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Showing papers on "Feed horn published in 2000"


Patent
10 Feb 2000
TL;DR: In this article, an azimuthally tunable resistivity measurement tool comprising transmitter coils and receiver coils, wherein at least some of the transmitter coils or receiver coils are skewed and oriented in differing aziruthal directions, is disclosed.
Abstract: An azimuthally tunable resistivity measurement tool comprising transmitter coils and receiver coils, wherein at least some of the transmitter coils or receiver coils are skewed and oriented in differing azimuthal directions, is disclosed. The transmitter coils transmit radio-frequency signals that propagate through a formation surrounding a borehole and the receiver coils measure the relative amplitude and phase of signals received from the surrounding formation. A method for detecting the location of a bed boundary relative to a borehole is also disclosed, including the steps of: generating first and second signals representing azimuthally sensitive measurements of phase shift and attenuation of an electromagnetic signal propagating through a formation around a borehole, wherein the azimuthal sensitivity of the first measurement is in a direction different than that of the second measurement, and receiving electromagnetic signals on first and second skewed receiver antennas respectively oriented in first and second azimuthal directions.

180 citations


Proceedings ArticleDOI
03 Dec 2000
TL;DR: In this paper, different profile options available to designers of circularly-symmetric feed horns are outlined and some new horn profiles are introduced and the radiation pattern properties of these horns are described.
Abstract: The different profile options available to designers of circularly-symmetric feed horns are outlined. Some new horn profiles are introduced and the radiation pattern properties of these horns are described.

51 citations


Patent
01 Mar 2000
TL;DR: In this article, a parabolic reflector antenna is used as an antenna for signal transmission between the radio communication base station and the mobile terminals by determining the curvatures and relative positions of a main-dish with a main reflecting surface and a sub-dishes with a sub reflecting surface.
Abstract: This specification discloses a parabolic reflector antenna, which is used as an antenna for signal transmission between the radio communication base station and the mobile terminals By determining the curvatures and relative positions of a main-dish with a main reflecting surface and a sub-dish with a sub-reflecting surface and means of determining the size of the feedback device and relevant distances in between, the present invention improves the signal reception and emission of the parabolic reflector antenna

29 citations


Patent
11 Aug 2000
TL;DR: In this paper, a horn reflect array antenna system and a method for producing a signal using a horn reflective array antenna is presented. But the system is not suitable for the use of a large number of antennas.
Abstract: In summary the present invention discloses a horn reflect array antenna system and a method for producing a signal using a horn reflect array antenna. The system comprises at least one reflective element illuminated by an incident radio frequency (RF) signal from a feed horn, the reflective element reflecting a portion of the incident RF signal as a portion of a reflected RF signal, and at least one phase shifting device, each phase shifting device coupled to a corresponding reflective element, wherein a beam pattern of the reflected RF signal is altered when the phase shifting element changes the phase of the portion of the reflected RF signal. A method in accordance with the present invention comprises illuminating a reflector with an RF signal emanating from a feed horn, wherein the reflector comprises at least one reflective element, reflecting at least a portion of the RF signal from the reflective element, wherein the reflective element comprises a phase shifting device, and changing a phase of the portion of the reflected RF signal with the phase shifting device, therein altering the radiation pattern of the reflected RF signal.

25 citations


Patent
Oliver W. Saunders1
17 Feb 2000
TL;DR: In this paper, an antenna system that includes one or more antenna feed horns (30) includes a plurality of micro-mechanical devices (38) positioned around the aperture (32) of the feed horn (30).
Abstract: An antenna system that includes one or more antenna feed horns (30), where each feed horn (30) includes a plurality of micro-mechanical devices (38) positioned around the aperture (32) of the feed horn (30). The micro-mechanical devices (38) are linear motion devices that can be activated to extend a conductive surface (40) beyond the end of the feed horn (30). By selectively actuating groups of the micro-mechanical devices (38) to extend the conductive surfaces (40), the end of the feed horn (30) can be changed to provide different asymmetrical configurations, causing the beam direction to change accordingly. The micro-mechanical devices (38) can be any suitable mechanical device, such as MEMS devices or carbon nanotube artificial muscles.

