Showing papers on "Feed horn published in 2004"

A smooth-walled spline-profile horn as an alternative to the corrugated horn for wide band millimeter-wave applications

Abstract: At millimeter-wave frequencies, corrugated horns can be difficult and expensive to manufacture. As an alternative we present here the results of a theoretical and measurement study of a smooth-walled spline-profile horn for specific application in the 80-120 GHz band. While about 50% longer than its corrugated counterpart, the smooth-walled horn is shown to give improved performance across the band as well as being much easier to manufacture.

Adaptive beam forming antenna system using a tunable impedance surface

Abstract: A method of and apparatus for beam steering. A feed horn is arranged so that the feed horn illuminates a tunable impedance surface comprising a plurality of individually tunable resonator cells, each resonator element having a reactance tunable by a tuning element associated therewith. The tuning elements associated with the tunable impedance surface are adjusted so that the resonances of the individually tunable resonator cells are varied in a sequence and the resonances of the individually tunable resonator cells are set to values which improve transmission of information via the tunable impedance surface and the feed horn.

A design study for the basic TEM horn antenna

Abstract: In this paper, a design study was performed for the basic TEM horn antenna. In the theoretical model, care was taken to avoid the problems associated with the use of gap sources when calculating the reflection coefficient and input impedance of the antenna. All numerical calculations were made with a program based on the method of moments, and the accuracy of the numerical calculations was established with measured results for selected antennas. The transverse electromagnetic (TEM) horn antenna is a popular broadband antenna. The basic antenna has a simple design consisting of two triangular plates and a feeding structure. The horn is described completely by only three variables: /spl alpha/, /spl beta/, and s. /spl alpha/ is the angular width of each plate, /spl beta/ is the angular separation between the two plates, and s is the length, measured from the drive point to the corner of the plate. The geometry of the basic TEM horn antenna does not require a particular choice of a feeding method.

RF transmitter arrangement for an MR system, and method for determining a setting parameter therefor

Abstract: A radio frequency transmitter arrangement for a magnetic resonance apparatus has a distribution unit and an antenna unit, wherein the antenna unit, to generate radio frequency fields, is fashioned in at least two orthogonal modes, and the distribution unit is fashioned for the division of an RF transmission signal into at least two mode feed signals. At least one adjustment unit is provided to adjust the amplitude and/or phase of one of the mode feed signals and is connected with the antenna unit such that each of the mode feed signals generates a radio frequency field in one of the modes. A multiple transmitter arrangement has at least two radio frequency transmitter arrangements and at least two 180° hybrids. A method is provided to determine at least one setting parameter of the adjustment unit.

Proximity detecting apparatus

Abstract: Arrangements according to the invention embody a radio frequency receiver for use in a proximity detecting system, the radio frequency receiver comprising at least one antenna coil operable to receive radio frequency signals; tunable receiver circuitry arranged in operative association with the antenna coil and being arranged to modify the frequency at which radio signals are received by the radio frequency receiver; and a signal processor arranged to amplify and filter signals received by the radio frequency receiver, wherein the radio frequency receiver is operable to receive and process radio signals of frequencies between 100kHz and 10MHz. By operating in the low frequency range, multi-path problems associated with high frequency equipment (such as reflections from objects located between the path of the transmitter and receiver) are significantly reduced, whilst distance between transmitter and receiver can be identified extremely accurately.

Antenna Instrumental Polarization and its Effects on E- and B-Modes for CMBP Observations

Abstract: We analyze the instrumental polarization generated by the antenna system (optics and feed horn) due to the unpolar- ized sky emission. Our equations show that it is given by the convolution of the unpolarized emission map Tb(; ) with a sort of instrumental polarization beam defined by the co- and cross-polar patterns of the antenna. This result is general, it can be applied to all antenna systems and is valid for all schemes to detect polarization, like correlation and dierential polarimeters. The axisymmetric case is attractive: it generates an E-mode-like pattern, the contamination does not depend on the scanning strategy and the instrumental polarization map does not have B-mode contamination, making axisymmetric systems suitable to detect the faint B-mode signal of the Cosmic Microwave Background Polarization. The E-mode of the contamination only af- fects the FWHMscales leaving the larger ones significantly cleaner. Our analysis is also applied to the SPOrt experiment where we find that the contamination of the E-mode is negligible in the '-range of interest for CMBP large angular scale investigations (multipole '< 10).

