Controllable beam scanning antenna

Abstract

A leaky wave antenna device (101) is provided, comprising a partial reflecting surface (2), a conductive grounding plate (3), an actuator (6), and a feed array (155). The feed array (155) comprises a plurality of spaced feed points (15). Each feed point (15) is arranged to couple a high-frequency input signal to the antenna (101). The partial reflecting surface (2) and the conductive grounding plate (3) are stacked and substantially parallel to each other, defining a cavity between them. The antenna device (101) is configured such that the beam (101) formed by the antenna device can be steered in a first direction by the operation of the actuator and in a second direction by changing the relative phase of the high-frequency signals coupled to the cavity by each of the feed points (15).

Description

[Technical Field]

[0001] The present invention relates to a leaky wave antenna having two-dimensional beam steering, and to a method for steering a beam in two dimensions. [Background technology]

[0002] Modern communication systems require antenna technology characterized by high efficiency, high data rates, and beam steering capabilities to meet consumer demand for data. This can be achieved by introducing antenna systems that operate in higher frequency bands than current infrastructure and by using components that can be integrated to impart superior characteristics to the antennas. Significant advancements have been made in beam scanning using Fabry-Perot antennas in recent years.

[0003] In a previous study by the present inventors (Rabbani, Churm & Feresidis; “Electro-Mechanically Tunable Meta-Surfaces for Beam-Steered Antennas from mm-Wave to THz”; Proceedings of the 50th European Microwave Conference; 12-14 January 2021; Utrecht; pp 416 to 419) (the full disclosure thereof is incorporated herein by reference), a leaky wave antenna (LWA) was developed using an extremely low-loss tunable meta-surface as a phase-shifting material to obtain beam steering capability.

[0004] According to the disclosures of this prior research, beam scanning is only possible in one plane. Scanning in two or more planes is desirable. [Overview of the Initiative] [Means for solving the problem]

[0005] According to the first aspect: partially reflective surface; conductive ground plate; Actuator; Multiple power sources A leaky wave antenna device is provided, comprising a partial reflector and a conductive ground plate, which are stacked and substantially parallel to each other, with a cavity defined between them; The power supplies are spaced apart in the array, and each power supply is positioned to couple the high-frequency input signal to the cavity; The antenna device is configured such that the beam formed by the antenna device can be steered in a first direction by the operation of an actuator.

[0006] The beam may be steered in a second direction by changing the relative phase of the high-frequency signals coupled to the cavity, depending on each of the power sources.

[0007] The device may further include a conductive grounding plate and a high-impedance surface arranged in a stacked configuration with a partial reflective surface. The high-impedance surface may be located between the partial reflective surface and the conductive grounding plate.

[0008] Beam steering may include (or consist of) selecting a fixed orientation (first direction and / or second direction) of the beam formed by the antenna. Beam steering may also include changing the orientation of the beam formed by the antenna to the first direction and / or second direction.

[0009] The actuator may be configured to adjust the distance between the grounding plate and the partial reflecting surface (PRS), and / or the distance between the grounding plate and the high impedance surface (HIS).

[0010] The actuator may be capable of adjusting the distance between the grounding plate and the partial reflecting surface, thereby steering the beam in a first direction. The actuator may move the partial reflecting surface and / or the grounding plate to steer the beam in a first direction. The actuator may be configured to change the distance between the high-impedance surface and the conductive grounding plate.

[0011] The feed points may be arranged in a linear one-dimensional array. The feed points may be located at the edge of the cavity. The feed points may be located in the center within the cavity. Each feed point may comprise a dipole or any other radiating feed element, including an open-end waveguide or slot. Hereafter, references to “singular dipole” or “plural dipole” can be replaced with any other suitable radiating feed element, such as an open-end waveguide or slot.

[0012] The power supply array may include an array of dipole pairs arranged on a power supply board.

[0013] Each dipole pair may include a first dipole positioned to couple the high-frequency signal to a first face of the cavity, and a second dipole positioned to couple the high-frequency signal to a second face of the cavity.

[0014] Each first dipole may comprise a first dipole arm on the front of the feed board and a second dipole arm on the rear of the feed board. Each second dipole may comprise a first dipole arm on the front of the feed board and a second dipole arm on the rear of the feed board.

[0015] Each power supply may be equipped with a power supply port for receiving high frequencies having a selected phase and / or amplitude.

[0016] The feed array may comprise a control element configured to control i) which of the feed sources is excited by a high-frequency signal, and / or ii) the relative phase and / or amplitude of the high-frequency signal coupled to each feed source. The feed array may be configured to provide a fixed phase delay to each feed source so as to provide a beam having a fixed orientation in a second direction. The feed array may comprise one or more transmission lines (or delay lines) of different configurations to fix the relative phase and amplitude of the signal supplied to each feed source.

[0017] In an embodiment comprising a first dipole and a second dipole, the control element may be operable such that the first dipole and the second dipole can be excited together or separately.

[0018] The feed array may comprise one or more switching devices arranged to reconfigure the coupling between the high-frequency signal and the cavity.

[0019] The antenna device may further comprise a phase controller configured to change the relative phase of the high-frequency signal supplied to each of the feed sources.

[0020] The partially reflective surface may comprise a metasurface including a conductive layer periodically patterned on a dielectric substrate. The partially reflective surface may be a fully metallic partially reflective surface (it is not essential for the PRS to comprise a dielectric substrate). The partially reflective surface may comprise a metallic (or metal) sheet having patterned through-holes. The patterned through-holes may be an array, and the array may be periodic or aperiodic. The antenna device may be a Fabry-Perot leaky-wave antenna.

