Multi-beam VICTS antenna and communication terminal

Abstract

The invention discloses a multi-beam VICTS antenna and a communication terminal, and the multi-beam VICTS antenna is of a multi-layer structure, and comprises a continuous cross section node slot radiation layer, a slow wave structure wave guide layer and a microstrip Rotmann lens feed network layer which are sequentially arranged from top to bottom. An air gap between the continuous section nodal gap radiation layer and the slow wave structure wave guide layer forms a quasi-plane parallel plate waveguide. An electromagnetic wave signal emitted by a satellite antenna enters a quasi-planar waveguide formed by the continuous cross section and the slow wave structure wave guide layer through a gap in the continuous cross section joint gap radiation layer, and electromagnetic waves are transmitted in the quasi-planar waveguide and are sent to the microstrip Rotmann lens feed network through the connection waveguide. And the beam is output from the beam port of the microstrip Rotmann lens. The multi-beam VICTS antenna provided by the invention can utilize multi-beam scanning in the same time period, has larger space coverage capability, and is beneficial to quick satellite finding when a communication-in-moving system is started and quick satellite recapturing after a satellite signal is lost.

Description

Technical Field

[0001] The present invention relates to a multi-beam VICTS antenna based on a microstrip Rotman lens, which can be used for rapid satellite search when a communication-in-motion system is started or loses lock. Background Art

[0002] Communication on the Move (COTM) stands for "Communication on the Move Satellite Ground Station." Through this system, a satellite signal transceiver system installed on a mobile carrier can achieve real-time communication while the carrier is in motion, continuously and stably transmitting multimedia information such as voice and images. Upon startup, the COTM system needs to acquire a satellite within a short period of time. While tracking a target satellite, the COTM system often experiences loss of lock, resulting in loss of satellite signal and communication interruption. This is primarily due to two factors: geographical obstruction and drift of the inertial navigation system. First, when the antenna passes through complex environments such as urban buildings, green belts, and trees, it can be partially or completely obscured. Complex obstructions can cause intermittent signal levels. Second, the inertial sensors in the COTM system inevitably drift. As the COTM tracking control system operates, these drift errors are not compensated, and the errors accumulate over time, eventually causing the antenna beam to deviate from the target satellite. Achieving rapid communication with satellites and rapidly reacquiring satellites after signal loss presents broad development prospects in the current field of satellite communications.

[0003] Traditional antennas for satellite communications in motion include reflector antennas, mechanically scanned array antennas, and fully phased array antennas. Reflector antennas achieve continuous beam scanning through two-dimensional scanning in elevation and azimuth. However, these antennas are bulky and require complex servo systems. They are suitable for shipboard and vehicle-mounted applications, but not for airborne platforms. Mechanically scanned array antennas typically feature one-dimensional electronic scanning in azimuth, but still require mechanical actuation to achieve beam scanning in elevation. This causes the antenna's array surface to rise above the surface of the carrier platform, making them unsuitable for airborne applications. Fully phased array antennas offer two-dimensional electronic scanning and can be used on airborne platforms, but are expensive, and antenna gain drops rapidly with wide scanning angles. Variable Inclination Continuous Transverse Stub (VICTS) antennas are widely used in satellite communication terminals due to their beam scanning capabilities. Compared to fully phased array antennas, VICTS antennas achieve high gain and flexible beam scanning without requiring numerous expensive T / R components. The radiator of the VICTS antenna is a Continuous Transverse Stub (CTS) array. The CTS array is an array of long slots with uniform cross-sections, fabricated on the metal plate on the upper wall of a parallel plate waveguide. Branch matching is added to the transverse slots to achieve radiation. The CTS antenna is a leaky wave antenna. Electromagnetic waves travel in the parallel plate waveguide, generating leaky waves at the continuous transverse stubs along the way, thereby achieving antenna radiation. This antenna has high feed efficiency and aperture efficiency, and is a high-gain antenna. The efficiency of the CTS antenna can be as high as 85%. Although the traditional single-beam VICTS antenna can achieve large-angle two-dimensional (azimuth and elevation) continuous scanning, because it only has one main beam, the beam coverage space is small during the star search process and cannot meet the needs of high-speed star search. Summary of the Invention

[0004] Technical problem: The technical problem to be solved by the present invention is to provide a multi-beam VICTS antenna and communication terminal that covers a large search space and effectively shortens the time to capture satellites.

