Terahertz programmable metasurface unit of RF MEMS switch

Abstract

The invention discloses a terahertz programmable metasurface unit of an RF MEMS switch, and belongs to the technical field of communication. A positive electrode control line; covering the ground on the back; a first substrate; a direct current grounding pole; mounting a patch; a signal line; an RF MEMS switch; and a DC bias line structure. On and off of the switch are controlled through change of direct-current voltage, the 180-degree reflection phase difference of the metasurface unit is achieved, and the technical effects that (1) the 180-degree reflection phase difference working bandwidth is large and ranges from 285GHz to 320GHz, and the reflection phase difference ranges from 172 degrees to 193 degrees; (2) the reflection phase is high in linearity, the reflection phase ranges from 117 degrees to 52 degrees when the switch is in a down state and the reflection phase ranges from-53 degrees to-129 degrees when the switch is in an up state at 285GHz to 320GHz; (3) the processing technology requirement is low, the second layer of anchor points and the lower electrode of the switch are respectively connected by adopting bias lines, and the electrode punching number is reduced; and (4) the bias line part is made of metal, so that the partial voltage of the bias line is reduced, and the driving voltage is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a terahertz programmable metasurface unit of an RF MEMS switch. Background Art

[0002] The frequency range of terahertz waves is 0.1THz to 10THz. It has the characteristics of high frequency, wide bandwidth, strong transmission ability, and rich information. It has broad application prospects in broadband communications, radar detection, imaging and other fields. However, its disadvantage is the large space path loss. To solve this problem, phased array technology can be used to improve antenna gain and beam scanning methods. Compared with T / R components, metasurfaces have advantages in cost, power consumption and weight in regulating the phase of electromagnetic waves.

[0003] Metasurface refers to an artificial structure that can flexibly control electromagnetic waves by periodically or non-periodically arranging sub-wavelength-scale structural units. Metasurface units can be designed independently, so that each unit can independently control the amplitude and phase of the electromagnetic wave, thereby obtaining a more complex field distribution result. Based on this phase or amplitude discontinuity, programmable metasurfaces can discretize units into finite types and describe them with digital codes. For example, if the reflection phases of two units differ by 180°, but the amplitudes are similar, two codes of "0" and "1" can be obtained. Metasurface arrays are mainly aimed at the fields of 5g and 6g wireless communications. They can be spliced, installed and deployed in hot traffic areas such as venues and shopping malls, and cooperate with existing base stations to achieve coverage blind spots. For programmable metasurfaces, the use of PIN diode phase modulation has the advantages of convenient control and easy integration, but it has the disadvantages of high insertion loss, low isolation, low linearity, small 180° phase difference bandwidth, and difficulty in independent control of a single unit;

[0004] Electrostatically driven RF-MEMS switches use the electrostatic force of the upper and lower plates to achieve the breaking function. Compared with other solid-state devices (pin diodes, MOSFET switches, HEMT switches), RF MEMS switches have the advantages of low insertion loss, high isolation, low power consumption, high linearity and high integration, but there are reliability issues. For electrostatically driven switches, adhesion, wear, dielectric damage, fatigue damage and warping deformation will occur due to temperature, load, vibration and charging. Summary of the invention

[0005] In view of the above-mentioned shortcomings, the present invention discloses a terahertz programmable metasurface unit of an RF MEMS switch.

[0006] These include:

[0007] The second substrate 16 has a square cross section and a side length of a sub-wavelength scale;

[0008] A positive control line 18 is formed on the lower surface of the second substrate 16 and is used to power the RF MEMS switch;

[0009] A back ground 15 is formed on the upper surface of the second substrate 16 and functions as a ground electrode and reflects electromagnetic waves;

[0010] A first substrate 14 is formed on the upper surface of the back cover 15;

[0011] A DC grounding column 12 passes through the first substrate 14, has a length equal to the thickness of the first substrate 14, and has an axis located on the symmetry axis of the first substrate, and is used to connect the lower electrode 6 of the RF MEMS switch and the back ground 15;

[0012] A DC positive pole 13, whose length is the sum of the thickness of the first substrate 14, the back cover 15, and the second substrate 16, and passes through the three, and whose axis is located on the symmetry axis of the first substrate, and is used to connect the second layer anchor point 5 of the RF MEMS switch and the positive control line 18;