[0021] The antenna device may optionally comprise a high-impedance surface disposed in a cavity between a partially reflective surface and a conductive ground plane. The high-impedance surface may optionally comprise a metasurface that includes a periodically patterned conductive layer on a dielectric substrate. The high-impedance surface may be an entirely metallic high-impedance surface (it is not mandatory for the HIS to comprise a dielectric substrate). The high-impedance surface may optionally comprise a metal sheet having patterned through-holes. The patterned through-holes may be in an array, and the array may be periodic or aperiodic.

[0022] The first array of conductive elements may optionally be formed on or in the dielectric substrate of the HIS, and the second array of conductive elements may optionally be formed on the dielectric substrate of the PRS. The conductive elements (or patterned holes) may optionally be formed, for example, by etching, printing and / or micromachining.

[0023] All of the conductive elements of the HIS may be substantially identical. The conductive elements of the first array may be square patches. The conductive elements of the HIS do not need to be square, and may have any other suitable geometric shape that can be modified to obtain the required phase shift sensitivity. The conductive elements of the HIS may have a first size and a first period. The actuator may be operable to enable movement of the ground plane relative to the HIS in order to steer a beam in a first direction. The actuator may move the ground plane or the HIS to achieve this relative movement between the ground plane and the HIS.

[0024] All of the conductive elements of the PRS may be substantially identical. The conductive elements of the PRS may be square patches. The conductive elements of the PRS do not need to be square, and may have any other suitable geometric shape that can be modified to obtain the required phase shift sensitivity. The conductive elements of the PRS may have a second size and a second period.

[0025] The first and second sizes and / or the first and second periods may be the same or different. The first size may be smaller than the second size. The first period may be smaller than the second period. In some embodiments, the first size is smaller than the second size, and the first period is smaller than the second period.

[0026] In embodiments comprising a dielectric substrate, the HIS and PRS conductive elements may be formed on the respective surfaces of the dielectric substrate facing the ground plate. This configuration maximizes control over the phase of the reflected wave. It is possible to form one or both of the HIS and PRS conductive elements on opposite surfaces of the respective dielectric substrates, but this may reduce the range of possible phase shifts and, consequently, the range of achievable beam steering.

[0027] The HIS dielectric substrate may have a thickness in the range of 0.01 to 2 wavelengths. The HIS dielectric substrate has a relative permittivity greater than 1, optionally about 2.3.

number

[0028] The PRS dielectric substrate may have a thickness in the range of 0.01 to 2 wavelengths. The PRS dielectric substrate has a relative permittivity greater than 1, optionally about 2.3.

number

[0029] The spacing h1 between HIS and PRS is typically approximately equal to a multiple of the operating half-wavelength, taking optimization and dielectric effects into account.

[0030] The spacing h2 between the first metasurface and the conductive grounding plate can be adjusted by a microactuator in some proportion to the wavelength, between 0 mm and 2 mm, and between 0 μm and 500 μm. In some embodiments, the spacing h2 can be adjusted to 25 μm to 400 μm. When the conductive elements of the first array on the HIS are in contact with the conductive grounding plate (h2 = 0 μm), the HIS becomes completely reflective, and the effect of the HIS is substantially lost.

[0031] The actuator may be configured to allow substantially continuous adjustment of the interval h2, or the actuator may be configured to adjust the interval h2 in steps.

[0032] The first and second arrays can be of various array sizes. Generally, a larger array is preferable from the viewpoint of waves passing through the metasurface (with respect to the wave wavelength λ). In some embodiments, the array may be on the order of 10λ × 10λ. In some embodiments, the array may be on the order of 100λ × 100λ or larger.

[0033] In some embodiments, beam steering in the range of at least -40° to +40° (with respect to the PRS normal) is achievable.

[0034] Multiple LWAs can be used in an array at geometrically spaced intervals, for example, to create sectors of ±40°. In this way, five LWAs can be used to cover 360° around a single radiating surface.

[0035] Embodiments of this disclosure provide highly efficient antenna devices particularly suitable for millimeter-wave and / or terahertz applications.

[0036] In some embodiments, good RF matching is achieved over 26 GHz to 28 GHz for h2 values ​​of 200 μm or less. This is a bandwidth wide enough for use in 5G infrastructure. Embodiments can be configured to operate at frequencies up to and / or above 100 GHz.

[0037] The actuator may include a piezoelectric actuator. The actuator may be configured to move a partially reflective surface, a high-impedance surface, or a conductive grounding plate. The actuator may be any other type of high-speed switching actuator, including, but not limited to, a solenoid actuator, an electroactive polymer actuator, a microelectromechanical system, a magnetically driven actuator, or a micromotor. The conductive grounding plate may be mounted on or connected to the microactuator so that the microactuator can move the conductive grounding plate relative to the HIS and / or PRS.

[0038] The HIS may be designed to impart a specific phase shift to the RF signal when the RF signal is reflected. By changing or adjusting the distance between the conductive grounding plate and the HIS, the amount of phase shift applied to the reflected RF wave can be changed. Thus, by controlling a microactuator, the reflection characteristics of the HIS can be dynamically changed. The HIS and PRS may be separated from each other by a distance h1. The HIS may be separated from the conductive grounding plate by a distance h2. The distance h1 may be fixed, while the distance h2 may be adjustable over a predetermined distance range by an actuator.

