A Shaped-Based Shaded Wave Feed Design Method

Abstract

This invention provides a beamformer-based feed design method. By utilizing a pattern synthesis method based on Fourier transform, the excitation amplitude and phase of each array element are obtained through inverse synthesis. The obtained excitation amplitude and phase of each array element are then assigned to that element. Full-wave simulation of the array is performed in electromagnetic simulation software to obtain the array's radiation pattern, which is compared with the desired feed radiation pattern. If deviations exist, the excitation amplitude and phase can be adjusted until the overlap with the desired feed radiation pattern reaches the target. This invention achieves nearly 90% efficiency after illuminating the reflector, far exceeding the efficiency of conventional feeds illuminating reflectors. Furthermore, different excitation coefficients can be flexibly constructed for different frequencies, achieving high-precision approximation of the ideal delta function across a wide frequency range. Higher gain can be obtained with the same aperture, or the aperture size of the reflector antenna can be reduced with the same gain requirements. This significantly improves system performance and reliability.

Description

Technical Field

[0001] This invention relates to the field of electrical component technology, and specifically to a shape-based shielded wave feed design method. Background Technology

[0002] In mobile telemetry, tracking, and control systems, and high-data-rate remote sensing systems, limitations such as the size of the container or the width restrictions during transport necessitate manual or electric folding of some medium-diameter reflector antennas, requiring specially customized container modifications. This folding mechanism leads to decreased reliability of the reflector, and the customized container modifications fail to meet the requirements of standardization, modularization, and cost increases. Conversely, some medium-to-large-diameter reflector antennas require umbrella-shaped folding to meet vehicle-mounted storage requirements. Umbrella-shaped folding typically requires a dozen or even dozens of reflector segments, each with its own drive and locking mechanism. This results in complex engineering implementation, high costs, difficulty in maintaining surface precision control, and relatively low reliability.

[0003] Using a radome feed can significantly increase the system's effective range or bandwidth and code rate, and also reduce the antenna aperture size. Conventional lobe-reversing folding can meet vehicle-mounted storage requirements. Lobe-reversing folding typically requires only two or three folds, each with its own drive and locking mechanism. This simplifies engineering implementation, reduces costs, ensures easy control of surface accuracy, and provides high reliability. In large-scale ground-based fixed telemetry, tracking, and control systems, and high-code-rate remote sensing data transmission systems, once the antenna aperture exceeds 7.3 meters, the costs of antenna structure and conformal design, antenna mount design, foundation construction, and system construction increase exponentially with the increase in reflector aperture. Therefore, in large-scale ground-based fixed stations, using a radome feed can significantly reduce the aperture size of large antennas while maintaining performance. Alternatively, under the constraint of the target range's infrastructure area, the same large-aperture antenna can achieve the capabilities of a larger-aperture antenna.

[0004] However, conventional feeds have a cosine function distribution in their radiation pattern, which leads to a contradiction between aperture efficiency and edge leakage efficiency. When the aperture efficiency is very high, the edge leakage energy is very large. These two efficiencies cannot be optimized at the same time, resulting in limited efficiency of conventional feeds.

[0005] Therefore, a radome feed that can improve antenna efficiency is needed. Summary of the Invention

[0006] This invention addresses the problem of antenna efficiency by providing a shaped-faceted feed design method. Utilizing a Fourier transform-based pattern synthesis method, the feed pattern is inversely synthesized to construct a feed pattern with a delta function shape. This ensures that the majority of the feed energy is contained within the sub-surface. Illuminating the reflector with this feed pattern yields an efficiency of nearly 90%, far exceeding the 60% efficiency of conventional feeds. This method has broad application prospects in systems such as telemetry, data transmission, and high-rate remote sensing.

