Topic
Cassegrain antenna
About: Cassegrain antenna is a research topic. Over the lifetime, 3207 publications have been published within this topic receiving 28278 citations.
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TL;DR: In this paper, a new design of the hat-fed reflector antenna for satellite communications is presented, where a low reflection coefficient, high gain, low sidelobes and low cross-polar level are required over a wide frequency band.
Abstract: We present a new design of the hat-fed reflector antenna for satellite communications, where a low reflection coefficient, high gain, low sidelobes and low cross-polar level are required over a wide frequency band. The hat feed has been optimized by using the Genetic Algorithm through a commercial FDTD solver, QuickWave-V2D, together with an own developed optimization code. The Gaussian vertex plate has been applied at the center of the reflector in order to improve the reflection coefficient and reduce the far-out sidelobes. A parabolic reflector with a ring-shaped focus has been designed for obtaining nearly 100% phase efficiency. The antenna's reflection coefficient is below -17 dB and the radiation patterns satisfy the M-x standard co- and cross-polar sidelobe envelopes for satellite ground stations over a bandwidth of 30%. A low-cost monolayer radome has been designed for the antenna with satisfactory performance. The simulations have been verified by measurements; both of them are presented in the paper.
37 citations
Patent•
09 Dec 2014
TL;DR: A surface scattering reflector antenna includes a plurality of adjustable scattering elements and is configured to produce a reflected beam pattern according to the configuration of the adjustable scattering element as mentioned in this paper, which can be used to obtain a more accurate reflector.
Abstract: A surface scattering reflector antenna includes a plurality of adjustable scattering elements and is configured to produce a reflected beam pattern according to the configuration of the adjustable scattering elements.
37 citations
TL;DR: In this article, a hybrid antenna (HA) with a modified beam steering method is proposed, which is capable of two-dimensional beam steering by means of two operations: rotation of the subreflector and phase control of the feed array.
Abstract: A hybrid antenna (HA) with a modified beam steering method is proposed. This antenna has a Cassegrain structure composed of two reflectors and a feeder. The parabolic-shaped main reflector is designed for high gain, while the subreflector is rotational and flat. The feeder is a phased array with arbitrary shaped aperture and 20 element antennas. The HA is capable of two-dimensional beam steering by means of two operations: rotation of the subreflector and phase control of the feed array. The subreflector is small in size and weight, so it can provide rapid beam scanning. Designed to be loaded in vehicles, the HA and can communicate with satellites on the move by tracking the beam control of the feed array. A prototype of the HA is fabricated with aluminum using a machining center operated by computerized numerical control. The prototype is operated at Ka-band for TX and K-band for RX with gains of 47 dBi and 44.4 dBi, respectively, at a steering angle of 0 deg. The two-dimensional beam steering within plusmn2deg with respect to 45deg elevation is realized by the subreflector and feed array. All radiation patterns in the beam steering zone meet ITU-R s.465-5 regulations.
36 citations
20 Jun 2004
TL;DR: In this article, Duan et al. used particle swarm optimization to solve the problem of shape the main reflector of a reflector antenna with F/D = 1.0.
Abstract: It has been shown that reflector antenna systems can benefit substantially from careful shaping of the main or sub-reflectors, or both, in order to maximize the antenna's performance (Duan, D.-W. and Rahmat-Samii, Y., 1995). Shaped reflectors can be used to achieve high efficiencies and gains, low side-lobe levels, and arbitrarily contoured beams. As the demands placed on satellite broadcasting and communications channels and the use of space-borne radar applications increase, so too do the requirements for the antennas on which these systems rely. The paper establishes particle swarm optimization as a candidate for solving difficult reflector synthesis problems. This is done by developing the tools required to perform the reflector synthesis and solving an example to serve as proof-of-concept. The example is to shape the main reflector of a reflector antenna with F/D=1.0, such that the scanning performance of the antenna. is improved.
36 citations
TL;DR: In this article, a computer program called DERIVE is described for the design of the reflecting surfaces of two-mirror radio telescopes, which can be used to improve existing telescopes at short wavelengths by correcting for the surface deviations of the primary reflector with a specially shaped secondary.
Abstract: A computer program called DERIVE is described for the design of the reflecting surfaces of two-mirror radio telescopes. It calculates the shape of a secondary reflector to any given primary by use of geometrical optics, yielding zero path length errors for all paraxial rays. The only condition to be fulfilled is (for Cassegrain types) that incoming rays, after reflection at the primary, do not cross each other before reaching the secondary. Equations for this condition are given. This method can be used to improve existing telescopes at short wavelengths by correcting for the surface deviations of the primary reflector with a specially shaped secondary. The results of 17 calculated examples are described, for various types of deviations
36 citations