Showing papers on "Feed horn published in 1992"

Integrated radio receiver/transmitter structure

Abstract: A single chip receiver/transmitter section (202) includes an antenna switch (208), a low noise amplifier (210), a power amplifier (212) and a first (214) and second (216) mixers. The antenna switch (206)includes an antenna terminal (256) which is coupled to an off-chip band pass filter (206) which provides all of the selectivity for radio (200). Also described is a transmitter/receiver structure (300) which incorporates a transmission line filter such as band pass filter (206) formed by substrates (304) and (306) and includes the single chip transmitter/receiver section (202) imbedded inside of the structure (300).

System for short-range transmission of signals over the air using a high frequency carrier

Abstract: A system is provided which transmits either analog or digital data signals over the air. The system includes including a transmitter and a receiver. The transmitter and receiver are arranged to transmit signals using a carrier signal having a high frequency such as in the range of 902-928 MHz. The transmitter and receiver are configured to provide for the transmission of two channels of stereophonic signals while maintaining high signal-to-noise ratios, good frequency response, and low distortion. To provide for the proper transmission of signals between transmitter 10 and receiver 12, these devices include oscillating circuits having ceramic resonators which provide a base frequency which is readily modulated to facilitate proper transmission of either analog or digital signals between the transmitter and receiver. To further improve the transmission capability between the transmitter and receiver, the transmitter and receiver both include substantial buffering, isolation and shielding between selected circuit components to prevent unwanted areas of frequency modulation within the transmitter and receiver.

Facility and method for the detection and monitoring of plumes below a waste containment site with radiowave tomography scattering methods

Abstract: An embodiment of the present invention is a toxic waste containment facility subject to leaking hazardous plumes into soils beneath and adjacent to the site. The facility includes a plurality of substantially horizontal underground drillholes adjacent to and below a waste containment pit. A radio transmitter and antenna are placed in a first underground drillhole proximate to a surface waste containment site. A radio receiver and antenna are placed in a second underground drillhole opposite to the first drillhole. A position indicator is used for gauging a plurality of locations of the radio transmitter and antenna within the first underground drillhole and the radio receiver and antenna within the second underground drillhole. A data processing unit analyzes data received from radio receiver and antenna and position indicator to measure radio signal attenuation between the radio transmitter and antenna and radio receiver and antenna. The transmitted signal from the radio transmitter and antenna are synchronized by a signal from the data processing unit. Fiber optic cables are used to couple signals between the radio transmitter and antenna and radio receiver and antenna with the data processing unit. Along each path, the operating frequency is increased until all of the transmitted energy is absorbed along the path to maximize resolution. Tomographic techniques are used to translate the data collected from a variety of transmitter and receiver positions into attenuation profiles that can image a toxic plume beneath the containment pit.

A 20-dB quasi-integrated horn antenna

Abstract: A multimode quasi-integrated dipole-fed horn antenna is presented with a performance comparable to that of waveguide-fed corrugated horn antennas. The antenna has been designed using full wave analysis and has been fabricated and tested at 91 GHz. The horn has a gain of 20 dB with very symmetric patterns, a Gaussian coupling efficiency of 97%, and a cross-polarization level of -22.7 dB. The antenna provides a significant improvement in integrated antenna designs and is suitable for millimeter-wave communication and radar systems and as a Gaussian-beam launcher in quasi-optical receiver systems. >

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). In a preferred embodiment, 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). The first and second feed horns (24,26) are preferably located separate from the reflective path (17) so as to avoid interference therewith. In an alternate embodiment, a subreflector (12') with a hyperboloidal reflective surface (13') may be used.

Polarization diversity system suitable for radio communication in indoor space

Abstract: A polarization diversity radio communication system suitable for radio communication in indoor space is provided for transmitting from a transmitter a series of data sequentially from one of two or more transmission antennas of the transmitter, and for reproducing the data received at a receiver through a single reception antenna of the receiver when the series data are received from the transmitter. Thus, the transmitted data from any part of the indoor space can be received efficiently, and a high S/N ratio can be assured on the reception side.

Antenna beam shaping by means of physical rotation of circularly polarized radiators

Abstract: Disclosed is an apparatus and method for shaping a beam of radiation from a circularly polarized beam shaping antenna to create a predetermined radiation pattern. A circularly polarized feed horn generates the beam of radiation to be shaped. Circularly polarized radiator elements attached to a ground plane are positioned to receive the beam of radiation. Each radiator element is physically rotated about an axis relative to the ground plane to alter its phase. The radiator elements are then operable to individually radiate a beam of radiation to form a combined radiation beam creating the predetermined radiation pattern.

