Compact Beamforming Module for Phased Array Antenna Systems

Abstract

The present invention relates to a compact beamforming module (10) for a phased array antenna comprising an RF switch (12) and a number of phase shifters (20), each of which has at least one ground defect structure (26 / 27 / 18) by applying a thin film structure on any type of substrate (22). The beamforming module of the present invention offers unique synergistic features and advantages, such as material selection independent of the type of substrate (22), ease of integration in semiconductor circuits, ease of use in high power amplifiers to provide a high EIRP antenna, and high spatial gain with cost efficiency.

Description

[Technical field]

[0001] The present invention relates to a beamforming module for smart antenna systems, in particular to a compact beamforming module for use in a phased array antenna. [Background technology]

[0002] Beamforming structures are widely used in satellites, aircraft, electronic weapons, radar communications, and navigation applications, allowing beam steering through the application of phase delays in antenna array elements. In phased array systems, beam steering or beamforming is accomplished electronically rather than mechanically, by using many antenna elements to control the direction of signal transmission or reception. Electronic control, along with faster scanning speeds, structural dimensions, fast switching speeds, prevention of transmission losses and incident interference or noise, cost, and mechanical maintenance needs, are important factors to consider for antenna systems.

[0003] Unlike adaptive antennas, which are more complex and expensive and require more advanced signal processing to function, switched beam antennas are built only by antenna arrays, beamforming networks, RF switches, and simple controller elements. The beamforming network, one of its most important parts, can be categorized into digital beamforming and RF beamforming, and RF beamforming usually involves lens-based and circuit-based multi-beam networks.

[0004] Semiconductor phase shifters, one of the essential elements of RF beamforming, are reciprocal in nature and can be classified as digital or analog, depending on whether the control element is used as an electronic switch or a continuously variable reactance. Examples of devices that can act as electronic switches are PIN diodes, GaAs FETs, and Schottky diodes. For analog processing, voltage-controlled varactor diodes are most commonly used. As a result, system preferences vary according to goals, needs, feasibility, and expectations.

[0005] US Patent No. 5,399,633 discloses a phased array antenna having a phase shifting device connected to a plurality of antenna elements, the phase shifting device including a substrate and a plurality of phase shifters on the substrate. Each phase shifter includes a ferromagnetic material or a ferroelectric material such as barium strontium titanate, and the phase shift is achieved by changing the dielectric constant of the material by a voltage applied to the selected thin or thick film material. There are also many teachings from the prior art on the applications of ferroelectric materials, such as their use as substrates, frequency selective surfaces or signal transmission media, or by depositing or coating the entire antenna or substrate with said materials.

[0006] Although such conventional applications may contribute to system performance to some extent through slight improvements in Q factor and low power processing, their use is still limited due to the very low Q factor of switch passive circuit parts such as filter banks and LC tank circuits in semiconductor processes including integrated circuits with passive elements such as CMOS or RFSOI.

[0007] The performance of a phase shifter is adversely affected by existing transmission losses. High transmission losses in series switching circuits used in conventional digital phase shifters that select fixed phase shift values ​​by switching are still a problem to be solved.

[0008] Phased array antennas are complex implementations that depend on many factors, such as frequency range, bandwidth, polarization, and effective radiated power (EIRP). Thus, the selection of materials, fabrication, and manufacturing processes for such antennas may be limited by the design characteristics of phase shifters, switches, and / or transmission lines based on specific materials and methods. As with some embodiments directed to metamaterial antennas or specific thin film substrates, the parameters that are most suitable for the signal distribution network are not necessarily suitable for the signal transmission network.

[0009] In the manufacture of beamforming modules, not only is cost-saving design a major concern, but physical size and power constraints should also be effectively overcome. Therefore, phase-shifting circuits and related components such as diodes and switches are required to be designed as small as possible, and to comply with the rules of distance between patches as well as the market standards of the components as a limiting factor. For example, when Ku and Ka band frequencies are intended to be reached by the antenna, the area in which components can be placed is reduced. Therefore, it is desirable that the components such as varactor diodes and switches can be integrated on the same substrate in the structure of the beamforming module.