[0013] The upper patch 7 is formed on the upper surface of the first substrate 14 and is symmetrically distributed on both sides of the DC positive pole 13 for scattering terahertz waves;

[0014] The signal line 8 is formed on the upper surface of the first substrate 14, symmetrically distributed on both sides of the DC positive pole 13, and connected to the upper patch 7, for connecting the upper patch 7;

[0015] RF MEMS switch 6, 5, 4, 3, 2, 17, 1, formed on the first substrate 14, located in the middle of the upper patch 7, across the signal line 8, used to connect or disconnect the signal line 8 to achieve a 180° reflection phase difference of the scattered electromagnetic wave;

[0016] The DC bias line structures 11, 10, 9 are formed on the upper surface of the first substrate 14 and are used to provide a DC voltage to the RF MEMS switch.

[0017] In some embodiments of the present invention, the back cover 15 has a circular hole to prevent it from being short-circuited with the DC positive pole 13 .

[0018] In some embodiments of the present invention, the RF MEMS switch includes a lower electrode 6, a second layer anchor point 5, an electrode dielectric layer 4, a first layer anchor point 3, an upper metal electrode 2, a signal bridge 17, and a skirt beam 1;

[0019] The lower electrode 6 is formed on the first substrate 14 and is located on both sides of the signal line 8. The side length of the lower electrode 6 is greater than the diameter of the DC grounding column 12 and serves as the negative electrode of the switch.

[0020] The second layer anchor point 5 is formed on the first substrate 14 and is located on both sides of the signal line 8. Its side length is equal to the diameter of the DC positive pole 13, its thickness is the same as the lower electrode 6, the upper patch 7, and the signal line 8, and its length is greater than the first layer anchor point 3, serving as the negative pole of the switch;

[0021] The electrode dielectric layer 4 is formed on the lower electrode 6, distributed on both sides of the signal line 8, and has an area larger than the lower electrode 6, and is used to isolate the lower electrode 6 from the upper metal electrode 2;

[0022] The first layer anchor points 3 are formed on the second layer anchor points 5 and are distributed on both sides of the signal line 8. The side close to the signal line 8 adopts a rounded transition to fix the upper metal electrode and form a switch gap.

[0023] The upper metal electrode 2 is located above the electrode dielectric layer 4, distributed on both sides of the signal line 8, and fixed at both ends on the first layer anchor point 3, serving as the upper switch electrode. After the driving voltage is applied, the signal bridge 17 is driven downward. The beam structure is a quadratic curve, and the beam junction is an arc transition. The width is smaller than the middle gap of the upper patch, and there is a release hole on it for sacrificial layer release and reducing downward pressure damping;

[0024] The signal bridge 17 is located directly above the signal line 8 and at the same level as the upper metal electrode 2, and is used to connect or disconnect the signal line 8. There are two circular contacts below to increase the switch clamping force;

[0025] The skirt beam 1 is formed on the upper metal electrode 2 and covers the upper metal electrode 2 and the signal bridge 17. Its function is to provide switch restoring force, avoid switch warping and deformation caused by uneven stress distribution, improve switch fatigue life, and separate the upper metal electrode 2 and the signal bridge 17 to isolate the influence of direct current on the radio frequency signal. There are release holes on it for sacrificial layer release and reducing downward pressure damping.

[0026] In some embodiments of the present invention, the DC bias line structure includes a non-metal bias line 11, an upper electrode metal bias line 10, and a lower electrode metal bias line 9;

[0027] The non-metal bias line 11 is formed on the first substrate 14 and symmetrically distributed on both sides of the DC grounding column 12, and is used to connect the second layer anchor point 5 and the lower electrode 6;

[0028] The upper electrode metal bias line 10 is symmetrically distributed on both sides of the signal line 8, connected to the non-metal bias line 11 and the second layer anchor point 5, and should be as far away from the upper patch 7 as possible to reduce the impact on the displacement current, and serves to connect the second layer anchor point 5 and reduce the voltage division caused by the resistance of the DC bias line;

[0029] The lower electrode metal bias line 9 is symmetrically distributed on both sides of the signal line 8, connected to the non-metal bias line 11 and the lower electrode 6, and should be as far away from the upper patch 7 as possible to reduce the impact on the displacement current. Its function is to connect the lower electrode 6 and reduce the voltage division caused by the resistance of the DC bias line.

