Cassegrain antenna

About: Cassegrain antenna is a research topic. Over the lifetime, 3207 publications have been published within this topic receiving 28278 citations.

Low-Profile Frequency-Scanned Antenna Based on Substrate Integrated Waveguide

Abstract: A beam scanning flat antenna array with the frequency that covers about the whole X-/Ku-band is proposed in this communication. The radiation element is the continuous transverse stub (CTS) constituted by the substrate integrated waveguide (SIW). The feed structure is an SIW parabolic reflector fed by a linear source with a metallic post, which exhibits a good impedance matching characteristics within a broad bandwidth. The beam steering direction is tunable with the frequency increasing within the operation band. The design principles of the SIW-based CTS array and the feed structure are explained in detail. One 16-element array is simulated, designed, and fabricated. The measurement results show that the antenna has a scanning angle range from 52.2° to −16.8° with the 3-dB gain from 8.5 to 14.1 GHz. At the center frequency of 12 GHz, it achieves a maximum gain of 18.1 dBi with an array size of $11.7\lambda _{0}\times 1.28\lambda _{0}$ , while the first sidelobe level is −11.4 dB and the 3-dB beamwidth is 6.5°.

A quasioptical feed system for radioastronomical observations at millimeter wavelengths

Abstract: We describe a quasioptical feed system for use with a 7-meter Cassegrain antenna at millimeter wavelengths. This system is designed to take full advantage of low noise, broadband mixer receivers and will be used for radioastronomical observations at frequencies between 60 GHz and 140 GHz. Two offset parabolic mirrors couple the radiation from the f/D = 5.7 antenna into the receiver feedhorn. A Fabry-Perot resonator operating at oblique incidence is used to inject the local oscillator energy into the signal path and to suppress response at the image frequency. The loss of the Fabry-Perot diplexer is 0.25 dB for the signal, while the coupling loss between the mixer waveguide flange and the main lobe of the antenna pattern should be ≤1 dB.

Meniscus-lens-corrected corrugated horn: a compact feed for a Cassegrain antenna

Abstract: The physical size of a corrugated conical horn feed having narrow beamwidth can be reduced considerably by correcting the spherical phase front in the aperture using a meniscus lens. Measured and calculated radiation characteristics of such lens-corrected scalar horns are presented. It is shown that the horns can provide efficient aperture illuminations when used as feeds for conventional Cassegrain antennas, for example radiotelescopes. Further, it is shown that the high crosspolarisation, which is normally present in lens horn designs, can be reduced to that of the horn itself by corrugating the lens surfaces with holes. Improved design formulas for such holes are given.

Low earth orbit earth station antenna

Abstract: An improved very small antenna terminal (VSAT) dual-beam antenna system for use with user subscriber terminals that communicate with low-earth orbiting and other satellites. In one embodiment, the dual-beam antenna system has two offset Gregorian dual-reflector antennas that each has an ellipsoidal subreflector and a rotatable paraboloidal reflector having a focus in common with a focus of the ellipsoidal subreflector. The rotatable paraboloidal reflector couples energy to and from the ellipsoidal subreflector. An RF feed system couples RF energy to and from the ellipsoidal subreflector. Rotating apparatus rotates the paraboloidal reflector and ellipsoidal subreflector together around an azimuth axis of the antenna. The rotating apparatus independently and simultaneously rotates the paraboloidal reflector about an axis between the paraboloidal reflector and ellipsoidal subreflector which points the antenna at an orbiting satellite. A controller is coupled to the rotating apparatus that controls rotation of the paraboloidal reflector and the antenna to point the antenna toward the orbiting satellite. The two antennas are preferably mounted side-by side and the one antenna is pointed at a first satellite while the second antenna tracks a rising satellite. A VSAT radio is automatically handed-off to the rising LEO satellite by switching it from the one antenna to the second antenna. Another embodiment may be used to track a inclined-orbit satellite having a figure-eight orbit, wherein the actuators move the antenna more slowly to track the satellite. Another embodiment employs a single antenna that is fixed relative to an orbiting satellite.

Analysis of a dual-reflect array antenna

Abstract: A modular technique for the analysis of a dual-reflectarray antenna (DRA) configuration is presented. The proposed analysis method has been used to design a DRA that emulates previous dual-reflector antennas in Ku- and W-bands including a reflectarray as a sub-reflector. The results for the DRA compare very well with those of the parabolic reflector and reflectarray sub-reflector; radiation patterns, antenna gain and efficiency are practically the same when the main parabolic reflector is substituted by a flat reflectarray, the gain being reduced by a few tenths of a dB as a result of the ohmic losses in the reflectarray. The phase adjustment on two surfaces provided by the dual-reflectarray configuration can be used to improve the antenna performance in some applications requiring multiple beams, beam scanning or shaped beams.