Showing papers on "Feed horn published in 2001"

Ka/Ku dual band feedhorn and orthomode transducer (OMT)

Abstract: A dual band, higher and lower frequency range transducer with a circular coaxial waveguide feed is described having a first junction for connection of a lower frequency range outer waveguide of the coaxial waveguide feed to at least two rectangular or ridge waveguides offset from the longitudinal axis of the transducer and a second junction for connection of the at least two rectangular or ridge waveguides to a further waveguide. A third junction is provided for connecting an inner waveguide of the coaxial waveguide feed to a higher frequency range waveguide. The transducer comprises at least first and second parts joined across a first plane substantially perpendicular to the longitudinal axis and including at least a portion of the higher frequency range waveguide extending within the first plane of the join. A seal such as an “O” ring seal may be placed easily in the plane of the join thus preventing moisture ingress. Similarly, a feed horn and input and output ports may be sealingly attached to the first and second parts of the transducer. The first and second junctions are preferably impedance matched turnstile junctions.

High radiation efficient dual band feed horn

Abstract: A multiple mode feed horn is provided for transmitting and receiving signals. The feed horn includes a transverse electric throat section, a transverse electric profile section, and a transverse electric aperture section. The transverse electric profile section propagates a first transverse electric (TE) mode. The transverse electric aperture section propagates a second TE mode. The multiple mode feed horn prevents propagation of traverse magnetic modes from said throat section to said aperture section.

Novel Gaussian beam method for the rapid analysis of large reflector antennas

Abstract: A relatively fast and simple method utilizing Gaussian beams (GBs) is developed which requires only a few seconds on a workstation to compute the near/far fields of electrically large reflector antennas when they are illuminated by a feed with a known radiation pattern. This GB technique is fast, because it completely avoids any numerical integration on the large reflector surface which is required in the conventional physical optics (PO) analysis of such antennas and which could take several hours on a workstation. Specifically, the known feed radiation field is represented by a set of relatively few, rotationally symmetric GBs that are launched radially out from the feed plane and with almost identical interbeam angular spacing. These GBs strike the reflector surface from where they are reflected, and also diffracted by the reflector edge; the expressions for the fields reflected and diffracted by the reflector illuminated with a general astigmatic incident GB from an arbitrary direction (but not close to grazing on the reflector) have been developed in Chou and Pathak (1997) and utilized in this work. Numerical results are presented to illustrate the versatility, accuracy, and efficiency of this GB method when it is used for analyzing general offset parabolic reflectors with a single feed or an array feed, as well as for analyzing nonparabolic reflectors such as those described by ellipsoidal and even general shaped surfaces.

Passive tracking system and method

Abstract: System and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes an antenna array with three antenna elements, which preferably are patch antenna elements spaced apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

Radio communication apparatus, transmitter apparatus and receiver apparatus

Abstract: A radio communication apparatus, a transmitter apparatus and a receiver apparatus that are capable of dealing with a plurality of signal waves. The radio communication apparatus has a millimeter wave transmitter (15) and a millimeter wave receiver (29). The millimeter wave transmitter (15) includes a multiplexing circuit (1), a millimeter wave up-converter (4) and an antenna (3). The millimeter wave receiver includes an antenna (31), a millimeter wave down-converter (32) and an output processing circuit (45). User-only signal waves are modulated by modulator circuits (121-124) such that they are located between the terrestrial waves and the satellite waves. The modulated signal waves are multiplexed in the intermediate frequency band, then converted into a millimeter wave band, and then transmitted. On the receiver side, the multiplexed waves are frequency down-converted, then separated, and then demodulated.