[0030] The technical effects achieved by the present invention are as follows:

[0031] 1. The 180° reflection phase difference has a wide working bandwidth, from 285 GHz to 320 GHz, the reflection phase difference ranges from 172° to 193°;

[0032] 2. High linearity of reflection phase. From 285 GHz to 320 GHz, the reflection phase ranges from 117° to 52° in the switch down state and from -53° to -129° in the switch up state.

[0033] 3. RF MEMS switches have high mechanical reliability. They use a skirt beam structure. After the switch is pulled down and deformed, the stress is evenly distributed, reducing the warping deformation of the switch. The beams are connected by arcs, without stress concentration. The arc connection increases the length of the connection, reduces the risk of fracture caused by switching cycles, and improves the fatigue life of the switch.

[0034] 4. The processing technology requirements are low. The second layer anchor point and the lower electrode of the switch are connected by bias lines, which reduces the number of electrode holes, reduces manufacturing costs, and improves manufacturing efficiency.

[0035] 5. Use metal in the bias line to reduce the voltage division of the bias line and lower the driving voltage.

[0036] Additional advantages, purposes, and features of the present invention will be described in part in the following description, and will become apparent to those skilled in the art after studying the following, or may be learned from the practice of the present invention. The purposes and other advantages of the present invention may be achieved and obtained by the structures specifically indicated in the specification and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the serial number and size of the cross section of a terahertz programmable metasurface unit of an RF MEMS switch;

[0038] Figure 2 It is an exploded diagram of the terahertz programmable metasurface unit number of an RF MEMS switch;

[0039] Figure 3 This is a three-dimensional model diagram of a terahertz programmable metasurface unit of an RF MEMS switch;

[0040] Figure 4The key dimensions and top view of a terahertz programmable metasurface unit of an RF MEMS switch;

[0041] Figure 5 It is a schematic diagram of strain simulation of an RF MEMS switch;

[0042] Figure 6 It is a simulation diagram of the driving voltage and unstable position of an RF MEMS switch;

[0043] Figure 7 This is a stress fatigue life simulation diagram of an RF MEMS switch with a skirt structure;

[0044] Figure 8 This is a stress fatigue life simulation diagram of a RF MEMS switch without skirt structure;

[0045] Fig. 9 This is a simulation diagram of the reflection phase difference of a terahertz programmable metasurface unit of an RF MEMS switch;

[0046] Fig.10 This is a simulation diagram of the terahertz programmable metasurface unit S11 of an RF MEMS switch;

[0047] Fig.11 It is a 1x16 linear array 3D pattern encoded by the terahertz programmable metasurface unit “0011” of an RF MEMS switch;

[0048] Fig.12 It is a 1x16 linear array two-dimensional directional pattern of the terahertz programmable metasurface unit "0011" encoding of an RF MEMS switch.

[0049] Markings in the figure: 1- skirt beam, 2- upper metal electrode, 3- first layer anchor point, 4- electrode dielectric layer, 5- second layer anchor point, 6- lower electrode, 7- upper patch, 8- signal line, 9- lower electrode metal bias line, 10- upper electrode metal bias line, 11- non-metallic bias line, 12- DC grounding column, 13- DC positive column, 14- first substrate, 15- back ground, 16- second substrate, 17- signal bridge, 18- positive control line. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0051] Aiming at the problems of high insertion loss, low isolation, low linearity, small 180° phase difference bandwidth, and difficulty in independent control of a single unit in the PIN diode of the programmable metasurface unit in the prior art, and the problems of stress concentration, fatigue damage, and warping deformation of the RF MEMS switch, the present invention provides a terahertz programmable metasurface unit of an RF MEMS switch, the principle of which is that when a DC voltage is not applied to the back ground 15 and the positive control line 18, the switch is in an up state, and when a DC voltage is applied, due to the electrostatic force between the upper metal electrode 2 and the lower electrode 6, the upper metal electrode 2 drives the signal bridge 17 to press down, and when the RF MEMS switch voltage reaches the driving voltage, the signal bridge 17 and the signal line 8 are in contact and turned on, and the switch is in a down state at this time, and by opening the switch, the electromagnetic wave reflection phase difference between the up state and the down state will differ by 180°, thereby realizing the "1bit" programmable function of the metasurface unit; a structure of a patch, a signal line, and a signal bridge on the unit is designed, so that the unit has a large working bandwidth and a high linearity of the reflection phase at a 180° reflection phase difference; an RF The MEMS switch skirt beam structure ensures uniform stress distribution after the switch is pulled down and deformed, reduces warping and deformation of the switch, and improves fatigue life; a RF MEMS switch composite beam structure is designed to separate the electrode and the signal bridge, reducing the interference of DC power on the RF signal; a unit bias line structure is designed to reduce the number of electrode holes, and each switch can be controlled individually; a unit metal and non-metal combined bias line is designed to reduce the bias line voltage divider.