[0039] In embodiments where the HIS is omitted, adjusting the distance between the conductive ground plate and the PRS can change the cavity depth of the Fabry-Perot leaking wave antenna.

[0040] The conductive grounding plate may comprise multiple grounding plate sections, and the actuator may be configured to independently change the distance between the partial reflective surface and each of the grounding plate sections.

[0041] The interval between power sources may be less than the wavelength of the antenna device's operating frequency.

[0042] According to the second aspect: Steering the beam from the leaky wave antenna in a first direction by adjusting the distance between the ground plate and the partial reflecting surface of the leaky wave antenna; and Steering the beam from the leaky wave antenna in a second direction by changing the relative phase of the signals applied to multiple feed points arranged to couple high-frequency signals to the leaky wave antenna. Methods including this are provided.

[0043] The method of the second embodiment may employ any of the features described with reference to the first embodiment.

[0044] Steering a beam may involve selecting a fixed orientation for the beam. Changing the relative phase of signals applied to multiple feed points may involve selecting a phase offset and / or amplitude offset for signals applied to multiple feed points to result in a fixed orientation for the beam.

[0045] LWA is a type of traveling wave antenna and should be distinguished from more common resonant antennas such as monopoles or dipoles. In an LWA, the radio frequency (RF) current that generates the transmitted radio signal travels in one direction along the antenna. This is in contrast to resonant antennas, where the RF current travels in both directions along the antenna and reflects between its ends. The traveling wave in an LWA is typically a fast wave with a phase velocity greater than the speed of light.

[0046] In the context of this application, a metasurface is a material having a periodic array of scattering elements that are small in size and period compared to the operating wavelength. A typical metasurface may comprise a thin dielectric substrate less than 1 mm thick having a two-dimensional array of conductive metal elements printed or etched onto the substrate, the conductive elements being on the order of millimeters in size.

[0047] Exemplary embodiments of the present invention will be described with reference to the attached drawings. [Brief explanation of the drawing]

[0048] [Figure 1a] Figure 1a shows a unit cell of a conventional high-impedance surface adjacent to a conductive grounding plate. [Figure 1b] Figure 1b shows a conventional leaky wave antenna (LWA) that has a high-impedance surface positioned between a partially reflective surface and a conductive grounding plate. [Figure 2] Figure 2 shows the simulated S11 amplitude response of the HIS from the LWA in Figure 1b for different displacements of the ground plate. [Figure 3]Figure 3 shows the simulated S11 phase response (relative phase shift between the incident free-space wave and the reflected free-space wave from the HIS) of Figure 1b for different displacements of the ground plate. [Figure 4] Figure 4 shows the beam scanning achieved by LWA in Figure 1b. [Figure 5] Figure 5 shows a further prior art LWA comprising a metal partial reflector with a circular aperture. [Figure 6] Figure 6 shows the simulated far-field radiation pattern of the LWA in Figure 5. [Figure 7] Figure 7 shows the simulated S11 response of the LWA in Figure 5. [Figure 8] Figure 8 shows an LWA with a central power supply equipped with a switchable dipole pair. [Figure 9] Figure 9 shows the simulated far-field gain (absolute value) of the LWA in Figure 8 at φ=90° for different displacements of the grounding plate. [Figure 10] Figure 10 shows a) a front view of the two-way switchable printed dipole feed unit, b) a first detail of the dipole feed unit, and c) a second detail of the dipole feed unit. [Figure 11] Figure 11 shows a rear view of the dipole feed section of Figure 10. [Figure 12] Figure 12 shows a leaky wave antenna according to an embodiment, which includes a feed array disposed at the edge of the antenna. [Figure 13] Figure 13 shows an exemplary fed printed dipole antenna. [Figure 14] Figure 14 shows the power supply array of Figure 12, independent of the HIS and PRS. [Figure 15] Figure 15 shows the beam steering of the antenna in Figure 12 in the yz plane by adjusting the distance h2. [Figure 16] Figure 16 shows the beam steering of the antenna in Figure 12 in the xz plane, achieved by adjusting the relative phase of the signals applied to each feed point. [Figure 17]Figure 17 shows the simulated radiation pattern of the antenna in Figure 12 resulting from beam steering in both the yz and xz planes. [Figure 18] Figure 18 shows a leaky wave antenna according to an embodiment, which includes a feed array located in the center of the antenna. [Figure 19] Figure 19 shows the central power supply array in more detail. [Figure 20] Figure 20 shows the central power supply array in more detail. [Figure 21] Figure 21 shows the central power supply array in more detail. [Figure 22] Figure 22 shows the beam steering of the antenna in Figure 18 in the yz plane by adjusting the distance h2. [Figure 23] Figure 23 shows the beam steering of the antenna in Figure 18 in the xz plane, achieved by adjusting the relative phase of the signals applied to each feed point. [Figure 24] Figure 24 shows the broadside beam formed from the antenna in Figure 18. [Figure 25] Figure 25 shows the simulated radiation pattern of the antenna in Figure 18 resulting from beam steering in both the yz and xz planes. [Modes for carrying out the invention]

[0049] Figure 1 shows a first LWA design comprising a tunable high impedance surface (HIS) 1 and a static partial reflection surface (PRS) 2, each formed as a metasurface and arranged substantially parallel to each other. The first LWA design is configured to operate at 37 GHz. As shown in Figure 1b), HIS 1 and PRS 2 are each formed by a two-dimensional array of square conductive patch elements etched onto a planar printed circuit board (PCB).

