Showing papers on "Feed horn published in 1993"

Portable radio communication device with wide bandwidth and improved antenna radiation efficiency

Abstract: A portable radio communication device capable of eliminating the deterioration of the radiation efficiency due to the occurrence of the dual resonance on the antenna, without reducing the bandwidth. A radio communication device, comprises: a device body (3) made of a conductor body, containing at least one of a radio transmitter and a radio receiver; and an antenna (5), mounted on the device body (3), formed by first and second strip-like conductor elements (5a, 5b) which are connected together at a feeding point (7) connected with said at least one of the radio transmitter and the radio receiver, the first and second strip-like conductor elements (5a, 5b) having an identical electrical length with each other.

Design of conical corrugated feed horns for wide-band high-frequency applications

Abstract: This paper presents a new analytical procedure for the design of the conical corrugated feed horns used in the millimeter and submillimeter wavelength range, which could achieve wide-band single-mode operation and wide-band, low return-loss impedance matching simultaneously. A test model of the feed horn designed using this procedure displayed excellent performance, and agreed well with the theoretical predictions. >

Design of offset-parabolic-reflector antennas for low cross-pol and low sidelobes

Abstract: The results of a computational study on the radiation properties of offset prime-focus-reflector antennas are reported Emphasis is on reducing sidelobes and cross polarization without sacrificing gain The influence of feed pointing is examined in detail A simple technique is introduced for determining the feed-pointing direction This technique yields near-minimum sidelobe levels over practical ranges of feed pointing, with only small penalties in gain and cross polarization >

Clockwise and counterclockwise circularly polarized wave common receiving apparatus for low noise converter

Abstract: The input probe of an LNB for commonly receiving clockwise and counterclockwise circularly polarized waves includes a rectangular microstrip patch, with the length of one edge of it being λ g /4, which is installed at the center of an annular strip shaped ground pattern, with a feed horn being disposed at the side opposite to a substrate. Four input probes are installed adjacently to the respective edges of the rectangular microstrip patch. The two pair of the input probes which are installed adjacently to the respective edges of the rectangular microstrip patch are respectively commonly connected to first and second feed lines. With this arrangement, the length of one input probe relative to that of the other one shows a difference of λ g /4.

Analysis of a cluster feed for the Arecibo trireflector system using forward ray tracing and aperture integration

Abstract: A cluster feed for the Gregorian dual-reflector feed of the Arecibo radio telescope is studied The system is analyzed by forward ray tracing from each individual feed horn via the three reflectors to the aperture The radiation pattern is determined by aperture integration The analysis method is very time efficient compared with physical optics (PO) integration, the latter being unusable at high frequencies because the computer time increases by a factor proportional to the frequency to the power 4 Results obtained by the ray tracing method and PO integration are in very good agreement at frequencies low enough to be used for PO calculations A special algorithm is developed to determine the squint and directivity of an individual main beam without computing the radiation pattern This makes it possible to use the program very efficiently when searching for optimum cluster feed geometries The computer programs are used to design a seven-element cluster feed for the Arecibo trireflector system >

Corrugated feed horn array structure

Abstract: A unitary array of efficient directional corrugated feed horns, each having a desired corrugated horn cross-section within close tolerances, as well as accurate positioning and orientation relative to each other. The unitary array structure is comprised of a plurality of thin platelets which are laminated together in a selected sequence. The unitary array design provides a mechanical structure to support millimeter and sub-millimeter wavelength electronic devices for reception or transmission of electromagnetic energy and cooling fluid circulation channels within the array to remove unwanted heat generated by the attached electronic devices. The design of the present invention affords a relatively lightweight structure through removal of unneeded materials by forming cavities within the structure while leaving sufficient material for the bonding of the platelet assembly.

A dual-band feed system

Abstract: With the dual-reflector antenna configuration widely used for both earthbound and spacecraft antennas, the feed design is a crucial part of the overall system. While feed horns have been developed to cover continuous bandwidth ratios of at least 2:1, widely separated bands are more difficult to design effectively within a single feed. To achieve the necessary bandwidth for, say, C/Ku-band simultaneous operation, the dielectrically loaded corrugated, dual-frequency horn as described by M.S. Narasimhan and M.S. Sheshadri (see IEEE Trans. Antennas. Propag., vol.Ap-27, 858-60, 1979), is a strong candidate. The authors outline their approach in analysing this type of feed horn used in conjunction with a coaxial diplexer to excite the two bands in the horn.