[0052] Isolation is defined as the ratio of the power of the RF signal leaking to other ports to the input power, and the unit can be decibel (dB); isolation is an indicator to measure the quality of the switch. When the switch is qualified, the isolation between the ports is good and the signal leakage is minimal.

[0053] Insertion loss is the loss of load power caused by inserting components or devices in the transmission system. It is expressed as the ratio of input power to the power delivered to the load and can be expressed in decibels (dB).

[0054] The reflection phase refers to the phase of the electromagnetic wave reflected by the unit at a distance of 1 micron from the unit surface.

[0055] The reflection phase difference refers to the unit reflection phase when the RF MEMS switch is in the up state minus the unit reflection phase when the RF MEMS switch is in the down state.

[0056] Terahertz refers to electromagnetic waves with frequencies in the range of 0.1-10 THz.

[0057] Stress refers to the internal force generated by the interaction between the various parts per unit area of ​​an object when it is deformed due to external factors such as force and temperature.

[0058] Stress concentration refers to the phenomenon of localized increase in stress in an object, which generally occurs where the shape of the object changes dramatically.

[0059] Fatigue life refers to the number of stress cycles a material experiences before fatigue failure.

[0060] The driving voltage refers to the minimum operating voltage of the switch from the up state to the down state. The switch is generally unstable at one-third of the pull-down gap, and the pull-down voltage at this time is the driving voltage.

[0061] Basquin's law is usually expressed as σa=σ′(2N) b , can be used to describe high cycle fatigue, where σa represents fatigue strength, σ′ represents fatigue strength coefficient, N represents fatigue life (number of cycles), and b represents fatigue strength index.

[0062] Figure 1 This is a schematic diagram of the serial number and size of the cross-section of a terahertz programmable metasurface unit of an RF MEMS switch. Figure 2 This is an exploded diagram of the terahertz programmable metasurface unit of an RF MEMS switch. Figure 3 This is a 3D model diagram of a terahertz programmable metasurface unit of an RF MEMS switch. Figure 4 Key dimensions and top view of a terahertz programmable metasurface unit of an RF MEMS switch. Figure 5 It is a schematic diagram of strain simulation of RF MEMS switch. Figure 1 and Figure 4 The key dimensions of the structure are shown in Table 1.

[0063] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, a terahertz programmable metasurface unit of an RF MEMS switch provided by the present invention comprises:

[0064] The second substrate 16 has a square cross section and a side length of a sub-wavelength scale. The material is quartz glass with a relative dielectric constant of 3.78 and a dielectric loss tangent of 0.0008. The material has the advantages of low cost and mature technology.

[0065] A positive control line 18 is formed under the second substrate 16 and is used for powering the RF MEMS switch. The material is Au and the thickness is 0.5 um.

[0066] The back cover 15 is formed on the second substrate 16, and functions as a grounding electrode and reflects electromagnetic waves. The material is Au, the thickness is 1um, and it is formed by bonding two layers of 0.5um Au-Au. There is a circular hole with a diameter of 80um, so that the DC positive pole 13 passes through to prevent short circuit;

[0067] The first substrate 14 is combined with the second substrate by Au-Au bonding through the 0.5um back cover 15 thereunder. The material is quartz glass with a relative dielectric constant of 3.78 and a dielectric loss tangent of 0.0008;

[0068] The DC grounding column 12 passes through the first substrate 14, and the cylindrical axis is located on the symmetry axis of the first substrate 14, connecting the lower electrode 6 of the RF MEMS switch and the back ground 15. The material is Au, and the diameter is 50um. Since the drilling diameter has a 5um error, the DC grounding column 12 should be as far away from the signal line 8 as possible to prevent it from affecting the RF signal;

