A low-cost passive phased array antenna

Abstract

The present invention discloses a low-cost passive phased array antenna, which belongs to the technical field of microwave millimeter wave antennas. The phased array antenna adopts a modular design, and is composed of a radiation module, a phase shifting module and a feeding network. In the phase shifting module, a dielectric loaded phase shifter is proposed: that is, by opening a non-radiation slot on the axis of the wide surface of the rectangular waveguide, and then loading a dielectric thin plate through the non-radiation slot, the penetration depth of the dielectric thin plate is controlled by a micromotor / micromotor of a phase adjustment device, thereby changing the transmission phase of the rectangular waveguide. The dielectric loaded phase shifter is further used in the design of a phased array antenna: after integrating the radiation module and the feeding network, the beam scanning is completed by adjusting the loading depth of the dielectric plates in different channels in real time. The present invention is suitable for applications where the scanning angle requirements are not too high, but the power capacity and cost requirements are relatively high.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave and millimeter wave antennas, and in particular to a low-cost passive phased array antenna. Background Art

[0002] Beam scanning is a key technology in antenna design. Generally speaking, it can be achieved through mechanical scanning or electronic scanning. Mechanical scanning uses a motor to drive gears and other transmission devices to achieve changes in the physical position of the array, thereby changing the beam pointing; a typical representative of electronic scanning is the phased array antenna, whose beam scanning principle is to use phase shifters or time delay technology to achieve changes in the array phase wavefront, while the antenna body can remain fixed. Compared with mechanical scanning, electronic scanning is fast, but the cost is higher. How to achieve low-cost phased array antennas is a hot topic of concern in academia and industry, and it has important research value and application prospects.

[0003] According to public reports, the main ways to achieve low-cost phased arrays are device loading and sparse arrays. The former replaces traditional phase shifters by loading low-cost PIN tubes or varactors on antenna units or feed transmission lines. However, due to the low cutoff operating frequency of the loaded device itself, the antenna performance is difficult to meet the requirements of engineering applications at the high end of the microwave band and the millimeter wave band. For example, the document "A defected microstrip structure (DMS)-based phase shifter and its application to beamforming antennas" C. Ding et al, IEEE Transactions on Antennas and Propagation, vol. 62, no. 2, pp. 641-651, 2014 proposed a beam scanning array antenna operating in the C band, which loads multiple groups of PIN diodes on the microstrip line feed network and controls their on and off states to achieve a stepped phase difference of the antenna unit, thereby forming a limited number of discrete beam states. The document “Steerable dielectric resonator phased-array antenna based on inkjet-printed tunable phase shifter with BST metal-insulator-metal varactors” M.Nikfalazar et al, IEEE Antennas and Wireless Propagation Letters, vol.15, pp.877-880, 2016 introduces a phased array antenna based on a varactor tube, which operates around 8 GHz and achieves ±30° beam steering by loading a bias voltage of 50 V.

[0004] Another way to achieve low-cost phased arrays is to use sparse arrays, such as the method used in the literature "Design of low-complexity 3-D underwater imaging system with sparse planar arrays" DD Zhao et al, IEEE Transactions on Instrumentation and Measurement, vol. 68, no. 10, pp. 3418-3432, 2019. The idea is to reduce the number of antenna units and channels by optimizing the array layout, thereby reducing costs, at the cost of lower antenna aperture efficiency.

[0005] It can be seen from the existing technology that it is difficult to strike a balance between performance and cost for phased array strategies. Summary of the invention

[0006] In view of this, the present invention provides a low-cost passive phased array antenna. The manufacturing method has the advantages of strong operability, low cost, high precision, etc.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A low-cost passive phased array antenna, comprising a radiation module, a phase shift module and a feeding network connected in sequence; the radiation module is a waveguide aperture array, which is composed of a plurality of parallel aperture radiation units; the aperture radiation unit comprises an inner aperture, an outer aperture and a step transition between the inner aperture and the outer aperture;

