIN diode 111 is turned off, the corresponding slot antenna 121 controlled by it participates in radiation.

In addition, the width and length of the second dielectric substrate 142 are the same as the width and length of the first dielectric substrate 141. For example, W1=8.0mm, L1=80.0mm. For the size of each slot antenna 121, the size of all slot antennas 121 can be the same. For the shape of the slot antenna 121, it can be a rectangle, the length of the slot antenna 121 is recorded as SL1, SL1=3.05mm, and the width of the slot antenna 121 is recorded as SW1=0.28mm. The total length occupied by the two rows of slot antennas 121 on the second dielectric substrate 142 can be recorded as D4, D4=6.65mm. As an optional embodiment, the material of the above-mentioned second dielectric substrate is RO4360G2, the dielectric constant is 6.4, the dielectric loss is 0.0038, and the substrate thickness is 60mil.

As an optional embodiment, referring to Figures 2 and 3, the control unit and the corresponding slot antenna 121 are electrically connected through the first metallized via 16. That is, in order to better use each control unit (specifically the PIN diode 111) to control the corresponding slot antenna 121, each slot antenna 121 and the corresponding control unit (specifically the PIN diode 111) can be electrically connected using a first metallized via 16.

Furthermore, if the working frequency band of the beam needs to be adjusted later, the size of the slot antenna 121 or the PIN diode 111 can be adjusted to control the amount of radiation involved in the slot antenna 121. This can make it easier to achieve beamforming for other millimeter-wave frequency bands, further reducing the difficulty of implementing the holographic antenna.

In this embodiment, the PIN diodes 111 on the first dielectric substrate 141 are arranged in two rows, and are electrically connected to the slot antennas 121 arranged in two rows on the second dielectric substrate 142 in a one-to-one correspondence, so that the slot antennas 121 can be easily controlled and the difficulty of realizing the holographic antenna can be reduced. At the same time, the PIN diodes 111 and the slot antennas 121 are electrically connected through the first metallized vias 16, so that no additional wiring is required for connection, thereby saving costs and reducing the size of the holographic antenna, and facilitating the realization of a miniaturized holographic antenna.

In order to realize the effective switching characteristics of the PIN diode 111 in the millimeter wave frequency band, the PIN diode 111 needs to add a choke branch 151 for controlling the circuit design. In another embodiment, the holographic antenna further includes a choke branch layer 15; the choke branch layer 15 and the feed network 13 are stacked in sequence and electrically connected to the control layer 11, and are used to block the AC signal passing through the control layer 11 and pass the DC signal. Here, the AC signal is blocked by the choke branch 151 in the choke branch layer 15. Then, when the choke branch layer 15 and the control layer 11 are connected, the choke branch 151 of the choke branch layer 15 can provide a better DC signal to the PIN diode 111 of the control layer 11. The better the DC signal of the PIN diode 111, the better the control performance will be, so that the control of the slot antenna 121 through the PIN diode 111 can be accurately achieved.

Commonly used choke branches 151 mainly include fan-shaped branches, as shown in FIG4 , which is a schematic diagram of the structure of a conventional choke branch 151. As shown in FIG4 , the size of the fan-shaped branch is CKL1*CKW1, 2.15mm*1.43mm, the size of the substrate is 8mm*4mm, the dielectric substrate is Ro4450F, the dielectric constant is 3.52, the dielectric loss is 0.004, and the thickness is 4mil (unit of length (mil), 1mil=1/1000inch=0.0254mm). The corresponding S parameters of the choke branch 151 based on the conventional technology are shown in FIG5 , wherein the S21 parameter of the choke branch 151 is ≤-30dB in the range of 25.5 to 26.5GHz, and the curve of the S11 parameter in the figure coincides with the curve of the S22 parameter, and coincides with the horizontal axis when the S parameter is 0. The curves of S12 parameter and S21 parameter coincide.

In order to achieve the same effect of the S parameter of the choke branch 151 as in the conventional technology, and also to reduce the size of the choke branch 151 to realize a miniaturized holographic antenna, the structure of the choke branch 151 is improved as shown in FIG6 , which is an example diagram of the structure of the improved choke branch 151. The choke branch 151 is a fan-shaped branch, and at least one signal input and output port is provided at the bottom of the fan-shaped branch, and at least one L-shaped branch is provided at the top of the fan-shaped branch, and the L-shaped branch is used to increase the current path of the fan-shaped branch.