[0069] The DC positive pole 13, the cylindrical axis is located at the center of the second-layer anchor point, the material is Au, the diameter is 50um, and the second-layer anchor point 5 of the RF MEMS switch is connected to the positive control line 18. Since the distance between the nearest centers of adjacent holes is 120±10um, the DC positive pole 13 and the DC ground pole 12 can only be designed on both sides of the signal line 8;

[0070] The upper patch 7 is formed on the first substrate 14 and symmetrically distributed on both sides of the DC positive pole 13, and is used to scatter terahertz waves. It is located on the same layer as the signal line 8, the lower electrode 6, the second layer anchor point 5, the lower electrode metal bias line 9, and the upper electrode metal bias line 10. The material is Au, and the thickness is 0.5um;

[0071] The signal line 8 is formed on the first substrate 14, symmetrically distributed on both sides of the DC positive pole 13, and connected to the upper patch 7, and is used to connect the upper patch 7. The width of the signal line 8 is 15um, which is larger than the width of the signal bridge to prevent poor contact caused by processing errors, and the spacing is 30um;

[0072] An RF MEMS switch is formed on the first substrate 14, located in the middle of the upper patch 7, and spans the signal line 8, and is used to connect or disconnect the signal line 8 to achieve a 180° reflection phase difference of the scattered electromagnetic wave. The switch includes a lower electrode 6, a second layer anchor point 5, an electrode dielectric layer 4, a first layer anchor point 3, an upper metal electrode 2, a signal bridge 17, and a skirt beam 1;

[0073] The second layer anchor point 5 is formed on the first substrate 14 and is located on both sides of the signal line 8. The boundary is tangent to the DC positive pole 13 and serves as the negative pole of the switch. The material is Au and the thickness is 0.5um. Since the MEMS processing technology first makes the 1um first layer anchor point 3 and then makes the second layer anchor point 5, the length of the second layer anchor point 5 is a10=50um, which is greater than the length of the first layer anchor point 3 a11=40um, and covers the first layer anchor point 3, so that the contact is good;

[0074] The electrode dielectric layer 4 is formed on the lower electrode 6 and distributed on both sides of the signal line 8. The material is Si3N4, and the relative dielectric constant is 7.6. The function is to form a capacitor structure with the lower electrode and the upper metal electrode to isolate the direct current short circuit. The shape is rectangular and the size is larger than the lower electrode to avoid the lower electrode and the upper metal electrode from directly contacting and short-circuiting.

[0075] The first layer anchor point 3 is formed on the second layer anchor point 5, distributed on both sides of the signal line 8, and a rounded transition is used on the side close to the signal line 8, which is used to fix the upper metal electrode and form a switch gap. The material is Au and the thickness is 1um; the upper metal electrode 2 is located above the electrode dielectric layer 4, distributed on both sides of the signal line 8, and the two ends are fixed on the first layer anchor point 3. It serves as the upper switch electrode. After the driving voltage is applied, the signal bridge 17 is driven downward. Its beam structure is a quadratic curve, and the beam junction is an arc transition. Its width is smaller than the middle gap of the upper patch. There is a release hole on it, which is used for sacrificial layer release and reducing downward pressure damping. The material is Au and the thickness is 0.5um;

[0076] The signal bridge 17 is located directly above the signal line 8 and at the same level as the upper metal electrode 2. It is used to connect or disconnect the signal line 8. The material is Au, the thickness is 0.5um, the width is 10um, and there are two circular contacts at the bottom to increase the clamping force of the switch. The contact area between the signal bridge 17 and the signal line 8 is 10umx10um. The contact area has a great influence on the radio frequency performance. The simulation shows that the smaller the contact area, the smaller the insertion loss of high-frequency electromagnetic waves and the higher the isolation.

[0077] The skirt beam 1 is formed on the upper metal electrode 2 and covers the upper metal electrode 2 and the signal bridge 17. Its function is to provide switch restoring force, avoid switch warping and deformation caused by uneven stress distribution, and improve switch fatigue life. It also separates the upper metal electrode 2 and the signal bridge 17 to isolate the influence of direct current on the radio frequency signal. There is a release hole on it for sacrificial layer release and reducing downward pressure damping. The material is SiO2 and the thickness is 1um.