21 citations


Journal ArticleDOI
TL;DR: In this article, a technique for enhancing the gain of a wide-flare angle pyramidal horn is described, where simple metal strips or baffles are placed inside the horn near its throat.
Abstract: A technique for enhancing the gain of a wide-flare angle pyramidal horn is described. The gain of the antenna is increased by placing simple metal strips or baffles inside the horn near its throat. Two baffles, an E- and an H-plane baffle, are described and analyzed. The baffles are first analyzed through two-dimensional (2-D) numerical calculations and then through measurements in an experimental X-band horn. Each baffle enhances the antenna's gain in the respective plane. When the baffles are implemented together the gain enhancement is additive in decibels. The numerical calculations and measurements show that baffles can he used to significantly reduce the size of pyramidal horn antennas.

20 citations


Patent
13 Jan 2000
TL;DR: An easily installable enhancement for replacing the reflective surface area for a satellite dish and method for using an installed dish as a reference, allowing the installation of a dish with added features without reacquiring the satellite signal or reaiming the dish as mentioned in this paper.
Abstract: An easily installable enhancement for replacing the reflective surface area for a satellite dish and method for using an installed dish as a reference, allowing the installation of a dish with added features without re-acquiring the satellite signal or reaiming the dish. In one variation, the enhancement includes a reflector addition, which is fitted with fasteners that locate the reflector against the existing dish. This variation includes use of the original feed horn, which is relocated using a feed horn support extension. This variation is also designed to avoid the “shadow” of the feed horn and its support arm, and to minimize the reflective surface area at the lower end of the dish, which reduces collection of such interfering material as snow, rain, and debris. In variations using increased reflector size, the enhancement reduces loss of signal during inclement weather or in other situations in which the satellite signal is partially blocked. In one variation, the added reflector is a standard parabolic reflector, such as a 24-inch dish, superimposedly installed over the original reflector. In a second variation, the added reflector is a custom designed parabolic surface that extends the existing dish surface only at the original reflector's circumferential edge. In a third variation, the added reflector is ring-shaped and similarly attached at the outer edge of the original reflector. Also disclosed is a system for attaching and making additional adjustments for applications using a more complex replacement reflector, such as for receiving signals from multiple satellites.

19 citations


Patent
Yoshiyuki Hoshi1
01 Sep 2000
TL;DR: In this paper, a transmitter antenna selector switch 109 or a receiver antenna selector switch 111 is respectively connected between the first antenna 101 a and the second antenna 101 b and the transmitter 103 or the receiver 105.
Abstract: According to the invention, a transmitter antenna selector switch 109 or a receiver antenna selector switch 111 is respectively connected between the first antenna 101 a and the second antenna 101 b and the transmitter 103 or the receiver 105 . Transmission signals output from the transmitter 103 are supplied to either the first antenna 101 a or the second antenna 101 b in transmission, while reception signals are received from either the first antenna 101 a or the second antenna 101 b via the receiver antenna selector switch 111 in reception.

18 citations


Journal ArticleDOI
TL;DR: In this paper, a K-band receiver terminal has been designed for /spl ap/77-K operation to support the NASA Glenn Research Center's direct-data-distribution (D/sup 3/) spare experiment.
Abstract: A K-band receiver terminal has been designed for /spl ap/77-K operation to support the NASA Glenn Research Center's direct-data-distribution (D/sup 3/) spare experiment. The D/sup 2/ experiment involves a 256-element phased-array antenna, aboard the Space Shuttle, transmitting dual 622-Mb/s beams to the ground terminal. The beams are left- and right-hand-side circularly polarized for isolation. The terminal consists of a Cassegrain reflector antenna with a corrugated feed horn, a six-pole YBa/sub 2/Cu/sub 3/O/sub 7/(-/spl delta/) microstrip bandpass filter, a three-stage InP high electron-mobility transistor monolithic-microwave integrated-circuit amplifier, and a 1-W at 80-K Stirling cycle cryocooler.