Referring to FIG. 4 and FIG. 6 , P1 and P2 are two ports of the choke branch 151 , and signals in the choke branch 151 can be input and output through the ports. For the improved choke branch 151, the size of the substrate is still 8mm*4mm. Compared with the conventional choke branch 151, an L-shaped branch is respectively arranged on both sides of its top, and the two L-shaped branches are symmetrically arranged. By setting the L-shaped branch, without changing the length of the choke branch 151, that is, the length of the choke branch 151 is still CKL1=2.15mm, the current path of the fan-shaped branch can be increased through the L-shaped branch, and the width of the choke branch 151 can be significantly shortened. The width of the choke branch 151 is shortened to CKW2=1.1mm, and the width is reduced by 0.33mm compared with the conventional choke branch 151, that is, the size of the above-mentioned choke branch is 2.15mm*1.1mm, thereby realizing a miniaturized choke branch 151, so as to reduce the difficulty of arranging the choke branch 151 on the dielectric substrate in the future.

Based on the improved choke branch 151, its corresponding S parameters can also be obtained, as shown in FIG7, wherein the S21 parameter of the improved choke branch 151 is ≤-30dB in the range of 25.5 to 26.5GHz, and the curve of the S11 parameter coincides with the curve of the S22 parameter in the figure, and coincides with the horizontal axis when the S parameter is 0, and the curve of the S12 parameter coincides with the curve of the S21 parameter. Compared with the S parameters of the conventional choke branch 151 in FIG5, the effect is basically the same, so the improved choke branch 151 in this embodiment will not change the effect that can be achieved by the S parameters of the choke branch 151, that is, it will not affect the performance of the choke branch 151.

As an optional embodiment, see Fig. 8, which is a schematic diagram of the specific structure of the choke branch layer 15 provided in another embodiment. The choke branch layer 15 includes a third dielectric substrate 143 and a plurality of choke branches 151 arranged on the third dielectric substrate 143, wherein the plurality of choke branches 151 are arranged in two rows and correspond one to one; the choke branches 151 in each row on the choke branch layer 15 are electrically connected to the control units in each row on the control layer 11 in a one-to-one correspondence.

The choke branches 151 arranged on the third dielectric substrate 143 are the same as the above-mentioned control layer 11 and the scattering unit 12. This is also for a 1*64 holographic antenna. Therefore, for the two rows of choke branches 151 arranged on the third dielectric substrate 143, each row may have 64 choke branches 151, that is, the third dielectric substrate 143 includes 2*64 choke branches 151.

For the two rows of choke branches 151 on the third dielectric substrate 143, the spacing between these choke branches 151 in the y-axis direction is recorded as D2, D2 = 1.13mm, which is the same as the spacing between each adjacent two control units in the y-axis direction mentioned above. In this way, each choke branch 151 can control the corresponding control unit first, and then each control unit can realize accurate control of the corresponding slot antenna 121. The spacing between the two rows of choke branches 151 is D5, D5=3.5mm. In addition, the width and length of the third dielectric substrate 143 are the same as those of the first dielectric substrate 141, for example, W1=8.0mm, L1=80.0mm. As an optional embodiment, the third dielectric substrate can be the same as the first dielectric substrate, for example, its material is RO4450F, the dielectric constant is 3.52, the dielectric loss is 0.004, and the substrate thickness is 4mil.

Further, in order to facilitate the control of the PIN diode 111 in the corresponding control unit through each choke branch 151, as an optional embodiment, the above-mentioned control units and the corresponding choke branches 151 are electrically connected through the second metallized via 17; here, for each choke branch 151 and the corresponding control unit (specifically the PIN diode 111), a second metallized via 17 can be used for electrical connection. That is to say, one side of each PIN diode 111 is a first metallized via 16, and the other side is a second metallized via 17. The second metallized via 17 can be set in one of the input and output ports of each choke branch 151, so as to save wiring design costs and reduce the assembly size of the choke branch 151.

In addition, the control line 1111 of the control layer 11 can be connected to the choke branch layer 15 through the second metallized via 17, that is, it can be electrically connected to the choke branch 151 through one of the input and output ports of each choke branch 151, or it can be electrically connected to the choke branch 151 through the other of the input and output ports of each choke branch 151. The size of the second metallized via 17 can be set according to actual conditions, for example, it can be between 0.01-0.5mm, assuming it can be 0.15mm.

