Showing papers on "Feed horn published in 1995"

Design and performance of a microstrip reflectarray antenna

Abstract: Microstrip reflectarray antennas present an alternative to conventional directive antennas in that they are flat, inexpensive, easy to install and manufacture, conformal to the mounting surface, easy to package, and they possess high power and beam steering capabilities. For the first time, a comprehensive, experimentally verified design procedure for the microstrip reflectarray is presented. In this design procedure, the microstrip reflectarray has been shown to be an effective linear array capable of beam switching and dual polarization. The design procedure also allows the array to be fed from a feed-horn offset at any given angle to the plane of the array. The design procedure is well suited for CAD programs. >

Conical Corrugated Microwave Feed Horn

Abstract: A conical corrugated microwave feed horn (10). A conical flare section (60) is formed at the aperture (20) of the feed horn (10) and a second smooth cylindrical section (200, 210) is formed at the throat (30) of the feed horn (10). The conical flare section (60) is formed with two regions (70, 220) whereby region (70) is a corrugated conical region formed at the aperture (20) and having a plurality of slots (70) formed parallel to the central axis (204) of the feed horn (10). Each slot (70) in the plurality of slots (70) has an inner surface (250) closest to the central axis (204) of the feed horn and an outer surface (240) furthest from the central axis (204). The first slot (70A) adjacent the smooth conical region (220) has first and second formed lips (280, 290) on the terminating end. The last slot (70C) of the plurality of slots (70) at the aperture (20) of the feed horn (10) has the terminating end of the inner surface (240B) extending in length beyond the length of the outer surface (240C).

An antenna system having a choke reflector for minimizing sideward radiation

Abstract: A antenna system of the present invention comprises a radiating means for radiating a radio frequency, which is converted from electric power, and which has a impedance matching unit and a power divider; a first reflecting means for reflecting and filtering said radio frequency; and at least one second reflecting means for filtering said radio frequency radiated in the sideward direction of said antenna system, which is vertically attached to said first reflecting means, and is able to be moved in a horizontal direction.

Dual-frequency microwave radio antenna system

Abstract: An antenna system for a navigation satellite receiver tuned to dual-frequency transmissions from orbiting navigation satellites. Respective L1 and L2 microwave patch antennas are mounted flat and adjacent to one another on a common ceramic substrate and have their centers grounded to a groundplane on the opposite side of the substrate with vias. Each patch antenna is connected to a respective near-by low-noise amplifier. The low-noise amplifiers are both connected to a signal combiner and a final radio frequency amplifier for down feed to a navigation satellite receiver. A direct current signal from the navigation satellite receiver is used on the down-feed to selectively control which one of the two low-noise amplifiers is to operate. Thus one coaxial down-feed supplies power to the low-noise amplifiers and provides for the selection between the L1 and L2 carrier frequencies on the down-feed.

High performance reflector hat antenna with very low sidelobes for radio-link applications

Abstract: Reflector antennas with self supported waveguide feeds of swan-neck type are often used in radio link systems. If there are requirements for very low sidelobes, it is common to attach an absorbing cylinder to the rim of the reflector. Both the cylinder and the feed are expensive to manufacture. The paper describes a so called hat antenna which is cheap to manufacture, compact, light-weight and in addition has very low sidelobe performance. An experimental model with 43 cm reflector diameter has been built and measured at 15 and 30 GHz.

Radio receiver for use in a radio tracking system

Abstract: A radio receiver unit for directionally tracking at least one radio transmitter in accordance with the invention includes a housing containing a radio receiver including a directional antenna for receiving radio transmissions from the at least one radio transmitter; a display, which is electrically coupled to the receiver and fixed in position with respect to the housing, for visually displaying a strength of the radio transmissions received by the directional antenna; and a field of view limiter for limiting light emanating from the display to a field of view of the display when a user holds the receiver unit in the user's hand away from the body of the user, the field of view being limited to planes extending upward from a plane of sight extending from the eyes of the user downward and intersecting a horizontal plane extending from the user's waist substantially at arms length of the user.

Ultra-wideband hybrid-mode feeds

Abstract: A modified dielectric cone-loaded horn is described that maintains excellent return loss and pattern symmetry over a bandwidth ratio greater than 30:1. The mechanisms responsible for the extremely broadband operation and its application as a feed horn for a reflector antenna are discussed.