18 citations


Patent
20 Jul 2000
TL;DR: In this article, the authors proposed a preferred anechoic chamber and chamber system, where a TEM antenna is terminated by a resistive card, or R-card, which can be used to illuminate the test zone in a tapered chamber without changing the feed antenna.
Abstract: The present invention includes tapered anechoic chambers and chamber systems. This invention also includes machines or electronic apparatus using these aspects of the invention. The present invention also includes methods and processes for using these devices and systems. In a preferred embodiment, a TEM antenna is utilized that is terminated by a resistive card, or R-card. This makes for a very broadband antenna that may be used to properly illuminate the test zone in a tapered chamber without changing the feed antenna. A preferred chamber utilizes an absorber layout that has never been applied to a tapered chamber, called a Chebyshev absorber layout. The concept is to place the wedge absorber tips at different heights relative to the mounting side wall and pyramidal absorber tips at different heights relative to the back wall. In this pattern, wave reflections off the pyramid tips and valleys behave very much like reflections in a multi-section transmission line. Using this Chebyshev layout around the test zone, the test zone fields will be very clean of stray signals and the polarization will be dictated by the feed horn. Also, it is then not necessary to use very thick absorber for low frequency applications, which tend to deteriorate over time. A preferred chamber also comprises a design wherein an entire tip portion of the tapered section is a separate unit. This unit is preferably designed to rotate on a system of rollers positioned between the unit and the main chamber. The result is that the polarization of the chamber can be easily changed from vertical to horizontal by simply rotating the feed structure, which can be done without disconnecting any cables to the feed.

16 citations


Patent
14 Mar 2000
TL;DR: In this paper, a multi-mode, multi-step feed horn for a satellite antenna array that includes multiple transition steps (28-34) that provide control of the mode content of the signal, and the generation of substantially equal E-plane arid H-plane beamwidths, with low cross-polarization and suppressed sidelobes, is presented.
Abstract: A multi-mode, multi-step feed horn (10) for a satellite antenna array that includes multiple transition steps (28-34) that provide control of the mode content of the signal, and the generation of substantially equal E-plane arid H-plane beamwidths, with low cross-polarization and suppressed sidelobes. In one particular embodiment, two transition steps (32, 34) allow the E-plane to expand and generate the higher order TM11 propagation mode. The transition steps (32, 34) and a phase section (18) allow the mode content to be oriented relative to each other in the proper phase so that the useful bandwidth is on the order of 10%-15%. Two other transition steps (28, 30) provide impedance matching between a throat section (12) and the mode content transition steps (32, 34) to prevent or minimize reflections.

Journal ArticleDOI
01 Feb 2000
TL;DR: In this paper, the authors proposed a coaxial orthogonal-mode-junction (OMJ) coupler with associated matching irises and transition steps for a wideband dielectric-cone-loaded feed horn.
Abstract: A circular coaxial waveguide with four side-coupled rectangular waveguides is proposed as a multiband coupler for a wideband dielectric-cone-loaded feed horn. This structure is designed to separate multiple bands from the lower band of the feed horn with minimum impact on the highest band propagating in the inner circular waveguide that makes up the core of the coaxial waveguide. The proposed coaxial orthogonal-mode-junction (OMJ) coupler with associated matching irises and transition steps is analysed using boundary-contour mode matching (BCMM) in conjunction with the mode-matching (MM) method. The results are verified using the finite-element method. The combination of BCMM and the MM method significantly speeds-up the design cycle of the proposed OMJ coupler so that computer optimisation of the structure is possible.

01 Jan 2000
TL;DR: The Large Adaptive Reflector (LAR) as discussed by the authors is a concept for a low-cost, large aperture, wideband, radio telescope, designed to operate over the wavelength range from 2 m to 1.4 cm.
Abstract: The Large Adaptive Reflector (LAR) is a concept for a low-cost, large aperture, wideband, radio telescope, designed to operate over the wavelength range from 2 m to 1.4 cm. It consists of a 200-m diameter actuated-surface parabolic reflector with a focal length of 500 m, mounted flat on the ground. The feed is held in place by a tension-structure, consisting of three or more tethers tensioned by the lift of a large, helium-filled aerostat-a stiff structure that effectively resists wind forces. The telescope is steered by simultaneously changing the lengths of the tethers with winches (thus the position of the feed) and by modifying the shape of the reflector. At all times the reflector configuration is that of an offset parabolic antenna, with the capability to point anywhere in the sky above -15° Elevation Angle. At mid-range wavelengths, the feed is a multi-beam prime-focus phased array, about 5 m diameter; at meter wavelengths, it is a single-beam phased array of up to 10 m diameter. Simulations have shown that in operating wind conditions (10 m / s average speed with 2.5 m / s gusts), the position of the feed platform can be stabilized to within a few cm over time scales of -20 s. Research indicates that the telescope concept is feasible and that an order of magnitude improvement in cost per m 2 of collecting area over traditional designs of large parabolic antennas can be achieved.