[0010] Therefore, there exists a need today to reduce or eliminate as much as possible the constraints on the aforementioned antenna design preferences while still achieving the aforementioned performance factors. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent No. 6,611,230 Summary of the Invention [Problem to be solved by the invention]

[0012] The main objective of the present invention is to provide a beamforming module with lower losses, higher energy efficiency, higher power handling and higher power output compared to conventional applications in phased array antenna systems.

[0013] Another important objective of the present invention is to provide a beamforming module having high quality (Q) value for the construction of switches and transmission lines without constraints on material structure or design and manufacturing methods, taking into account the design preferences of phased array antennas.

[0014] Another object of the present invention is to provide a compact and cost-effective antenna beamforming module to achieve higher physical size savings.

[0015] It is yet another object of the present invention to provide a synergistic switching technique between passive circuits with different degrees of phase shift within an antenna beamforming module. [Means for solving the problem]

[0016] In order to achieve the above-mentioned object of the present invention, a compact beamforming module for a phased array antenna is provided, which comprises at least one phase shifter disposed on a substrate and having a coupled line constructed on a defective ground structure, and an RF switch.

[0017] A varactor is connected to each diagonally opposite end of the coupled line of the phase shifter, which includes two coupled transmission lines. In response to an applied voltage, the capacitance of the varactor, and therefore the conduction phase of the coupled line circuit, can be changed to achieve a predetermined phase shift result. Preferably, the varactor structure is transferred to a thin film to further reduce the design size.

[0018] The odd / even mode impedance is appropriately adjusted by the ground defect structure and the coupled line placed thereon. The ground defect structure has the effect of increasing the even mode impedance. The optimization is achieved by adjusting the characteristic impedance and the length of the transmission line connected to the coupled line. Optionally, a capacitor can be added between the coupled lines, which has the effect of reducing the odd mode impedance.

[0019] Said varactor consists of a thin film component grown on a surface. The thin film acts as a dielectric between metal electrodes coated on the surface and provides capacitance. The voltage dependent capacitance is obtained by the dielectric constant of the ferroelectric material changing with voltage. Preferred features for varactor selection are a suitable maximum / minimum capacitance ratio achievable as a function of applied voltage, low process sensitivity and low nonlinearity, as well as operability at low voltages. According to the invention, the varactor preferably comprises a thin film component grown on a sapphire or alumina ceramic, preferably a ferroelectric material, in particular barium strontium titanate (BST) or zinc oxide (ZnO).

[0020] The desired phase shift according to the present invention is provided by coupled lines on a ground defect structure on any rigid substrate with high dielectric constant, such as aluminum, sapphire, GaAs, GaN, CMOS, and SiC, without any limitation on the material, number, or layer structure of the substrate.

[0021] The beamforming module of the present invention includes RF switches (switching circuits), each of which is preferably made of sapphire, Si or Al. 2 O 3 Vanadium dioxide (VO 2 The switching function is VO 2 This is done by using the thermochromic characteristics of thin-film circuits to direct the RF signal to the desired line, while the other line is terminated with a high impedance. Both reflective and absorptive switches can be used in this context.

[0022] Each switching circuit has multiple, preferably two, VO 2 Connected to thin film line. VO 2 The thin film has high resistance insulator properties below a certain transition temperature, and has low resistance conductor properties above that temperature. The thin film properties are controlled by increasing the thin film temperature by passing a current through a control line connected to a switching circuit.