Radio transmitter/receiver for wireless local area network

Abstract: A wireless local area network includes a radio transmitter/receiver for transmitting and receiving in accordance with the FCC rules for the ISM band. The receiver/transmitter supports spread spectrum frequency hopping in the 2.4 GHz ISM band and can be tuned to one of e.g. 82 different frequencies spaced at 1 MHz intervals. The radio transmitter/receiver is a low cost, low power, small size unit located on a printed circuit board in a PCMCIA form factor. Third order mixers are used in combination with a switched prescaler for a low cost and compact frequency control system capable of rapid switching of the radio between transmitting and receiving functions. No special shielding is needed between the frequency control circuitry and the receiver IF circuitry.

Antenna for use with a radio installed in an expansion slot of a computer system

Abstract: An antenna that may be retrofitted for incorporation in an internal compartment of a computer terminal when a radio transmitter or receiver is installed in an expansion slot of the computer terminal. The present invention provides a radio receiver/transmitter communication system for a computer terminal. The computer terminal includes an expansion slot operative to receive a radio transmitter or receiver and includes an enclosed compartment defined in the housing of the computer terminal. The enclosed compartment is separate from the expansion slot. The radio receiver/transmitter communication system includes a printed circuit board and a radio frequency communication medium. The radio frequency communication medium is etched on a first side of the printed circuit board, thereby forming a circuit board antenna, and the printed circuit board antenna is positioned within the enclosed compartment of the computer terminal. The radio communication system also includes a radio transmitter/receiver expansion board installed in the expansion slot and a connection cable connected to and providing a transmission path between the radio frequency communication medium of the circuit board antenna and the radio transmitter/receiver. The radio communication system is preferably implemented in a portable computer terminal that includes a the stylus pen slot as an internal compartment.

Elliptic beam horn antenna

Abstract: An elliptic beam antenna easy to design and simple in structure. To generate elliptic beams of about the same size regardless of the kind of polarized waves for excitation, a horn antenna or waveguide structure intended for radiating out radio waves into space features the provision of diamond aperture, modified from the conventional circular, elliptical, square or rectangular one and excitation of radio waves in diagonal directions.

Analysis and design of millimeter wave microstrip reflectarrays

Abstract: The reflectarray combines features of reflector and array antennas. Reflectarrays are illuminated by a feed antenna which excites an array of radiating elements comprising a reflecting surface, and these elements produce a radiated field. Some types of reflectarrays, including the microstrip reflectarray, also produce a specularly reflected field component, as in the case of a reflector antenna. The total field then consists of the radiated field from the patches and the specular reflection. The design and analysis of two millimeter wave microstrip reflectarrays, operating around 27-28 GHz, are discussed. The first design utilises a corrugated conical horn feed and square patch radiating elements to accommodate dual polarisation. The main beam is steered to 25/spl deg/ off broadside in the vertical plane. The second design uses rectangular patches for linear polarization, and a backfire feed which greatly simplifies the feed supporting structure, and a broadside main beam. Measured patterns, gain, and a loss budget are presented and the performance is compared with typical microstrip array antennas. The generation of cross-polarized components of the radiated field is also discussed.

A shaped dual-reflector antenna with a tilting flat subreflector for scanning applications

Abstract: A scanning dual-offset reflector antenna using the simple motion of a flat subreflector to illuminate different parts of a shaped main reflector is presented. A particular case having a 20-degree linear field-of-view (for a DBS application) with a 30/spl lambda/ aperture diameter is explored. The main reflector surface is shaped to minimize the phase aberrations across the field-of-view. Once the main reflector surface is designed, the subreflector parameters are determined to ensure optimum focusing across the field-of-view. >

On the analysis and design of the frequency selective surface for the N-Star satellite Ku/S-shaped reflector

Abstract: The N-Star satellite Ku/S antenna system consists of the main shaped reflector, frequency selective subreflector FSS, the S-band helices, and the Ku-band corrugated feed horn. The Ku/S subreflector consists of a planar frequency selective surface which is transmissive at the S-band, and reflective at the Ku-band. The analysis and design procedure, as well as the performance of the frequency selective subreflector, are presented.

Very small aperture terminal and antenna for use therein

Abstract: A data transmitting/receiving satellite terminal for transmitting to and receiving from a geosynchronous satellite (11) employs an antenna (15A, 15B) having nulls in its antenna receiving pattern at a first frequency corresponding to satellites spaced at regular intervals from the satellite. In addition, a phase and amplitude compensation network (23A, 23B) adjusts a phase and amplitude of the transmitted signal to compensate for transmitting at a different frequency than for which the antenna is optimally designed. The antenna includes a main parabolic reflector, and two side parabolic reflectors offset from a plane parallel to the main parabolic reflector. Each of the reflectors uses a dual frequency feed horn to couple energy to and from the reflector to a dipole exciter to which the receiving electronics are coupled. The above terminal is particularly useful in C-Band applications.