Patent
31 Jan 2000
TL;DR: In this paper, a coaxial turnstile junction for combining and directing both satellite uplink and downlink signals is proposed, which includes a tapered section (30 ) to provide better impedance matching of the downlink signal.
Abstract: A coaxial turnstile junction ( 10 ) for combining and directing both satellite uplink and downlink signals. The junction ( 10 ) includes a tapered section ( 30 ) to provide better impedance matching of the downlink signal between a waveguide structure ( 14 ) and a plurality of symmetrically disposed downlink waveguides ( 38-44 ). The junction ( 10 ) includes a first end ( 26 ) that is in signal communication with an antenna feed horn ( 12 ). The junction ( 10 ) includes a cylindrical outer wall ( 28 ) and a cylindrical inner wall ( 18 ) that are coaxial and define an outer chamber ( 22 ) and an inner chamber ( 24 ). The outer wall ( 28 ) extends into the tapered section ( 30 ) where the tapered section ( 30 ) contacts the inner wall ( 18 ) and closes the outer chamber ( 22 ). The waveguides ( 38-44 ) are positioned around the outer wall ( 16 ) and are in signal communication with the outer chamber ( 22 ) through openings in the tapered section ( 30 ). Irises ( 46-52 ) are provided at the connection between the downlink waveguide ( 38-44 ) and the outer chamber ( 22 ) for impedance matching purposes. Satellite downlink signals from the downlink waveguides ( 38-44 ) are sent to the feed horn ( 12 ) through the outer chamber ( 22 ). Satellite uplink signals received by the feed horn ( 12 ) are directed through the inner chamber ( 24 ) to receiver circuitry. The dimensions of the irises ( 46-52 ) and the flare angle of the tapered section ( 30 ) are selected and optimized so that the downlink signal propagating down the waveguides ( 38-44 ) is impedance matched to the downlink signal propagating through the outer chamber ( 22 ).

Proceedings ArticleDOI
TL;DR: The Large Adaptive Reflector (LAR) as mentioned in this paper is a concept for a low-cost, large aperture, wideband, radio telescope, designed to operate over the wavelength range from 2 m to 1.4 cm.
Abstract: The Large Adaptive Reflector (LAR) is a concept for a low- cost, large aperture, wideband, radio telescope, designed to operate over the wavelength range from 2 m to 1.4 cm. It consists of a 200-m diameter actuated-surface parabolic reflector with a focal length of 500 m, mounted flat on the ground. The feed is held in place by a tension-structure, consisting of three or more tethers tensioned by the lift of a large, helium-filled aerostat -- a stiff structure that effectively resists wind forces. The telescope is steered by simultaneously changing the lengths of the tethers with winches (thus the position of the feed) and by modifying the shape of the reflector. At all times the reflector configuration is that of an offset parabolic antenna, with the capability to point anywhere in the sky above approximately 15 degree Elevation Angle. At mid-range wavelengths, the feed is a multi-beam prime-focus phased array, about 5 m diameter; at meter wavelengths, it is a single-beam phased array of up to 10 m diameter. Simulations have shown that in operating wind conditions (10 m/s average speed with 2.5 m/s gusts), the position of the feed platform can be stabilized to within a few cm over time scales of approximately 20 s. Research indicates that the telescope concept is feasible and that an order of magnitude improvement in cost per m2 of collecting area over traditional designs of large parabolic antennas can be achieved.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Proceedings ArticleDOI
16 Jul 2000
TL;DR: In this paper, the characterization and design of 30 GHz two-lens and lens-fed reflector antenna systems is presented, where a hyperhemispherical substrate lens feeds either a larger but thin hyperbolic lens or a parabolic reflector.
Abstract: In this paper, the characterization and design of 30 GHz two-lens and lens-fed reflector antenna systems is presented. In this approach, a hyperhemispherical substrate lens feeds either a larger but thin hyperbolic lens or a parabolic reflector. The attractive feature of these two-antenna systems is that it leads to a 75% reduction of the lens material, while maintaining about the same length and on-axis characteristics as the single lens antenna. In these two-antenna systems, limited scan capability is possible which can lead to relaxed alignment requirements between a receiver and a transmitter for line-of-sight broadband wireless links.