[0078] A DC bias line is formed on the first substrate 14 and is used to provide a DC voltage to the RF MEMS switch, including a non-metallic bias line 11, an upper electrode metal bias line 10, and a lower electrode metal bias line 9; the non-metallic bias line 11 is formed on the first substrate 14, symmetrically distributed on both sides of the DC grounding column 12, and is used to connect the second layer anchor point 5 and the lower electrode 6; the upper electrode metal bias line 10 is symmetrically distributed on both sides of the signal line 8, connected to the non-metallic bias line 11 and the second layer anchor point 5, and should be as far away from the upper patch 7 as possible to reduce the impact on the displacement current, and functions to connect the second layer anchor point 5 and reduce the voltage division caused by the resistance of the DC bias line; the lower electrode metal bias line 9 is symmetrically distributed on both sides of the signal line 8, connected to the non-metallic bias line 11 and the lower electrode 6, and should be as far away from the upper patch 7 as possible to reduce the impact on the displacement current, and functions to connect the lower electrode 6 and reduce the voltage division caused by the resistance of the DC bias line.

[0079] Figure 6 This is a simulation diagram of the driving voltage and unstable position of an RF MEMS switch. The horizontal axis represents the displacement of the center point of the signal bridge, and the vertical axis represents the driving voltage required for the center point of the signal bridge to reach the desired position. When the center point of the signal bridge drops by 0.4um, the required driving voltage is 8.8V. At this time, the electrostatic force and the switch restoring force reach a balance, the switch is in an unstable state, and finally closes. When the center point of the signal bridge drops more than 0.4um, Figure 6 The driving voltage in the simulation diagram decreases because the distance between the electrodes becomes smaller, the plate capacitance becomes larger, and the driving voltage required for the switch to achieve balance decreases.

[0080] Figure 7 This is a stress fatigue life simulation diagram of an RF MEMS switch with a skirt structure; Figure 8 This is a stress fatigue life simulation diagram of an RF MEMS switch without skirt structure. When the switch is pressed from the initial state to 0.8um and cycles 1E10 times, the fatigue strength coefficient σ′ of Au is simulated in COMSOL Multiphysics using Basquin's law.

[0081] According to the literature, it is set to 68MPa, and the fatigue strength index b is set to 0.9. Figure 7 The RF MEMS switch with skirt structure shows fatigue failure after 1.32E8 cycles. Figure 8 The simulation results show that the RF MEMS switch without skirt beam suffers fatigue failure after 1.56E6 cycles, and the stress fatigue life of the switch with skirt beam is increased by 100 times compared with that without skirt beam.

[0082] Fig. 9This is a simulation diagram of the reflection phase difference of the terahertz programmable metasurface unit of an RF MEMS switch. It can be seen that when the metasurface unit is in the "0" and "1" states, the reflection phase difference ranges from 172° to 193°, and the operating frequency is from 285GHz to 320GHz, so 180°

[0083] The reflection phase difference has a large working bandwidth; the reflection phase of the metasurface unit has high linearity. From 285 GHz to 320 GHz, the reflection phase range in the switch down state is 117° to 52°, and the reflection phase range in the switch up state is -53° to -129°.

[0084] Fig.10 The present invention is a simulation diagram of a terahertz programmable metasurface unit S11 of an RF MEMS switch. It can be seen that from 280 GHz to 300 GHz, the unit reflection amplitudes in the switch up state and down state are both less than 2 db; from 280 GHz to 315 GHz, the unit reflection amplitudes in the switch up state and down state are both less than 3 db; if the lower electrode metal bias line (9) and the upper electrode metal bias line (10) are replaced with TaN material non-metallic bias lines, through HFSS software simulation, from 280 GHz to 320 GHz, the unit reflection amplitudes in the switch up state and down state are both less than 1 db.

[0085] Fig.11 It is a 1x16 linear array 3D directional pattern of the terahertz programmable metasurface unit "0011" encoding of RF MEMS switches. Fig.12 It is a 1x16 linear array 2D pattern of terahertz programmable metasurface unit "0011" encoding of RF MEMS switch. Fig.11 and Fig.12 When “0011” is used as the encoding for a sub-array, a ±30° dual beam is obtained by simulating a 1x16 linear array in HFSS.

[0086] Table 1 Unit dimensions

[0087]

[0088]

[0089] The above parameters are only examples, and the present invention is not limited thereto, and can also be reasonably adjusted based on specific application scenarios.