Multibeam antenna for receiving satellite waves

Abstract: A multibeam antenna for simultaneously receiving waves from one or more communication satellites and a broadcast satellite, which are apart in their stationary orbit positions over the equator, is disclosed. The antenna employs an offset parabolic face, used as a reflector for receiving satellite broadcast waves, a converter having a primary radiator for receiving communication satellite Waves set at the focus point of the offset parabolic face, and a converter having a primary radiator for receiving broadcast satellite waves set near the envelope of the broadcast waves reflected from the offset parabolic face. The offset parabolic face is pointed in the direction of the communication satellite such that the plane of symmetry of the offset parabolic face is coincident with a plane specified by the communication satellite, the broadcast satellite, and the receiving point of the antenna. By utilizing this arrangement, an antenna that is relatively inexpensive to manufacture and is easily installable and adjustable may be obtained.

Wide scanning spherical antenna

Abstract: A novel method for calculating the surface shapes for subreflectors in a suboptic assembly of a tri-reflector spherical antenna system is introduced, modeled from a generalization of Galindo-Israel's method of solving partial differential equations to correct for spherical aberration and provide uniform feed to aperture mapping. In a first embodiment, the suboptic assembly moves as a single unit to achieve scan while the main reflector remains stationary. A feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan thereby eliminating the need to oversize the main spherical reflector. In an alternate embodiment, both the main spherical reflector and the suboptic assembly are fixed. A flat mirror is used to create a virtual image of the suboptic assembly. Scan is achieved by rotating the mirror about the spherical center of the main reflector. The feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan.

Portable radiotelephony transmitter/receiver

Abstract: This transmitter/receiver (1) is of the type comprising, integrated into the same hand-held assembly (2), an earpiece, a microphone, radio signal reception and transmission circuits, with a power transmitter stage and an antenna (3) radiating the signal produced by this power stage. According to the invention, screen-forming metallic means (5) are provided, interposed between the antenna and the user holding the handset applied against his head (4), these screen-forming means being, in operating position, sized and arranged in such a way that the cerebral volume of this user is situated essentially in the radio frequency shadow cast (X) by the screen-forming means with respect to the antenna.

FLAPS reflector antennas

Abstract: A flat parabolic surface (FLAPS) reflector is a thin (planar or conformal) surface consisting of an array of elements, each functioning as a radiator and phase shifter. Unlike a conventional planar array, however, the elements on the FLAPS surface are spatially fed using a feed assembly, as in a conventional reflector system. This results in an antenna technology that offers the advantages of both planar arrays and reflector systems. Additionally, FLAPS technology offers packaging and deployment ease and is suitable for a variety of manufacturing processes and procedures using low-cost materials. Other features, such as polarization control, large apertures with low windloading, and low-cost electronic beam switching, are also possible. Initially developed for defense microwave and millimeter-wave radar applications, FLAPS antennas are now being developed and fielded in many defense as well as commercial radar and communications systems. >

A shaped reflector design for the DirecTv direct broadcast satellite for the United States

Abstract: A design for the DirecTv DBS (direct broadcast satellite) coverage of the United States using a single shaped reflector is presented This design is interesting and challenging because of the high ratio of the area of the coverage to the area of the pencil beam obtained using an unshaped reflector (>40) For the initial multifeed study, a parabolic reflector with a diameter of 96" was considered After a detailed trade-off study, a design with a 56-element feed array was chosen For the shaped reflector approach, a diameter of 85" was chosen after an initial trade-off study A sensitivity study using a 'potato-chip' distortion model was conducted >

Method of identifying antenna-mode scattering centers in arrays from planar near field measurements

Abstract: A method of identifying antenna-mode scattering centers in an aperture device or array from planar near field measurements. Antenna-mode scattering centers may be determined for aperture assemblies, phenomenological models of apertures, and antenna arrays comprising a feed and an array of antenna elements. The method uses a scanning probe and receiver for making near field measurements. A feed horn and signal source illuminates the device. An absorber is disposed between the device and the probe and this combination is illuminated. A first set of data is collected over a planar surface in a near field region of the device. The device is then illuminated with the absorber removed. A second set of data is collected over a planar surface in a near field region of the device. The difference between the first and second sets of data is determined to provide data indicative of the near field response of the probe to the near field scattered from the device. Data indicative of the scattered far field from the device is computed using a planar near-to-far-field transform. The computed far field data is then converted from probe coordinates to device coordinates. The converted far field data is equated to data corresponding to the far field of an array device whose excitation weights are a product of a reflection coefficient looking into the feed at a junction between an antenna element and the feed, and a horn-element coupling factor between the feed horn and an antenna element that is proportional to power received by an individual antenna element from the feed horn. A copolarized component of the far field is divided by a copolarized component of an embedded element pattern to produce a scalar array pattern. The excitation weights are determined using an inverse fast Fourier transform (FFT) of the scalar array pattern. The reflection coefficients are determined by dividing the excitation weights by the horn-element coupling factor. Finally the antenna-mode scattered far field may be computed for an arbitrary incident plane wave having the predetermined angle of arrival and polarization at a predetermined frequency, which antenna-mode scattered far field is indicative of the antenna-mode scattering centers in the device.