Electronically scanning direction finding antenna system

Abstract: An electronic scanning radio direction finding system (1) for accurate direction finding of radio frequency signals using singly or doubly flared cylindrical reflectors (2) surrounded by a circular array of inwardly facing feed horns (9). The array is operated as a phased array to determine the direction of origin of received signals. The feed horns (9) can also be used to transmit RF signals on very narrowly controlled beams with minimal side lobes. The flared cylindrical reflector (2) and its circular feed horn array may be paired with circular log periodic arrays operable at similar frequency ranges or different frequency ranges to provide more precise direction finding and direction finding of signals at frequencies beyond the range of the flared cylindrical reflector (2) and its circular feed horn array (9).

Antenna systems for reliable satellite television reception in moisture conditions

Abstract: More reliable satellite television reception in moisture conditions is provided by recognizing the critical relationship between satellite signal transmissivity and the effects of superhydrophobocity. Instead of trying to use a hydrophobic or superhydrophobic coating or material to shed water from a satellite antenna, superhydrophobic materials and coatings are strategically utilized to minimize the impact of water on the transmissivity of the satellite signal through transmissive surfaces in the antenna system. In a preferred embodiment, an exterior surface of a feed horn cover is coated with a superhydrophobic material to maintain a more consistent satellite signal reception. In an alternate embodiment, an exterior surface of a dome covering a small dish DBS satellite television antenna system is coated with a superhydrophobic material to minimize the overall satellite signal loss during moisture conditions so as to permit a dome to be effectively used over a small dish DBS satellite television antenna system.

Feed assembly for multi-beam antenna with non-circular reflector, and such an assembly that is field-switchable between linear and circular polarization modes

Abstract: A feed assembly for an antenna having a non-circular reflector, in which the feed assembly includes a feed horn capable of correcting the distortions of circularly polarized signals caused by the non-circular reflector profile, and wherein the feed horn is coupled with a polarizer that is field-switchable between linear and circular polarization modes of operation. The feed assembly can include a second receive-only feed located in close proximity to the feed horn for communication with adjacent satellites.

Radio transmitter and radio receiver

Abstract: PROBLEM TO BE SOLVED: To provide proper radio communications by selecting a combination of transmitting antennas from a plurality of transmitting antennas, according to a selection index for each subcarrier configured by correlation between transmitting antennas. SOLUTION: The radio transmitter comprises a plurality of transmitting antennas (Tx1-TxN) capable of transmitting a radio signal, an acquisition portion (21) for acquiring a propagation path response information indicative of a propagation path response formed by each of the transmitting antennas and the receiving antenna of a transmission destination, selection control units (22, 23, 23) for computing for each subcarrier a selection index value indicative of correlation between the transmitting antennas from the acquired propagation path response information and selecting a combination of the transmitting antennas for each subcarrier based on the selection index value. The radio transmitter transmits a radio signal using the selected combination of the transmitting antennas. COPYRIGHT: (C)2006,JPO&NCIPI

Multiple Co-Polar Co-Channel Point-to-Point Radio Transmission

Abstract: The use of multiple antennas both at transmitter and receiver improves the spectral efficiency in wireless communications. We propose a multiple antenna system, which is tailored for the scenario of line-of-sight fixed radio. The interference is removed by means of an equalizer operating at the receiver side without any onerous pre-processing at the transmit side. A suitable choice of the spatial separation among the individual transmit/receive antennas guarantees not only the possibility to re-use the frequency band but also an increase in the power efficiency respect to a single-input-single-output system.

Predicting directivity of standard-gain pyramidal-horn antennas

Abstract: Improvements proposed over the years in the edge-diffraction model for a pyramidal-horn antenna have been extended to include the three-dimensional nature of the pyramidal horn in evaluating the edge-diffraction fields. The theoretical model was compared with measured results, measured over a number of years at an international standards laboratory for frequencies ranging from 2.45 GHz to 18 GHz, with measurement uncertainties between /spl plusmn/0.04 dB and /spl plusmn/0.1 dB.

