Reflective passive phased array element and design method, terahertz antenna and electronic device

Abstract

The present invention relates to the field of phased array technology, and discloses a reflective passive phased array element and a design method, a terahertz antenna, and an electronic device. The reflective passive phased array element includes: a metal ground layer, a substrate layer, and a radiation phase modulation layer stacked in sequence; the radiation phase modulation layer includes a radiation antenna for receiving an electromagnetic wave signal, an electrical tuning load that adds a reflection phase shift and reflection insertion loss to the electromagnetic wave signal and radiates the electromagnetic wave signal back into space; and a choke bias line for providing a bias voltage to the electrical tuning load. By providing a three-dimensional structure stacked in sequence, the present invention facilitates the miniaturization of the element, enables wafer-level on-chip integration in the terahertz frequency band, and has the advantage of being scalable to a large aperture; by adding a reflection phase shift and reflection insertion loss to the received electromagnetic wave signal through the radiation phase modulation layer and radiating the processed electromagnetic wave signal back into space, the passive phased array element can achieve an equal-amplitude single-bit phase modulation function.

Description

Technical Field

[0001] The present invention relates to the technical field of phased array, and in particular to a reflective passive phased array element and a design method thereof, a terahertz antenna and an electronic device. Background Art

[0002] The terahertz band is the basis for the next-generation high-speed communication technology and a series of new imaging applications. The terahertz band can provide high-capacity communication support for future communication applications, such as 6G communication, inter-satellite communication, etc. The terahertz band can also provide higher imaging resolution for terahertz imaging applications, such as terahertz penetration imaging, terahertz security inspection imaging, etc. The performance of these future communication and imaging applications, such as communication distance, tracking rate, imaging distance, imaging frame rate, and field of view, is related to the performance of the terahertz antenna.

[0003] In order to achieve high-quality communication and imaging in the terahertz band, a general terahertz antenna needs to have a large aperture and a fast beam switching rate. The design of a large-aperture antenna can make up for the deficiencies caused by large path attenuation in the high-frequency band. Currently, the terahertz band antennas mostly adopt a large-aperture dual-reflector antenna with a sub-reflector or a mechanically scanned large-aperture antenna. However, the maximum scanning angle or beam scanning rate of these antennas cannot meet the requirements of future applications.

[0004] Currently, the terahertz on-chip integrated active phased array element can overcome the disadvantages of traditional mechanically scanned terahertz antennas. However, the active phased array element in the terahertz band faces great difficulties in integrating a miniaturized solid-state terahertz source and in designing and integrating a feeding network, so it is difficult to integrate a large antenna aperture. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a reflective passive phased array element and a design method thereof, a terahertz antenna and an electronic device in view of the problems existing in the prior art.

[0006] To solve the above technical problem, an embodiment of the present invention provides a reflective passive phased array element for realizing on-chip integration in the terahertz band. The reflective passive phased array element includes: a metal ground layer, a substrate layer, and a radiation phase modulation layer stacked in sequence;

[0007] The radiation phase modulation layer includes a radiation antenna for receiving an electromagnetic wave signal emitted by a feeder of a passive phased array antenna, an electrical tuning load for adding a reflection phase shift and a reflection insertion loss to the electromagnetic wave signal and radiating the electromagnetic wave signal back into space, and a choke bias line for providing a bias voltage for the electrical tuning load and changing the impedance of the electrical tuning load by changing the bias voltage.

[0008] To solve the above technical problems, an embodiment of the present invention provides a design method for a reflective passive phased array element, including the following steps:

[0009] Determine the impedance Z of the solid-state tuning device of the electrically tunable load in the radiation phase modulation layer d parameters, including the parasitic series capacitance C p and the parasitic series resistance R s ;

[0010] Determine the matching inductance L according to the following formula s : L s = 1 / (2ω 2 C p ); Adjust the physical structure size of the inductor to obtain the required inductance Ls;

[0011] Determine the input impedance Z of the matching radiation antenna according to the following formula in :

[0012]

[0013] where ω = 2πf0, f0 is the specified operating frequency; Adjust the physical structure size of the receiving antenna to obtain the required input impedance Z in , and make the radiation antenna operate at the specified frequency f0.