Broadband omnidirectional microwave antenna.

Abstract: An omnidirectional microwave antenna comprises a conical reflector and a conical feed horn. The conical reflector has a reflecting surface defined by a cone having an axis and a surface of revolution around the axis. The line of intersection between the surface of revolution and a plane passing through the axis and the surface of revolution is a segment of a parabolic curve. The reflector includes a flange extending outward from an outermost circumference of the surface of revolution of the cone. The conical feed horn feeds microwave energy to the conical reflector from a location along the axis of the cone. The feed horn has an aperture whose center is located approximately at the apex of the cone. The flange has absorptive material mounted thereto for absorbing microwave energy impinging thereon.

Simulation of reflector antenna covered by a circular radome

Abstract: The effects of radomes have previously been studied by using such traditional approaches as local flat-slab approximation, local circularly curved surface approximation, thin-layer approximation, finite element solution, etc. For a canonical radome geometry like a circular cylindrical one, it is possible to derive the Green's function in explicit form, by using the addition theorems for cylindrical functions. This enables one to write further an electric field integral equation over the reflector's surface, and solve it by the moments method (MM). However, even for a free-space geometry, the MM results in prohibitively large CPU time, if a reflector is larger than 20 lambda. What is even more disappointing, the MM is known to be heavily inaccurate if a kind of shell resonance takes place. Therefore, in the present analysis the authors combine the Green's function approach to account for the radome, with the method of regularization for solving the scattering from the reflector accurately. Besides, to simulate a directive feed in an equally accurate manner, the authors use the complex source point (CSP) concept. The latter is known as a very efficient way to account for the feed directivity without loosing mathematical correctness.< >

Flat printed lens and reflector antennas

Abstract: The performance of the printed single and double layer phase correcting arrays is theoretically analysed. Then, the latest development of the single printed reflector is reported. The successful design of a practical size single printed reflector for the reception of direct broadcasting by satellite (DBS) is described. The reflector covers three full Fresnel zones and a quarter wave zone, and has a 59.4 cm diameter and 0.8 focal length to diameter ratio. A 43% maximum antenna efficiency and a bandwidth of greater than 10% were measured. The close-in sidelobes of the antenna are about -22 dB and the far-out sidelobes are below -30 dB. >

The analysis of a segmented paraboloidal reflector with hexagonal flat sections

Abstract: Segmented reflectors are an important sub-category of reflector antennas where the smooth compound curvature of the reflector is approximated by many small flat sections. The general dynamics (GD) paraboloidal truss antenna described by Fager and Garriot (1969) consists of a large number of hexagonal flats. This antenna was initially intended for space deployment, but this antenna appears to be suitable for terrestrial applications as well. Like most terrestrial reflectors, the GD antenna, consists of both a reflector and a backing structure, yet has demonstrated considerably reduced weight and volume (when folded for shipping) over usual fabrication methods currently in use. The GD antenna, is reminiscent of Buckminster Fuller's Montreal '67 Expo double layer dome. Both the backing structure of the GD reflector and Fuller's dome use a octahedron-tetrahedron (OCTET) truss. Thus, some of the techniques used by civil engineers in the design of large clear span structures could be used in the design of large reflectors, as, for example, earth terminal antennas for satellite communications or radio astronomy antennas. The GD reflector is a tensile mesh net consisting of hexagonal flats. A modified version has pentagons, tetragons, and truncated hexagons along the rim to more closely approximate a circular rim reflector. Thus, it would be desirable to compute the radiation patterns due to polygonal segmentation. Heretofore, reflectors with surface errors would be analyzed by statistical means such as those shown in Ruze's paper (1966). The line integral method, described here, provides an accurate deterministic method of field computation.

A feeder horn, intended particularly for two-way satellite communications equipment

Abstract: A feeder horn for two-way satellite telecommunications includes a central transmitter/receiver horn (10) and at least three separate measuring horns (11, 12, 13) which are positioned symmetrically relative to the symmetry line (O) of the feeder horn. All horns are produced mechanically in a one-piece metal structure (1) which includes a transceiver-horn (10) accommodating and through-penetrating centre opening (100) which merges with a transmitter waveguide (101) and a receiver waveguide (102) which are separated by a filter of the orthomode transducer type (OMT), which is constructed for separating differing polarizations and comprises an output to the centre opening (100) of the metal structure and two inputs to respective waveguides for the transmitter and receiver waveguides (101, 102); wherein the metal structure further includes a bottom-defined opening (110, 120, 130) for each of the measuring horns (11, 12, 13), a switching device (111, 121, 131) anchored in the metal structure (1) for each of the measuring horns and moat-like channels (104, 114, 124, 134) provided around each opening (100, 110, 120, 130) in the metal structure, to isolate electromagnetically each horn in relation to each other horn.