Radio transmission control method, radio receiver apparatus, and radio transmitter apparatus

Abstract: Conventionally, if the number of transmission antennas is greater than that of reception antennas, different signals simultaneously transmitted from the transmission antennas cannot be separated from one another at the receiving end, resulting in a significant degradation of received-signal quality. A transmitter and a receiver each have a plurality of antennas. The transmitter transmits a pilot signal. The receiver receives the pilot signal, calculates transmission-related information corresponding to the pilot signal, selects, based on this calculated information, a transmission signal to be used by the transmitter, and notifies the transmitter of the selected signal. The transmitter selects, from the informed transmission signal, transmission antennas and uses the selected antennas to transmit information signals, so that a signal separation can be easily performed at the receiving end.

System and method for highly directional electronic identification and communication and combat identification system employing the same

Abstract: An antenna for directional electronic communication, a directional communication system, a method of conducting directional communication, a combat identification system and a method of identifying friendly forces. In one embodiment, the antenna includes: (1) a conductive shield having an opening at an end thereof and a radio frequency absorptive material located on an inner surface thereof, (2) a Luneberg lens located within the conductive shield and (3) a feed horn located proximate a portion of the Luneberg lens that is distal from the opening.

Cartridge-Type 800 GHz Receiver for the Atacama Submillimeter Telescope Experiment (ASTE)

Abstract: We have developed a cartridge-type 800 GHz receiver for the ASTE telescope in Atacama, Chile. The receiver has been assembled with a cooled receiver optics, a Nb-based SIS mixer, a local oscillator (LO) optics and IF components in a 170 mm diameter column-type cartridge. The cooled optics is composed of a single ellipsoidal mirror to couple between the feed horn and the subreflector of the antenna, and an LO coupler with 10 % eciency. Owing to its cartridge and cryostat structure, the mechanical vibrations of the GM cryocooler are significantly reduced, therefore, the receiver is highly stable on the telescope. The receiver noise temperature using a Nb-based SIS mixer and a 4i8 GHz HEMT amplifier is attained to 1300 K in DSB at an LO frequency of 815 GHz. The system noise temperature, Tsys, was typically 4000i8000 K in DSB at an LO frequency of 812 GHz during the operations, which depended on the atmospheric opacity. The typical zenith opacity at an LO frequency of 812 GHz was » 1. The half-power beam width (HPBW) of the main beam was

Effect of aperture feed and reflector configuration on the time- and frequency domain radiation patterns of reflector impulse radiating antennas

Abstract: The prompt off-boresight radiation from an arbitrary reflector impulse radiating antenna (IRA) is considered in both the time and frequency domains using a time-domain physical optics formalism. The theory is used to compare the performance between reflector IRAs with common transverse electromagnetic feed configurations that have been designed to maximize the boresight fields. It is found that moving the feed arms of reflector IRAs toward the vertical helps to reduce sidelobe levels, as reflector IRAs with their feed arms oriented at 60/spl deg/ from the horizontal have sidelobes that are 4-5 dB lower in the H plane and 1-2 dB lower in the E plane than more traditional reflector IRAs with feed arms oriented at 45/spl deg/. The lower sidelobes are accompanied by a higher peak gain, albeit with a wider beamwidth. There are corresponding significant differences in the time domain waveforms that result. The theory is verified by comparison with experimental data from a half IRA with feed arms at 45/spl deg/. The peak fields, pulse widths, and overall waveform shapes agree well between theory and experiment, though there are temporal asymmetries in the measured data that are not predicted by the theory.

Multi-beam Antenna Analysis

Abstract: This paper describes the antenna analysis of the multi-beam for communication satellite. The design core parameters of the antenna system are optimal antenna diameter, feed horn type and horn size, F/D, and the coordinate of offset horns. The paper deals with the method to determine design core parameters of optimal antenna diameter, feed horn type and horn size. F/D. and the coordinate of offset horns, and the performances of design result

Virtual-antenna receiver

Abstract: The invention is directed to the reception of high rate radio signals (for example DVB-T signals) while the receiver is moving at a high speed (for example in or with a car). Two or more antennas (12, 16) are closely spaced and arranged behind each other in the direction of motion (v) for receiving the radio signals. A signal is obtained which represents a virtual antenna (26) that is at least temporarily stationary with respect to the environment, despite the movement of the receiver. The receiving signal of the virtual antenna (26) suffers at least less distortions than a signal received by one of the first and second antennas (12, 16). In accordance with the invention the signal which represents the virtual antenna (26) is obtained under the control of a feedback signal (SYNC) of the receiver.