In this embodiment, the holographic antenna also includes a choke branch layer 15, so that the DC control of the PIN diode 111 in the control layer 11 can be better achieved through the choke branch layer 15. In addition, the choke branch layer 15 includes a plurality of choke branches 151 corresponding to the control unit one by one, and can be electrically connected through metallized vias, so that they can be set and controlled one by one, which can simplify the control of the control unit by the choke branch 151 and achieve precise control. Furthermore, the choke branch 151 includes an L-shaped branch that increases the fan-shaped branch current path, so that it is easy to reduce the size of the choke branch 151 and more convenient to achieve a miniaturized holographic antenna.

The following embodiments mainly illustrate the specific structure of the feed network 13. In another embodiment, the feed network 13 includes a first ground plane layer 131, a guide strip layer 132, and a second ground plane layer 133 stacked in sequence; the first ground plane layer 131, the guide strip layer 132, and the second ground plane layer 133 constitute a stripline waveguide; the first ground plane layer 131 is closer to the scattering unit 12 relative to the second ground plane layer 133, the guide strip layer 132 is arranged between the first ground plane layer 131 and the second ground plane layer 133, and the second ground plane layer 133 is farther away from the scattering unit 12 relative to the first ground plane layer 131.

Here, the first ground plane layer 131, the guide tape layer 132 and the second ground plane layer 133 can all be arranged on a corresponding dielectric substrate, wherein the length and width of the three corresponding dielectric substrates are the same as the length and width of the first dielectric substrate 141 mentioned above, for example, W1=8.0mm, L1=80.0mm.

Among them, for the first grounding plate layer 131, referring to FIG. 9, a first grounding plate layer provided in another embodiment 131 is a schematic diagram of a specific structure. It can be an upper ground plane layer in the feed network 13. As an optional embodiment, a plurality of rectangular slots 1311 are provided on the first ground plane layer 131. The plurality of rectangular slots 1311 are arranged in two rows and correspond one to one. The rectangular slots 1311 in each row on the first ground plane layer 131 correspond one to one with the slot antennas 121 in each row on the scattering unit 12, so as to leak the decelerated transverse electromagnetic waves to the slot antennas 121.

Similar to the control layer 11, this is also for a 1*64 holographic antenna. For the two rows of rectangular slots 1311 arranged on the dielectric substrate where the first ground plane layer 131 is located, each row may be arranged with 64 rectangular slots 1311, that is, the dielectric substrate includes 2*64 rectangular slots 1311. The rectangular slots 1311 here are essentially the same as the slot antenna 121, both of which are slots etched on the copper foil of the dielectric substrate. However, the rectangular slots 1311 here are different in size from the slot antenna 121. The width occupied by the two rows of rectangular slots 1311 here is different from the width occupied by the two rows of slot antennas 121, and is smaller than the width occupied by the two rows of slot antennas 121. For example, the width occupied by the two rows of rectangular slots 1311 here can be recorded as D6, and D6 can be exemplarily D6=2.3mm. The number of rectangular slots 1311 and slot antennas 121 is equal and one-to-one corresponding, so that the TEM wave can be easily leaked to the corresponding slot antenna 121 through each rectangular slot 1311 to excite the corresponding slot antenna 121. It should be noted that the size and position of the rectangular slot 1311 here will affect the matching and beamforming effects of the holographic antenna, so the size of the rectangular slot 1311 can be obtained at the optimal time by simulating the matching and beamforming effects of the holographic antenna.

As for the second grounding plate 133, see Fig. 10, which is a schematic diagram of the specific structure of the second grounding plate 133 provided in another embodiment. It can be the lower grounding plate in the feeding network 13, and the second grounding plate 133 is not provided with a rectangular gap 1311 on the dielectric substrate, so it has a relatively complete ground.

As for the conductive tape layer 132, referring to FIG11, which is a schematic diagram of a specific structure of the conductive tape layer 132 provided in another embodiment, a long strip-shaped metal conductive tape 1321 (for example, copper) is arranged on the dielectric substrate, and the length of the metal conductive tape 1321 is the same as that of the dielectric substrate, which is 80.0 mm, and the width can be recorded as W2, which is 0.85 mm.