Feed horn for circularly polarized wave

Abstract: PROBLEM TO BE SOLVED: To attain ease of assembly at a low cost by decreasing number of components to simplify the structure. SOLUTION: A wall 2 is provided on a depth end of a feed horn 1 through integral forming or the like, slots 7, 8 are formed to the wall in a chevron shape to convert an incident circularly polarized wave into a linearly polarized wave. A waveguide 6 forms the wall, a chassis 3 and a conductor foil of a lower face of a printed circuit board 4, the linearly polarized wave converted by the slots 7, 8 from the circularly polarized wave is coupled with a microstrip line on an upper face of the printed circuit board via a probe 5 stood upright on the printed circuit board in the direction of the arrow B and the wave is transmitted to an LNB circuit. The length of the slots 7, 8 is selected to be λ/2 with respect to a wavelength of a received radio wave and placed orthogonally in a propagation direction with a interval of λ/4. Or in place of the probe, the slot is provided by removing the conductor foil of a lower face of the printed circuit board and the polarized wave may be coupled with the micro strip line via the slot. In this case, a slope is provided to a chassis under the slot and a direction of an electric field is changed by 90 deg. so as to propagate the linearly polarized wave in the direction of the slot.

Design of multimode shaped reflector antennas

Abstract: Communication and broadcast satellites commonly employ contoured beam antennas to achieve efficient coverage of irregularly shaped geographical service areas. The use of shaped reflector antennas in generating a contoured beam is presently the preferred solution. A single corrugated horn is used to illuminate an offset reflector whose shape is designed to approximate the required radiation pattern. The paper describes a synthesis method for multimode shaped-reflector antennas that is based on physical optics calculations and simultaneously allows the synthesis of the reflector surface, the feed array and the multimode beam forming network (BFN). The application of this method to the next generation of European telecommunication missions (EUTELSAT III), demonstrates that, by using arrays with few radiating elements, this antenna configuration combines the structure simplicity and the electrical performance of a single beam shaped-reflector antenna with the capability of generating two or more simultaneous overlapped contoured beams without significant performance degradations. >

Parabolic receiving antenna appts.

Abstract: The parabolic antenna with the feed part (10) is connected to the receiving equipment by a coaxial cable. The parabolic reflector (12) focusses the electromagnetic signals, from a transmitter or relay satellite, on to the feed part or point. This reflector and the feed point are connected to one another, and to the supporting arm (14). The back of the reflector is provided with a heat-insulating and electrically insulating layer (16). This is weather-resistant and made, for example, from a polyurethane foam (18).

Phase-center effects on wide-band horn pattern measurements in small anechoic chambers

Abstract: The use of large feed horns is well known, with reference to satellite ground station reflector antennas. These antennas essentially produce high gain pencil beams. Due to the use of shaped reflectors for satellite contour beam applications there is renewed interest in large primary feeds such as corrugated horns, trifurcated horns and pyramidal horns. Due to the sensitivity of the large contour beams with reference to the incident feed illumination, it is necessary to characterize these primary feeds very accurately. The theoretical radiation patterns are used for synthesizing the shape of the reflector. Once the shaped reflector is fabricated, very limited mechanisms are available in a shaped reflector system to compensate for the imperfections in the measured feed radiation pattern. Thus, it is necessary to verify the feed radiation patterns in amplitude and phase by measurements before integrating the feed with the shaped reflector. This paper discusses a few precautions to be undertaken while carrying out radiation pattern measurements on these large feeds. In many C-band shaped reflector antennas the feeds are required to operate over the transmit (3.6-4.2 GHz) and receive (5.85-6.425 GHz) bands. These feeds are about about 10 to 15" in diameter and are characterized by large variations in phase centers over the frequency band. This variation leads to an interesting phenomena while carrying out measurements in small anechoic chambers which are commonly used for feed horn measurements. The variation in phase centers requires a correction to the measured radiation pattern which is described. Failure to do so will lead to erroneous radiation patterns as illustrated.

Electronic Compensation For Distortion Of Antenna Reflector

Abstract: Proposed method of obtaining approximately desired radiation or reception pattern from antenna that includes reflector based on concept of superposition of electromagnetic fields generated by multiple feedhorns or feed antenna elements arrayed at various positions near reflector and excited at electronically adjustable magnitudes and phases. In intended application, reflector nominally paraboloidal, feed elements N feedhorns in hexagonal array, and method used to compensate for deviations of real reflector surface from nominal paraboloidal shape. Method and concept also applicable to electronic beam steering and electronic antenna compensation in other situations.