Variable beamwidth and zoom contour beam antenna systems

Abstract: Variable beamwidth antenna systems for use on spacecraft that is capable of changing their beamwidths while the spacecraft in on orbit. The variable beamwidth antenna systems include a main reflector, a subreflector, a feed horn, a main reflector displacement mechanism and a feed horn (or subreflector) displacement mechanism. For broaden the beamwidth, the RF feed horn and the subreflector are moved close together by proper distance. The main reflector is moved away from the subreflector along a line through centers of their respective surface by a distance given by a predetermined equation. Another embodiment of the present invention provides for a zoom contour beam antenna system that radiates a contour beam and whose beam is variable or zoomable.

Profiled corrugated circular horns analysis and synthesis via an artificial neural network

Abstract: In many reflector and lens antennas profiled corrugated circular horns constitute one of the best feed solution thanks to their polarization purity and small size. In this paper, a method for the design of these feeds by using an artificial neural network (ANN) approach is described. The results obtained with such an approach are investigated both for the analysis and for the synthesis problem, and compared with the standard methods. This unconventional solution gives a good level of accuracy and shorter processing times especially for the synthesis problem, where there is still a lack of affordable and fully automated procedures.

Compact, lightwelght, steerable, high-power microwave antenna

Abstract: A compact, lightweight, steerable, high-power, microwave weapon including a self-powered, steerable vehicle having at least one exterior antenna support surface, a self-powered, microwave radiation source mounted in the vehicle and including a waveguide to connect the power source to the exterior surface, a feed horn, extending from the waveguide means, including a window transparent to microwave energy for receiving and radiating a pulsed, high-energy microwave radiation beam, a transreflector fixedly mounted on the exterior surface arranged spaced-apart and above the feed horn and having a concave surface facing the feed horn window and formed of a plurality of electrical conductors held in parallel order in a frame, and a twistreflector pivotally mounted opposite and spaced-apart from the concave surface of the transreflector and adapted to receive microwave energy reflected to it from the concave surface of the transreflector and to rotate the polarization by 90° and reflect the microwave energy back to the transreflector for passing through the transreflector and forming a narrow, pencil-like beam of high-energy radiation in polarized form extending outward from the convex surface of the transreflector.

Antenna apparatus including compound curve antenna structure and feed array

Abstract: An antenna apparatus that includes a beam control system and a beam collimating system having a compound curve antenna structure is provided. The compound curve antenna structure can be two-dimensional or three-dimensional. In one embodiment, the curve is parabolic and the compound curve antenna structure includes first and second parabolic reflector sections that are spaced from each other. A feed array of the beam control system is disposed therebetween at the base ends of the two parabolic reflector sections. When the compound curve antenna structure is three-dimensional, the two parabolic reflector sections are part of a body of revolution. The control system also includes memory storage that stores predetermined data related to controlling activation of each of a plurality of feed elements of the feed array. The predetermined data is based on information obtained using a reference beam with the compound curve antenna structure. In that regard, reflections and contact of EM radiation of the reference beam are monitored for a number of different scan angles. Based on the identities of the particular feed elements that are involved or receive EM radiation associated with the reference beam, determinations are made regarding the content of the predetermined data to be stored to be subsequently used in controlling activation of desired feed elements in generating a transmit beam or receiving a return beam at a desired angle of a number of scan angles.

Main reflector and subreflector deployment and storage systems

Abstract: Deployable antenna systems 10, 10a for use on a spacecraft 20 that is moveable from a stowed position to a deployed position. Two embodiments are discloded that include one or two sets of main reflector assembly 16 (and optional adjustment mechanism 18) and subreflectors 17. The antenna systems include one or more feed horn assembly 11 fixedly attached to the spacecraft and a rotatable hinge 12 attached to the spacecraft. A substantially rigid reflector support structure 13 is attached to the hinge and rotates about a hinge axis. The main reflector assembly 16 (and optional adjustment mechanism 18) is attached to a lower portion 14 of the support structure and the subreflector is attached to an upper portion 15 of the support structure. The subreflector has a fixed relation relative to the main reflector assembly and has a fixed relation relative to the one or more feed horn assembly when the antenna system is in the deployed position so that the antenna systems generate predetermined beam coverage patterns.

