An implementation method for improving the working bandwidth of an existing antenna

Abstract

The application discloses an implementation method for improving the working bandwidth of an existing antenna and relates to the technical field of antennas. The method comprises the following steps: determining the position and contour of a turnover mechanism according to the size of the original feed network structure; estimating the radiation aperture and physical size of a new feed source according to the newly-added working frequency band and the position of the turnover mechanism and in combination with a reflector antenna model; selecting a small phased array as the new feed source; taking the performance of the reflector antenna as a target, using an optimization algorithm to perform amplitude-phase weighting optimization on each unit of the array feed source; and designing a corresponding simulation link according to the weighting coefficient. The working switching of the new frequency band array feed source and the original feed source is realized through the turnover mechanism, the new feed source adopts an array and compensates for the energy loss caused by longitudinal defocusing through amplitude-phase weighting of each unit, the working frequency band can be effectively widened without affecting the performance of the original antenna, and the method is suitable for the normal feeding or deflection feeding scene of a single reflector or multiple reflectors.

Description

Technical Field

[0001] This invention addresses the need to broaden the operating frequency band of existing reflector antennas and relates to a method for improving the operating bandwidth of existing antennas in the field of antennas. Background Technology

[0002] In astronomical research, radio signals emitted by celestial bodies in the universe contain a wealth of information, with a wide and complex frequency range. With the rapid development of radio astronomy, the demand for more detailed and comprehensive celestial observations is constantly increasing. Expanding the bandwidth of radio telescope antennas enables them to capture radio signals across multiple frequency bands, allowing us to gain a more complete understanding of the physical processes, structure, and evolution of celestial bodies.

[0003] Radio telescope antennas operate in different frequency bands for different applications. For missions such as pulsar detection and observation of neutral hydrogen in the Milky Way, antennas primarily cover the UHF, L, and S bands; for high-resolution imaging of black holes, quasars, and radio galaxies, they mainly operate in the C, X, and Ku bands; while for deep space tracking and control missions serving lunar and Martian probes, the core operating frequency bands are the S, X, and Ka bands. Given the continuous growth in the number of radio telescope antennas in China, antenna resources have reached regional saturation. Therefore, expanding the operating frequency bands and tapping into the potential of the equipment has become a key path to improve the overall effectiveness of my country's radio telescope antenna systems.

[0004] While ensuring that the performance indicators of existing radio telescope antennas are not disturbed, exploring the potential of equipment by expanding the operating frequency band has become a key path to improve the overall effectiveness of my country's radio telescope antenna system. Summary of the Invention

[0005] In view of this, the present invention broadens the operating frequency band of the antenna without affecting the performance of the existing antenna. It uses a flipping device to realize the switching between the new frequency band feed and the original feed. The new feed uses an array as the feed. By applying different amplitude and phase weights to each element, the loss caused by the longitudinal defocus of the feed is compensated, and the new feed achieves high-efficiency illumination.

[0006] The specific technical solution adopted in this invention is as follows: A method for improving the operating bandwidth of an existing antenna, wherein the antenna includes a reflector and an existing feed network, comprising the following steps: Step 1: Based on the structural dimensions of the existing feed network, determine the installation position and outline of the flipping mechanism, which is used to switch between the new feed and the existing feed network. Step 2: Based on the new operating frequency band and the installation position of the flipping mechanism, and in conjunction with the electromagnetic model of the reflector, determine the radiation aperture and physical dimensions of the new feed source; Step 3: Select a small phased array as the new feed source based on its physical size and operating frequency band; Step 4: Taking the electrical performance of the reflector antenna as the target, the amplitude and phase weighting coefficients of each element in the small phased array are optimized using an optimization algorithm so that the optimized antenna achieves the best electrical performance in the newly added operating frequency band. Step 5: Based on the optimized amplitude and phase weighting coefficients, design the corresponding analog link to achieve amplitude and phase weighting in the newly added operating frequency band.

[0007] Furthermore, the installation position of the flipping mechanism in step 1 is specifically as follows: when the flipping mechanism drives the new feed source to enter the working position, the new feed source has longitudinal defocus relative to the focal point of the reflective surface, and the flipping mechanism and the new feed source do not block the optical path of the original feed source network.

[0008] Furthermore, the specific details of determining the radiation aperture and physical dimensions of the new feed source in step 2 are as follows: Based on the electromagnetic model of the reflector, the focal plane field distribution of the reflector after longitudinal defocusing is simulated and calculated, and the radiation aperture and physical dimensions of the new feed source are determined according to the focal plane field distribution.

[0009] Furthermore, in step 3, the small phased array is a Vivaldi array, a cross dipole array, a checkerboard array, or a waveguide array.

[0010] Furthermore, the electrical performance of the reflector antenna in step 4 includes at least one of antenna efficiency, noise temperature, and sensitivity; the optimization algorithm is a genetic algorithm, a global optimization algorithm, or a local optimization algorithm.