Mount structure of feed horn stationary arm for parabolic antenna

Abstract: PURPOSE:To provide mount structure of the feed horn stationary arm assembled simply without use of a tool or the like by devising the feed horn fixing arm such that a direction of the feed horn fixing arm is changed, a tip of the stationary arm is set to a rear side of a parabolic dish to attain folding and packing and setting the tip to a front side of the parabolic dish to make the assembling complete. CONSTITUTION:The structure is made up of support metallic fixtures 9, 12 supporting a feed horn stationary arm 5 at least at two positions, a stationary part 11 formed by forming a cross sectional area of the feed horn stationary arm 5 inserted between the support metallic fixtures 9, 12 as a square shape, and a direction designation means being a pressing spring 10 pressing the stationary section 11, and the feed horn stationary arm 5 is fitted to a rear side of a parabolic dish 1 to select the direction of the tip of the feed horn stationary arm 5 to a front side of the parabolic dish 1 or the rear side.

Optimum shaping technique for advanced dual-gridded shaped reflectors

Abstract: Current and proposed satellite communications systems demand dual-linearly polarised transmit-receive antennas for contoured and/or multiple beam coverages. The proven means of satisfying these requirements is by the use of dual-gridded parabolic reflectors with two separated feed arrays radiating opposite linear polarizations. The two parabolic dishes are gridded in perpendicular directions and placed in front of one another with independent focal points to maintain separated the relevant feed arrays and beamforming networks. This paper describes the results of an activity performed on the design of large and highly-shaped dual-gridded reflector antennas. The critical aspects in developing a reflector shaping technique based on an optimization algorithm are discussed. The advantage in compensating for the effects of reflector thermal distortions during the electrical antenna design are also demonstrated. This novel technique allows a less critical thermal control of the reflector assembly, with a consequent reduction of the development time, hardware mass, and ohmic losses.

Method and arrangement for improving radio coverage

Abstract: The invention relates to a method and arrangements for improving radio coverage in a mobile radio network, radio waves emitted by a fixed station being reflected from a passive reflector into an area to be covered and radio waves emitted in the area to be covered being reflected from the reflector to the fixed station.

TEM horn antenna for pulse radiation: an optimized design

Abstract: Various schemes have previously been used to improve the performance of the TEM horn as a pulse radiator; these include shaping of the metallic plates of the horn and using both continuous and discrete resistive loading. In most cases an empirical approach was followed in optimizing the horn. In the present paper the FDTD numerical method is used in an interactive mode to "optimize" various parameters of the horn [Shlager et al. 1994). The computed performance for the final design is compared with measurements made on an actual antenna.

Feed horn for right/left hand circularly polarized wave

Abstract: PURPOSE:To provide an LNB antenna integrated with feed horn for receiving right/left hand circularly polarized wave in which one converter converts a polarized microwave rotated in the right or left direction into a linearly polarized wave. CONSTITUTION:One end of a circular waveguide 1 is provided to a microwave reception aperture 2 and the other end is formed blind, an LNB base plate 3 is arranged to the aperture of the circular waveguide, a 1st layer circular dielectric board 4 having a parallel grating pattern 5 to the other side and whose thickness is a 1/4 wavelength of a converted microwave and a 2nd layer circular dielectric board 6 having a conductor pattern whose thickness is a 1/8 wavelength of a converted microwave to its one side are arranged to the other end and a parallel grating pattern 5 of the 1st layer board 4 is turned clockwise or counter clockwise by 4 deg. with respect to the lengthwise direction of the LNB base plate 3.

Antenna supporting device

Abstract: PURPOSE:To reduce the size and weight of this antenna supporting device, to simplify its setting work and to minimize a set area by supporting the intermediate point of an arm connected between a reflector and a feed horn in the device by a mount on a pole. CONSTITUTION:The mount 8 is inserted into the upper end of the pole 13, a bolt C12 is screwed into a screw hole 14, the azimuth angle of the reflector 1 is matched with a satellite by rotating the mount 8, and a bolt B10 is screwed into a screw hole A11. Then the arm 3 on a through hole A9 is moved to a necessary position in the back-and-forth direction, the elevation angle of the reflector 1 is matched with the satellite, the bolt C12 is clamped to support the mount 8 on the pole 13, and a bolt 10 is clamped so as to hold and fix the arm 3 between the lower edge of the hole A9 and the tip of the bolt 10. Consequently the reflector 1 and the feed horn 6 are supported on the pole 13 through the mount 8 and the arm 3.