Dual-band equal-beam reflector antenna system

Abstract: A satellite antenna system employing a dual-band feed horn and dual-band beam forming network. The feed horn provides a common aperture for both satellite uplink and downlink communications signal. The feed horn includes corrugations on an inside surface defining two sets of alternating channels having different depths to create circularly symmetric beams for the uplink and downlink signals. The antenna system includes at least one reflector, where the reflector shape, position, and the configuration of the feed horn, is determined so that the mainlobe of the lower frequency downlink feed signal illuminates the entire reflector, and the mainlobe of the higher frequency uplink feed signal illuminates an inner portion of the reflector. The first sidelobes of the higher frequency feed signal illuminate the outer portion of the reflector so that the uplink and downlink antenna signals have the same beamwidth, and thus cover the same cell size on the Earth.

Surveillance radar scanning antenna requiring no rotary joint

Abstract: A wave-scanning antenna is disclosed that does not require a rotary joint. The antenna produces a collimated beam that can be scanned through 360 degrees. The beam is directed perpendicular to the antenna's axis of rotation to form a disc-like surveillance volume, or at an angle above or below the perpendicular to form a cone-shaped surveillance volume. The radar's structure contains a transmitter and receiver coupled to a horn protruding through open centers of the support bearing and driven gear into the antenna housing. Energy emitted by the horn proceeds upward until deflected through an angle of 90 degrees by an angled reflector located on the axis of rotation. The energy is collected by a dielectric lens and focused into a collimated beam. Reflected energy is collected by the lens and directed by the reflector to the horn, where it is fed to a waveguide coupled to the receiver.

Full wave analysis and experimental verification of a broadband ridged horn antenna system with parabolic reflector

Abstract: In this paper we investigate the radiation pattern of a complete 1-18 GHz antenna system featuring a 1.8 in parabolic reflector and a double ridged broadband feed horn with coaxial input using a combination of the method of moments (MoM) and a physical optics (PO) approach. It was found that in the lower frequency range the horn antenna system exhibits a single main lobe in the direction of the center horn axis as expected. However, contrary to common belief, at frequencies greater than 12 GHz, the main lobe starts to split into four main lobes pointing into off-center-axis directions with a broadside gain reduction. This effect was observed both theoretically and experimentally. Although this type of antenna has existed for over four decades, up to now there is no explanation for this unwanted behavior in the open literature. In the past, several electromagnetic simulations of ridged horn antennas were made, but not over such a broad operational frequency range and neither including the coaxial feed nor the complete parabolic reflector system. The purpose of this investigation is to close this gap and to contribute to a better understanding of broadband ridged horn antennas.

Prompt aperture efficiencies of impulse radiating antennas with arrays as an application

Abstract: A concept of prompt aperture efficiency is introduced for the purpose of comparing and optimizing the performance of impulse radiating antennas (IRAs). The aperture efficiencies of popular lens and reflector IRAs are computed as the ratios of peak radiated power densities on boresight compared with that produced by an ideal IRA with an aperture of equal area and equal total input power. Loss of aperture efficiency occurs through two distinct mechanisms: from power that falls outside the aperture and is lost and from nonuniform power and polarization distributions within the aperture. Both loss mechanisms are addressed, and means for increasing efficiencies are identified. The optimum aperture for a given feed structure is derived. Prompt aperture efficiencies approaching 100% are feasible in TEM-horn arrays and similar structures.

Antenna aperture cover for attenna pointing and improved antenna pointing method using aperture cover

Abstract: An improved apparatus and method for pointing a satellite dish to receive signals from a geo-synchronous satellite. An aperture cover is used to partially block electromagnetic radiation provide to a feed horn and power and/or signal quality measurements are taken with the aperture cover covering various portions of the feed horn opening. Based on these power and/or signal quality measurements, it is determined in what direction and what angle in that direction the satellite dish must be re-oriented to achieve optimal signal strength from a geo-synchronous satellite or other fixed position microwave source.