[0014] To solve the above technical problems, an embodiment of the present invention also provides a terahertz antenna, including a plurality of reflective passive phased array elements described in the above technical solution. The reflective passive phased array elements are integrated on-chip in the terahertz frequency band, and the array elements are electrically connected through a choke bias line.

[0015] To solve the above technical problems, an embodiment of the present invention also provides an electronic device, including the terahertz antenna described in the above technical solution.

[0016] The beneficial effects of the present invention are as follows: The passive phased array element provided by the present invention, which supports high integration with a small period in the terahertz frequency band, is beneficial to the miniaturization of the array element by setting a three-dimensional structure of a metal ground layer, a substrate layer, and a radiation phase modulation layer stacked in sequence. It can be integrated on-chip at the wafer level in the terahertz frequency band and has the advantage of large-aperture expansion; The radiation phase modulation layer receives the electromagnetic wave signal emitted by the feed of the passive phased array antenna, and after adding a reflection phase shift and reflection insertion loss to the electromagnetic wave signal, radiates the electromagnetic wave signal back into space, enabling the passive phased array element to achieve an equal-amplitude single-bit phase modulation function.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the principle of the terahertz antenna provided by the embodiment of the present invention;

[0019] Figure 2 Side view of the passive phased array element structure provided by the embodiment of the present invention;

[0020] Figure 3 Top view of the structure of the passive phased array chip provided by the embodiment of the present invention;

[0021] Figure 4 Circuit diagram of the passive phased array element provided by the embodiment of the present invention;

[0022] Figure 5 Complex plane diagram of the solid-state electronic tuning device without loaded inductance elements in different states provided by the embodiment of the present invention;

[0023] Figure 6 Schematic diagram of the complex plane of the terahertz solid-state device with loaded inductance in different states provided by the embodiment of the present invention;

[0024] Figure 7 Structure diagram of the passive phased array element based on HEMT device provided by the embodiment of the present invention;

[0025] Figure 8 Phase simulation result of the electromagnetic wave reflected by the passive phased array element based on HEMT device provided by the embodiment of the present invention;

[0026] Figure 9 Amplitude simulation result of the electromagnetic wave reflected by the passive phased array element based on HEMT device provided by the embodiment of the present invention. Detailed implementation manners

[0027] The following specific examples illustrate the implementation manners of the present disclosure. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. The present disclosure can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts belong to the scope of protection of the present disclosure.

[0028] Note that the following description pertains to various aspects of embodiments within the scope of the appended claims. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of the aspects set forth herein can be used to implement a device and / or practice a method. Additionally, this device can be implemented and this method can be practiced using other structures and / or functionality in addition to one or more of the aspects set forth herein.

[0029] An embodiment of the present invention provides a terahertz antenna 100. As Figure 1 shown, the terahertz antenna 100 includes an integrated passive phased array chip 101 and a wave control component 103. The integrated passive phased array chip 101 includes two-dimensional expandable passive phased array elements 102. The wave control component 103 provides a DC bias 105 and a wave control code 104 for the integrated passive phased array chip 101. The passive phased array elements 102 in the integrated passive phased array chip 101 receive the incident electromagnetic wave 106 emitted by the passive phased array antenna feed source. After adding the reflection phase shift φ and reflection insertion loss IL generated by such passive phased array elements, an electromagnetic wave signal 107 is generated and radiated back into space, which enables the proposed passive phased array elements 102 to achieve a phase modulation function.