[0007] This invention provides a shape-based shielded wave feed design method, comprising the following steps: S1. The excitation amplitude and phase of each feed element are obtained by inverse synthesis using one-dimensional discrete Fourier inverse transform. S2. Assign the excitation amplitude and phase of each feed array element to each feed array element, and perform full-wave simulation of the array in electromagnetic simulation software to obtain the feed array radiation pattern. S3. Compare the feed array pattern with the desired feed pattern. If there is a deviation, adjust the excitation amplitude and phase, and return to step S1 until the overlap between the feed array pattern and the desired feed pattern reaches the target. The desired feed pattern conforms to the δ function: ; in, x Let θ be the taper angle of the secondary reflector, and θ be the maximum value of the taper angle of the secondary reflector.

[0008] In the shaped beam feed design method described in this invention, as a preferred embodiment, in step S1, the time-domain input of the one-dimensional discrete Fourier inverse transform is: ; in, Let j be the sampling interval, and j be the imaginary part. k =0, 1, 2, ... N -1, N For a period of time, Frequency domain output; ; Where λ is the wavelength, all M The set of excitation amplitudes of each array element is ,in A m ( m =1, 1, 2, ... M ) represents the excitation amplitude of the m-th array element; First, set an initial value for the time-domain input, then perform a one-dimensional discrete Fourier inverse transform, and then obtain the feed array pattern through step S2. Adjust the time-domain input value to make the feed array pattern approximate the δ function.

[0009] The shaped shielded feed design method described in this invention, as a preferred embodiment, aims to achieve the desired radiation pattern function F( k ) can be represented as , AF(k) is the array factor.

[0010] The present invention discloses a shape-based shielded feed design method, in which each feed element is connected to a digital R component. The digital R component performs filtering, amplification, down-conversion, and sampling. The sampled digital signal is output to the DBF digital array signal processing and synthesis system to obtain the delta function pattern.

[0011] The shaped shroud feed design method described in this invention, as a preferred embodiment, in step S1, can utilize the feed scanning principle to simultaneously generate multiple offset multi-beams for system imaging acquisition guidance. Alternatively, different array element combinations and amplitude and phase excitation coefficients can be selected to obtain sum and difference beams with different beamwidths after illuminating the reflecting surface, which are used for system single-pulse acquisition guidance.

[0012] The shaped radome feed design method described in this invention, as a preferred embodiment, uses an array element with a wide beam and small aperture, which can be a folded arm cross dipole, a dielectric antenna element, or a microstrip antenna element.

[0013] The present invention provides a shape-based radome feed design method, in which the feed array elements are arranged in a rectangular grid or a triangular grid, and the entire array surface is arranged in a regular hexagonal or circular pattern.

[0014] The shaped waveguide feed design method described in this invention, as a preferred embodiment, can be applied to mobile measurement and control systems and high-code-rate remote sensing data transmission systems.

[0015] The shaped wave feed design method described in this invention, as a preferred embodiment, uses the wave feed obtained in step S3. When the wave feed is reversed and folded, only two or three folded lobes are needed, and each folded lobe has an independent drive mechanism and a locking and positioning mechanism.

[0016] The shaped waveguide feed design method described in this invention, as a preferred embodiment, can be applied to large ground-based fixed stations. A shrouded feed is used to reduce the aperture size of a large antenna without changing its performance, or to enable a large-aperture antenna to achieve the same aperture size under the constraints of the target range infrastructure area.

[0017] The basic design concept of this invention is as follows: Conventional feed patterns exhibit a cosine function distribution, where aperture efficiency and edge leakage efficiency are contradictory. High aperture efficiency results in high edge leakage energy. To maximize the product of aperture efficiency and edge leakage efficiency, a compromise design is required. Feed illumination taper is typically between 10dB and 12dB, as these two efficiencies cannot be simultaneously optimized, leading to limited efficiency in conventional feeds. However, a feed pattern with a delta function shape can simultaneously optimize both aperture efficiency and edge leakage efficiency, ensuring that the majority of the feed energy is contained within the sub-plane, thus significantly improving antenna efficiency. This design has broad application prospects in systems such as telemetry, tracking, and data transmission, and high-rate remote sensing, including but not limited to the following scenarios: In mobile telemetry and control and high-code-rate remote sensing data transmission systems, due to limitations such as the size of the container or the transport width limit, using a radome feed can significantly increase the system's operating distance or bandwidth or code rate, even with a limited antenna aperture.