[0023] The present invention also provides a method for manufacturing a compact beamforming module for a phased array antenna comprising at least one phase shifter and an RF switch arranged in at least one layer on at least one substrate. Conductive elements well known from the prior art are provided for defining signal and transmission paths / lines on said substrate, said conductive elements being arranged on the signal paths / lines. The method essentially comprises the following steps: - placing each phase shifter and RF switch on at least one ground defect structure, the phase shifter including a coupled line formed from two coupled transmission lines; providing at least one varactor connected to each diagonally opposite end of coupled lines in the phase shifter to induce a phase shift in a signal, the varactor comprising a ferroelectric material and the RF switch comprising a thin film layer of vanadium dioxide.

[0024] All basic components used in the construction of the beamforming module, in particular the components, connections and material structure of the RF switches / switching circuits and the ferroelectric varactors, have been described so far and therefore will not be repeated. For compact beamforming modules it is preferable to use thin film processes on said substrates well known from the prior art.

[0025] Within the scope of the present invention, much higher Q-factors and power handling can be achieved at lower costs thanks to the fact that the coupled lines, varactors and switches are essentially realized together in thin films on any substrate, instead of processes such as CMOS, RFSOI, etc. For example, compared to a conventional semiconductor process with a Q-factor of 10 and a power of 100 milliwatts, according to the present invention, said values ​​are increased by about 10 times. Thus, a synergistic switching approach is achieved between passive circuits in the beamforming module that provide different degrees of phase shift.

[0026] The compact beamforming module of the present invention can operate independent of substrate type, and therefore can be directly coupled to GaAs, GaN, FET, or MMIC type ICs.

[0027] In another embodiment of the invention, four separate connections to the four corners, such as those in a beamforming integrated circuit, can be provided in the beamforming module as surface mounted components. The power combiner / splitter lines connecting the four branches can also be fabricated on the components as thin film circuits. Similarly, additional switches can be employed at these four terminals to provide polarization selection, or for example, a branch line coupler can be included in this switch. In another preferred alternative embodiment of the invention, the main circuit is formed on alumina in the beamforming module, and the varactors and switches, together with the thin film components, can be constructed on sapphire as flip chip surface mount. In this way, the limitations of the thickness of the thin layer, the limitations of the number of modules due to the number of varactors and switches available from the thin layer, and the need for stringent drilling requirements can be eliminated.

[0028] These and other aspects, structural and inherent features, advantages, and embodiments of the present invention will become more apparent and be more clearly understood by reference to the following detailed description, examples, and associated drawings.

[0029] The drawings are not necessarily to scale, and unimportant details may be omitted to avoid obscuring aspects of the invention. Wherever possible, the same reference numbers are used throughout the figures and description to refer to the same or like parts, and for simplicity, reference numbers may not be repeated for those parts in all the figures. [Brief description of the drawings]

[0030] [Figure 1a] FIG. 1 is an exemplary top view of a single channel compact beamforming module according to the present invention showing the main components on a single substrate; [Figure 1b] FIG. 1 is an exemplary top view of a four-channel compact beamforming module in accordance with the present invention showing the main components on a single substrate. [Figure 2a] FIG. 1 is an exemplary perspective view from a top of a preferred phase shift circuit; [Figure 2b] FIG. 2b is an exemplary perspective view from the bottom of a preferred phase shift circuit with a varactor component fabricated with surface mount flip chip technology as an alternative embodiment to the built-in varactor component of FIG. 2a. [Figure 3a] FIG. 1 is an exemplary center front vertical cross-sectional view of reflective and absorptive components of a preferred RF switching circuit according to the present invention. [Figure 3b] FIG. 1 is an exemplary top view of the reflective and absorptive components of a preferred RF switching circuit according to the present invention. [Figure 3c] FIG. 1 is an exemplary top view of the reflective and absorptive components of a preferred RF switching circuit according to the present invention. [Figure 4a] 1 is a graph illustrating the return loss of an exemplary phase shifting circuit according to the present invention over frequency and voltage change; [Figure 4b] 1 is a graph illustrating the insertion loss of an exemplary phase shift circuit according to the present invention over frequency and voltage change; [Figure 4c] 1 is a graph illustrating the phase shifting performance of an exemplary phase shifting circuit according to the present invention over frequency and voltage change; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] As shown in Figures 1a and 1b, a compact beamforming module (10) for a phased array antenna according to the present invention comprises an RF switch (12) and at least one phase shifter (20) including a coupled line (28) connected to a varactor (30), and is constructed on a thin film structure disposed on a ground defect structure (26, 27). With said embodiment, a synergistic switching approach between passive circuits is maintained, and higher Q values ​​and higher power handling can be achieved at low cost.