[0005] Technical solution: The purpose of the present invention is achieved through the following technical solutions: The present invention first provides a multi-beam VICTS antenna, comprising: a continuous section slot radiation layer, a slow-wave structure waveguide layer, and a microstrip Rotman lens feeding network layer arranged in order from top to bottom; The continuous section gap radiation layer is used to receive or transmit electromagnetic waves; There is a gap between the continuous section segment gap radiation layer and the slow wave structure waveguide layer, and a quasi-parallel plate waveguide is formed between the continuous section segment gap radiation layer and the slow wave structure waveguide layer for transmitting the electromagnetic wave signal received or emitted by the continuous section segment gap radiation layer; The microstrip Rotman lens feeding network layer is connected to the quasi-parallel waveguide, and is used to receive the electromagnetic wave signal transmitted by the quasi-parallel plate waveguide and generate a multi-beam signal, and the generated multi-beam signal is output from different beam ports; or is used to input the transmission signal from different beam ports to generate a multi-beam signal, and the generated multi-beam signal is transmitted through the quasi-parallel plate waveguide.

[0006] The continuous section slot radiation layer includes a circular metal plate and a CTS radiation branch group on the circular metal plate. The slot widths of the CTS radiation branch group are designed to meet the good sidelobe characteristics of the antenna. A rectangular step is arranged above the CTS radiation branch group to achieve good matching with free space.

[0007] There is a fixed gap between the continuous section slot radiation layer and the slow wave structure waveguide layer, forming a quasi-parallel plate waveguide therebetween for transmitting the electromagnetic waves received by the continuous section slot radiation layer to the microstrip Rotman lens feeding network.

[0008] The slow-wave structure waveguide layer and the microstrip Rotman lens feeding network layer are connected into a whole through a connecting waveguide. When the antenna is working, the whole structure rotates together.

[0009] The microstrip Rotman lens feed network is a microstrip structure, comprising a microstrip Rotman lens floor, a microstrip Rotman lens dielectric plate disposed on the microstrip Rotman lens floor, and a copper clad pattern disposed on the surface of the microstrip Rotman lens dielectric plate. The electromagnetic wave signal transmitted from the slow-wave structure waveguide layer to the microstrip Rotman lens network layer via the connecting waveguide is converted from the waveguide to the microstrip line through a waveguide-ridge waveguide-microstrip line transition.

[0010] The present invention also provides a communication terminal, comprising the multi-beam VICTS antenna provided above.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The present invention is a multi-beam VICTS antenna that combines a VICTS antenna with a Rotman lens. While having the advantage of large-angle continuous scanning, it can realize the simultaneous existence of multiple radiation (or reception) beams, so that the antenna can scan simultaneously through multiple beams, covering a large search space and effectively shortening the time required to capture a satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1This is a disassembled structural diagram of the multi-beam VICTS antenna of the present invention; Figure 2 A side view of the multi-beam VICTS antenna of the present invention; Figure 3 A side view of a partial detail of the multi-beam VICTS antenna of the present invention; Figure 4 This is a diagram showing the split structure of the waveguide layer and the internal cavity of the feed layer of the multi-beam VICTS antenna of the present invention; Figure 5 Schematic diagram of VICTS antenna beam scanning; Figure 6 This is the schematic diagram of the microstrip Rotman lens; Figure 7 This is a structural diagram of the microstrip Rotman lens of the multi-beam VICTS antenna of the present invention; Figure 8 Schematic diagram of the microstrip-ridge waveguide-waveguide transition structure; Figure 9 Schematic diagram of multi-beam scanning of the multi-beam VICTS antenna of the present invention. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is further introduced below in conjunction with specific implementation methods.

[0014] like Figure 1 As shown in the figure, the multi-beam VICTS antenna based on a microstrip Rotman lens provided by the present invention has an overall planar multi-layer structure. From top to bottom, it comprises a continuous cross-section slot radiation layer 1, a slow-wave structure waveguide layer 2, and a microstrip Rotman lens feed network layer 3. Two semicircular holes are cut in the slow-wave structure waveguide layer 2 to expose the microstrip Rotman lens feed network layer 3 located below it. Figure 2 and Figure 3 The cross-section of the multi-beam VICTS antenna is shown in Figure 2. The connection details between the slow-wave structure waveguide layer 2 and the microstrip Rotman lens feed network layer 3 are shown in Figure 3. Figure 4 For the sake of clarity, Figure 4 The slow-wave structure waveguide layer 2, microstrip Rotman lens feeding network layer 3, connecting waveguide 21 and leakage stop groove 22 only give the cavity outline. In fact, these structures are air cavities made in the metal block, which rotate together during beam scanning.