Claims

1. A terahertz programmable metasurface unit of an RF MEMS switch, characterized in that: include: A second substrate (16) having a square cross section and a side length of a sub-wavelength scale; A positive electrode control line (18), located on the lower surface of the second substrate (16) and connected to the DC positive electrode column (13); A back-covering (15) located on the upper surface of the second substrate (16); A first substrate (14) is located on the upper surface of the back cover (15); A DC grounding column (12), passing through the first substrate (14), having a length equal to the thickness of the first substrate (14); The DC positive pole (13) has a length equal to the sum of the thicknesses of the first substrate (14), the back cover (15) and the second substrate (16), and passes through the three. The DC grounding pole (12) and the DC positive pole (13) are parallel to each other and are both located on the symmetry line of the first substrate (14). Two groups of upper patches (7) are provided, both of which are located on the upper surface of the first substrate (14), and the two groups of upper patches (7) are symmetrically distributed on both sides of the DC positive pole (13); A signal line (8) is located on the upper surface of the first substrate (14), between the two groups of upper patches (7), and connected to the two groups of upper patches (7); The RF MEMS switch is located above the signal line (8).

2. A terahertz programmable metasurface unit of an RF MEMS switch according to claim 1, characterized in that: The back cover (15) is provided with a circular hole for the DC positive pole (13) to pass through.

3. The terahertz programmable metasurface unit of the RF MEMS switch according to claim 1, characterized in that: The RF MEMS switch comprises a lower electrode (6), a second layer anchor point (5), an electrode dielectric layer (4), a first layer anchor point (3), an upper metal electrode (2), a signal bridge (17) and a skirt beam (1); Two lower electrodes (6) are provided, both formed on the first substrate (14) and respectively located at two ends of the signal line (8), and the side length of each lower electrode is greater than the diameter of the DC grounding column (12); There are two second-layer anchor points (5), both formed on the first substrate (14) and respectively located outside the two lower electrodes (6), and the side lengths of the two second-layer anchor points (5) are equal to the diameter of the DC positive pole (13); The first layer anchor points (3) are provided with two, which are respectively located at the top of the corresponding second layer anchor points (5); Two upper metal electrodes (2) are provided, which are respectively installed on the top of the corresponding first layer anchor points (3), and the two upper metal electrodes (2) extend towards each other with a distance between them; The signal bridge (17) is located between the two upper metal electrodes (2) and is supported by the skirt beam (1); The skirt beam (1) is formed on the two upper metal electrodes (2), covers the upper metal electrodes (2) and the signal bridge (17), and separates the upper metal electrodes (2) and the signal bridge (17), and has a release hole for sacrificial layer release and reducing downward pressure damping.

4. The terahertz programmable metasurface unit of the RF MEMS switch according to claim 3, characterized in that: The signal bridge (17) is located directly above the signal line (8) and at the same level as the upper metal electrode (2), and is used to connect or disconnect the signal line (8), and has two circular contacts below it.

5. The terahertz programmable metasurface unit of the RF MEMS switch according to claim 1, characterized in that: The RF MEMS switch also includes a DC bias line structure, which includes a non-metal bias line (11), an upper electrode metal bias line (10), and a lower electrode metal bias line (9); The non-metal bias lines are provided with two, corresponding to the upper electrode and the lower electrode respectively; One of the lower electrodes is connected to a DC grounding column (12), and the two lower electrodes are connected in sequence through a lower electrode metal bias line a, a non-metal bias line a and a lower electrode metal bias line b; One of the second layer anchor points (5) is connected to the DC positive pole; the two second layer anchor points (5) are connected via an upper electrode metal bias line a, a non-metal bias line b and an upper electrode metal bias line b.

6. The terahertz programmable metasurface unit of the RF MEMS switch according to claim 5, characterized in that: Two non-metal bias lines (11) are formed on the first substrate (14) and are symmetrically distributed on both sides of the DC grounding column (12).

7. The terahertz programmable metasurface unit of the RF MEMS switch according to claim 5, characterized in that: The upper electrode metal bias line (10) is symmetrically distributed on both sides of the signal line (8), connected to the non-metal bias line b and the second layer anchor point (5), and deviates from the upper patch (7).

8. The terahertz programmable metasurface unit of the RF MEMS switch according to claim 5, characterized in that: The lower electrode metal bias line (9) is symmetrically distributed on both sides of the signal line (8), connected to the non-metal bias line a and the lower electrode (6), and deviates from the upper patch (7).

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