A compact single-horn C/X dual band and circular polarized Tx & Rx antenna system

Abstract: Single frequency band antenna systems for satellite communications are gradually evolving into multi-band antenna systems. The complexity of the feed in these systems increases when dual circular polarization and simultaneous high power emission and low noise reception are required for each band. It is not always possible to integrate multi-band feeds into small antenna apertures because the feed tube of these systems has to be large enough to host all the feed components. This paper describes a single-horn 1.9 m antenna, C/X dual band, transmission and reception, dual circular polarized feed system. The frequencies of operation are: Rx-C, 3.4-4.2 GHz; Tx-C, 5.85-6.65 GHz; Rx-X, 7.25-7.75 GHz; Tx-X, 7.9-8.4 GHz.

Performance of multimode (TE 11 +TE 21 ) feed horn for offset reflector antenna providing multiphase centres

Abstract: The phase centre of a feed horn is a theoretical point along the axis of the horn which is the centre of curvature of the phase fronts of the spherical waves. In most feeds, there is a phase centre region rather than a single point because radiation is due to a summation of spherical waves, which seems to emanate from the aperture [1]. Determination of the feed phase centre helps, its location relative to the focal point of the reflector. Different techniques to compute and determine the phase centre location in single and dual reflector geometries are reported in [1-3]. However, when the feed horn has a multimode excitation, the amplitude and phase control of modes provide different constant phase centre locations, which in turn helps to conceptualize a virtual array on the reflector antenna aperture [4].

3D-feed horn antenna-coupled microbolometer

Abstract: In this paper, we proposed a microbolometer coupled with 3D feed horn antenna. It is a new device that enhances the performance of the microbolometer by coupling 3D horn shape antenna. We designed the optimum horn antenna size that has 20.08 dB directivity. And we designed the microbolometer as a circular shape in order to reduce the coupling loss between the horn antenna. We confirmed that the detectivity of the designed microbolometer would be improved as the noise characteristics of the microbolometer are enhanced by coupling feed horn antenna which acts as a cold shield. The detectivity of the designed 3D antenna-coupled microbolometer was improved about seven times more than that of the conventional microbolometer in state of background limited infrared performance. Fabrications of the microbolometer are carried out by a surface micromachining method. We achieved the thermally good isolated floating structure. And the 3D feed horn antenna was constructed by using a mirror-reflected parallel beam illuminator (MRPBI) system which is invented for rotating and tilted illumination. Using this method, we acquired the feed horn shape antenna mold. And we also acquired antenna plate by using PDMS injection method. Finally, to couple the antenna and the microbolometer, we proposed the PDMS injection bonding method.

Offset hybrid antenna using focuser

Abstract: A Ka-band offset hybrid antenna having a shaped focuser is disclosed. The Ka-band offset hybrid antenna having a shaped focuser, including: a shaped focuser for reflecting a received plane wave to focus an energy of the received plane wave on an offset focal line and reflecting a transmitting signal; and an active feed array module for receiving the reflected received plane wave from the shaped focuser and radiating the transmitting signal to the shaped focuser antenna, wherein the active feed array module including a feed horn array antenna having a plurality of single horns and an active channel block (ACB) having multi-active channels for changing a direction angle of transceiving beam.

Converter for radio wave reception and antenna apparatus

Abstract: A radio wave reception converter receives a radio wave and converts the radio wave into an electric signal, and includes a horn introducing a radio wave, and a waveguide arranged at the rear of the horn for guiding a radio wave introduced by the horn. An insulation sheet is located between the waveguide and the horn to seal hermetically the interior of the waveguide and the horn. The connecting part between the waveguide and the horn is covered with an exterior cabinet. The front opening of the horn is covered with a feedome. The structure facilitates the connecting work between the waveguide and the horn, and can ensure airtightness at the connecting part.