Systematic approach to control feed scattering and multiple reflections in symmetrical primary-fed reflector antennas

Abstract: An improved method for accurately analysing symmetrical primary-fed reflector antennas is presented. The method, which is referred to as the multiple-scattering approach, takes into account the blockage caused by the feed in a very accurate way by also including the mutual coupling between the feed and the reflector. The coupling is treated as a multiple-scattering process. It is expressed in terms of the scattering pattern of the feed, which is the scattered field when the feed is excited by a plane wave with unity amplitude. To validate the method, a reflector antenna with a self-supported dipole-disk feed is investigated. The gain, the copolar sidelobes and the cross-polar level are much more accurately predicted by the multiple-scattering approach than by existing methods, provided that the scattering pattern of the feed can be determined with sufficient accuracy.

Radio frequency energy jamming system

Abstract: A transmitter/receiver system is provided wherein a transmitter of such system produces a transmitted signal frequency modulated in accordance with the level of a modulating signal and a receiving antenna has an output thereof coupled to a receiver through a switch means, for coupling or inhibiting signals received by the receiving antenna from passing to the receiver selectively in accordance with the level of the modulating signal.

A novel dual antenna measurement of the angular distribution of received waves in the mobile radio environment as a function of position and delay time

Abstract: A dual antenna experiment to estimate the angular distribution of received waves in a mobile radio environment as a function of position and delay time at 2.3 GHz using a Cox-type channel sounder is described. The two receive antennas had a transverse separation of 0.49 lambda . The test area is a mix of modern high-rise buildings and warehouses lined by expanses of water. No line-of-sight path exists between transmitter (30-m elevation) and the mobile receiver (2.6-m elevation). As the receiver moves, a two-dimensional grid of I and Q-responses from each antenna is recorded. The data are correlated offline with a reference pseudo-random binary sequences and then processes to give estimated 360 degrees plots of the incident power's angular distribution at different delay times. This information is useful for the design of adaptive array antenna diversity systems. >

Infrared mapping of transient electromagnetic fields radiated by high power microwave pulsed sources

Abstract: The intensity of the transient field radiated from a high-power microwave (HPM) pulsed source is measured using an infrared (IR) mapping technique. The electromagnetic (EM) waveguide mode generated in the interior source region of the HPM source is determined. The transverse electromagnetic (TEM) mode excited in the antenna feed structure is mapped in the cross section of the feed horn. The radiated EM field exterior to the HPM source in the main beam of the TEM horn is mapped to determine the near and far field structure of the HPM source. >

Concealed radio transmitter in a tapemeasure

Abstract: According to the invention there is provided a concealed radio transmitting device which includes a radio transmitter, an antenna coupled to the radio transmitter, power supply for supplying electric power to the transmitter, an on/off device connected between the power supply and the radio transmitter, and a housing shaped as a tape measure adapted for containing the radio transmitter, the antenna, the power supply and the on/off device, and wherein further the concealed radio transmitting device includes in the radio transmitter an audio input, and a microphone connected to the audio input for transferring audio signals to the transmitter.

Reflector/feed(s) synthesis challenges for satellite contour beam applications

Abstract: A newly developed generalized reflector/feed(s) diffraction synthesis methodology that is capable of synthesizing various antenna configurations effectively is presented. Based on this synthesis method, the feasibility of several CBRA (contour beam reflector antenna) configurations, such as a paraboloidal reflector fed by a large array, a shaped reflector illuminated by a single feed, and a shaped reflector fed by a small, array, are properly assessed for a representative application in a unified fashion. Numerical examples are given to illustrate CBRA synthesis for a challenging and difficult contour coverage-the US Eastern Time Zone. >

Waveguide converter for transmitting input radio wave with proceeding direction thereof changed to waveguide path

Abstract: A bend portion is provided on the inside of a waveguide main body for bending a proceeding direction of a radio wave from a waveguide on the side of a primary feed horn. The radio wave is transmitted with its proceeding direction changed such that an electric field of the radio wave is parallel with a conversion unit. Further provided on the inside of the waveguide main body is a conversion unit including a microstrip line for converting the radio wave from the bend portion to supply electric power.

Analysis of circular horn antennas using the FD-TD method

Abstract: Application of the vector two-dimensional FD-TD (finite-difference time-domain) method to the analysis of circular horn antennas is presented. An antenna should maintain axial symmetry of boundary conditions and can be arbitrarily shaped in two other directions, in the cylindrical coordinate system. The medium filling the antenna can be inhomogeneous. Modes of excitation of sinusoidal dependence on angle can be considered. A full-wave solution is obtained. An example of a circular horn antenna has been computed and compared with experimental data. >

Weather guard for parabolic-antenna polariser - comprises transparent plastic cap resistant to UV without dampening or scattering waves

Abstract: The all-weather guard for the polariser of a parabolic antenna and its feed horn, it comprises a protective cap for the polariser in the direction of the antenna dish. This is of transparent plastic, resistant to ultra-violet rays and which does not dampen or scatter the electromagnetic waves, while there is a hollow chamber in front of the polariser. The cap, and any adapter between it and the polariser, can be of polyethylene resistant to ultra-violet rays, and 1 to 1.5mm. thick. The cap can fit on the polariser and have a ventilation system on the underside. It can be tubular, with a flat or arched and inclined front end plate. ADVANTAGE - Light weight, low cost, and prevents weather affecting picture quality.