[0009] The phase shift module includes a dielectric-loaded waveguide phase shifter and a phase adjustment device; the dielectric-loaded waveguide phase shifter includes a rectangular waveguide, a rectangular groove is provided on the wide surface of the rectangular waveguide, and a dielectric plate penetrating into the rectangular waveguide is provided in the rectangular groove; the phase adjustment device is used to adjust the penetration depth of the dielectric plate in the rectangular waveguide to change the phase shift amount; the axis of the rectangular groove coincides with the axis of the wide surface of the rectangular waveguide 211, and the extension direction of the rectangular groove is the same as the extension direction of the rectangular waveguide;

[0010] The feeding network includes a cascaded waveguide power divider and a port transition structure.

[0011] Furthermore, the width of the rectangular groove 212 is greater than the thickness of the dielectric plate 213 , the length of the rectangular groove 212 is greater than the length of the dielectric plate 213 , and the height of the dielectric plate 213 is greater than the height of the rectangular waveguide 211 .

[0012] Furthermore, there is at least one rectangular groove, and the central axis of each rectangular groove coincides with the central axis of the wide surface where it is located.

[0013] Furthermore, a rectangular groove is provided on one wide surface of the rectangular waveguide, or rectangular grooves are provided on two opposite wide surfaces.

[0014] Furthermore, the shape of the dielectric plate acting in the rectangular waveguide cavity is rectangular, trapezoidal or elliptical.

[0015] Furthermore, the phase adjustment device 22 includes a driving motor 221 , a lifting device 222 , a clamp 223 and a platform 224 .

[0016] Furthermore, the driving motor is a micromotor.

[0017] The beneficial effects of the above technical solution of the present invention are:

[0018] The present invention realizes a phase-variable waveguide phase shifter by opening a non-radiative slot on the axis of the waveguide wide surface, loading a dielectric thin plate with adjustable penetration depth through the non-radiative slot, and using the phase shifter in the design of an array antenna to achieve continuous beam scanning. The invented low-cost phased array antenna has the characteristics of broadband, high efficiency, and large power capacity, and can be expanded to the millimeter wave frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of the structure of a phase shift module according to an embodiment of the present invention;

[0021] Figure 3 is an assembly diagram of a dielectric loaded phase shifter according to an embodiment of the present invention;

[0022] Figure 4 is a structural diagram of a radiation module according to an embodiment of the present invention;

[0023] Figure 5 is a schematic diagram of the composition of a feeding network according to an embodiment of the present invention;

[0024] Figure 6 It is a typical beam scanning simulation diagram of an embodiment of the present invention.

[0025] In the figure: radiation module 1, aperture radiation unit 11, outer aperture 111, inner aperture 112, step transition 113, phase shift module 2, dielectric loaded waveguide phase shifter 21, rectangular waveguide 211, rectangular slot 212, dielectric plate 213, phase adjustment device 22, drive motor 221, lifting device 222, fixture 223, platform 224, feeding network 3, waveguide power divider 31, port transition structure 32. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] A low-cost phased array antenna, from front to back, is a radiation module 1, a phase shift module 2 and a feeding network 3. The radiation module 1 is a waveguide aperture array, which is composed of a plurality of aperture radiation units 11. The aperture radiation unit 11 includes an outer aperture 111, an inner aperture 112 and a step transition 113; the phase shift module 2 is composed of a dielectric loaded waveguide phase shifter 21 and a phase adjustment device 22. The dielectric loaded waveguide phase shifter 21 is composed of a rectangular waveguide 211, a rectangular slot 212 and a dielectric plate 213. The phase adjustment device 22 is composed of a driving motor 221, a lifting device 222, a fixture 223 and a platform 224; the feeding network 3 is composed of a plurality of waveguide power dividers 31 and a port transition structure 32 in cascade.

[0029] Furthermore, the rectangular groove 212 is located on one wide side of the rectangular waveguide 211, and its axis coincides with the wide side axis of the rectangular waveguide 211, and the groove depth is the same as the waveguide wall thickness. The width of the rectangular groove 212 is slightly greater than the thickness of the dielectric plate 213, and the length of the rectangular groove 212 is slightly greater than the length of the dielectric plate 213. The height of the dielectric plate 213 is greater than the height of the rectangular waveguide 211.