[0050] HIS1 and PRS2 are, respectively, relative permittivity

number

[0051] HIS1 is positioned above the conductive grounding plate 3 substantially parallel to it, and is spaced a distance h2 above the grounding plate 3. PRS2 is positioned on top of HIS1, spaced a distance h3 above HIS1. Distance h3 defines the cavity height of the LWA and determines the resonant frequency of the LWA. The total area of ​​the HIS / PRS assembly is approximately 3cm × 9cm. The grounding plate 3 is mounted on a piezoelectric actuator 6 and is vertically displaceable by the piezoelectric actuator 6 so that the distance h2 can be changed. Figure 1a) shows an independent unit cell of HIS1 in Figure 1b), but is upside down compared to Figure 1b). The unit cell comprises a single square conductive patch element 4 on the first dielectric substrate 100. The conductive grounding plate 3 is spaced a distance h2 from the first dielectric substrate 100.

[0052] The corresponding edges of HIS1 and PRS2 are connected by a reflector 7 on one side of the LWA, and a printed dipole fed antenna 8 is provided between HIS1 and PRS2, adjacent to the reflector 7.

[0053] Figures 2 and 3 show the simulated S of the HIS reflection coefficient for various distances h2 for the LWA of Figure 1b) operating in the 35GHz-40GHz frequency band. 11 Amplitude and S 11shows the phase response. The spacing h2 between the ground plates can be varied from 0 μm to 400 μm. It can be seen that a change of 40 μm to 400 μm (Δh2=360 μm) brings about a reflection coefficient phase shift Δφ HIS = 142° for HIS1, while exhibiting a negligibly low loss of about 0.06 dB at 37 GHz (φ HIS ).

[0054] A flexure-amplified piezoelectric actuator 6 may be employed to adjust the distance h2 between the periodic array layer of HIS1 and the ground plate 3.

[0055] Similarly, the simulated S 11 absolute amplitude (R) and phase φ QRS of PRS2 can be obtained, which are 0.94 and 156° respectively at 37 GHz. The directivity and main beam angle of the LWA depend on the S 11 responses of both HIS1 and PRS2 according to the following relationship.

Mathematical expression

Mathematical expression

[0056] By using equations (1) and (2), it is predicted that as shown in Fig. 3, the LWA will exhibit a beam steering range of about 37° (from 14° to 51°) for a HIS phase shift Δφ HIS =142° at 37 GHz.

[0057] The piezoelectric actuator 6 may also be a linear piezoelectric actuator with a flexure expansion function, capable of producing a displacement of up to 0.5 mm. The piezoelectric actuator 6, on which the grounding plate 3 is provided, is expandable and contractible in response to the applied DC bias voltage, thereby allowing the distance h2 to be changed as needed.

[0058] The LWA's printed dipole antenna 8 is a half-wavelength antenna designed to operate at 37 GHz. The directivity of the printed dipole antenna 8 is enhanced by placing a reflector 7 (see Figure 1b) 0.9 mm from the back of the antenna 8. By integrating the printed dipole antenna 8 into the LWA, which has 9 × 27 PRS elements and 16 × 49 HIS elements, and performing appropriate simulations centered on the 37 GHz operating frequency, it was found that the S2 change (δh2) from 40 μm to 400 μm was less than -10 dB at approximately 37 GHz. 11 A response is obtained. The maximum gain of the LWA is 23.9 dBi with a maximum beam steering of 33° at 37 GHz.

[0059] In this embodiment, HIS is not required and can be omitted.

[0060] A second LWA design is shown in Figure 5 (this may be useful in the low THz band, e.g., around 280 GHz, but may be applicable to other frequencies as well). This second LWA design features a circular aperture period PRS10 and omits the HIS near the ground plate 3. In this modification, the PRS10 is displaced perpendicular to the ground plate 3 by a piezoelectric actuator 6, thereby allowing adjustment of the resonant cavity height h3. The PRS10 is in the form of a metal layer with a thickness h1 = 0.3 mm and has a two-dimensional 11 × 31 array of circular apertures 11, each with a diameter of 0.6 mm and a period of 0.75 mm. The metal ground plate 3 has a thickness h2, and the PRS10 is positioned 0.46 mm above the ground plate 3, and the cavity height h3 is variable from 0.44 mm to 0.5 mm by applying different DC bias currents to the piezoelectric actuator 6. The thickness h2 is typically on the order of millimeters to form a stable base and allow the flange of a standard waveguide feed section to be securely fixed. Preferably, the thickness h2 is greater than the skin depth, and ideally greater than twice the skin depth. The LWA is excited by a waveguide-fed slot element 12 formed toward one edge of the ground plate 3.

[0061] Embodiments having or not having HIS1 adjacent to the grounding plate 3 can be designed for frequencies of at least 20 GHz to 1 THz.

[0062] Figures 6 and 7 show the simulation results for a second LWA design operating at 280 GHz, with Figure 6 showing the FRP on the H plane and Figure 8 showing the S 11 The response is shown, for different values ​​of h3 in each case. The LWA has a maximum gain of 18 dBi and is known to produce beam steering over a range of approximately 18° with a gain loss of less than 3 dB over a displacement range of 0.06 mm. However, S 11 The response has been found to be above -10 dB for some displacements.