[0032] The coupled line (28) is conventionally formed by appropriately coupling two transmission lines (17) taking into account the impedance and frequency values ​​of odd and even modes. The term varactor (30) refers to a semiconductor diode acting as a voltage-dependent capacitor, and may also be called a varicap diode, a tuning diode, or a voltage-variable capacitor diode. The term ground defect structure (DGS) (26, 27, 18) refers to slots, voids, or defects of various geometric shapes integrated on a ground plane / layer / line, and is also called defective or imperfect ground structures, i.e. defects or voids placed on a ground plane formed on any surface (i.e., underside) of the substrate (22) according to the invention. Meanwhile, it is clear that the abbreviation RF means radio frequency and microwave.

[0033] As more clearly shown in FIG. 2a, in a preferred embodiment of the invention, the phase shifter (20) essentially consists of a coupled line (28) with a varactor (30) formed on a primary ground defect structure (26). If further required, in another embodiment, a secondary ground defect structure (27) may also be formed. For ease of illustration as a non-limiting example, the two coupled lines (28) are shown here in a mutual (anti-symmetric) arrangement, each of which has equivalent components (30, 34) built on a single substrate (22), and which comprise ground defect structures (26, 27), of which the first structure (26) is formed in the shape of a vertically extending elongated rectangle, and the second pair (27) are arranged in a U-shape with their ends facing each other and surrounding the first structure.

[0034] The capacitance varies with the voltage applied to the varactor 30, thereby varying the transmission phase of the coupled line circuit 28 to produce a desired phase shift effect. The varactor 30 preferably has a thin film component grown on its surface, preferably selected from ferroelectric materials, preferably barium strontium titanate (BST).

[0035] By using BST thin film varactors (30) in a preferred embodiment of the invention, the required variable capacitance can be provided, for example in a MIM structure (having a metal-insulator-metal based topology), on the same substrate (22) on which the coupled lines (28) are formed, with a specific maximum / minimum capacitance ratio of, for example, 1.4 to 3.0. As well, further advantages such as low voltage operation and low nonlinearity are obtained. Thus, the need for an additional discrete diode in a different process, such as a hyperphase varactor epitaxially grown on GaAs, and extra pads and wire ties for connecting this diode can be eliminated.

[0036] The odd-even mode impedance is appropriately adjusted by the ground defect structure (26, 27) and the coupled line (28) built thereon. The ground defect structure (26, 27) increases the even mode impedance. The optimization is achieved by adjusting the characteristic impedance and length of the transmission line (17) connected to the coupled line (28). Optionally, a capacitor (32) having an odd mode impedance reducing effect can be added between the coupled lines (28). Similarly, an inductor (34) can be added between the two varactors if necessary. Thus, a low odd mode impedance and a high even mode impedance can be achieved, and a high value of the phase shifter (20) performance can be obtained, together with the low parasitic capacitance of the selected BST varactor (30), for example.

[0037] The width of the void provided on the ground layer forming the ground defect structure (26), as well as the width and distance between the lines (28) are all calculated according to the dielectric constant and height of the substrate (22). The length of the coupled lines (28) is determined according to the operating frequency band, as well as the dielectric constant and height of the substrate material (22).

