Dual vertical beam properties of doubly curved reflectors

Winter, C.

doi:10.1109/tap.1971.1139903

Cited by 14 publications

(4 citation statements)

References 3 publications

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“…To avoid this problem Raytheon undertook a program to combine the upper beam with the lower beam in varying amounts as a function of range. (17). Figure 24 shows the physical layout of the antenna with the two horns.…”

Section: Insects Seen With Mti Insects Seen With Mti and Stcmentioning

confidence: 99%

<title>Moving Target Indication Radar</title>

Shrader

1977

SPIE Proceedings

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MTI (Moving Target Indication) radar systems have been built for many years, based on system concepts evolved in the early 1950's. Digital techniques now permit easier implementation, but do not change the basic concepts; staggered repetition periods to eliminate blind speeds; and MTI cancellers with the velocity response shaped by feed forward and feedback techniques. Many of the existing systems are very successful, even though their performance, measured in terms of MTI improvement factor or subclutter visibility, often falls far short of the performance predicted from linear theory. The basic MTI concepts and definitions are presented, and the real problems of modern surface -based MTI radar systems are discussed. Future signal -processing techniques are postulated.

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Section: Insects Seen With Mti Insects Seen With Mti and Stcmentioning

confidence: 99%

<title>Moving Target Indication Radar</title>

Shrader

1977

SPIE Proceedings

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“…The said proportionality must be held from a minimum angle of sin −1 h/|r| max to the maximum elevation angle for which the coverage is required [3]. Cosecant-squared radiation pattern antennas have been implemented in diverse configurations, such as doubly-curved reflectors [5][6][7][8][9], reflectarrays [10][11][12][13], and pillboxes [14]. Among them, doublecurvature reflectors are widely used in navigational systems due to their outstanding functionalities.…”

Section: Introductionmentioning

confidence: 99%

A New Analytical Redesign of a Double-Curvature Reflector Antenna Using Invasive Weed Optimization (Iwo) Algorithm

Vedaee¹,

Askari²,

Sadeghi³

et al. 2021

PIER C

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This paper presents an efficient method to redesign a horn-fed, double-curvature reflector antenna. It helps reconstruct or repair the reflector according to a correct reference or analyze its radiation characteristics through full-wave electromagnetic simulations. The proposed method mainly consists of five stages. At first, it is necessary to obtain initial data in the form of three-dimensional coordinates of a sufficient number of points sampled from the reflector's different surface areas, especially from its central section curve and its peripheral contour. Then, the best-fitting surface to the sampled points is found using geometrical-optics (GO)-based formulations in an invasive weed optimization (IWO) algorithm. The GO relations extend the reflector laterally using elevation angle, horizontal, or focal point strips. As these are intrinsic formulations for designing doubly-curved reflectors, the fitted surface can resolve the possible defects in the reference reflector's geometry or inaccuracies in the sampled information partly. For this purpose, the reflector's central section curve is estimated by fitting a fifth-degree polynomial curve to the data sampled from it. Also, two kinds of errors, which are based on Euclidean distances, define the optimization algorithm cost function for more reliable surface fitting. In the third stage, the fitted surface's peripheral contour is adjusted to match the outline of the reference reflector using the points sampled from this section. In stage four, the redesigned reflector in the form of a point cloud is converted to a .stl file format for further simulation in a fullwave electromagnetic software. Finally, the similarity between the redesigned and reference reflectors' radiation patterns is examined using a radiation-based cost function in an iterative process, and the previously devised four stages repeat until appropriate results are obtained. In particular, an already designed and fabricated UHF band, doubly-curved reflector antenna, capable of generating a cosecantsquared radiation pattern in the elevation plane and narrow in the azimuth, is redesigned using 99 points sampled from it. It is found that horizontal strips can best fit the reflector with the small normalized error about 3 mm at the end of the IWO algorithm, indicating a nearly perfect geometrical similarity between the redesigned and reference reflectors. For further verification of the suggested method, the redesigned reflector's radiation pattern is simulated in CST simulation software, and the results are compared with the measured radiation pattern of the fabricated reflector and the simulated radiation pattern of the antenna's initial CAD model in the azimuth and elevation planes. Specifically for the redesigned antenna, the amounts of HPBW and sidelobe level in the azimuth plane are about 2.6 • and 29.85 dB, respectively. Also, the amounts of gain, HPBW, and predefined parameters of α and β in the elevation plane are 28.25 dB, 13.5 • , 5.07 dB, and 11.7 • , respectively. All of the measured ...

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“…For example, a Gregorian double reflector antenna with an off‐focal feed array produces multiple beams at 12.7 GHz . A dual‐focal double‐reflector multibeam antenna is shaped to control the feed spillover for an improved aperture efficiency . The abovementioned articles adopt effective solutions when facing various problems, such as energy overflow control, aperture efficiency enhancement, and section size reduction.…”

Section: Introductionmentioning

confidence: 99%

“…11 A dual-focal double-reflector multibeam antenna is shaped to control the feed spillover for an improved aperture efficiency. [12][13][14] The abovementioned articles adopt effective solutions when facing various problems, such as energy overflow control, aperture efficiency enhancement, and section size reduction. This article aims to reduce the blockage of the feed without changing its position.…”

Section: Introductionmentioning

confidence: 99%

A K / Ka ‐band dielectric and metallic 3D printed aperture shared multibeam parabolic reflector antenna for satellite communication

Zhu

Zhang

Huang

2020

Int J RF Microw Comput Aided Eng

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A K/Ka‐band (22‐33 GHz) high‐gain aperture shared multibeam parabolic reflector antenna is proposed. It performs a two‐dimensional beam scanning from a shared single parabolic reflector by introducing off‐focal feeds. The feed array is placed on and off the focal of the parabolic reflector. Traditionally, the feed blockage has a great impact on the performance of the antenna, which reduces the gain and increases the sidelobe level. The purpose of this paper is to suppress the negative effects of feed blockage by using hybrid material processing method. Both dielectric and metallic 3D printing technologies are used for antenna fabrication. The parabolic reflector antenna is printed by selective laser melting using aluminum alloy. The feed array and the supporting structures are printed by stereolithography apparatus in resin to control the blockage. The method helps to suppress the sidelobe level from −10 to −15 dB and to enhance gain by up to 2.3 dBi. The reflection coefficient is less than −10 dB, while the coupling coefficient between the ports is less than −20 dB over the entire designed band. At 31.5 GHz, the simulated maximum gain of the antenna are 30.7, 29.1, and 29.7 dBi, when different port separately excites. Multiple beams at ±15° and 0° are observed on both E‐ and H‐planes. Besides, it also verifies the possibility to use dielectric and metallic 3D printing technologies in hybrid for microwave device fabrication.

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Dual vertical beam properties of doubly curved reflectors

Cited by 14 publications

References 3 publications

<title>Moving Target Indication Radar</title>

<title>Moving Target Indication Radar</title>

A New Analytical Redesign of a Double-Curvature Reflector Antenna Using Invasive Weed Optimization (Iwo) Algorithm

A K / Ka ‐band dielectric and metallic 3D printed aperture shared multibeam parabolic reflector antenna for satellite communication

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