[0063] Figure 8 shows a third LWA. Similar to the LWA in Figure 1b), this LWA comprises a tunable high impedance surface (HIS) 1 and a static partial reflecting surface (PRS) 2, each formed as a metasurface and arranged substantially parallel to each other. The illustrated LWA is configured to operate at 26 GHz to 28 GHz, but may be configured to operate at other GHz frequencies as needed.

[0064] HIS1 and PRS2 are each formed by a two-dimensional array of conductive patch elements etched onto planar dielectric PCB substrates 100 and 200. Substrates 100 and 200 each have a relative permittivity

number

[0065] HIS1 is etched to define a first two-dimensional array of conductive patch elements 4. PRS2 is etched to define a second two-dimensional array of conductive patch elements 5. HIS1 is positioned above the conductive grounding plate 3 substantially parallel to it, and is spaced above the grounding plate 3 by a distance h2. PRS2 is positioned on HIS1, and is spaced above HIS1 by a distance h1. The distance h1 defines the cavity height of the LWA and determines the resonant frequency of the LWA. The grounding plate 3 is mounted on a piezoelectric actuator 6 and can be displaced vertically by the piezoelectric actuator 6 so that the distance h2 can be changed.

[0066] Instead of a feed antenna located adjacent to the reflector at one edge of the LWA, a feed section 150 with a switchable dipole pair is positioned between the HIS1 and PRS2 at a location corresponding to the center of the first and second arrays. By employing a switchable dipole pair at this position, an increase in the beam steering angle θ is obtained, which in this example is ±40° with respect to the vertical direction of the PRS2.

[0067] As shown in detail in Figures 10 and 11, and further described herein, the power supply unit 150 is configured to selectively excite the LWA structure to expand the available beam scanning range.

[0068] Metamaterial devices can be designed to reflect waves to which a specific phase shift has been applied. This can be achieved using a high-impedance surface composed of a sheet of periodic metal patches printed on a dielectric substrate, suspended above a ground plate. By changing the distance between the periodic array and the ground plate, the amount of phase shift applied to the reflected wave can be changed. Therefore, the reflection characteristics of the high-impedance surface can be dynamically altered using a piezoelectric actuator (or other high-speed switching microactuator).

[0069] When such a HIS1 is incorporated into a leaky wave antenna (using a designed partial reflector (PRS)2) and fed from the center by a switchable dipole 150, as shown in Figure 8, a highly directional antenna is obtained that can efficiently steer the main radiated beam at millimeter-wave frequencies where other competing technologies typically experience high losses.

[0070] This beam steering mechanism does not have active elements in the RF path itself and provides best-in-class efficiency. For example, good RF matching of the embodiment in Figure 8 between approximately 26 GHz and 28 GHz has been demonstrated with a radiation efficiency of over 90% for spacing h2 up to 0.32 mm. This is a sufficiently wide bandwidth for modern communication systems used in 5G infrastructure.

[0071] A pair of switchable dipoles 150 may be used to excite either the right or left portion of the antenna, thereby achieving the beam steering performance shown in Figure 9, where Figure 9 shows the far-field gain (absolute value) (φ=90°) for various spacings h2 from 0.0 mm to 0.32 mm when the switchable dipole feed section 150 is exciting either the right or left portion of the antenna. Beam angles between ±40° are possible, allowing the 5G infrastructure to direct data towards individual consumers moving within the service area of ​​a particular antenna system. These devices may be configured to meet the electromagnetic requirements of the 5G system.

[0072] The table below summarizes the simulation results (peak gain, peak gain angle, and half-power beamwidth) for the antenna in Figure 8 at 26 GHz.

[0073] [Table 1]

[0074] Figure 10a) shows a front view of an exemplary two-way switchable printed dipole feed unit 150. The feed unit 150 comprises a conductive track printed on the front surface of a dielectric substrate 200a having an RF connector 201 at one end. In the illustrated configuration, the dielectric substrate 200a is a 0.254 mm thick RT / Duroid 5880 substrate, but it will be noted that other suitable dielectric substrates may be used. The feed line 202 extends from the RF connector 201 through the bias network 203 toward the front dipole arms 204a and 204b, as shown here facing toward the RF connector 201. The front dipole arms 204a and 204b are shown in detail in Figure 10c).

[0075] In the bias network 203, shown in detail in Figure 10b), a capacitor 205 is provided to prevent reverse flow of the DC bias current supplied at V1 towards the RF connector 201. An inductor 206 is provided between V1 and the feed line 202 to prevent reverse flow of the RF current into the DC bias circuit. A resistor 208 is provided in the bias network 203 to control the DC bias current to an appropriate level for the pin diodes 207a and 207b that connect the feed line 202 to the front diode arms 204a and 204b. As shown in Figure 10c), the DC bias current is terminated at V2 or V3 via inductors 209, 210 and resistors 211 and 212, respectively.

[0076] As shown in Figure 11, a ground strip line 213 is provided on the back surface of the dielectric substrate 200a. The ground strip line 213 extends along the path of the feed line 202 and includes rear-side dipole arms 214a and 214b facing away from the RF connector 201. The ground strip line 213 is located at a distance of one-quarter wavelength from the feed line 202 and functions as a reflector directing the radiation of the dipole antenna in the y-axis direction.