[0018] In mobile telemetry, tracking, and control systems, and high-rate remote sensing data transmission systems, some medium-aperture reflector antennas require manual or electric folding and special modifications to the container to house the reflector. Using a radome feed, the antenna gain and system G / T value can be maintained while reducing the reflector antenna diameter. This eliminates the need for reflector folding or special container modifications, allowing the antenna to be housed without the need for folding or special container modifications. This avoids the reliability degradation caused by folding mechanisms and the incompatibility and increased costs associated with custom container modifications.

[0019] In mobile telemetry, tracking, and control systems and high-rate remote sensing data transmission systems, some medium-to-large aperture reflector antennas need to be folded in an umbrella shape to meet vehicle-mounted storage requirements. Umbrella-shaped folding typically requires a dozen or even dozens of reflector lobes, each with its own drive mechanism and locking and positioning mechanism. This makes the engineering implementation complex, costly, and difficult to maintain the surface accuracy, resulting in relatively low reliability.

[0020] Using a domed feed can reduce the antenna aperture size, and conventional lobe-folding designs can meet vehicle-mounted storage requirements. Lobe-folding typically requires only two or three folds, each with its own drive and locking mechanism. This simplifies implementation, reduces cost, ensures easy control of surface accuracy, and provides high reliability. In large-scale ground-based fixed telemetry, tracking, and command (TT&C) and high-rate remote sensing data transmission systems, when the antenna aperture exceeds 7.3 meters, the costs of antenna structure and conformal design, antenna mount design, foundation construction, and system construction increase exponentially with the increase in reflector aperture. Therefore, in large-scale ground-based fixed stations, using a domed feed can significantly reduce the antenna aperture size while maintaining performance. Alternatively, under the constraint of the test range's infrastructure area, the same large-aperture antenna can achieve the capabilities of a larger-aperture antenna.

[0021] The present invention has the following advantages: Multi-mode delta-function feeds based on a single antenna, utilizing different mode ratios to construct delta-function feed patterns, can achieve center frequency efficiencies exceeding 70%. However, limited flexibility and accuracy in multi-mode configuration, coupled with poor approximation of the ideal delta function, restricts further efficiency improvements. Furthermore, the narrow bandwidth of multi-mode feeds limits their application. Existing systems such as telemetry and data transmission, and high-rate remote sensing commonly employ cosine distribution feed patterns, achieving efficiencies of around 60% when illuminating parabolic antennas. By using array feeds and constructing feed patterns with a delta-function shape, and employing digital methods to achieve high-precision amplitude and phase excitation coefficients, illuminating reflectors yields nearly 90% efficiency, significantly higher than conventional feeds illuminating reflectors. Moreover, different excitation coefficients can be flexibly constructed for different frequencies, achieving high-precision approximation of the ideal delta function across a wide bandwidth. Higher gain can be obtained with the same aperture, or the aperture size of the reflector antenna can be reduced while maintaining the same gain requirements. In specific application scenarios, this can significantly improve system performance, reduce engineering implementation difficulty and system construction costs, and enhance system reliability. Attached Figure Description

[0022] Figure 1 A flowchart of a shape-based shielded wave feed design method; Figure 2 A schematic diagram of a 127-element array arranged in a regular hexagonal shape according to a triangular grid array, which is a design method for a shaped waveguide feed. Figure 3 The feed pattern with a delta function shape is constructed using a shape-based shading-wave feed design method. Figure 4 The amplitude and phase excitation coefficients of some array elements are given by a shape-based shrouded wave feed design method. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0024] like Figure 1 As shown, a shape-based radome feed design method utilizes a Fourier transform-based pattern synthesis method to inversely synthesize the array feed pattern, constructing a feed pattern with a delta function shape. After illuminating the reflector with this feed pattern, an efficiency of nearly 90% is obtained, which is much higher than the 60% efficiency of conventional feeds. Higher gain can be obtained under the same aperture, or the aperture size of the reflector antenna can be reduced under the same gain requirements.