An efficient dual frequency antenna feed

Abstract: Terminals for weather satellite readout require a compact feed for small reflector antennas and operate at L-band (1670-1710 MHz) and S-band (2200-2300 MHz). Both bands require right hand circular polarization and L-band requires linear polarization as well. The analysis and measurement of a novel dual frequency antenna feed is described. Stacked microwave patches for operation at the two separated frequency bands are surrounded by a corrugated surface to improve illumination efficiency. The feed is configured for orthogonal linear polarization, has filtering and modest preamplification with amplitude and phase matched LNAs for each linearly polarized feed terminal, and uses a quadrature hybrid to combine the two outputs for circular polarization. Linear polarization is obtained by turning off one of the preamplifiers.

Satellite ground station antenna with wide field of view and nulling pattern

Abstract: The present invention is applicable to satellite ground station antennas having a wide field of view in comparison to the satellites with which the antenna connects. One embodiment includes a parabolic reflector having a size that corresponds to a beam with an angular half-width larger than the spacing between neighboring interfering satellites. It also has a feed coupled to the parabolic reflector configured to have a high sensitivity for a target satellite within the angular half-width of the reflector beam and a low sensitivity for neighboring interfering satellites within the angular half-width of the reflector beam. Another embodiment includes projecting a first radiation pattern, such as a digital communications link, between a ground station antenna and a target satellite and projecting a second radiation pattern to a target interferer.

Feed-Horn Antenna for Enhanced Uncooled Infrared Sensor Using Novel UV Lithography, Plastic Micromachining and Mesh Structure Bonding

Abstract: In this paper, we report a uncooled infrared sensor coupled with a 3-dimensional (3D) feed-horn shape micro-electro-mechanical system (MEMS) antenna using novel UV lithography technique for fabricating a 3D feed-horn-shaped mold array, obtaining parallel light using a mirror-reflected parallel-beam illuminator (MRPBI) system and plastic micromaching. The microassembly of infrared detector and 3D feed-horn-shaped antenna arrays is difficult using the conventional MEMS bonding process. To overcome limitation, the proposed novel 3D MEMS bonding technique is mesh structure bonding (MSB) using microchannels with micromolding in capillaries by polydimethylsiloxane (PDMS). The feasibility of fabricating both a 3D feed-horn MEMS antenna and a mold array was demonstrated. As a result, it seems possible to use a 3D feed-horn-shaped MEMS antenna to improve uncooled infrared sensor performance and applications to fabricate MEMS device.

Feed horn antenna including circular-polarizer and straight type mode converter to illuminate shaped reflector at Ka-band

Abstract: A feed horn antenna including circular-polarizer and straight type mode converter for a phased array is proposed to illuminate a shaped reflector antenna and be extended to an array of 8/spl times/1. The proposed antenna has a very good radiation pattern and wide axial ratio bandwidth compared to the microstrip elements. In additional to that, if we replace the dielectric type polarizer with oval shape waveguide, insertion loss is reduced.

Integrated feed horn device

Abstract: An integrated feed horn device including three sets of integrally formed feed horn devices is provided. The integrated feed horn device may receive satellite signals reflected by a single parabolic reflector antenna, wherein the satellite signals are transmitted by three satellites separated by small angles. The integrated feed horn device may comprise a first waveguide, a second waveguide and a third waveguide, wherein the first waveguide, the second waveguide and the third waveguide may be adopted for receiving a first satellite signal, a second satellite signal, and a third satellite signal. Each of the satellite signals described above is transmitted by different satellites.

A scattering matrix-based beamformer for wide-angle scanning in hybrid antennas

Abstract: This paper presents a new approach to beamforming in hybrid antennas. Using a scattering matrix model for the hybrid antenna system, a bidirectional transformation is developed that relates the signals at the hybrid system feed to the signals that would be present in a planar array at the location of the reflector aperture. For example, the received fields at the feed of a hybrid antenna system may be transformed into the fields at the reflector aperture, and these reflector aperture fields may then be processed as if they were received by a planar or linear array. Similarly, the desired field or current distribution across the reflector aperture when transmitting may be transformed into the required field or current distribution at the hybrid system feed. This method allows standard linear or planar array analysis and synthesis techniques to be used with the hybrid system. Examples are provided for transmit and receive weight synthesis.