[0077] Each of the front and rear dipole arms 204a, 214a and 204b, 214b defines a pair of dipoles, one on each side of the feed line 202 and the ground strip line 213. The dipoles can be excited separately or together depending on the operation of the PIN diodes 207a and 207b. For example, when the PIN diode 207a is switched to supply current to the front dipole arm 204a, the dipole formed by the front dipole arm 204a and the rear dipole arm 214a is excited and ready for radiation. Similarly, when the PIN diode 207b is switched to supply current to the front dipole arm 204b, the dipole formed by the front dipole arm 204b and the rear dipole arm 214b is excited and ready for radiation. When only one dipole is excited and radiating, the beam is steered toward the corresponding side (positive or negative y-axis) of the LWA. When both dipoles are excited and radiating (in phase), the beam becomes a central beam.

[0078] Depending on whether one or both of the pin diodes 207a and 207b are switched ON by the illustrated printed dipole feed unit 150, the radiation of the main beam is directed to the left, right, or center, S 11 This makes it possible to maintain reflection losses below 10 dB. Once the appropriate state of PIN diodes 207a and 207b is set for the desired beam orientation, the bias voltage of the piezoelectric actuator 6 is changed, which adjusts the separation distance h2 and thus adjusts HIS1, steering the LWA main beam to the desired directional angle (e.g., elevation angle).

[0079] The above approach allows for beam steering in one direction (i.e., selection of an angle in a specific plane). For example, beam steering in Figure 8 is limited to the yz plane only. Adjusting the beam angle in the xz plane is not possible simply by adjusting the distance between the ground plate and the PRS2.

[0080] To enable 2D beam steering (for example, beam steering in two mutually orthogonal planes such as xz and yz), multiple feed points may be provided to couple an RF signal to a leaky wave antenna as described above. By controlling the relative phase of the RF signal in each of the multiple feed points, beam steering in the xz plane becomes possible. In polar coordinates, the adjustment of the beam angle due to the movement of the grounding plate can be considered as an adjustment of the elevation angle, and the adjustment of the beam angle due to the relative phase of the multiple feed points can be considered as an adjustment of the azimuth angle.

[0081] Figure 12 shows a leaky wave antenna device 101 according to an embodiment comprising a high-impedance surface (HIS) 1, a partial reflecting surface (PRS) 2, a feed array 155, and a reflector 153. Although not shown in Figure 12, the antenna device 101 also comprises a grounding plate and an actuator configured to adjust the distance between the grounding plate and the high-impedance surface 1 (as described above).

[0082] HIS1 may be similar to those described with reference to Figures 1b) and 8, and the features described for those examples are also applicable here. The antenna width (x direction) is 105.6 mm and the length (y direction) is 95.1 mm (approximately 10λ × 10λ for a design frequency of 26.5 GHz), but other dimensions may be used in other examples.

[0083] The feed array 155 is positioned between the HIS1 and PRS2, at the edge of the antenna device 101. The feed array 155 has multiple identical feed power supplies 15. In this example, there are 10 feed power supplies 15, but other numbers of feed power supplies may be used. Each feed power supply 15 is equivalent and is arranged in a linear array, spaced apart in the x-direction. In this example, the spacing between adjacent feed power supplies is 10 mm (other spacings may be used in other examples).

[0084] An example of a power supply 15 is shown in detail in Figure 13. The power supply 15 comprises a printed dipole antenna having a dielectric substrate (e.g., RT / Duroid 5880 with a thickness of 0.254 mm) and conductive elements (e.g., copper patterned by etching) on ​​both sides thereof. A high-frequency connector 201 (e.g., a miniature coaxial connector) is provided on the edge of the power supply 15. On the first surface of the substrate (shown in Figure 13b), the conductive elements include a strip line connecting a first dipole arm 204a to the connector 201. On the second surface of the substrate, the conductive elements include a second dipole arm 214b. The first and second dipole arms are oriented in opposite directions, with the first dipole arm 204a oriented in the -x direction and the second dipole arm 214a oriented in the +x direction). The printed dipole antenna is configured to radiate in the y direction when a suitable RF signal is supplied via the connector 201.

[0085] The RF signal can be distributed among the power sources 15 of the power supply array 155, and a beam can be formed by controlling the relative phase of the signal applied to each power source 15. According to linear phased array theory, the phase difference dφ at adjacent power supply points in a linear phased array is obtained as follows.

number

[0086] [Table 2]

[0087] Figure 14 shows a feed array 155 comprising 10 printed dipole antennas assembled independently of HIS1 and PRS2.

[0088] The choice of distance between feed points is important for defining the beam direction due to phase offset, and λ / 2 is often chosen. In this case, the spacing d between feed points 15 is 10 mm (approximately λ), which is the minimum spacing that can accommodate the printed dipole antenna shown in Figure 13. In the example in Figure 12, a phase controller (not shown) may be used to control the phase delay of each feed point 15.

[0089] The reflector 153 comprises thin conductive elements positioned perpendicular to the substrate of each power supply 15 (i.e., parallel to the xz plane) and on both sides of the power supply 15, which reflect the electromagnetic energy excited therefrom toward a cavity defined between HIS1 and PRS2. The electromagnetic waves propagate through the cavity and "leak" from PRS2 in the direction of the yz plane determined by the distance between HIS1 and a ground plate (not shown), as described with reference to Figure 8, for example.