[0015] A plurality of transverse branch slots 11 are made on the continuous section slot radiation layer 1 of the multi-beam VICTS antenna. The widths of the transverse branch slots 11 are different and need to be designed separately to meet the good sidelobe characteristics of the antenna.

[0016] The upper portion of the slow-wave structure waveguide layer 2 is a quasi-parallel plate waveguide 23 formed between the layer and the continuous section slot radiation layer 1. The lower portion is a cavity 24 for accommodating the microstrip Rotman lens feed network layer 3. A connecting waveguide 21 connecting the quasi-parallel plate waveguide 23 and the lower cavity 24 is formed at the end of the slow-wave structure waveguide layer 2. The microstrip Rotman lens feed network layer 3 is disposed within the lower cavity 24. A waveguide-ridge waveguide-microstrip line transition 4 is disposed within the lower cavity 24 to connect the connecting waveguide 21 and the microstrip Rotman lens feed network layer 3.

[0017] When the antenna is used for receiving, the electromagnetic waves received by the continuous section slot radiation layer 1 are transmitted in the quasi-parallel plate waveguide formed by the continuous section slot radiation layer 1 and the slow wave structure waveguide layer 2. Then, through the connecting waveguide 21, the waveguide-ridge waveguide-microstrip line transition 4, and the microstrip line 5, the signal is input into the microstrip Rotman lens feed network layer 3 and transmitted to the beam port to form a receiving beam. If the continuous section slot radiation layer 1 is driven to rotate independently by a servo motor, pitch angle scanning can be achieved, such as Figure 5 When the motor drives the continuous section slot radiation layer 1 and the slow wave structure waveguide layer 2 to rotate together, the multi-beam VICTS antenna can achieve azimuth scanning. The connecting waveguide 21 is provided with a matching step 211, see Figure 4 On one side of the connecting waveguide 21 is a leakage prevention groove 22 for preventing leakage of electromagnetic waves.

[0018] Figure 6 This diagram illustrates the integrated module of a microstrip Rotman lens and antenna, illustrating its operating principle. When electromagnetic waves are fed from one of beam ports 11 (1, 2, 3, ..., M) and reach the antenna array 13 (1, 2, 3, ..., N) at array port 12 (array port), a linear phase gradient is generated at each antenna, resulting in a beam pointing corresponding to that port. Feeding from different beam ports produces different phase gradients and beam pointings at the antenna array, enabling spatial scanning within a certain range. When fed simultaneously from different beam ports, the antenna can simultaneously generate multiple beam pointings, each corresponding to the feed port. According to the reciprocity principle, when an antenna receives electromagnetic waves from multiple directions, it generates signal outputs at different beam ports.

[0019] The microstrip Rotman lens of the present invention has 7 beam ports 31 and 12 array ports 32. There are 5 idle ports on both sides of the lens, which are generally connected to matching loads to absorb stray electromagnetic waves. The radio frequency signal transmitted from the slow wave structure waveguide layer 2 to the microstrip Rotman lens feed network layer 3 through the connecting waveguide 21 must be converted from the waveguide to the microstrip line through the waveguide-ridge waveguide-microstrip line transition 4. The unit structure of a waveguide-ridge waveguide-microstrip line transition 4 is as follows: Figure 3 and 7 As shown in the dotted box, each unit of the waveguide-ridge waveguide-microstrip line transition 4 includes two metal isolation walls 41 and a metal ridge 42 set between the two metal isolation walls. The metal ridge 42 is provided with a step matching structure 421. Figure 8 By varying the height of the step 421 on the metal ridge, mode conversion and impedance matching from the waveguide to the microstrip line can be achieved. One side of the microstrip line is connected to the underside of the metal ridge, and the other side is connected to the array port 32 of the Rotman lens. After the multi-beam signal is transmitted from the waveguide to the microstrip line, it is input into the Rotman lens network 3 through the array port 32 and output at the beam port 31. The signal outputs from different ports in the beam port 31 correspond to receive beams with different directions.