[0038] In a preferred embodiment, conductive screw holes (36) are drilled to ensure connection of the varactor (30) to the ground plane underneath the substrate (22). In an alternative embodiment of the invention as illustrated in Fig. 2b, instead of the screw holes, conductive connectors (37) on the varactor (30) components formed on a substrate (38) using surface mount flip chip technology are soldered to another substrate or substrates. A similar approach can be applied to the RF switching circuit (12) according to the invention.

[0039] Figure 3a shows a front vertical cross-sectional view of an exemplary embodiment of an RF switch (12) according to the present invention. Figures 3b and 3c show top views of an RF switching circuit (12) having a reflective component (12a) and an absorptive component (12b) in the form of a single-pole omnidirectional (SPDT) switch. The RF switch (12) is made of a thin-film vanadium dioxide (VO 2 ) ingredients.

[0040] The switching function is VO 2 This is implemented using the thermochromic properties (metal to insulator transition) of the thin film layers (14) to transmit the RF signal to the desired line (19) while the other line is terminated with high impedance. Each switching circuit (12) has at least two VO 2 It is connected to a thin film line (14).

[0041] VO 2 The thin film has high resistance insulator properties below a certain transition temperature and low resistance conductor properties above said temperature. The properties of the thin film can be controlled by increasing the temperature of the thin film by passing a current through a conductive control line (16) connected to a switching circuit and cooling it without current. In said embodiment, a dielectric ground defect structure (18) formed on a substrate (22) on which the thin film (14) is disposed and a thin film (14) and control line (16) are preferably formed of SiO 2 to isolate the heat of the thin film from surrounding components and / or other films. 2 At least one thin insulating layer (15) is provided which comprises:

[0042] In a preferred embodiment, VO grown on the same substrate 2 Thin film fabricated switching eliminates the need for additional switch circuitry built with discrete switch integration or discrete diodes.

[0043] The beamforming module (10) of the present invention further comprises a coupling capacitor (44), preferably a DC-coupled MIM capacitor, which is coupled to the VO 2 Each pair of thin film wires (14) is connected to the other. Compared to the single channel one, the multi-channel beamforming module also includes a power divider / collector (40) and a printed resistor (42) for each resistive power divider / collector (40) (FIGS. 1a-1b).

[0044] For example, four reflector antenna components, each of which can be connected to two differently polarized feed backbones, are arranged in a phased array 8x8 antenna, feeding each beamforming module (10) configured on a printed circuit board. Depending on the antenna arrangement and design, all polarization options (vertical, horizontal, circular, etc.) can be supported.

[0045] As an application example, Macom's HyperAbrupt GaAs varactor diodes (two per 0402 package) were connected to one end of each coupled line on a printed circuit board and voltages were applied in the range of 0 to 19 V. The obtained return loss, insertion loss, and phase shift performances according to frequency and voltage changes are shown in the graphs of Figures 4a to 4c, respectively.

[0046] The phase shifter configuration of the present invention is demonstrated by higher performance results than digital phase shifter integrated circuits in which fixed phase shift values ​​are selected by switching. The performance metric here is obviously the ratio of phase shift in degrees to transmission loss in dB. This is achieved because it eliminates the need for series switches traditionally used in the circuit, and the associated transmission losses.

[0047] In the example, the S-parameters of the phase shifter are reported in the range of 7.25-8.40 GHz, covering the entire frequency band of X-band SATCOM transmitters (7.90-8.40 GHz) and receivers (7.25-7.75 GHz). For the entire frequency range, the return loss is less than -10 dB and the full phase range of 360 degrees can be obtained with a transmission loss value of less than 3 dB, or about 2 dB, and thus the obtained FoM (Figure of Merit) value of about "360° / 2 dB" is found to be unique. The results show much better performance compared to loss values ​​of more than 6 dB in close prior art applications such as CMOS, SOI, and GaN.