[0030] The radiation phase modulation layer of the passive phased array element 102 includes a radiation antenna 108, an electrically tunable load, and a choke bias line. The electrically tunable load includes an inductive element 109 and a solid-state electrically tunable device 110. One end of the inductive element 109 is directly connected to the antenna end 114 of the radiation antenna 108, and the other end is directly connected to the RF input end 115 of the solid-state electrically tunable device 110. The incident electromagnetic wave emitted by the passive phased array antenna feed source is received by the radiation antenna 108 of the passive phased array element and transmitted to the input port of the electrically tunable load composed of the inductor 109 and the solid-state electrically tunable device 110. After adding the reflection phase shift φ and reflection insertion loss IL generated by such an electrically tunable load, the electromagnetic wave signal is radiated back into space, which enables the proposed phased array element to achieve a phase modulation function.

[0031] The cut-off frequency f of the solid-state electrically tunable device T is greater than a first preset value (such as 0.5f0) or the resistance R per unit width of the solid-state electrically tunable device w and the capacitance C wThe product of is less than a second preset value (such as 1 / πf0) and the size of the solid-state electrically adjustable device is less than 1 / 10 of the free space wavelength. The electrically adjustable load is an electrically adjustable integrated three-port solid-state device, such as a HEMT device, a FET device, etc.; or an electrically adjustable integrated two-port solid-state device, such as a PIN diode, a Schottky diode, etc.

[0032] The passive phased array element 102 includes two mutually isolated choke bias lines. A choke bias line 111 is directly connected to the antenna terminal 114 of the solid-state electrical tuning device to provide a control voltage V m,n Another choke bias line 112 is directly connected to the DC control port 113 of the electrically adjustable load to provide a reference voltage V ref The change of bias voltage can change the impedance Z of the solid-state electronic device. d The impedance Z of the solid-state electronic device is determined by specifying the frequency f0. d and the radiating antenna input impedance Z in The relationship between can make the reflection phase shift φ switch between 0° and 180°, and the reflection insertion loss IL does not change, which enables the proposed phased array element to realize the single-bit electrically adjustable equal-amplitude phase shift function.

[0033] Figure 2 The structure side view of the passive phased array element 200 in the exemplary embodiment is illustrated, which includes three layers, from bottom to top, a metal layer 201, a substrate layer 202, and a radiation phase-modulation layer 203. The thickness of the semiconductor material of the substrate layer carrying the radiation phase-modulation layer is less than one tenth of the free space wavelength. The radiation phase-modulation layer is used to receive the electromagnetic wave signal emitted by the passive phased array antenna feed source, and after adding the reflection phase shift and reflection insertion loss to the electromagnetic wave signal, radiate the electromagnetic wave signal back into space.

[0034] By setting up a three-dimensional structure in which a metal stratum, a base layer, and a radiation phase-modulation layer are stacked in sequence, it is beneficial to miniaturize the array element and can be integrated on a large scale on a wafer, with the advantage of large-aperture scalability; the radiation phase-modulation layer receives the electromagnetic wave signal emitted by the passive phased array antenna feed source, and after adding the reflection phase shift and reflection insertion loss to the electromagnetic wave signal, the electromagnetic wave signal is radiated back into space, so that the passive phased array element can realize the phase modulation function.

[0035] Figure 3 FIG. 3 illustrates a top view of the structure of a passive phased array chip 300 in an exemplary embodiment. Passive phased array elements 302 are highly integrated in a two-dimensional plane 301 through electrical connections. The control voltage V m,n and reference voltage V ref They are led out through the connecting choke bias line 303 and the connecting choke bias line 304 respectively.

[0036] Figure 4The circuit diagram of a passive phased array element in an exemplary embodiment is illustrated. The incident electromagnetic wave signal is coupled to port 403 of a hybrid adjustable load Z that includes a solid-state electrical adjustment device and an inductor. Therefore, the reflected electromagnetic wave signal is appended with an additional phase φ and an additional phase shift insertion loss ILp. Considering that the insertion loss ILa introduced by the radiating antenna has a small value, the total phase shift θ and insertion loss ILe of the passive phased array element are mainly determined by the reflection coefficient Γ at this port. Considering that the reflection coefficient Γ = (Z L - Z L ) / (Z in + Z L ), the reflection characteristics of the antenna element are mainly jointly determined by the input impedance Z in of the radiating antenna and the adjustable load Z in .