[0025] The feed pattern has a delta function shape, and the rising and falling edges of the delta function shape are approximately equal to the taper angle of the sub-reflector.

[0026] The sub-reflector's irradiation taper angle is... x Let θ be the maximum value of the taper angle of the secondary reflector. Then the desired radiation pattern δ function can be expressed as: (1) Consider a linear array with element spacing d and a total number of elements M. The mathematical expression for the radiation pattern of this array is: (2) in, AF(k) For array factor, EF(k) The array element radiation pattern is given, where k = 0, 1, 2, ..., N-1, and N is the period. Only the case where the array element is a point source (omnidirectional radiation) is considered; therefore, the element radiation pattern is... Then we have: (3) Where λ represents wavelength and j is the imaginary part. Here, all... M The set of excitations of each array element is abbreviated as: ,in A m ( m =1, 1, 2, ... M If is the excitation of the m-th array element, then the desired pattern function F( k ) can be represented as That is, the representation of array factor and array pattern is consistent.

[0027] Here, the one-dimensional discrete Fourier inverse transform is expressed as: (4) here, The sampling interval is...k =0, 1, 2, ... N -1. N By comparing equations (3) and (4) with the periodicity, the relationship between the array factor AF and the array element excitation can be derived.

[0028] By using a pattern synthesis method based on Fourier transform, the excitation amplitude and phase of each array element are obtained through inverse synthesis. The excitation amplitude and phase of each array element are then assigned to each array element. The array is then subjected to full-wave simulation in electromagnetic simulation software (HFSS simulation software) to obtain the array's pattern. This pattern is then compared with the desired feed pattern. If there is a deviation, the excitation amplitude and phase can be adjusted until the pattern has a high degree of overlap with the desired feed pattern.

[0029] Each array unit is followed by a digital R component, which includes filtering, amplification, down-conversion, and sampling functions. The sampled digital signal is sent to the DBF digital array signal processing to synthesize the delta function pattern required for synthesis.

[0030] By synthesizing the radiation pattern, a delta function is generated to illuminate the reflector surface and obtain a high-efficiency, high-gain beam. At the same time, multiple offset multi-beams can be generated simultaneously using the feed scanning principle for system imaging acquisition guidance. Different array element combinations and amplitude and phase excitation coefficients can also be selected to obtain sum and difference beams with different beamwidths after illuminating the reflector surface for system single-pulse acquisition guidance.

[0031] The antenna array elements can be in the form of array units with wide beam and small aperture, such as folded arm cross-shaped dipoles, dielectric antenna units, and microstrip antenna units. The array elements are arranged in rectangular grids or triangular grids, and the entire array surface is arranged in regular hexagonal or circular shapes.

[0032] In this embodiment, the excitation amplitude and phase of each array element are obtained through inverse synthesis using a pattern synthesis method based on Fourier transform. The excitation is then designed through forward simulation, such as... Figure 2 The amplitude and phase of the 127 elements shown are combined into a radiation pattern that takes the shape of a delta function. The rising and falling edges of the delta function shape are approximately the cone angle of the sub-reflector.

[0033] By using a feed pattern with a delta function shape to illuminate the reflector, the efficiency obtained is much higher than that of conventional feeds illuminating the reflector.

[0034] Each array unit is followed by a digital R component, which includes filtering, amplification, down-conversion, and sampling functions. The sampled digital signal is sent to the DBF digital array signal processing unit to synthesize a delta function pattern.

[0035] The reflector of the high-efficiency array feed is a Cassegrain antenna, consisting of a parabolic primary reflector and a hyperbolic secondary reflector. The focal point of the hyperbolic secondary reflector coincides with the focal point of the parabolic primary reflector. The feed is located at the focal point of the mirror hyperbolic secondary reflector. The electromagnetic waves irradiated from the feed to the secondary reflector are reflected back to the primary reflector and then focused into a plane wave, forming a high-gain narrow beam pattern.