As an optional embodiment, the feed network 13 further includes at least one non-circuit layer; the at least one non-circuit layer is disposed between the first ground plane layer 131 and the guide tape layer 132 .

That is to say, in the feeding network 13, one or more dielectric substrates may be provided, on which no metal layer is provided, and which is a non-circuit layer, ie, has no circuit and does not participate in the signal processing process.

In addition, in order to facilitate data communication between the scattering unit 12 and the feeding network 13, as an optional embodiment, the above-mentioned scattering unit 12 and the feeding network 13 are electrically connected through a third metallized via 18. Among them, each dielectric substrate in the feeding network 13 can be provided with a number of third metallized vias 18 that are equal to the number of slot antennas 121 in the scattering unit 12 and correspond to each other, and the spacing is also equal, so as to better realize the stripline waveguide propagation mode and grounding effect through each third metallized via 18 and the slot antenna 121. The size of the third metallized via 18 can be set according to actual conditions, for example, it can be between 0.01-0.5mm, assuming it can be 0.2mm. In addition, in order to facilitate assembly, the second metallized via 17 A first circular groove 171 may be provided on the front side, and a second circular groove 172 may be provided on the back side. The size of the first circular groove 171 and the size of the second circular groove 172 may be set according to actual conditions.

In this embodiment, the feeding network 13 includes a first grounding plate layer 131, a guide strip layer 132, and a second grounding plate layer 133 which are stacked to form a stripline waveguide. This makes it easier to excite the slot antenna 121 through the stripline waveguide to achieve beam forming and grounding effects. In addition, the non-circuit layer included in the feeding network 13 can provide optionality for the subsequent expansion of the function of the holographic antenna and facilitate the subsequent improvement of the structure of the holographic antenna. Furthermore, the feeding network 13 can be electrically connected to the scattering unit 12 through the third metallized via 18, which can save wiring, further reduce the size of the holographic antenna, and realize a miniaturized holographic antenna.

Based on the above description of the components of the holographic antenna, the specific components of the holographic antenna are given below. As shown in Figure 12, the dielectric substrates of the 1*64 holographic antenna are PP1 from top to bottom, which is RO4450F, with a dielectric constant of 3.52, a dielectric loss of 0.004, and a substrate thickness of 4 mil. CORE1 is RO4360G2, with a dielectric constant of 6.4, a dielectric loss of 0.0038, and a substrate thickness of 60 mil. PP2, PP3, and PP4 are the same as PP1. CORE2 is RO4835, with a dielectric constant of 3.66, a dielectric loss of 0.0037, and a substrate thickness of 10 mil. CORE3 is RO4835, with a dielectric constant of 3.66, a dielectric loss of 0.0037, and a substrate thickness of 60 mil. The thickness of the entire substrate is 146 mil, or 3.7084 mm.

Among them, L1 is the control layer, L2 is the scattering unit, L3 is the first ground plane layer, L4 and L5 are non-circuit layers, L6 is the conduction layer, L7 is the second ground plane layer, and L8 is the choke branch layer. L1 and L2 and the dielectric substrate therein are connected through the first metallized via, L1-L8 and the dielectric substrate therein are connected through the second metallized via, and L2-L7 and the dielectric substrate therein are connected through the third metallized via. Among them, the size of the first metallized via can be R1=0.1mm (generally referring to the radius), the size of the second metallized via can be R2=0.15mm (generally referring to the radius), and the size of the third metallized via can be R3=0.2mm (generally referring to the radius). At the same time, Figure 13 shows the sizes of the parameters involved in each layer and the dielectric substrate.

It can be seen from the specific structure of the above holographic antenna that the holographic antenna is a stripline waveguide-excited slot antenna, and the radiation of the slot antenna is controlled by the holographic beam amplitude control theory and a PIN diode with a choke branch to achieve beam scanning.

In addition, the impedance bandwidth of the above 1*64 holographic array antenna is 25.5~26.5GHz (reflection coefficient is less than -10dB), and the relative bandwidth is 3.8%. When the stripline waveguide structure is used to excite the slot antenna loaded with the substrate RO4360G2TM with a high dielectric constant (6.4), the high dielectric constant can increase the reflectivity of the stripline waveguide, reduce the propagation speed of the TEM wave, weaken the frequency scanning characteristics of the holographic structure, and realize the broadband scanning characteristics, and the beam pointing can maintain good consistency at 25.5~26.5GHz. At the same time, the above holographic antenna can be applied to higher or lower frequency millimeter wave broadband scanning antenna needs by changing the size of the slot antenna.