[0037] The solid-state electrical adjustment device includes a circuit model 400 in two different states. In the first state, the device model 401 is equivalent to a resistor R1, and the load impedance Z L = R1 at this time. In another state, the device model 402 can be equivalent to a resistor R2 in series with a parasitic capacitor C d , and the load impedance Z p = R2 + 1 / (jωC d ) at this time. Among them, ω is defined as 2πf0, and f0 is the specified operating frequency. Since the adjustable resistance in the terahertz band has little effect, the resistance values in the two states can be considered as the parasitic series resistance R p , that is, R1≈R2 = R s . The time for the solid-state electrical adjustment device to complete one state switch is less than 5 μs.

[0038] By cooperating with the impedance Z s of the solid-state electrical adjustment device, the physical dimensions of the specially designed radiating antenna and the inductor element can be changed to change the inductance Ls of the inductor element and the value of the input impedance Z d of the radiating antenna, and it is possible to achieve a reflected electromagnetic wave with an equal amplitude (within ±0.5 dB) and an accurate 180° (±20°) phase adjustment of the phased array element in two different states.

[0039] Figure 5 Illustrates the complex plane design method in different states of a solid-state electrical adjustment device without an inductor in an exemplary embodiment. When no inductor is loaded, there is an adjustable load Z in in the complex plane. Two Z L points are located on the positive semi-axis of the real axis and the fourth quadrant of the complex plane. To achieve a 180° phase adjustment, the connection of the impedance -Z L and Z in needs to pass through two adjustable Z in ​L The connection between them means that the antenna impedance has an imaginary part. The radiating antenna cannot operate in a resonant state, and the matching effect of the radiating antenna is poor.

[0040] Figure 6 Illustrates the complex plane design method in different states of a solid-state electronically tunable device with a loaded inductor in an exemplary embodiment. When a inductor is loaded, a single solid-state electronically tunable device and the inductor element have an adjustable load Z on the complex plane L . Two Z L points are located in the first and fourth quadrants of the complex plane. To achieve a 180° phase shift, the connection of impedance -Z in and Z in needs to pass through the connection line between two Z L . Different from not loading the inductor element, at this time, the connection of impedance -Z in and Z in can pass through the real axis, and the radiating antenna operates in a resonant state at this time, and the matching effect of the radiating antenna is better.

[0041] The inductance L of the inductor element s is designed according to formula (1):

[0042] L s = 1 / (2ω 2 C p ) (1)

[0043] where ω is defined as 2πf0, f0 is the specified operating frequency, and C p is the parasitic series capacitance. By adjusting the structural dimensions of the inductor element, the required value of the inductance Ls can be achieved. Thus, for the passive phased array element in two different states, the insertion loss is consistent, and a precise equal-amplitude (±0.5 dB) reflected electromagnetic wave is achieved.

[0044] The input impedance Z of the radiating antenna in is designed according to formula (2):

[0045]

[0046] At this time, by coordinating with the impedance value Z of the solid-state electronically tunable device d , and through special design of the size of the radiating antenna to adjust the value of the input impedance Z of the radiating antenna in , a precise 180° (±20°) phase-shifted reflected electromagnetic wave can be achieved for the passive phased array element in two different states.