[0030] Furthermore, the dielectric plate 213 enters the rectangular waveguide 211 through the rectangular slot 212 to form a dielectric loaded waveguide phase shifter 21 , and the phase shift amount is changed by adjusting the penetration depth of the dielectric plate 213 in the rectangular waveguide 211 .

[0031] Furthermore, the shape of the dielectric plate 213 can be changed by cutting or chamfering, such as a trapezoidal shape, to improve the reflection characteristics of the electromagnetic waves in the rectangular waveguide 211 .

[0032] Furthermore, the inner aperture 112 has the same cross-sectional dimensions as the rectangular waveguide 211 , and the step transition 113 may be a multi-step transition structure to achieve a gradual structural change from the inner aperture 112 to the outer aperture 111 , and together with the outer aperture 111 , undertake impedance transformation between the outlet of the rectangular waveguide 211 and free space.

[0033] The following is a more specific embodiment:

[0034] The structure of this embodiment is as follows Figures 1 to 5 As shown, it includes, from front to back, a radiation module 1, a phase shift module 2 and a feeding network 3.

[0035] like Figure 1 As shown, one side of the radiation module 1 is connected to the free space, the combining port of the feeding network 3 is connected to the transceiver, and the other sides of the radiation module 1 and the feeding network 3 are respectively connected to the two ends of the phase shift module 2.

[0036] like Figure 2 and 3As shown, the phase shift module 2 is composed of a dielectric loaded waveguide phase shifter 21 and a phase adjustment device 22. The dielectric loaded waveguide phase shifter 21 is composed of a rectangular waveguide 211, a rectangular slot 212 and a dielectric plate 213. The phase adjustment device 22 is composed of a driving motor 221, a lifting device 222, a clamp 223 and a platform 224. The loading depth of the dielectric plate 213 in the rectangular waveguide 211 is controlled by the phase adjustment device 22, thereby adjusting the phase shift amount of the rectangular waveguide segment. Beam scanning is achieved by dynamically configuring the phase shift amount of each phase shift channel.

[0037] In the embodiment, since the dielectric plate 213 enters the waveguide through the non-radiative slot on the central axis of the wide surface of the rectangular waveguide 211, that is, the rectangular slot 212, to achieve loading, the insertion loss of the phase shifter mainly comes from dielectric loss and reflection loss, and the contribution of radiation loss can be ignored. In order to reduce the reflection loss, the shape of the dielectric plate 213 can be changed by cutting or chamfering, for example Figure 1 The trapezoidal structure shown in the figure. In order to ensure high power characteristics as much as possible, the top of the wedge-shaped structure can be rounded to eliminate the tip discharge phenomenon.

[0038] like Figure 4 As shown, the radiator 1 is composed of a plurality of aperture radiating units 11. The aperture radiating unit 11 includes an outer aperture 111, an inner aperture 112 and a step transition 113. The step transition 113 can be a multi-step transition structure to achieve a gradual change in structure from the inner aperture 112 to the outer aperture 111, and together with the outer aperture 111, it undertakes the impedance transformation between the outlet of the rectangular waveguide 211 and the free space, thereby further improving the reflection characteristics of the antenna.

[0039] like Figure 5 As shown, the feeding network 3 is composed of a plurality of waveguide power dividers 31 and a port transition structure 32 cascaded together for channel synthesis and interface conversion, thereby realizing low-loss interconnection between the phased array antenna and the transceiver.