[0011] Furthermore, in step 5, the model of each device in the simulated link is determined based on its approximation of the amplitude-phase weighting coefficients, so as to restore the amplitude-phase weighting coefficients to the greatest extent.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention breaks away from the traditional approach of requiring a new multi-frequency feed network to broaden the antenna's operating frequency band. By using a flipping mechanism, the new frequency band array feed network is switched with the original feed network, thereby broadening the antenna's operating frequency band. 2. Using an array feed for the new frequency band feed can compensate for the energy loss caused by the longitudinal defocus of the new feed and improve the antenna performance of the new frequency band. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the technical principle of the single-reflector antenna used in this invention.

[0014] Figure 2 This is a schematic diagram illustrating the technical principle of the Gregorian dual-reflector antenna used in this invention.

[0015] Figure 3 This is a schematic diagram illustrating the technical principle of the Cassegrain dual-reflector antenna used in this invention.

[0016] Figure 4 This is a schematic diagram illustrating the technical principle of the single-biased antenna used in this invention.

[0017] Figure 5 This is a schematic diagram of a simulated reflective surface model according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the simulation array model according to an embodiment of the present invention; Figure 7 This refers to the serial number of the simulation array model unit in this embodiment of the invention; Figure 8 This is the normalized radiation pattern of the antenna feeder system in this embodiment of the invention when its performance is optimal in the new frequency band; Figure 9 This is an example diagram of the flipping mechanism structure in an embodiment of this project; Figure 10 This is an example diagram of the feed array structure in an embodiment of this project.

[0018] Among them, 1. a new feed source, and 2. a reflective surface. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Reference Figure 1 A method for improving the operating bandwidth of existing antennas includes the following steps: Step 1: Determine the position and outline of the flipping mechanism based on the structural dimensions of the original antenna feed network; Step 2: Based on the new operating frequency band and the position of the flipping mechanism, and in conjunction with the reflector antenna model, estimate the radiation aperture of the new feed and determine the physical dimensions of the new feed. Step 3: Select a suitable small phased array as the feed source based on the physical size of the feed source; Step 4: Taking the performance of the reflector antenna as the target, an optimization algorithm is used to optimize the array feed element so that the antenna performance is optimal after applying different amplitude and phase weights to each array element. Step 5: Based on the weighting coefficients, design the corresponding analog link to optimize the antenna performance in the new frequency band.

[0021] Complete the design of the array feed source and feed switching mechanism.

[0022] In step 1, the reflector antenna can be a single-reflector antenna or a multi-reflector antenna, and both prime-fed and offset-fed antennas are applicable. The small phased array in step 3 includes, but is not limited to, Vivaldi arrays, crossed dipole arrays, checkerboard arrays, waveguide arrays, etc.; specific types are described in detail below. Figures 1 to 4 The schematic diagram is shown below. The optimization algorithms in step 4 include, but are not limited to, genetic algorithms, global optimization algorithms, and local optimization algorithms. The simulation link in step 5 should be selected based on the actual condition of the device, choosing the model that best matches the weighting coefficients.

[0023] Example 1:

[0024] This embodiment uses a 13 m Cassegrain antenna as an example to illustrate the specific implementation process of the method of the present invention.

[0025] The antenna currently operates in the 1.1 GHz to 1.75 GHz frequency band, and it is proposed to expand the operating frequency band to a new one. The basic parameters of the antenna are as follows: main reflector diameter 13 m, sub-reflector diameter 1.3 m, half-illumination angle 17°, and the reflector model is shown below. Figure 5 As shown.

[0026] Step 1: Determine the position and outline of the flipping mechanism Based on the structural dimensions of the existing antenna feed network, the installation position and outline of the flipping mechanism are determined. The flipping mechanism is mounted on the support structure behind the antenna sub-reflector, located to the side of the existing feed network, ensuring that the newly added feed does not obstruct the optical path of the original feed. Simultaneously, in operation, the flipping mechanism should minimize the longitudinal defocus distance of the new feed relative to the focal point of the reflector to reduce performance loss caused by defocusing. An example of the flipping mechanism's structure is shown below. Figure 9 As shown.

[0027] Step 2: Determine the radiation aperture and physical dimensions of the new feed source. Based on the newly added operating frequency band and the location of the flipping mechanism, a reflector antenna model is established in electromagnetic simulation software. The feed source is placed at the corresponding position after longitudinal defocusing, and the amplitude and phase distribution of the antenna focal plane field are obtained through simulation calculations. Based on the range of energy concentration areas in the focal plane field distribution, the radiating aperture of the new feed source is estimated, and thus the physical size of the new feed source is determined. In this embodiment, the simulated focal plane field distribution shows that when the radiating aperture of the new feed source is approximately 250 mm in diameter, it can effectively cover the main lobe energy region of the focal plane field.