Patent
21 Mar 2000
TL;DR: In this paper, variable beamwidth antenna systems for use on spacecraft that are capable of changing their beamwidths while the spacecraft in on orbit are presented. But 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.
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.

Journal ArticleDOI
TL;DR: The absolute temperature of the cosmic microwave background (CMB) has been measured at a frequency of 1280 MHz by a modified version of the L-band receiver used in the giant meter radio telescope (GMRT) as mentioned in this paper.
Abstract: The absolute temperature of the cosmic microwave background (CMB) has been measured at a frequency of 1280 MHz. The observation was made with a modified version of the L-band receiver used in the Giant Metre wavelength Radio Telescope (GMRT): the feed horn was replaced by a corrugated plate and the receiver was placed on the ground, directed at zenith, and shielded from ground radiation by an aluminium screen with corrugated edges. Novel techniques have been adopted for •reducing and cancelling unwanted contributions to the system temperature of the receiver and •calibrating the contributions from the feed assembly and receiver. The thermodynamic temperature of the CMB is estimated to be 3.45 ± 0.78 K.

Journal ArticleDOI
TL;DR: Using a dual reflector antenna to improve the bandwidth of a free space material measurement system that was based on dielectric lens horn antennas shows that, for a system that costs less, the operating frequency band of the lens system may be doubled.
Abstract: This paper reports on using a dual reflector antenna to improve the bandwidth of a free space material measurement system that was based on dielectric lens horn antennas. Low-cost offset parabolic dishes, intended for the domestic satellite TV market, are used to generate the required focused beam. Results show that, for a system that costs less, the operating frequency band of the lens system may be doubled.

01 Jan 2000
TL;DR: In this article, the absolute temperature of the cosmic microwave back ground (CMB) has been measured at a frequency of 1280 MHz with a modified version of the L-band receiver used in the GMRT.
Abstract: The absolute temperature of the cosmic microwave back- ground (CMB) has been measured at a frequency of 1280 MHz. The observation was made with a modified version of the L-band receiver used in the Giant Metre wavelength Radio Telescope (GMRT): the feed horn was replaced by a corrugated plate and the receiver was placed on the ground, directed at zenith, and shielded from ground radiation by an aluminium screen with corrugated edges. Novel techniques have been adopted for • reducing and cancelling unwanted contributions to the system tempera- ture of the receiver and • calibrating the contributions from the feed assembly and receiver. The thermodynamic temperature of the CMB is estimated to be 3.45 ± 0.78 K.

Patent
27 Apr 2000
TL;DR: In this paper, a system and method for eliminating pointing error in a beacon tracking system due to uncontrolled differences in passive loss or in amplification of the separate signals involved in creating a pilot signal is presented.
Abstract: A system and method for eliminating pointing error in a beacon tracking system due to uncontrolled differences in passive loss or in amplification of the separate signals involved in creating a pilot signal A locally generated reference signal (30) is radiated onto a set of feed horns (14), at least three (20, 22, 24) of which are used to track a pilot signal (18) The reference signal (30) is detected and used in an automatic gain control feedback loop (44, 46, 48) to maintain equal gain on the separate feed horn channels The equalized signal is processed (62) to produce precision tracking signals