[0040] A specific design of a low-cost phased array antenna has been completed for this solution. In this embodiment, a low-cost phased array antenna is a 1×4 array with a center frequency of 10GHz, and an electromagnetic full-wave simulation is performed on it in Ansys Electronics Desktop. The size of the outer aperture 111 of the aperture radiation unit 11 is 19.05mm×13.03mm, and the length is 4.5mm; the size of the inner aperture 112 is 19.05mm×9.525mm, which is the same as the inner size of the cross-section of the standard BJ120 rectangular waveguide. The array element spacing between the aperture radiation unit 11 and the adjacent radiation unit is selected to be 22.05mm, that is, 0.735λ0. The rectangular waveguide 211 in the dielectric loaded waveguide phase shifter 21 uses a standard BJ120 rectangular waveguide tube, and the material can be aluminum, copper, or aluminum alloy, copper alloy, etc.; the length of the rectangular slot 212 is 180mm, the width is 0.9mm, and the thickness is the same as the wide surface thickness of the rectangular waveguide 211; the material of the dielectric plate 213 is Rogers R04003, the dielectric constant is 3.55, the loss tangent is 0.0027, the thickness is 0.813mm, the length is 178mm, the two ends are cut corners, and the overall shape is trapezoidal. In order to obtain the maximum phase shift, the maximum insertion depth of the dielectric plate 213 is selected to be the narrow side size of the rectangular waveguide tube, that is, 9.525mm, and the dielectric plate is designed to reserve a connection part for connecting with the clamp 223 in the phase adjustment device 22. The driving motor 221 drives the lifting device 222 to adjust the loading depth of the dielectric plate 213 in the rectangular waveguide 211. The phase adjustment device 22 adopts a micromotor / micromotor structure to achieve miniaturization design. The feeding network 3 includes two-stage 1-to-2-way H-plane waveguide power dividers 31 and a port transition structure 32, which is simplified as an E-plane waveguide elbow. The simulation results show that the designed 1×4 array has an antenna voltage standing wave ratio of less than 2 in the range of 9GHz to 11GHz. By adjusting the loading depth of the four dielectric plates, continuous beam scanning of ±23° can be achieved. Figure 6 At the center frequency, the scanning gain is less than 1dB, and within the scanning angle, the antenna efficiency is greater than 70%.

Claims

1. A low-cost passive phased array antenna, comprising a radiation module, a phase shift module and a feeding network connected in sequence; characterized in that: The radiation module is a waveguide aperture array, which is composed of a plurality of parallel aperture radiation units; the aperture radiation unit includes an inner aperture, an outer aperture, and a stepped transition between the inner aperture and the outer aperture; The phase shift module comprises a dielectric-loaded waveguide phase shifter and a phase adjustment device; the dielectric-loaded waveguide phase shifter comprises a rectangular waveguide, a rectangular groove is provided on a wide surface of the rectangular waveguide, a dielectric plate penetrating into the rectangular waveguide is provided in the rectangular groove; the phase adjustment device is used to adjust the penetration depth of the dielectric plate in the rectangular waveguide to thereby change the phase shift amount; the axis of the rectangular groove coincides with the axis of the wide surface of the rectangular waveguide (211), and the extension direction of the rectangular groove is the same as the extension direction of the rectangular waveguide; The feed network includes a cascaded waveguide power divider and a port transition structure; The width of the rectangular groove (212) is greater than the thickness of the dielectric plate (213), the length of the rectangular groove (212) is greater than the length of the dielectric plate (213), and the height of the dielectric plate (213) is greater than the height of the rectangular waveguide (211); There is at least one rectangular groove, and the central axis of each rectangular groove coincides with the central axis of the wide surface where it is located.

2. A low-cost passive phased array antenna according to claim 1, characterized in that: A rectangular groove is arranged on one wide surface of the rectangular waveguide, or rectangular grooves are arranged on two opposite wide surfaces.

3. A low-cost passive phased array antenna according to claim 1, characterized in that: The shape of the dielectric plate acting in the rectangular waveguide cavity is rectangular, trapezoidal or elliptical.

4. The low-cost passive phased array antenna according to claim 1, characterized in that: The phase adjustment device (22) comprises a drive motor (221), a lifting device (222), a clamp (223) and a platform (224).

5. A low-cost passive phased array antenna according to claim 4, characterized in that: The driving motor is a micro motor.

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