Method and apparatus for automatically identifying an antenna connected to a radio transmitter and for automatically controlling a transmitter

Abstract: A transmission system or apparatus includes a transmitter or source of transmitted RF or microwave power which is selectively connectable via a transmitter connector to an antenna having an antenna feed via an antenna connector so that a variety of antennas with differing characteristics can be used with a given transmitter. Each antenna preferably has a marker or indicating element incorporated into the antenna feed. The marker or indicating element includes a physically measurable property or parameter corresponding to a physical characteristic of the attached antenna. In the preferred embodiment, the indicating element is a resistance connected in parallel with the antenna feed and having a selected resistance value (e.g., in ohms) which indicates the physical characteristic of gain for antenna. The transmission system also includes an indicating element sensor configured to sense or measure the marker or indicating element and generate a transmitter control signal in response to that measurement. The method for automatically generating the control signal can be implemented in programmable steps as computer software and may include use of a Look Up Table (LUT) having a range of indicator element characteristic values and a range of corresponding transmitter control signal values or, alternatively, can include use of a computation sequence which takes an indicator element characteristic value as an input variable and generates a control signal value in response thereto.

High efficiency corrugated horn and flat top multiple beam antenna

Abstract: A broadband corrugated feed horn and flat top multiple beam antenna for use in satellite communication systems, and the like. The profile of corrugations of the horn is specially tuned or designed to flatten the aperture field distribution. As a result, the aperture efficiency increases, and the gain of the corrugated horn also increases. Also, the circular aperture and corrugated construction of the horn result in improved circular polarization characteristics. The flat top multiple beam antenna comprises an oversized reflector and a plurality of high efficiency feed horns that exhibit a flat top aperture field. The present high efficiency corrugated feed horns may be used in the flat top multiple beam antenna. The flat top multiple beam antenna has a reduced interference signal level, increased gain in the coverage area, and improved frequency reusability from a four-color to three-color configuration.

Generalized-Multipole-Technique - Mode-Matching-Technique Hybrid Method for Elliptical Stepped Horn Antennas Analysis

Abstract: A hybrid method for the full-wave efficient analysis of stepped horn antennas is presented. The internal part of the antenna, i.e. the step discontinuities extended from the antenna input to its aperture are analysed by a mode matching technique (MMT); the external part of the horn antenna is analysed by the generalised multipole technique (GMT). In this way it is feasible to take into account the real external shape of the antenna (by GMT) and also to analyse in an effient and accurate manner its inner part (by MMT). The hybrid method is applied to the case of stepped horn antennas with elliptical cross-sections; theoretical and experimental results are provided to confirm the validity of the proposed approach.

Radio communication system, radio transmitter, and radio receiver

Abstract: PROBLEM TO BE SOLVED: To provide a simple and low-cost radio communication system wherein its frequency-diversity is so realized effectively even when using such a high-frequency band as a millimeter wave as to prevent any signal interruption. SOLUTION: The radio communication system has a radio transmitter 61 and a radio receiver 62. The radio transmitter 61 at least has an IF-signal generating portion 78 for modulating an intermediate-frequency band by an input signal 63, a signal distributing portion 64 for performing the distributions of the signal fed from the IF-signal generating portion 78, and a plurality of signal transmitting portions 65 for so converting into a radio-frequency band the signals distributed in the signal distributing portion 64 as to transmit radio- frequency-band conversion signals. The radio receiver 62 for so receiving the radio-frequency-band conversion signals as to obtain again the receiving signal of the intermediate-frequency band. COPYRIGHT: (C)2003,JPO

Integrated dual-directional feed horn

Abstract: An integrated dual-directional feed horn, for receiving RF signals from two satellites in small angle, includes a LNBF (first low noise block with integrated feed) and a second LNBF. The antenna dish focus the received RF signals onto receipt points of the focus plane, and the two LNBFs receive focused RF signals. The first LNBF receives circular polarized waves from the BSS satellite. The second LNBF receives linear polarized waves from the FSS satellite. One characteristic of the invention relies on integrating two LNBFs and making the two LNBFs adjacent to each other in the direction of short axis. Accordingly, the two LNBFs receive RF signals from two satellites in small angle. Increasing the length of the long axis thereof increases the areas of the wave-guides. The signal gain and communication quality are obtained.