Proceedings ArticleDOI
TL;DR: In this article, an X band, high gain spot beam antenna with accurate beam steering and shaping, and low sidelobe levels is presented, which is comprised of an offset parabolic reflector with overlapping feed cluster.
Abstract: ALCATEL develops reflector antennas with multifeed arrays for civil and military communications satellites. In this paper, an X band, high gain spot beam antenna with accurate beam steering and shaping, and low sidelobe levels is presented. The selected antenna is comprised of an offset parabolic reflector with overlapping feed cluster. Pattern synthesis is performed with an active beamforming network (BFN). Design rules are gained from a detailed analysis of the antenna architecture. A demonstrator is designed and measured. Low sidelobes (-25 dB), accurate steering (0.05/spl deg/), and good agreement between theoretical and experimental spots are demonstrated. Attention is paid to optimizing the design of constitutive elements (lightweight planar focal array, shaped reflector).

Patent
29 Feb 2000
TL;DR: In this paper, a wireless remotely controlled power retractable antenna for a vehicle radio system is presented, where the receiver/controller is adapted to receive a signal from a hand held transmitter.
Abstract: A wireless remotely controlled power retractable antenna for a vehicle radio system. A power retractable antenna is provided with a receiver/controller. Rather than rely on signals from the radio or other hard-wired device, the receiver/controller is adapted to receive a signal from a hand held transmitter. The hand held transmitter has up and down buttons for sending a specific signal representative of the desired antenna position. When it is desired to raise the antenna, the up button is depressed and the transmitter sends an up signal to the receiver/controller. When the antenna is desired in the down position, the down button is simply depressed and the transmitter sends a down signal to the receiver/controller. The controller operates a motor to drive the antenna in accordance with the received signal.

Patent
Matthias Lungwitz1
28 Nov 2000
TL;DR: In this article, a radio transmitter/radio receiver unit with a stable antenna gain that remains practically constant was proposed, where a dielectric body whose dielectrics can be modified is placed in the vicinity of an antenna body.
Abstract: The invention relates to a radio transmitter/radio receiver unit which is capable of transmitting and receiving in different frequency ranges with a stable antenna gain that remains practically constant. According to the invention, a dielectric body, whose dielectricity can be modified is placed in the vicinity of an antenna body. A control unit supplies a d.c. voltage to the antenna which causes the dielectricity of the dielectric body to be modified. The control unit modifies the d.c. voltage value until the dielectricity guarantees an optimum value for at least one physical input variable, which represents the reception and transmission quality.

28 Jan 2000
TL;DR: In this paper, the authors evaluated the performance of using dual frequency GPS satellite measurements corrected by the WAAS broadcast data for time and frequency transfer and found that the directional antenna should eliminate the effects of multipath and could potentially provide a very clean continuous signal.
Abstract: This paper extends the program (Ref. 1) to evaluate the WAAS potential as a time transfer and a time distribution system. This paper reviews the performance of using dual frequency GPS satellite measurements corrected by the WAAS broadcast data. In our previous work (Ref. 1) we found that the code and carrier measurements made on the signal coming from the WAAS Geostationary satellite were at least a magnitude noisier than GPS. We attributed most of this error to multipath errors and to the fact that the WAAS signal is narrow band (2MHz) and cannot be improved by modern multipath-resistant correlation techniques. This paper examines the use of a directional antenna focused on the WAAS satellite. The directional antenna should eliminate the effects of multipath and could potentially provide a very clean continuous signal for time and frequency transfer. A feed Hornand directional parabolic dish antennas were tested over a short baseline at USNO. The directional dish antenna was found to produce 25% cleaner data than the feed horn. Because of the very high signal to noise ratio level attained by using the high gain dish antenna, we found that the receiver maintained phase lock for days. Data from the directional dish antenna was collected at USNO and NRC. Results from this 700Km base line revealed ns level performance for time transfer and 1E-15 level frequency transfer after only 8 hours of observation.