The following gives the corresponding millimeter wave frequencies of 25.5GHz, 26GHz, and 26GHz when the 1*64 holographic antenna beam points to 0°. The 2D radiation pattern at 26.5GHz is shown in Figures 14, 15, and 16, respectively, where the horizontal axis is the beam angle, the vertical axis is the gain, and the solid line and the dotted line are the gain in the theta direction and the gain in the phi direction, respectively. When the antenna works at 25.5GHz, the gain is 9.2dBi, the 3dB beamwidth is 6°, the sidelobe suppression ratio is -9.7dB, and the beam pointing deviation is -2°. When the antenna works at 26GHz, the gain is 11.9dBi, the 3dB beamwidth is 6°, the sidelobe suppression ratio is -10.4dB, and the beam pointing deviation is 0°. When the antenna works at 26.5GHz, the gain is 11.4dBi, the 3dB beamwidth is 7°, the sidelobe suppression ratio is -11.6dB, and the beam pointing deviation is 4°. It can be seen from FIGS. 14-16 that within the wideband 1 GHz range, the holographic antenna according to the embodiment of the present application has a better beam pointing effect, and the beam pointing accuracy is ±4°, that is, the radiation performance of the holographic antenna is better.

The 3D radiation diagram of the holographic antenna when the millimeter wave frequency is 26 GHz is given below. As shown in FIG. 17 , it can be seen that the holographic antenna in this embodiment has the characteristics of high gain and narrow beam.

Based on the above holographic antenna structure, the following embodiment describes a method for preparing the holographic antenna.

In another embodiment, as shown in FIG. 18 , a method for preparing a holographic antenna is provided, and the method may include the following steps:

S102, pressing the scattering unit and the feeding network and the substrate therebetween to obtain a formed intermediate layer, and making a third metallized via hole passing through the intermediate layer.

S104, pressing the control layer, the choke branch layer and the middle layer together to obtain an initial holographic antenna.

S106, making a first metallized via hole passing through the control layer and the scattering unit of the initial holographic antenna, and making a second metallized via hole passing through the initial holographic antenna, to obtain a formed holographic antenna.

Specifically, when preparing a holographic antenna, the first step may be to first press the L2 to L7 layers (i.e., the scattering unit to the second ground plane layer), and use a mechanical drilling process to make a through hole of the L2 to L7 layers with a diameter of 0.4 mm, that is, to make a third metallized via. The second step may be to press the L1 layer (i.e., the control layer) and the L8 layer (i.e., the choke branch layer) with the formed L2 to L7 layers to form an L1 to L8 board substrate. The third step may be to make a laser blind hole of L1 to L2 with a diameter of 0.2 mm, that is, to make the first metallized via, and at the same time make a mechanical drilled through hole of the L1 to L8 layers with a diameter of 0.3 mm, that is, to make the second metallized via, and finally obtain a holographic antenna.

The size of the 1*64 holographic antenna obtained above is 80mm*8mm*3.71mm. It can be seen that the process of the holographic antenna is relatively simple and the size is small. It is easier to integrate with other circuits in the subsequent development, that is, it can reduce the difficulty of developing the entire integrated circuit including the holographic antenna.

In the above-mentioned method for preparing the holographic antenna, the holographic antenna is prepared through a pressing process and a drilling process, the process is relatively simple and the size is small, thereby reducing the difficulty of preparing the holographic antenna and improving the preparation efficiency of the holographic antenna.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims (18)

1. A holographic antenna, characterized in that the holographic antenna comprises a control layer, a scattering unit, a substrate and a feeding network which are stacked in sequence;

   The control layer is used to control the radiation of the scattering unit;

   The scattering unit is arranged between the control layer and the feeding network, and is used for radiating energy;

   The feeding network includes a stripline waveguide for generating and transmitting transverse electromagnetic waves;

   The substrate is arranged between the feeding network and the scattering unit, and is used to reduce the transmission speed of the transverse electromagnetic wave, and output the decelerated transverse electromagnetic wave to the scattering unit to stimulate the scattering unit to radiate energy.
2. The holographic antenna according to claim 1, characterized in that the control layer comprises a first dielectric substrate and a plurality of control units arranged on the first dielectric substrate, wherein the plurality of control units are arranged in two rows and correspond one to one;