[0048] The phase shifter is based on variable capacitance, unlike phase shifters that use the variable properties of ferroelectric materials. Depending on the substrate used, the coupled line has a high quality factor and the applied voltage provides the phase shift by changing the capacitance of the varactor connected only to this line. In this respect, high performance is obtained. Also, the process variations are not large, since the crystal structure obtained depending on the growth process parameters of the thin film varactor has a limited impact on the performance.

[0049] The key performance indicator is R on and C Off are equal to each other, said frequency being calculated according to the following formula:

number

[0050] In embodiments of the present invention, switch transmission losses are lower than semiconductor switches. Switching speeds are faster than MEMS switches. This is important for communication systems that use time division multiplexing (TDMA) and time division duplexing (TDD) waveforms. Similarly, antenna transmit / receive mode transitions must be fast in radar and electronic weapon systems.

[0051] The quality (Q) factor, which represents the conservation of energy in a phase shifter, i.e. the ratio of the energy stored to the energy lost in the system, is one of the important indicators. In this respect, a higher Q factor is a desirable feature for low-loss transmission lines and filters. The thin-film circuits are built on substrates with very low dielectric loss coefficients by high-precision laser processing. This achieves advantages such as sensitivity to low-frequency errors and suppression values ​​of the band passing / printing the filter.

[0052] By combining the two basic control elements provided by the module and method according to the invention, in a small physical area on the same substrate, completely independent of the substrate, easy integration with semiconductor circuits and possibility of use with high power amplifiers to provide high EIRP antennas are unique synergistic features, giving a compact and advantageous structure by giving a high synergy and performance to the whole component.

[0053] Although specific examples and embodiments of the present invention have been described above, it is clear to those skilled in the art that various changes, modifications, and adaptations can be made without departing from the spirit and scope of the present invention. For example, thanks to the beamforming module of the present invention, there are no restrictive and binding conditions on antenna design preferences. For example, by using the module, antenna design can be made on any substrate through the fabrication of any layered structure.

[0054] Since the thin film design can be used as an isolated unit providing input / output as a module, there is no restriction on the method or material selection that requires the film to be grown on it. Thus, the embodiment of the present invention can also perform the function of an integrated circuit that can be used in a target circuit by being mounted on its surface. In terms of general characteristics compared to conventional applications in phased array antennas, the beamforming module of the present invention has low losses, high energy efficiency, high power handling, and high power output. Similarly, higher efficiency in the transmit state and lower noise in the receive state can be achieved.

[0055] It is therefore intended that the appended claims ensure that such changes and modifications are included within their scope of protection without departing from the scope and completeness of the present invention. [Explanation of symbols]

[0056] 10 Beamforming Module 12 RF switch (RF switching circuit) 12a Reflective RF Switch Components 12b Absorption RF Switch Components 14 Thin film layer / line (VO 2 ) 15 Insulating layer 16 Control (conductive connection) line 17 Transmission Lines 18 Insulating Ground Defect Structure 19 RF signal connection points / lines 20 Phase shifter (phase shift circuit) 22 Substrate 26 Primary Ground Defect Structure 27 Secondary Ground Defect Structures 28 Coupled (transmission) line 30 Varactor (thin film) 32 Capacitor 34 Inductor 36 screw holes 37 Connector 38 Surface Mount Board 40 Power divider / collector 42 Printed resistor 44 Coupling Capacitor

Claims

1. A compact beamforming module (10) for a phased array antenna, comprising at least one phase shifter (20) and an RF switch (12) arranged on at least one layer on at least one substrate (22), wherein the at least one phase shifter (20) is formed by two coupled transmission lines and includes a coupling line (28) constructed on a ground defect structure (26, 27); at least one varactor (30) is connected to one end of the two transmission lines, at least one varactor (30) is connected to the other end of the two transmission lines, and the ends of the two transmission lines to which the varactor (30) is connected are connected to the respective diagonal ends of the coupling line (28) that face each other; the varactor (30) and the RF switch (12) are made of a thin film structure; the RF switch (12) includes a thin film layer (14) of vanadium dioxide Characterized in that it is a beamforming module.