Satellite TV receiver for multiple satellites - has fixed dish with feed-horn mounted in such way to allow adjustment to receive signals from one or more nearby satellites.

Abstract: The television satellite receiver has a parabolic disc (2) that acts as a reflector to direct signals to a feed-horn (3) that is mounted on an arm (4). A mounting (9) secures the arm to the main fixed mounting for the dish. An extension connects with a pivot lever (12) and this connects with an eccentric with a pin on a plate that can be moved by a motor. The feed-horn moves in a curved path when the motor is driven and allows alignment with a specific line of reception to a satellite. In this way input from several satellites may be received. USE/ADVANTAGE - Allows reception from several nearby geo-stationary satellites. Technically simple arrangement requiring only one feed-horn.

A dual reflector antenna for omnidirectional coverage

Abstract: A new type of omnidirectional antenna is presented, consisting of a parabolic reflector and a conical reflector, arranged to radiate, with a proper choice of the feed, vertical polarization in the horizontal plane. The main characteristics of this antenna are the following: a radiated field which is vertically polarized; very low losses; a higher bandwidth with respect to an array; good matching at several frequencies (for a feed diameter ranging from 1 to 2 /spl lambda/), in a relatively wide bandwidth; the possibility of obtaining a prescribed power density distribution in the elevation angle by appropriately shaping the conical reflector; and ease of manufacture. >

A dual offset shaped reflector for elliptical beams

Abstract: Presents the design techniques for dual offset shaped reflectors, with special emphasis on sidelobe and cross polar performance. The method is systematic and not based on ad hoc assumptions. The principles of the method are described, with an outline of the numerical solution technique included. A specific design of which a breadboard model has been manufactured, integrated and tested as part of an INTELSAT R&D study, is evaluated where the importance of choosing the right analysis method and as accurate input data as possible is demonstrated by comparing analysis and measurements. This provides the basis for using the same method in the design of the two Ku-band spot beam antennas, S1 and S2, on the INTELSAT VIII series spacecraft, which is currently being built by GE Astro Space, with DASA and TICRA as sub-contractors for the spot beam antennas.

Dual-band reflector feed system for classical Cassegrain radio telescopes

Abstract: The authors describe a dual-band feed system, operating at S- and X-band, that can be temporarily mounted and used in a classical Cassegrainian-type radio telescope without removing the existing feed systems. The feed system, designed to give as high efficiency as possible in both bands, consists of two offset primary-fed parabolic reflectors, one for each frequency band. The X-band reflector, located behind the S-band reflector, radiates through a plane dichroic surface that replaces the central part of the S-band reflector. The feed system is to be used for space geodesy utilizing the very-long-baseline interferometry (VLBI) technique and has been tested and used at a radio telescope in Chile. Results of both a theoretical design study and measurements are given. >

TDF antenna for multisatellite reception using 3D Fresnel principle and multilayer structure

Abstract: The Telediffusion de France (TDF) solution for multisatellite reception is to develop an antenna whose concept is based on diffraction theory The first step concerns low-cost TVRO (TV receive only) for DBS (direct broadcast satellite) Then, a more sophisticated antenna could be developed for professional use (cable head-end) A parabolic Fresnel zone antenna has been designed to provide two symmetrical focal points by diffraction with spacing of approximately 40/spl deg/ Consequently, a fixed antenna is able to receive simultaneously incident plane waves with a large incidence angle over a range of some 60/spl deg/ The surface of a conventional parabolic antenna is modified by a set of concentric metal rings with an elliptical shape to provide this scanning effect A preliminary theoretical analysis and practical experiments have confirmed the multisatellite design of the half-wavelength correction >

Gain enhancement in dielectric core filled multimode conical horn antenna

Abstract: Dielectric core inserted multimode conical horns for optimizing the feed horn performance with low sidelobe and cross-polarization together with increased directivity and gain are investigated Multiflare conical horns were designed at K/sub u/-band frequencies, and were studied experimentally with dielectric core inserts made of low-loss polyethylene and polystyrene Radiation pattern measurements were for HE/sub 11/ mode excitation of the horn by a TE/sub 11/ mode in the input circular waveguide at frequencies of 10 to 18 GHz It is observed that the performance of the horn is similar to that of the dielectric loaded multiflare conical horn studied by the author earlier (1992) But the distinctive difference is that in the present horn the gain performance is less sensitive to frequency compared to that with wall dielectric loading >