A radio system with multi-element antennas

Abstract: A radio hardware concept for indoor WLAN applications is described in which both the transmitter and the receiver use multi-element antennas. The system exploits the increased capacity of the multiple-input multiple-output (MIMO) indoor radio channel and it is designed especially for high data rates. A technique to measure the MIMO channel matrix is described. A weak pseudo-noise sequence out of a set of Gold codes is added to each transmitted signal from which the amplitude and phase of the carrier corresponding to that antenna is identified at each receive antenna. The data signals are reconstructed at the receiver in a weighted-signal combining network where IQ modulators steer the complex weights. Fully transparent transmission at high data rates is possible in this way.

Feed-reflector design for large adaptive reflector antenna (LAR)

Abstract: A novel feed-reflector system for large Cassegrain antennas of radio astronomy and deep-space communication applications is investigated. This feed-reflector is used to illuminate a hyperboloid subreflector with a 5-10 m diameter located 500 m above the ground. Because the subreflector is located in the near field of the feed-reflector antenna, a theory based on the near field focusing properties of paraboloid reflectors is established. The focusing at near distance is formed by moving the feed horn away from the focal point of the feed-reflector. In this theory, the properties of axial defocused paraboloid reflectors at near distance are investigated in more detail. By using equivalence path law, the subreflector shape is obtained. It is found that the hyperbola can approximate the subreflector well. A detailed ray tracing is performed on the entire system which reveals that the feed system uses some part of the subreflector three times. The gain, side lobe level, cross polarization, and aperture distribution are calculated for different feed horn locations and taper at the edge of the feed-reflector and also for different sizes and eccentricities of the subreflector. Peak efficiency in excess of 74.8% and side lobe level around -20 dB are obtained for an unshaped system. The performance of the system over the operating band (1-22 GHz) is also studied and shown that the lower-frequency limit is dependent on subreflector and feed-reflector sizes.

A microwave horn antenna for level measurement systems

Abstract: A microwave horn antenna structure suitable for use in time of flight ranging systems and level measurement instruments. The horn antenna comprises a high gain antenna with a small aperture. The horn antenna includes a dielectric lens for focussing and directing transmitted electromagnetic energy to the surface of a material, e.g. liquid, held in a container. The electromagnetic energy reflected from the surface of the material are received by the horn antenna and converted in an electrical signal. The electrical signal is processed to determine the level of the material held in the container.

Method and apparatus for zooming and reconfiguring circular beams for satellite communications

Abstract: A method and system for reconfiguring an antenna system are disclosed. The system comprises a feed horn, a subreflector, and a main reflector. The feed horn is pointed at an axis removed from the bisector axis of the subreflector. The distance between the feed horn and the subreflector can be changed to defocus the feed horn with respect to the subreflector, wherein a size of the outgoing beam emanating from the main reflector changes when the distance between the feed horn and the subreflector, wherein the axis of the feed horn is aligned differently from the bisector axis of the subreflectro, adn changing the distance between the feed horn and the subreflector to defocus the feed horn with respect to the subreflector, wherein in a size of an outgoing beam emanating from a main reflector changes when the distance between the feed horn and the subreflector is changed.