[0020] When the VICTS antenna is interconnected with the Rotman lens feed network, the antenna can simultaneously receive (or radiate) electromagnetic waves in multiple directions, i.e., a multi-beam VICTS antenna. When there is relative rotation between the radiating layer and the slow-wave structure layer, the multiple beams of the antenna scan in the elevation plane; when the antenna rotates as a whole, the multiple beams rotate around the normal direction to achieve azimuth scanning, such as Figure 9 As shown in the figure. In practical applications, the radiation layer, slow-wave structure layer, and feed layer will be mounted on two coaxial drive motors. After power is applied, the servo control system achieves relative rotation of the two parts. Because multiple beams are simultaneously involved in scanning, the airspace covered by multiple beams is much larger than that covered by a single beam in the same amount of time. Therefore, through the two rotational motions mentioned above, the multi-beam VICTS antenna based on the microstrip Rotman lens can effectively increase the beam scanning rate, achieving rapid beam scanning across the entire upper half of space, which is conducive to rapid satellite search.

Claims

1. A multi-beam VICTS antenna, characterized in that: include: The continuous section slot radiation layer, slow wave structure waveguide layer and microstrip Rotman lens feeding network layer are arranged in order from top to bottom; The continuous section gap radiation layer is used to receive or transmit electromagnetic waves; There is a gap between the continuous section segment gap radiation layer and the slow wave structure waveguide layer, and a quasi-parallel plate waveguide is formed between the continuous section segment gap radiation layer and the slow wave structure waveguide layer for transmitting the electromagnetic wave signal received or to be transmitted by the continuous section segment gap radiation layer; The microstrip Rotman lens feeding network layer is connected to the quasi-parallel waveguide, and is used to receive the electromagnetic wave signal transmitted by the quasi-parallel plate waveguide and generate a multi-beam signal, and the generated multi-beam signal is output from different beam ports; or is used to input the transmission signal from different beam ports to generate a multi-beam signal, and the generated multi-beam signal is transmitted through the quasi-parallel plate waveguide.

2. The multi-beam VICTS antenna according to claim 1, characterized in that: The upper part of the slow-wave structure waveguide layer is a quasi-parallel plate waveguide formed between the layer and the continuous section gap radiation layer, the lower part of the slow-wave structure waveguide layer is a cavity for placing the microstrip Rotman lens feeding network layer, and a connecting waveguide connecting the quasi-parallel plate waveguide and the lower cavity is formed at the end of the slow-wave structure waveguide layer; the microstrip Rotman lens feeding network layer is arranged in the lower cavity.

3. The multi-beam VICTS antenna according to claim 2, characterized in that: The microstrip Rotman lens feed network layer is a microstrip structure, including a microstrip Rotman lens floor, a microstrip Rotman lens dielectric plate and a microstrip Rotman lens; the microstrip Rotman lens dielectric plate is arranged on the upper surface of the microstrip Rotman lens floor; the microstrip Rotman lens is a copper-clad pattern arranged on the upper surface of the microstrip Rotman lens dielectric plate.

4. The multi-beam VICTS antenna according to claim 3, characterized in that: The copper-clad pattern on the upper surface of the microstrip Rotman lens dielectric plate includes a beam port, an array port and an idle port; the array port of the microstrip Rotman lens is connected to the quasi-parallel waveguide.

5. The multi-beam VICTS antenna according to claim 4, characterized in that: A waveguide-ridge waveguide-microstrip line transition is provided between the quasi-parallel wave waveguide and the microstrip line of the microstrip Rotman lens feeding network layer. The waveguide-ridge waveguide-microstrip line transition is used to realize the transition conversion from the quasi-parallel waveguide to the microstrip line, thereby realizing the interconnection between the quasi-parallel waveguide and the Rotman lens network layer.

6. The multi-beam VICTS antenna according to claim 5, characterized in that: The waveguide-ridge waveguide-microstrip line transition device comprises two metal isolation walls and a metal ridge arranged between the two metal isolation walls.

7. The multi-beam VICTS antenna according to claim 6, characterized in that: A step matching structure is provided on the metal ridge, and mode conversion and impedance matching from waveguide to microstrip line are achieved by changing the height of the metal ridge.

8. The multi-beam VICTS antenna according to any one of claims 1 to 7, characterized in that: The continuous section node gap radiation layer includes a circular metal plate and a CTS radiation branch node group on the circular metal plate.

9. The multi-beam VICTS antenna according to any one of claims 1 to 7, characterized in that: The slow-wave structure waveguide layer and the microstrip Rotman lens feeding network layer are connected into a whole through a connecting waveguide; the continuous cross-section section radiation layer is rotatable relative to the whole formed by the slow-wave structure waveguide layer and the microstrip Rotman lens feeding network layer, thereby realizing continuous scanning of the azimuth and elevation beams.

10. A communication terminal comprising the multi-beam VICTS antenna according to any one of claims 1 to 9.

Images