Microwave receiving level detector

Abstract: PURPOSE:To move and adjust the direction of a parabolic antenna, while looking at a receiving level by attaching integrally the level detector to a feed horn of the parabolic antenna. CONSTITUTION:This detector consists of a level detector having a level detecting part 1 which is provided with a fitting means for attaching integrally to a signal output terminal of a feed horn 2 provided in a parabolic antenna 4, and detects a receiving signal level, and a power source part 9 separated from the level detecting part 1, detects the receiving signal level by attaching the level detecting part 1 to the signal output terminal of the feed horn 2 by the fitting means at the time of adjusting the direction of the parabolic antenna 4, moves the direction of the parabolic antenna, while looking at the receiving level, and can adjust and set the direction of the parabolic antenna 4.

Confocal parabolic reflector antenna design trade-offs

Abstract: Three dual reflector configurations were designed and examined in detail. These are: on offset confocal parabolic antenna fed by a small phased array (image plane system) with both small and large magnification ratios, and a center-fed Cassegrain reflector antenna with a defocused feed array. Simulations show that the dual reflector configuration, center-fed by a phased array, while mechanically desirable, possesses high sidelobes as a result of aperture blockage. The offset-fed configuration, being free of blockage, can achieve very low sidelobes, the level being a function of the feed size used. If elements with amplitude excitations from 0 to -20 dB are activated in the feed array, the secondary sidelobes will be typically below -35 dB. >

Reusing antenna of dual band frequency

Abstract: PURPOSE: To provide frequency re-use capability for a dual band frequency antenna by constituting the antenna of a 4-terminal waveguide network, a feed horn and a polarizer. CONSTITUTION: A waveguide 12 has a 4-terminal waveguide network. Ports 20, 22 are used for transmitting an orthogonal linearly polarized wave signal with a 1st frequency, which is a transmission band frequency range of 4.035-4.200GHz. Other ports 24, 26 are used for receiving an orthogonal linearly polarized wave signal with a 2nd frequency, which is a reception band frequency range of 6.260-6.425GHz. The four independent linearly polarized wave signals are combined and enter a common square waveguide 12 to stimulate a quadrangular pyramid feed horn 14. A meander line polarizer 16 coupled with an opening 17 of the horn 14 convert the linearly polarized wave signals into two circularly polarized wave signals rotated opposite to each other and emits a circularly polarized wave field at a transmission band frequency from an antenna 10. Furthermore, the polarizer 16 converts the two circularly polarized wave signals rotated opposite to each other into two orthogonal linearly polarized wave signals.

Polarization signal receiver

Abstract: The utility model relates to a polarization signal receiver comprising a feed horn 4 The opening of the polarization signal receiver is provided with a dust cover; the outer side near the opening is provided with a scalar ring 3; a converter 5 is arranged in the opening; a probe 6 is arranged on the feed horn 4 through which signals are coupled with a low-noise amplifier 7 on the back side of the feed horn The polarization signal receiver is provided with the high efficient polarization of matched wideband resistance and a TVRO system to combine with the low-noise amplifier into a whole body to sufficiently cover C and Ku frequency bands in order to increase the intensity of receiving signals

Analysis of circular reflectors by complex source-dual series approach

Abstract: Two-dimensional circular reflector antennas are analyzed by a rigorous analytical-numerical technique for both E and H polarization cases. The method is used in combination with the complex source approach. The convergence of the solution is guaranteed and any desired accuracy can be obtained. Some principal results on reflector antennas are examined by the exact circular reflector solution. >

A shaped dual reflector antenna system for generating a plurality of beam coverages

Abstract: A dual-reflector antenna system (40) is provided for generating a shaped main beam radiation pattern (20) and at least one additional secondary spot beam radiation pattern (30, 32). The antenna system (40) includes a main shaped reflector (10) having a shaped reflective surface (11) operatively coupled to a subreflector (12) for communicating therewith. A main feed horn (14) communicates directly with the subreflector (12) so as to reflect first energy to and from the main reflector (10) within a shaped beam radiation pattern (20). The subreflector (12) has an ellipsoidal reflective surface (13) which communicates directly with the main reflector (10) via an inverted reflective path (17) which has a converging focal point (18). One or more auxiliary feed horns (24, 26) are operatively coupled directly to the main reflector so as to directly communicate therewith and reflect second energy within one or more additional radiation patterns (30, 32).