   Each of the control units includes a PIN diode, and a switching state of the PIN diode corresponds to whether the scattering unit radiates energy.
3. The holographic antenna according to claim 2, characterized in that the scattering unit comprises a second dielectric substrate and a plurality of slot antennas arranged on the second dielectric substrate, wherein the plurality of slot antennas are arranged in two rows and correspond to each other one by one;

   The slot antennas in each row on the scattering units are electrically connected to the control units in each row on the control layer in a one-to-one correspondence.
4. The holographic antenna according to claim 3 is characterized in that the spacing between the slot antennas in the extension direction of the scattering unit is 1.13 mm.
5. The holographic antenna according to claim 3 is characterized in that the control unit and the corresponding slot antenna are electrically connected through a first metallized via.
6. The holographic antenna according to any one of claims 3 to 5, characterized in that the holographic antenna further comprises a choke branch layer;

   The choke branch layer and the feed network are stacked in sequence and electrically connected to the control layer, so as to block the AC signal passing through the control layer and pass the DC signal.
7. The holographic antenna according to claim 6, characterized in that the choke branch layer comprises a third dielectric substrate and a plurality of choke branches arranged on the third dielectric substrate, wherein the plurality of choke branches are arranged in two rows and correspond one to one;

   The choke branches in each row on the choke branch layer are paired with the control units in each row on the control layer. Should be electrically connected.
8. The holographic antenna according to claim 7 is characterized in that the choke branch is a fan-shaped branch, at the bottom of the fan-shaped branch is provided with at least one signal input and output port, at the top of the fan-shaped branch is provided with at least one L-shaped branch, and the L-shaped branch is used to increase the current path of the fan-shaped branch.
9. The holographic antenna according to claim 7 is characterized in that the size of the choke branch is 2.15mm*1.1mm.
10. The holographic antenna according to claim 7, characterized in that each of the control units and the corresponding choke branches are electrically connected through a second metallized via;

    The control line of the control layer is connected to the choke branch layer through the second metallized via.
11. The holographic antenna according to claim 10, characterized in that one side of each of the PIN diodes is the first metallized via hole, and the other side is the second metallized via hole.
12. The holographic antenna according to any one of claims 3 to 5, characterized in that the feeding network comprises a first ground plane layer, a guide strip layer and a second ground plane layer which are stacked in sequence;

    The first ground plate layer, the guide strip layer and the second ground plate layer constitute the stripline waveguide;

    The first ground plane layer is closer to the scattering unit than the second ground plane layer, the conduction band layer is arranged between the first ground plane layer and the second ground plane layer, and the second ground plane layer is farther from the scattering unit than the first ground plane layer.
13. The holographic antenna according to claim 12, characterized in that a plurality of rectangular slots are provided on the first ground plane layer, and the plurality of rectangular slots are arranged in two rows and correspond to each other one by one;

    The rectangular slots in each row on the first ground plane layer correspond one-to-one to the slot antennas in each row on the scattering unit, and are used to leak the decelerated transverse electromagnetic waves to the slot antennas.
14. The holographic antenna according to claim 12 is characterized in that the feeding network further comprises at least one wireless circuit layer; the at least one wireless circuit layer is arranged between the first ground plane layer and the guide strip layer.
15. The holographic antenna according to any one of claims 1 to 3, characterized in that the scattering unit and the feeding network are electrically connected through a third metallized via.
16. The holographic antenna according to claim 7 is characterized in that the substrate thickness of the first dielectric substrate is 4 mil; the substrate thickness of the second dielectric substrate is 60 mil; and the substrate thickness of the third dielectric substrate is 4 mil.
17. A communication device, characterized by comprising the holographic antenna according to any one of claims 1-16.
18. A method for preparing a holographic antenna, characterized in that it is applied to the holographic antenna according to any one of claims 1 to 16, and the method comprises:

    The scattering unit, the feeding network and the substrate therebetween are pressed together to obtain a formed intermediate layer, and a a third metallized via through the intermediate layer;

    Laminating the control layer, the choke branch layer and the intermediate layer to obtain an initial holographic antenna;

    A first metallized via hole is made through the control layer and the scattering unit of the initial holographic antenna, and a second metallized via hole is made through the initial holographic antenna to obtain a formed holographic antenna.