[0090] Figure 15 shows the simulated radiation pattern 250 from antenna 101, demonstrating that by moving the grounding plate 3 (relative to HIS1 and PRS2 to change d2), the beam can be steered in the yz plane such that the peak gain direction 251 of the radiation pattern 250 from antenna 101 is a selectable angle θ in the yz plane. The grounding plate 3 is shown in Figure 15 (the offset between grounding plate 3 and HIS1 is not necessarily to scale).

[0091] Figure 16 shows a simulated radiation pattern 250 from antenna 101, demonstrating that the beam can be steered in the xz plane such that the peak gain direction 251 of the radiation pattern 250 from antenna 101 is a selectable angle θ in the xz plane by adjusting the relative phase of the RF signal applied to the feed 15. In Figure 16, the phase difference dφ between adjacent feed 15s is indicated by the x-direction arrow 252.

[0092] Figure 17 shows the results obtained when the beam direction is set to 10° in the xz plane (by controlling the relative phase of the power supply 15) and 20° in the yz plane (by controlling the distance h2).

[0093] The complete simulation results of beam scanning in both the xz and yz planes are shown in the table below (: frequency, f; beam steering angle θ in the xz plane; beam steering angle θ in the yz plane; displacement / modification of h2; directivity; maximum achieved gain; total efficiency, radiant efficiency, sidelobe level (SLL) in the xz plane; and sidelobe level in the yz plane).

[0094] [Table 3]

[0095] The results show that antenna 101 performs well within a range of ±48° in the yz plane and ±25° in the xz plane. Directivity is in the range of 17.31 to 26 dBi, while radiation efficiency is maintained at unprecedented levels because this structure does not incur significant losses. The total efficiency begins to decrease when the beam is directed at extreme angles due to a mismatch between the resonant frequencies of the fed dipole and the rest of the structure (shift from 26.5 GHz to 27.5 GHz).

[0096] One of the challenges with antenna array 101 is the sidelobe level (SLL), which begins to degrade when the beam is steered over a wide angle. Sidelobes can be suppressed by selectively tapering the amplitude of the RF signals introduced into different feed sources. In this antenna, a broadside beam direction (i.e., parallel to the z-direction and 0° in the xz and yz planes) is not possible.

[0097] Antenna 101 employs multiple separate power supplies 15, each mounted on a separate circuit board. This is not mandatory, and in some embodiments, the multiple power supplies may be mounted on a single circuit board, which may allow for smaller spacing between the power supply elements.

[0098] An alternative leak wave antenna 102 is shown in Figure 18. The antenna is similar to that in Figure 12, and the features described with reference to Figure 12 are applicable to Figure 18. However, in antenna 102, the feed array 156 is located in the center of antenna 102 and is bidirectional. The size of antenna 102 has also been increased to W × L = 79.4 mm × 184.9 mm (approximately 7λ × 16λ).

[0099] As clearly shown in Figure 19, the power supply array 156 comprises a single power supply board with multiple printed dipoles. Each printed dipole is the same as those described with reference to Figures 10 and 11, and the features described above are applicable as a whole to the dipoles of the power supply array 156, and similar features are denoted by the same reference numerals in Figures 19-22.

[0100] In contrast to the power supply unit 150 shown in Figures 10 and 11, each power supply dipole 150a in the power supply array 156 is powered by individual ports 301. Each power supply dipole 150a has a signal port 301 on the front side of the board 200a and a corresponding ground port on the rear side of the board 200a. The relative phase of the signals supplied to each port 301 is controlled by a phase controller (not shown). The ports 301 are numbered 1 to 11, starting from the lower (-y) left (-x) corner and moving towards the lower (-y) right (+x) corner. The ports 301 are numbered 12 to 22, starting from the upper (+y) right (+x) corner and moving towards the upper (+y) left (-x) corner.

[0101] When ports 1-11 are excited, electromagnetic waves are introduced into the antenna and propagate in the -y direction. When ports 12-22 are excited, electromagnetic waves are introduced into the antenna and propagate in the +y direction. When all ports 1-22 are excited, the beam is scanned in the broadside direction, which was not possible in the examples in Figures 12 to 17. This approach makes it possible to apply amplitude and phase independently to each feed point, and allows for an increase in the beam scanning angle due to the small spacing of the feed point dipoles 150a.

[0102] A reflector 153 is provided perpendicular to the substrate 200a of the power supply array 156, which helps to direct the RF signal in the desired direction and suppress unwanted reflections.

[0103] By arranging two or more power supplies on a common board in this way, This makes it possible to reduce the distance between adjacent power sources (for example, to a distance of λ / 2 or less). The closer proximity of the power sources expands the beam scanning range of antenna 102.

[0104] Figures 22 and 23 show beam scanning in the xz and yz planes, respectively, by controlling the phase difference dφ between the power supplies 150a and by changing the distance h2 between the grounding plate 3 and HIS1, in a manner very similar to that shown (and described) in Figures 15 and 16.

[0105] Figure 24 shows a broadside beam where the beam direction is 0° in the xz plane and 0° in the yz plane.

[0106] Figure 25 shows the simulated radiation pattern 250 of the leaky wave Fabry-Perot antenna shown in Figures 18-21, with beam directions of 10° in the xz plane and 20° in the yz plane.

[0107] The antenna designs shown in Figures 18-21 were simulated to determine their performance, and the results are shown in the table below.