A beamwaveguide design for high-power applications

Abstract: A beam waveguide (BWG) design suitable for high-power applications is described. The design features a transmit-only, four-port high-gain horn as input to a BWG system with a single parabolic mirror and three flat plates. The use of a single parabolic mirror is such that the highest field concentration is no greater than that caused by the horn itself. The horn is linearly polarized and a grid reflector is used to reflect the orthogonal polarization into the receive feed. A rotatable dual polarizer provides for arbitrary transmit polarization. The dual-reflector system is shaped to provide uniform illumination over the main reflector and therefore maximum gain for the given size aperture. Measured data from a scale model BWG system are presented.

Scalar feed horn

Abstract: PURPOSE:To use a scalar feed horn in a wide frequency band by providing concentric circular chokes in specified angle areas with respect to the direction of respective linearly polarized waves as against respective linearly polarized waves to which two frequencies are orthogonally linearlly polarized wave-fed and setting the radiation patterns of respective frequencies to be satisfactory patterns symmetric as against an axis. CONSTITUTION:The scalar feed horn has a horn which is formed by a circular waveguide 3 and the concentric circular chokes 2a and 2b suppressing a backward current at the external side of the opening surface 1. Then, the scalar feed horn common to the two frequencies of the orthogonally linearly polarized wave, in which the electromagnetic wave of a first frequency is fed by a vertically polarized wave, and the electromagnetic wave of a second frequency is fed by a horizontally polarized wave, is formed. Here, the first concentric circular choke suppressing the backward current in the first frequency in the angle of + or -45 deg. as against the direction of the electromagnetic wave fed by the first frequency and the choke suppressing the backward current in the second frequency is given to the angle area of + or -45 deg. as against the direction of the polarized wave of the electromagnetic wave fed by the second frequency.

L-band integrated feed array design for mobile communication satellites

Abstract: The space segment of a mobile communication satellite system such as the North American Mobile Communication Satellite System (MSAT) must provide high radiated power densities on the ground to allow mobiles with small, low-gain antennas to communicate via satellite. With the emerging high-power mobile communication satellite systems, the risk of interference caused by passive intermodulation (PIM) is a very important spacecraft design performance parameter. Separate transmit and receive reflector antennas are used on the MSAT spacecraft to reduce the risk of PIM. In addition, PIM avoidance is a major design driver for the transmit antenna reflector and primary feed array. Significant design effort and breadboard activities at Spar have resulted in the development of a primary feed array suitable for mobile satellite applications. The authors present the integrated feed design approach which has been selected. The author describes the feed element, which consists of an output band-pass filter integrated with a cup dipole radiator. The measured test results of the developed hardware are also presented.

Feed horn for both circularly polarized wave and linearly polarized wave

Abstract: PURPOSE:To use one and the same antenna for receiving a circularly polarized wave and a linearly polarized wave by selecting a length of a phase circuit (dielectric board) in its lengthwise direction to be a length capable of converting a circularly polarized wave into a linearly polarized wave and turning a exciting probe so as to receive a circularly polarized radio wave and a linearly polarized radio wave. CONSTITUTION:In the case of receiving a circularly polarized radio wave, a relative angle between a center line 10 of a dielectric board 3 and a part of a tip of an exciting probe 4 bent at a right angle is selected to be almost 45 deg.. Thus, the radio wave converted into a linearly polarized wave is excited in the excitation probe 4, the exciting probe 4 converts the radio wave into an electric signal and the signal is propagated in the inside of a square waveguide 8, the linearly polarized radio wave is excited again in the inside of the square waveguide 8 and the radio wave is propagated to a converter (LNB). In the case of receiving a linearly polarized radio wave, the relative angle between a center line 10 of a dielectric board 3 and a part of a tip of an exciting probe 4 folded at a right angle is selected to be almost 0 deg. or 90 deg.. Thus, the radio wave is exited to the exciting probe 4.