[0047] Figure 7Illustrated is a structural diagram of a passive phased array element 700 based on HEMT devices in an exemplary embodiment, including a radiation phase modulation layer 704, a substrate layer 705, and a metal substrate layer 706. The radiation phase modulation layer 704 includes a radiation antenna 701, an inductive element 702, and a solid-state electrically tunable device 703 based on HEMT devices. The solid-state electrically tunable device 703 may desirably include an electrically tunable integrated three-port solid-state device, such as a FET device, etc.; or an electrically tunable integrated two-port solid-state device, such as a PIN diode, a Schottky diode, etc. Therefore, regarding Figure 7 the specific illustrative diagram of the solid-state electrically tunable device 703 based on HEMT devices therein is only for the purpose of discussion.

[0048] The DC voltage bias lines include: a drain reference voltage bias line 707, a gate reference voltage bias line 708, and a source control voltage bias line 709. Therefore, regarding Figure 7 the specific illustrative diagram of the solid-state electrically tunable device 707 based on HEMT devices therein is only for the purpose of discussion. The DC bias lines of the solid-state electrically tunable device may desirably include straight lines, or serpentine bias lines. Therefore, regarding Figure 7 the specific illustrative diagram of the straight-line-based bias lines therein is only for the purpose of discussion.

[0049] The substrate layer 705 of the passive phased array element based on HEMT devices is GaN material epitaxially grown on a sapphire substrate. The passive phased array element adopts a 0.7-μm GaN HEMT process, and the model of the GaN HEMT based on this is R s = 60 Ω, C p = 15 fF. The passive phased array element may desirably adopt a smaller process. Therefore, regarding Figure 7 the process based on HEMT devices therein is only for the purpose of discussion.

[0050] The solid-state electrically tunable device 703 based on HEMT devices has two switching states. When the bias voltage is 0 V, the two-dimensional electron gas in the active region is turned on, so the device is equivalent to a parasitic resistance R s and a resistance R on . When the applied voltage exceeds the threshold voltage V T , the two-dimensional electron gas in the active region is depleted and presents a cut-off state, so the HEMT device is equivalent to a series circuit of a series resistance R s and a cut-off capacitor C off . Because the gate length of the HEMT device in the THz frequency band is relatively small, the influence of the on-resistance R on can be ignored.

[0051] Figure 8Illustrates the phase simulation results of the electromagnetic wave reflected by the passive phased array element based on HEMT devices in the exemplary embodiments. The results of the simulated reflection coefficient (S11) are shown in the figure, and a phase shift of 169° is generated at 213 GHz.

[0052] Figure 9 Illustrates the amplitude simulation results of the electromagnetic wave reflected by the passive phased array element based on HEMT devices in the exemplary embodiments. The results of the simulated reflection coefficient (S11) achieve an insertion loss of -14.6 dB at 213 GHz. The antenna loss ILa can be regarded as -0.6 dB.

[0053] An embodiment of the present invention also provides a design method for a passive phased array element, including the following steps:

[0054] Determine the impedance Z of the solid-state electronically tunable device of the electronically tunable load in the radiation phase modulation layer d parameters, including the parasitic series capacitance C p and the parasitic series resistance R s ;

[0055] Determine the matching inductance Ls according to the following formula: Ls = 1 / (2ω 2 C p ); Adjust the physical structure size of the inductance to obtain the required inductance Ls;

[0056] Determine the input impedance Z of the matching radiation antenna according to the following formula in : where ω = 2πf0, and f0 is the specified operating frequency; Adjust the physical structure size of the receiving antenna to obtain the required input impedance Z in , and make the radiation antenna operate at the specified frequency f0.

[0057] In the above embodiments, the array element design with loaded inductance can improve the matching of the antenna. Compared with the array element design without loaded inductance, it is easier to achieve the single-bit phase modulation effect; Compared with the design method of adjusting the resonance frequency to achieve single-bit phase modulation, this design method can achieve the effect of equal amplitude of the reflection coefficient in two states.

[0058] An embodiment of the present invention also provides an electronic device, including the terahertz antenna provided in the above embodiment.