[0108] [Table 4]

[0109] This antenna design allows scanning in the xz plane at an angle of θ = ±30° (a slightly larger range than that shown in the previous design). Scanning in the yz plane is similarly achieved by displacement between the ground plate and the HIS (e.g., by a piezoelectric actuator), and the scanning angle range in the yz plane remains the same at θ = ±42°. Performance metrics in this design are significantly improved. SLL is reduced to a range of -6.9 to -16 dB, and further improvements are possible for very wide angles by tapering the amplitude of the signal supplied to different feed points.

[0110] Other advantages of this approach include the ability to activate as many (or fewer) power sources as desired, and to change the beam width of the main lobe (in some cases and applications, a wider beam is required).

[0111] In some embodiments, the RF power supply cable may be directly connected to the bottom side of the power supply array (which may protrude through HIS1 or PRS2 in some embodiments).

[0112] In some embodiments, a single-point feeding mechanism may be used for the leaky wave antenna, and the excitation and phase difference control of the fed dipole may be achieved by a varactor and diode connected to a feeding array board. A bias network may be provided on the feeding array board.

[0113] Throughout this specification and in its claims, the terms “comprise” and “contain” and their variations mean “including, but not limited to,” and are not intended to exclude other elements, integers, or steps. Throughout this specification and in its claims, singular forms include plural forms unless otherwise specified in the context. In particular, where the indefinite article is used, this specification should be understood to intend both plural and singular forms unless otherwise specified in the context.

[0114] While exemplary embodiments have been described, further modifications are possible, and the scope of the invention should be determined by reference to the appended claims.

Claims

1. Leakage wave antenna device: Partially reflective surface; conductive ground plate; Actuator; A power supply array comprising multiple spaced-apart power supplies, each arranged to couple a high-frequency input signal to the antenna. A leaky wave antenna device comprising the following, wherein the partial reflecting surface and the conductive ground plate are stacked and substantially parallel to each other, with a cavity defined between them; An antenna device configured such that the beam formed by the antenna device can be steered in a first direction by the operation of the actuator, and in a second direction by changing the relative phase of the high-frequency signal coupled to the cavity by each of the power supplies.

2. The antenna device according to claim 1, wherein the power supply is arranged in a linear one-dimensional array.

3. The antenna device according to claim 2, wherein the power supply is located at the edge of the cavity.

4. The antenna device according to claim 2, wherein the power supply is located in the center within the cavity.

5. The antenna device according to any one of claims 1 to 4, wherein each power supply is equipped with a dipole.

6. The antenna device according to claim 5, wherein the power supply array comprises an array of pairs of radiated power supply elements arranged on a power supply substrate.

7. The antenna device according to claim 6, wherein each pair of radiating power-feeding elements comprises a first radiating power-feeding element arranged to couple the high-frequency signal to a first surface of the cavity, and a second radiating power-feeding element arranged to couple the high-frequency signal to a second surface of the cavity.

8. The antenna device according to claim 7, wherein each first radiating feeding element comprises a first dipole arm on the front of the feeding board and a second dipole arm on the back of the feeding board, and each second radiating feeding element comprises a first dipole arm on the front of the feeding board and a second dipole arm on the back of the feeding board.

9. The antenna device according to any one of claims 1 to 8, wherein each of the aforementioned power supplies is provided with a power supply port for receiving high frequencies having a selected phase and / or amplitude.

10. The antenna device according to any one of claims 1 to 9, wherein the power supply array comprises i) a control element configured to control which of the power supplies is excited by a high-frequency signal, and / or ii) the relative phase and / or amplitude of the high-frequency signals coupled to each power supply.

11. The antenna device according to claim 10, wherein the power supply array is configured to fix the relative phase and amplitude of the signals supplied to each power supply.

12. The antenna device according to claim 10, comprising the subject matter of claim 7, wherein the control element is operable so that the first dipole and the second dipole can be excited together or separately.

13. The antenna device according to claim 11, wherein the power supply array comprises one or more switching devices arranged to reconfigure the coupling between the high-frequency signal and the cavity.

14. The antenna device according to any one of claims 1 to 13, further comprising a phase shifter configured to change the relative phase of the high-frequency signals supplied to each of the aforementioned power supplies.

15. The antenna device according to any one of claims 1 to 14, wherein the partial reflective surface comprises a metasurface having a periodically patterned conductive layer, and the antenna device is a Fabry-Perot leaking wave antenna.

16. The antenna device according to any one of claims 1 to 15, further comprising a high-impedance surface disposed in the cavity between the partial reflective surface and the conductive ground plate.

17. The antenna device according to claim 16, wherein the high-impedance surface comprises a periodically patterned conductive layer.

18. The antenna device according to any one of claims 1 to 17, wherein the actuator comprises a piezoelectric actuator.

19. The antenna device according to any one of claims 1 to 18, wherein the actuator is configured to move the partial reflective surface or the conductive grounding plate.

20. The antenna device according to any one of claims 1 to 19, wherein the conductive grounding plate comprises a plurality of grounding plate sections, and the actuator is configured to independently change the distance between the partial reflective surface and each of the grounding plate sections.

21. The antenna device according to any one of claims 1 to 20, wherein the interval between the power supply units is less than the wavelength of the operating frequency of the antenna device.

22. The antenna device according to any one of claims 1 to 21, wherein the actuator is configured to adjust the distance between a conductive ground plate and a partial reflective surface, or the antenna device according to claim 16, wherein the actuator is configured to adjust the distance between a conductive ground plate and a partial reflective surface, and / or the distance between a conductive ground plate and a high impedance surface.

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