2. The beamforming module according to claim 1, characterized in that the ground defect structure (26, 27) comprises a primary ground defect structure (26) and a secondary ground defect structure (27).

3. The beamforming module according to claim 1, characterized in that a capacitor (32) is provided between the coupling lines (28) to reduce the odd-mode impedance.

4. The beamforming module according to claim 1, characterized in that two varactors (30) are provided at the diagonal ends of the coupling line (28) that face each other, an inductor (34) is provided between the varactors (30), and each varactor includes a ferroelectric material grown on a sapphire or alumina ceramic surface, particularly barium strontium titanate or zinc oxide.

5. The beamforming module according to claim 1, characterized in that the RF switch (12) includes a reflective RF switching circuit (12a) and an absorptive RF switching circuit (12b). **Claim 6**: The beamforming module according to any one of claims 1 to 5, wherein each RF switch (12) includes a thin insulating layer (15), a conductive control line (16), and an insulating ground defect structure (18), the thin insulating layer (15) is provided between the conductive control line (16) and the thin film (14), and the insulating ground defect structure (18) is formed on a substrate (22) on which the thin film (14), the thin insulating layer (15), and the control line (16) are disposed. **Claim 7**: The beamforming module according to any one of claims 1 to 6, wherein each RF switch (12) includes a layer of vanadium dioxide (14) grown on a sapphire, silicon, or alumina ceramic surface. **Claim 8** The beamforming module according to claim 5, wherein each reflection and absorption RF switching circuit (12a, 12b) is connected to at least two vanadium dioxide thin film lines (14) connected to a common transmission line (17). **Claim 9** The beamforming module according to any one of claims 1 to 8, wherein the substrate (22) is selected from the group consisting of aluminum, sapphire, GaAs, GaN, CMOS, and SiC as a high dielectric constant material. **Claim 10** The beamforming module according to claim 8, further comprising a coupling capacitor (44) connected to a pair of the at least two vanadium dioxide thin film lines (14) via the common transmission line (17). **Claim 11** The beamforming module according to any one of claims 1 to 10, further comprising a power divider / combiner (40) and a printed resistor (42) for each resistive power divider / combiner (40). **Claim 12** A method of manufacturing a small beamforming module (10) for a phased array antenna, comprising at least one phase shifter (20) and an RF switch (12) disposed on at least one layer on at least one substrate (22), wherein a conductive element is provided on the substrate (22) to define a signal transmission path / line. - A step of arranging an RF switch (12) composed of bit phase shifters (20) and a thin film layer of vanadium dioxide on at least one ground defect structure (26, 27, 18), wherein each bit phase shifter (20) includes a coupled line (28) formed from two coupled transmission lines. including The thin film layer (14) of vanadium dioxide of the RF switch (12) is grown on a sapphire, silicon or alumina ceramic surface. By each bit phase shifter (20), a signal phase shift is caused by at least one varactor (30) having a thin film structure connected to one end of the two coupled transmission lines and at least one varactor (30) having a thin film structure connected to the other end of the two coupled transmission lines. The ends of the two coupled transmission lines to which the varactor (30) is connected are connected to the ends facing the diagonal of the coupled line (28). Reducing the odd-mode impedance through a capacitor (32) provided between the coupled lines (28). A method characterized by this. **Claim 13**: The method according to claim 12, further reducing the odd-mode impedance and increasing the even-mode impedance through two varactors (30) provided at one end of the coupled line (28) and an inductor (34) between these varactors (30). **Claim 14**: The method according to claim 12 or 13, characterized in that each varactor (30) is made of a ferroelectric material containing barium strontium titanate or zinc oxide grown on a sapphire or alumina ceramic surface. **Claim 15**: The method according to any one of claims 12 to 14, characterized in that a thin film process is used on the substrate (22) in the small beamforming module (10).

Images