Feed horn

About: Feed horn is a research topic. Over the lifetime, 2395 publications have been published within this topic receiving 26548 citations. The topic is also known as: feedhorn.

Expandable panel and truss system/antenna/solar panel

Abstract: Disclosed is an expandable panel and truss structure capable of being stowed in a storage container (canister) for transportation into space and deployed to form structures such as antennas, solar panels or similar space or terrestial structures. The antenna formed comprises the panels stored as hinged pairs (sets) folded in accordian-like fashion together with the expandable trusses and other devices necessary for antenna space operation, such as attitude control and antenna feed. The panel sets are deployed from the canister to form a toroidal ring, circular in cross-section when deployed, for supporting the antenna lens and to form a feed support boom utilizing the canister as part of the antenna structure. The canister is connected to the ring and support boom in the deployed state by the expandable trusses. A fully automatic system is included for deploying the antenna and for holding the antenna structure in its deployed state. By adding a second (back) boom and reflector screen, a paraboloidal antenna is formed. In a second embodiment, utilizing the same storage and deployment principle but with panel sets which are triangular in cross-section, when deployed, either an offset (asymmetrical) paraboloidal or a feed horn type antenna structure is formed. In another embodiment of the invention, utilizing the same principle and with panel sets which are triangular in cross-section, when deployed, a solar panel array is formed. Also disclosed is a foldable truss geostationary platform and package for transfer into a geostationary orbit. Finally, an alternate mechanism is disclosed in the form of a pantograph for deploying panel sets to form a truss.

Design Guidelines of Horn Antennas That Combine Horizontal and Vertical Corrugations for Satellite Communications

Abstract: Today, telecommunication satellite horn antennas are required to be wideband mainly because of the additional bandwidth necessary to accommodate more transponders to increase the capacity of the new satellite services. In this aspect, horn antennas play a key role in the development of wider bandwidth services on board satellites because now-a-days, with recent advances in orthomode junctions and transducers, they are usually the bandwidth limiting component of a satellite antenna as often low crosspolar level is the toughest specification parameter. In this paper, the design guidelines for horn antennas that combine horizontal and vertical corrugations are explained, the method to prepare a preliminary profile for optimization is shown, and an example of a satellite feedhorn with severe requirements is presented.

Multi-chroic Feed-Horn Coupled TES Polarimeters

Abstract: Multi-chroic polarization sensitive detectors offer an avenue to increase both the spectral coverage and sensitivity of instruments optimized for observations of the cosmic-microwave background (CMB) or sub-mm sky. We report on an effort to adapt the Truce Collaboration horn coupled bolometric polarimeters for operation over octave bandwidth. Development is focused on detectors operating in both the 90 and 150 GHz bands which offer the highest CMB polarization to foreground ratio. We plan to deploy an array of 256 multi-chroic 90/150 GHz polarimeters with 1024 TES detectors on ACTPol in 2013, and there are proposals to use this technology for balloon-borne instruments. The combination of excellent control of beam systematics and sensitivity make this technology ideal for future ground, ballon, and space missions.

Additive Manufacturing of Ka-Band Dual-Polarization Waveguide Components

Abstract: Additive manufacturing (AM) is emerging as a key technology for the minimization and integration of microwave antenna systems. Among the several AM processes, selective laser melting (SLM) is rather convenient for waveguide components, since it allows for all-metal parts with a mechanical accuracy within 30–60 $\mu \text{m}$ and an equivalent surface electrical resistivity in the range of 10–20 $\mu \Omega \text {cm}$ . This paper reports on the assessment of the SLM applicability to the manufacturing of dual-polarization waveguide components operating in Ka-band, namely, a septum polarizer, a smooth-wall feed horn integrated with the septum polarizer, and an orthomode transducer (OMT). In order to achieve high electromagnetic performance in the Ka-band, the architectures have been optimized for the manufacturing process, above all in terms of orientation on the building platform and minimization of supporting structures. As a consequence, the corresponding prototypes exhibit measured performances in significant agreement with the predicted values. As an example, the return loss of all the components has been measured to be as high as 25 dB, while the measured isolation between the rectangular waveguide ports of the OMT is better than 47 dB.

Gravity-dependent signal path variation in a large VLBI telescope modelled with a combination of surveying methods

Abstract: The very long baseline interferometry (VLBI) antenna in Medicina (Italy) is a 32-m AZ-EL mount that was surveyed several times, adopting an indirect method, for the purpose of estimating the eccentricity vector between the co-located VLBI and Global Positioning System instruments. In order to fulfill this task, targets were located in different parts of the telescope’s structure. Triangulation and trilateration on the targets highlight a consistent amount of deformation that biases the estimate of the instrument’s reference point up to 1 cm, depending on the targets’ locations. Therefore, whenever the estimation of accurate local ties is needed, it is critical to take into consideration the action of gravity on the structure. Furthermore, deformations induced by gravity on VLBI telescopes may modify the length of the path travelled by the incoming radio signal to a non-negligible extent. As a consequence, differently from what it is usually assumed, the relative distance of the feed horn’s phase centre with respect to the elevation axis may vary, depending on the telescope’s pointing elevation. The Medicina telescope’s signal path variation ΔL increases by a magnitude of approximately 2 cm, as the pointing elevation changes from horizon to zenith; it is described by an elevation-dependent second-order polynomial function computed as, according to Clark and Thomsen (Techical report, 100696, NASA, Greenbelt, 1988), a linear combination of three terms: receiver displacement ΔR, primary reflector’s vertex displacement ΔV and focal length variations ΔF. ΔL was investigated with a combination of terrestrial triangulation and trilateration, laser scanning and a finite element model of the antenna. The antenna gain (or auto-focus curve) ΔG is routinely determined through astronomical observations. A surprisingly accurate reproduction of ΔG can be obtained with a combination of ΔV, ΔF and ΔR.