Feed horn for switching horizontally and vertically polarized wave

Abstract: PURPOSE:To reduce the conversion loss by using a ridge waveguide so as to convert an electromagnetic wave in the coaxial mode outputted from a circular waveguide into an electromagnetic wave in the waveguide mode and outputting the wave with respect to a horizontally and vertically polarized wave switching feed horn. CONSTITUTION:A ridge waveguide 6 formed by providing a taper on a ridge structure section 8 at an opening is coupled to the outer wall of an end face 4 of a circular waveguide 2 while its axis is in a direction intersecting orthogonally with the prolonged line of a guide axis of a circular waveguide 2. A probe 3 having a turning axis perpendicular to the end face 4 is provided and inserted in the ridge waveguide 6 while being prolonged to the outside from the opening 5, and connected to an insulation shaft in the inside of a through-hole 12 provided to the ridge structure section 8 and penetrated through the ridge waveguide 6 and connected to a drive section 7 provided on the outside. Then the probe 3 is turned around the guide axis of the circular waveguide 2 as a center, one electromagnetic wave among plural electromagnetic waves introduced to the circular waveguide 2 is coupled, the electromagnetic wave is sent by the probe 3 in the coaxial mode to the ridge waveguide 6, and a signal is outputted from the ridge waveguide 6.

Horizontal and vertical polarized wave changeover feed horn

Abstract: PURPOSE:To reduce a conversion loss by converting an electromagnetic wave of a coaxial mode outputted from a circular waveguide into a waveguide mode through the use of a semi-coaxial cavity resonator and outputting the wave with respect to a horizontally and vertically polarized wave changeover feed horn. CONSTITUTION:A cavity resonator 6 is bonded to an outer wall of a termination face 4 of a circular waveguide 2 in a direction in which the guide axes are coincident with each other, a square waveguide 8 is bonded to a side face of the cavity resonator 6 via a coupling opening in a direction in which the guide axes are orthogonal to each other, one end of a center conductor 7 is extended and inserted into the circular waveguide 2 from an opening 5 provided to a termination face 4 to act like a coupling probe 3, and the other end is connected to an insulation shaft 9 and penetrated through the cavity resonator 6 and connected to a drive section 10 provided to an outside, the coupling probe 3 is turned to be coupled with one of plural electromagnetic waves introduced to the circular waveguide 2, the electromagnetic wave is propagated to the cavity resonator 6 in the coaxial mode and resonated at a prescribed frequency and outputted through the opening of the cavity resonator 6 in the waveguide mode.

Analysis of H-plane sectoral dielectric horn antennas

Abstract: The plane-wave approach has been used to analyze the radiation from H-plane hollow sectoral dielectric horn antennas. Theoretical and experimental radiation patterns at X-band for 20/spl deg/, 30/spl deg/, and 40/spl deg/ flare angles, dielectric thickness of 0.30 cm and 0.44 cm, and axial length of one /spl lambda/ have been obtained. >

Electromagnetic analysis of horn with ortho-mode transducer

Abstract: A new electromagnetic modeling activity has been carried out resulting in a significant improvement in the design and optimization capability of a feed system consisting of horn connected to an ortho-mode-transducer (OMT). The tools for the analysis of the horn, the OMT, and their combination, resulting in an integral analysis of the feed system, are described. The adopted approach is suitable for the extension of the analysis to waveguide structures, like matching networks, typical of a feed system. Some of the analytical results are supported by experimental results. The recent development of two methods for analysis of the OMT is emphasized. >

Mode matching analysis of small Cassegrainian reflector antennas

Abstract: It is shown that a combined circular and cylindrical mode matching techniques previously developed for the analysis of frequency diplexing structures (see S.M. Tun, International Conference on Computation in Electromagnetics, London, UK, IEE Conf. no.350, p.230-3, 1991) can be used to model compact Cassegrainian reflector antennas with aperture diameters less than 20 wavelengths. Such small antennas are difficult to design due to the presence of multiple interactions between the feed, subreflector and the main reflector. The analysis method is capable of taking into account all these interactions by representing the two reflectors and the feed as a series of cylindrical waveguide segments. Dielectric supports and lens structures can also be incorporated in the analysis. The analysis software has been successfully used to design a small splash plate feed antenna with low sidelobes. Although the mode matching method is not as flexible as those based on methods of moments, the authors illustrate that it can be used to predict radiation performance of small reflector antennas in the forward direction.