[0036] Based on the operating frequency band, a folding-arm cross-shaped vibrator was selected as the array element, with an element spacing of 66mm, approximately 0.53 times the wavelength of the upper sideband of the operating frequency band. The 127 array elements are arranged in a triangular grid layout, forming a regular hexagon after arraying.

[0037] The main reflector has a size of 12000mm, a focal diameter ratio of 0.35, a focal length of 4200mm, a sub-reflector size of 1800mm, and an illumination angle of ±15° for the feed to illuminate the sub-reflector.

[0038] like Figure 1 , 2 As shown, a pattern synthesis method based on Fourier transform is used to reverse synthesize the pattern of the array feed, obtaining the excitation amplitude and excitation phase of 127 array elements. The synthesized pattern has a delta function shape, with the rising edge at approximately -15° and the falling edge at approximately +15°.

[0039] The excitation amplitude and phase of the 127 elements are as follows: serial number Amplitude (V) Phase (Deg) serial number Amplitude (V) Phase (Deg) serial number Amplitude (V) Phase (Deg) serial number Amplitude (V) Phase (Deg) 1# 0.2334 0 33# 0.0859 0 65# 0.0320 -180 97# 0.0507 -180 2# 0.2131 0 34# 0.0859 0 66# 0.0320 -180 98# 0.0507 -180 3# 0.2131 0 35# 0.0859 0 67# 0.0320 -180 99# 0.0507 -180 4# 0.2131 0 36# 0.0859 0 68# 0.0320 -180 100# 0.0507 -180 5# 0.2131 0 37# 0.0859 0 69# 0.0320 -180 101# 0.0507 -180 6# 0.2131 0 38# 0.0165 0 70# 0.0320 -180 102# 0.0507 -180 7# 0.2131 0 39# 0.0165 0 71# 0.0320 -180 103# 0.0507 -180 8# 0.1584 0 40# 0.0165 0 72# 0.0320 -180 104# 0.0507 -180 9# 0.1584 0 41# 0.0165 0 73# 0.0320 -180 105# 0.0507 -180 10# 0.1584 0 42# 0.0165 0 74# 0.0320 -180 106# 0.0507 -180 11# 0.1584 0 43# 0.0165 0 75# 0.0320 -180 107# 0.0507 -180 12# 0.1584 0 44# 0.0165 0 76# 0.0320 -180 108# 0.0507 -180 13# 0.1584 0 45# 0.0165 0 77# 0.0320 180 109# 0.0507 -180 14# 0.1584 0 46# 0.0165 0 78# 0.0320 180 110# 0.0507 180 15# 0.1584 0 47# 0.0165 0 79# 0.0320 180 111# 0.0507 180 16# 0.1584 0 48# 0.0165 0 80# 0.0320 180 112# 0.0507 180 17# 0.1584 0 49# 0.0165 0 81# 0.0320 180 113# 0.0507 180 18# 0.1584 0 50# 0.0165 0 82# 0.0320 180 114# 0.0507 180 19# 0.1584 0 51# 0.0165 0 83# 0.0320 180 115# 0.0507 180 20# 0.0859 0 52# 0.0165 0 84# 0.0320 180 116# 0.0507 180 21# 0.0859 0 53# 0.0165 0 85# 0.0320 180 117# 0.0507 180 22# 0.0859 0 54# 0.0165 0 86# 0.0320 180 118# 0.0507 180 23# 0.0859 0 55# 0.0165 0 87# 0.0320 180 119# 0.0507 180 24# 0.0859 0 56# 0.0165 0 88# 0.0320 180 120# 0.0507 180 25# 0.0859 0 57# 0.0165 0 89# 0.0320 180 121# 0.0507 180 26# 0.0859 0 58# 0.0165 0 90# 0.0320 180 122# 0.0507 180 27# 0.0859 0 59# 0.0165 0 91# 0.0320 180 123# 0.0507 180 28# 0.0859 0 60# 0.0165 0 92# 0.0507 -180 124# 0.0507 180 29# 0.0859 0 61# 0.0165 0 93# 0.0507 -180 125# 0.0507 180 30# 0.0859 0 62# 0.0320 -180 94# 0.0507 -180 126# 0.0507 180 31# 0.0859 0 63# 0.0320 -180 95# 0.0507 -180 127# 0.0507 180 32# 0.0859 0 64# 0.0320 -180 96# 0.0507 -180 　 　 like Figure 3 , Figure 4 As shown, a simulation was conducted using a 12-meter reflector and a Cassegrain antenna. The simulation results show an antenna gain of 48.29 dB, an efficiency of 88%, a feed line loss of approximately 1.1 dB, and a calculated G / T value of 25 dB / K, which is close to the specifications of a 15-meter reflector. In contrast, a conventional feed irradiation of a 12-meter Cassegrain antenna results in a gain of approximately 46.0-46.5 dB, an efficiency of approximately 50%-60%, and a G / T value of 21-22.5 dB / K.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A beamform-based feed design method, characterized in that: Includes the following steps: S1. The excitation amplitude and phase of each feed element are obtained by inverse synthesis using one-dimensional discrete Fourier inverse transform. S2. Assign the excitation amplitude and phase of each feed array element to each feed array element, and perform full-wave simulation of the array in electromagnetic simulation software to obtain the feed array radiation pattern. S3. Compare the feed array pattern with the desired feed pattern. If there is a deviation, adjust the excitation amplitude and phase, and return to step S1 until the overlap between the feed array pattern and the desired feed pattern reaches the target. The desired feed pattern conforms to the δ function: ； in, x Let θ be the taper angle of the secondary reflector, and θ be the maximum value of the taper angle of the secondary reflector.