Proceedings ArticleDOI
TL;DR: In this article, an approach to the synthesis of FHA for limited field of view in one plane is developed, which can be generalized in several directions: offset system with no blockage, dual-reflector system with ordinary (commercial) main parabolic reflector and a small focuser-subreflector, etc.
Abstract: In this paper, an approach to the synthesis of FHA for limited field of view in one plane is developed. From the considered examples, it can be seen that in the case of limited field of view, the FHA allows us to appreciably reduce the feed array size and the controlled element number as compared with the HA with parabolic cylindrical reflector. The considered approach to FHA synthesis can be generalized in several directions: (a) offset system with no blockage, (b) dual-reflector system with ordinary (commercial) main parabolic reflector and a small focuser-subreflector, (c) HA with a divergent reflector for extended field of view, etc.

Proceedings ArticleDOI
01 Jan 2000
TL;DR: In this paper, the authors proposed new designs of broadband dual-polarized patch antennas fed by hybrid feeds of an aperture-coupled feed and a gap-couple feed, or an aperture coupled feed with a capacitively coupled feed.
Abstract: We propose new designs of broadband dual-polarized patch antennas fed by hybrid feeds of an aperture-coupled feed and a gap-coupled feed or an aperture-coupled feed and a capacitively-coupled feed. For these hybrid feed designs, since the gap-coupled feed or the capacitively-coupled feed has no backward radiation, their possible port coupling with the aperture-coupled feed in the region between the ground plane and the reflecting plate will be eliminated, which facilitates the design problem when a reflecting plate is required for practical applications. Also, for the proposed antennas with a thick air substrate studied in this article, the 10-dB return-loss impedance bandwidths for the two polarizations can both be greater than 10% and high isolation (>-30 dB) between the two feeding ports over the entire impedance bandwidth can be obtained. Good cross-polarization levels for the radiation patterns of the two polarizations are also observed.

Patent
12 Jul 2000
TL;DR: In this paper, a waveguide and a horn are connected to the waveguide by an opening portion of a circular section, and the horn portion has an elliptic tapered portion which expands in a horn shape.
Abstract: A feed horn (3) comprises a waveguide (5) having an opening portion of a circular section and a horn portion (4) having an elliptic open end (6) and connected to the waveguide. On an inner slant peripheral surface of the horn portion are formed a plurality of elliptic grooves (7) at radial intervals axially from a front end of the horn portion toward the waveguide, as well as a plurality of axially extending elliptic ridges partitioned by the grooves. Tip ends of the ridges are formed with a difference in height so as to approach the waveguide successively as they are positioned radially centrally. The horn portion (4) has an elliptic tapered portion (9) which expands in a horn shape from one axial end (4a) of the horn portion (4) toward a front end (4b) of the elliptic open end (6), namely, the axial front end of the horn portion.

Patent
04 Feb 2000
TL;DR: A Gregorian reflector antenna system optimized for an elliptical antenna aperture was proposed in this article, which consists of a main reflector, a sub-reflector, and a feed horn for illuminating the subreflector.
Abstract: A Gregorian reflector antenna system optimized for an elliptical antenna aperture. The Gregorian reflector antenna system comprises a main reflector, a subreflector, and a feed horn for illuminating the subreflector. The subreflector illuminates the main reflector with an elliptically shaped feed cone of energy. The subreflector has a surface defined by the equation x 2 a 2 + y 2 b 2 + z 2 c 2 = 1 , where x, y, and z are three axes of the Cartesian coordinate system. The terms a, b, and c are three parameters that define the surface of the subreflector

Patent
10 Feb 2000
TL;DR: In this article, an antenna with an EM feed, a rear parabolic twist reflector, a front transreflector and a front parabolic trans reflector is defined, mounted, or otherwise formed on a parabolic surface of a base.
Abstract: An antenna ( 1 ) having an EM feed ( 6 ), a rear parabolic twist reflector ( 3 ) and a front transreflector ( 2 ) The transreflector is closer to the parabolic twist reflector than the focal point of the parabolic twist reflector, and the twist reflector is defined, mounted, or otherwise formed on a parabolic surface ( 17 ) of a base ( 13 ) The base is dimensioned and arranged to provide a foundation aligning an axis of the parabolic twist reflector with an axis of the antenna, and is further dimensioned and arranged to maintain substantial alignment of the feed and twist reflector with variations in ambient temperature that would otherwise produce at least one of warping and misalignment of the parabolic twist reflector in the absence of the base