[0028] Step 3: Select a suitable small phased array as the feed source Based on the feed physical dimensions and operating frequency band determined in step two, a cross-dipole array was selected as the new feed. The array adopts a hexagonal arrangement with a total of 7 elements and an element spacing of 152 mm. The array model is shown below. Figure 6As shown. The array elements are numbered according to a hexagonal arrangement, as follows: Figure 7 As shown (unit 1 is the central unit, and units 2 to 7 are the peripheral units). The overall size of the array matches the radiation aperture determined in step two.

[0029] Step 4: Determine the amplitude and phase weighting coefficients of the array feed using an optimization algorithm. Using the aperture efficiency of the reflector antenna as the optimization objective, a genetic algorithm is employed to optimize the amplitude and phase weighting coefficients of the seven array feed elements. During the optimization process, different amplitude and phase weighting coefficients are applied to each array element to achieve optimal electrical performance of the antenna in the newly added operating frequency band. Optimization algorithms include, but are not limited to, genetic algorithms, global optimization algorithms, and local optimization algorithms; this embodiment uses a genetic algorithm for iterative optimization.

[0030] After optimization and iteration, each element obtained a set of optimal amplitude and phase weighting coefficients. These weighting coefficients were then substituted into the antenna model for simulation verification. The normalized radiation pattern of the antenna is shown below. Figure 8 As shown in the figure. Simulation results show that the antenna aperture efficiency reaches over 50% at high, medium, and low frequencies, meeting the requirements of engineering applications.

[0031] Step 5: Design the corresponding simulated link Based on the amplitude and phase weighting coefficients obtained in step 4, a corresponding analog link is designed. The analog link includes a power distribution network, an amplitude adjustment network, and a phase adjustment network, used to convert one input signal into seven feed signals with specific amplitude and phase relationships, which are then sent to seven array units. In actual design, the device model that can best reproduce the weighting coefficients should be selected based on the actual situation of the available devices on the shelf, ensuring that the amplitude and phase deviations of each channel are within acceptable limits.

[0032] After completing the above steps, the design of the array feed and flipping mechanism is complete. The specific structure of the flipping mechanism is as follows: Figure 9 As shown, the specific structure of the feed array is as follows: Figure 10 As shown.

Claims

1. A method for improving the operating bandwidth of an existing antenna, wherein, The antenna includes a reflector and an existing feed network, characterized by comprising the following steps: Step 1: Based on the structural dimensions of the existing feed network, determine the installation position and outline of the flipping mechanism, which is used to switch between the new feed and the existing feed network. Step 2: Based on the new operating frequency band and the installation position of the flipping mechanism, and in conjunction with the electromagnetic model of the reflector, determine the radiation aperture and physical dimensions of the new feed source; Step 3: Select a small phased array as the new feed source based on its physical size and operating frequency band; Step 4: Taking the electrical performance of the reflector antenna as the target, the amplitude and phase weighting coefficients of each element in the small phased array are optimized using an optimization algorithm so that the optimized antenna achieves the best electrical performance in the newly added operating frequency band. Step 5: Based on the optimized amplitude and phase weighting coefficients, design the corresponding analog link to achieve amplitude and phase weighting in the newly added operating frequency band.

2. The method for improving the operating bandwidth of an existing antenna according to claim 1, characterized in that, The specific installation position of the flipping mechanism in step 1 is as follows: when the flipping mechanism drives the new feed source to enter the working position, the new feed source has longitudinal defocus relative to the focal point of the reflective surface, and the flipping mechanism and the new feed source do not block the optical path of the original feed source network.

3. The method for improving the operating bandwidth of an existing antenna according to claim 1, characterized in that, The specific steps for determining the radiation aperture and physical dimensions of the new feed in step 2 are as follows: Based on the electromagnetic model of the reflector, the focal plane field distribution of the reflector after longitudinal defocusing is simulated and calculated, and the radiation aperture and physical dimensions of the new feed are determined according to the focal plane field distribution.

4. The method for improving the operating bandwidth of an existing antenna according to claim 1, characterized in that, In step 3, the small phased array is a Vivaldi array, a cross dipole array, a checkerboard array, or a waveguide array.

5. The method for improving the operating bandwidth of an existing antenna according to claim 1, characterized in that, The electrical performance of the reflector antenna in step 4 includes at least one of antenna efficiency, noise temperature, and sensitivity; the optimization algorithm is a genetic algorithm, a global optimization algorithm, or a local optimization algorithm.

6. The method for improving the operating bandwidth of an existing antenna according to claim 1, characterized in that, In step 5, the model of each device in the analog link is determined according to its approximation of the amplitude and phase weighting coefficients, so as to restore the amplitude and phase weighting coefficients to the greatest extent.

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