2. The beamformed feed design method based on shape-forming as described in claim 1, characterized in that: In step S1, the time-domain input of the one-dimensional discrete Fourier inverse transform is: ； in, Let j be the sampling interval, and j be the imaginary part. k =0, 1, 2, ... N -1, N For a period of time, Frequency domain output; ； Where λ is the wavelength, all M The set of excitation amplitudes of each array element is ,in A m ( m =1, 1, 2, ... M ) represents the excitation amplitude of the m-th array element.

3. The beamformed feed design method based on shape-forming as described in claim 2, characterized in that: Desired pattern function F( k ) can be represented as , AF(k) is the array factor.

4. The beamform feed design method based on shape shaping according to claim 1, characterized in that: Each feed element is connected to a digital R component, which performs filtering, amplification, down-conversion, and sampling. The sampled digital signal is output to the δ function pattern required for DBF digital array signal processing and synthesis.

5. The beamformed feed design method based on shape-forming as described in claim 1, characterized in that: In step S1, multiple offset multi-beams can be generated simultaneously using the feed scanning principle for system imaging acquisition guidance. Different array element combinations and amplitude and phase excitation coefficients can also be selected to obtain sum and difference beams with different beamwidths after illuminating the reflective surface, which can be used for system single-pulse acquisition guidance.

6. The beamform feed design method based on shape shaping according to claim 1, characterized in that: The feed element is an array unit with a wide beam and small aperture, and the feed element is a folded arm cross dipole, a dielectric antenna unit, or a microstrip antenna unit.

7. The beamform feed design method based on shape shaping according to claim 1, characterized in that: The feed array elements are arranged in a rectangular grid or a triangular grid, and the entire array surface is arranged in a regular hexagon or a circle.

8. The beamform feed design method based on shape shaping according to claim 1, characterized in that: The shielded wave feed design method can be applied to mobile measurement and control systems and high-code-rate remote sensing data transmission systems.

9. The beamformed feed design method according to claim 8, characterized in that: When using the shielded wave feed obtained in step S3, only two or three folded lobes are needed for the melon-shaped reversal folding. Each folded lobe has an independent drive mechanism and a locking and positioning mechanism.

10. The beamform feed design method based on shape shaping according to claim 1, characterized in that: The shielded wave feed design method can be applied to large ground fixed stations. A shrouded feed is used to reduce the aperture size of a large antenna without changing its performance, or to enable a large-aperture antenna to achieve the same aperture size under the constraints of the target range infrastructure area.

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