Wideband propagation measurements for indoor Rician fading radio channels at 62.4 GHz

Abstract: Distributions of 62.4 GHz wideband propagation measurements undertaken in two different indoor radio channels to measure space-frequency correlation functions are presented. The values of 90th percentile of the coherence bandwidth at 0.9 correlation level for all locations stays below 72 MHz. Minimum and maximum B/sub 0.9/ coherence bandwidths obtained in a long narrow corridor with a directional horn transmit and an omnidirectional receive antenna are 1.10 MHz and 105.33 MHz respectively. It has been observed that the coherence bandwidth is highly variable with the location of the receiver with respect to the base station.

Antennas and feed support structures having wave-guides configured to position the electronics of the antenna in a compact form

Abstract: The present invention provides various wave-guides and support structures that are used in conjunction with feed structures to form compact antennas. Specifically, in one embodiment, the present invention provides a wave-guide design used for connecting the feed of an antenna to various electronics, such as a transmitter or receiver. The wave-guide of this embodiment includes a first end for connecting to the feed and a second end for connection to either a transmitter, receiver, or other electronic components. Importantly, the body of the wave-guide extends in a direction towards the reflector of the antenna so that the second end of the wave-guide is positioned closer to the reflector than the first end of the wave-guide. As such, the transmitter or receiver that is connected to the second end of the wave-guide is located in close relationship with the reflector, thereby creating a compact, aesthetically pleasing antenna structure.

A 60 GHz conical horn antenna with polarizer fed by quasi-Yagi antenna

Abstract: A meander-line polarizer integrated with a quasi-Yagi antenna fed conical horn was designed and tested. Acceptable performance for many commercial applications in the desired millimeter wave frequency range 58 to 62 GHz has been achieved. This medium gain antenna comprises a microstrip to horn transition and a polarization conversion in a relatively simple and compact way. At the 60 GHz center frequency the gain into each linear polarization was 9 dB, the return loss 9 dB, and the axial ratio 0.24 dB. In the frequency range 58 to 62 GHz the gain was better than 6 dB into each linear polarization, and the return loss was better than 8 dB. Within the previous frequency range and within the elevation angle range /spl plusmn/30/spl deg/ of the principal planes the ratio of the two orthogonal components was better than 6 dB.

Integrated dual beam reflector antenna

Abstract: The present invention discloses a method for generating multiple antenna beams and a system for generating multiple antenna beams. The system comprises a first reflector surface that has a primary and at least a first auxiliary surface, and a second reflector surface, and also comprises first, second, and third feed horns. The first feed horn illuminates the primary surface with radio frequency (RF) energy, the second feed horn illuminates the auxiliary surface with RF energy, and the third feed horn illuminates the second reflector surface with RF energy. The first feed horn and third feed horn are removed from an axis of symmetry of the first auxiliary surface. The method comprises illuminating a primary portion of a first reflector surface with radio frequency (RF) energy from a first feed horn, illuminating an auxiliary portion of the first reflector surface with RF energy from a second feed horn, illuminating a second reflector surface with RF energy from a third feed horn, wherein the first feed horn and third feed horn are removed from an axis of symmetry of the auxiliary portion of the first reflector surface.

Multi-band corrugated antenna feed horn with a hexagonal aperture and antenna array using same

Abstract: Feed horn apparatus for use in a multiple-feed antenna system. The present invention comprises a corrugated feed horn and an antenna array or cluster of feed horns arranged in a hexagonal lattice pattern. The feed horn comprises a hexagonal aperture formed by a circular-to-hexagonal transition section a corrugated section disposed adjacent to the circular-to-hexagonal transition section, a tapered section disposed adjacent to the corrugated section, and an input section having an input/output port disposed adjacent to the tapered section. The corrugated feed horn has good beam pattern symmetry, low cross-polarization, and sidelobe levels, along with an increased horn aperture area. As a result, the efficiency of the corrugated feed horn is improved by transitioning from a circular to the hexagonal aperture.

Multimode antenna optimization

Abstract: The design and optimization of the TOPHAT feed horn is presented. This horn is a nonimaging antenna with a few modes. Diffraction effects are approximated using ray-trace techniques with the addition of phase information.