[0059] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A reflective passive phased array element, characterized in that The reflective passive phased array element is used to achieve on-chip integration in the terahertz band, and the reflective passive phased array element includes: a metal ground layer, a substrate layer, and a radiation phase modulation layer stacked in sequence; The radiation phase modulation layer includes a radiation antenna for receiving an electromagnetic wave signal emitted by a feed of a passive phased array antenna, an electrical tuning load for adding a reflection phase shift and a reflection insertion loss to the electromagnetic wave signal and radiating the electromagnetic wave signal back into space, and a choke bias line for providing a bias voltage to the electrical tuning load and changing the impedance of the electrical tuning load by changing the bias voltage; The electrical tuning load includes an inductive element and a solid-state electrical tuning device; one end of the inductive element is connected to the radio frequency input end of the radiation antenna, and the other end is connected to the input end of the solid-state electrical tuning device; The choke bias line includes a control voltage choke bias line and a reference voltage choke bias line; the control voltage choke bias line is connected to the non-DC control end of the solid-state electrical tuning device for providing a control voltage; the reference voltage choke bias line is connected to the DC control end of the solid-state electrical tuning device for providing a reference voltage.

2. The reflective passive phased array element according to claim 1, characterized in that, The cut-off frequency f of the solid-state electrically tunable device T is greater than a first preset value, or the resistance R per unit width of the solid-state electrically tunable device w and the capacitance C w has a product less than a second preset value; and the size of the solid-state electrically tunable device is less than 1 / 10 of the free space wavelength.

3. The reflective passive phased array element according to claim 1, wherein The impedance Z of the solid-state electronic tuning device d is as follows: When the bias voltage provided by the choke bias line is zero, the solid-state electrically tunable device is equivalent to a resistor R1, and the impedance Z d = R1; When the bias voltage provided by the choke bias line exceeds the threshold voltage, the solid-state electrically tunable device is equivalent to a resistor R2 and a parasitic series capacitor C p , the impedance Z d = 1 / (jωC p ); + R2 where ω = 2πf0, and f0 is the specified operating frequency; R1 ≈ R2 = R s , R s is the parasitic series resistance of the solid-state electronic tuner device, and C p is the parasitic series capacitance of the solid-state electronic tuner device.

4. The reflective passive phased array element according to claim 1, wherein The inductance L of the inductive element s is: L s = 1 / (2ω 2 C p ), where ω = 2πf0, f0 is the specified operating frequency, and C p is the parasitic series capacitance of the solid-state electronically tunable device.

5. The reflective passive phased array element according to claim 1, characterized in that The input impedance Z of the radiating antenna in is as follows: where R s is the parasitic series resistance of the solid-state electronically tunable device, ω = 2πf0, f0 is the specified operating frequency, and C p is the parasitic series capacitance of the solid-state electronically tunable device.

6. The reflective passive phased array element according to any one of claims 1 to 5, characterized in that, The substrate layer carrying the radiation phase modulation layer has a thickness less than one-tenth of the free space wavelength.

7. A design method for a reflective passive phased array element according to any one of claims 1 to 6, characterized in that, Including the following steps: Determine the impedance Z of the solid-state electronically tunable device of the electronically tunable load in the radiation phase modulation layer d parameters, including the parasitic series capacitance C p and the parasitic series resistance R s ; Determine the matching inductance L according to the following formula s : L s = 1 / (2ω 2 C p ); Adjust the physical structure size of the inductance to obtain the required inductance L s ; Determine the input impedance Z of the matching radiating antenna according to the following formula in : where ω = 2πf0, and f0 is the specified operating frequency; adjust the physical structure size of the receiving antenna to obtain the required input impedance Z in , and make the radiating antenna operate at the specified frequency f0.

8. A terahertz antenna, characterized in that, Including a plurality of reflective passive phased array elements as described in any one of claims 1 to 6, the reflective passive phased array elements achieve on-chip integration in the terahertz band, and the elements are electrically connected through choke bias lines.

9. An electronic device, characterized in that, Including the terahertz antenna as claimed in claim 8.

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