Phase center and radiation behaviour of Ku-band corrugated horn

Abstract: The radiation pattern and phase center behavior of a circular corrugated horn with variable ridge widths is calculated. The field equations and the radiation patterns are based on the model method and the equivalent current sources, respectively. The phase center is determined from samples of the computed radiation patterns. When the ratio of the ridge to the slot width changes from 0.25:1 to 0.4:1, the variations of the phase center, and the radiated co- and cross-polar level of the horn at 11.7 and 14.5 GHz are tabulated for ridge width to slot width ratios of 0.25, 0.30, 0.35, and 0.40 to 1. >

Helical feed horn

Abstract: PURPOSE:To make an axial ratio broad, to make the size small and to facilitate assembly by providing a tapered feed horn section whose opening has a maximum diameter to the feed horn, providing a helical element in the horn and connecting the helical element to a microstrip line on a board. CONSTITUTION:An outer appearance of a helical feed horn 10 is cylindrical and a circular opening 18 one side of which is opened is formed, the diameter is decreased from the opening toward the inside and the depth has a conical truncated horn 22 having a reflecting face 20. A helical element 20 is arranged along a center axis line of the horn 22. A focus 27 of an offset parabolic reflecting mirror 12 is placed between the opening 18 and a tip of the helical element 26 toward the opening 18. A high frequency board 28 is provided to a rear side of the reflecting face in face contact thereto. Thus, since the helical element is provided in the horn, the total length of the helical feed horn is decreased and the size is made small.

Radiation characteristics of loaded shaped splash plate antennas

Abstract: The radiation characteristics of splash plate feed antennas are studied numerically using the method of moments to solve an exact surface integral equation formulation A step-by-step procedure was used to improve the radiation characteristics of the feed, resulting in several good feed designs The feed efficiency was improved significantly While the cross-polarization level of this feed is acceptable, it is higher than the level achieved by corrugated feeds >

Performance of a small reflector with a splashplate feed

Abstract: Reflector antennas with aperture diameters of less than ten wavelengths are difficult to design with good sidelobe performance because of blockage problems. A small prime focus reflector for 8.4 GHz has been designed using mode-matching techniques. The design was aimed at providing sidelobes of less than -20 dB without degrading the gain excessively. In order to minimise blockage problems, a splashplate feed was chosen. The diameter of the integrated subreflector must be small and has to be optimised in order to offset blockage losses against diffraction and spillover losses. The feed dimensions must also be optimised to reduce blockage losses. The measured results agree well with predictions. The target of less than -20 dB sidelobes was achieved with an aperture efficiency of 60% and the authors conclude that mode-matching is a useful approach to the design of such small antennas. >

Analysis of a generalized dual reflector antenna system using physical optics

Abstract: Reflector antennas are widely used in communication satellite systems because they provide high gain at low cost Offset-fed single paraboloids and dual reflector offset Cassegrain and Gregorian antennas with multiple focal region feeds provide a simple, blockage-free means of forming multiple, shaped, and isolated beams with low sidelobes Such antennas are applicable to communications satellite frequency reuse systems and earth stations requiring access to several satellites While the single offset paraboloid has been the most extensively used configuration for the satellite multiple-beam antenna, the trend toward large apertures requiring minimum scanned beam degradation over the field of view 18 degrees for full earth coverage from geostationary orbit may lead to impractically long focal length and large feed arrays Dual reflector antennas offer packaging advantages and more degrees of design freedom to improve beam scanning and cross-polarization properties The Cassegrain and Gregorian antennas are the most commonly used dual reflector antennas A computer program for calculating the secondary pattern and directivity of a generalized dual reflector antenna system was developed and implemented at LeRC The theoretical foundation for this program is based on the use of physical optics methodology for describing the induced currents on the sub-reflector and main reflector The resulting induced currents on the main reflector are integrated to obtain the antenna far-zone electric fields The computer program is verified with other physical optics programs and with measured antenna patterns The comparison shows good agreement in far-field sidelobe reproduction and directivity

Synthesis of elliptical Taylor distributions using a three-reflector antenna with a symmetric main reflector

Abstract: The Taylor circular distributions and corresponding far-field expressions are reformulated in a more general elliptical-aperture form. Synthesis of the desired distributions is then accomplished by means of a tilted axially symmetric paraboloidal main reflector and two shaped subreflectors. >

Electromagnetic Waves, Propagation and Antennas

Abstract: This chapter discusses the properties of electromagnetic waves and antennas. Electromagnetic waves consist of energy in the form of electric (E) and electromagnetic (H) fields that are interdependent. The waves propagate through space because of an energy source, with the two fields acting at right angles to each other and mutually at right angles to the direction of propagation. By convention, the plane of polarization of these waves is associated with the E field. Vertical and horizontal polarizations are used extensively in terrestrial communication frequency reuse systems. The E field is either vertical or horizontal with respect of the Earth's surface. An antenna is essentially a transducer designed to obtain maximum transfer of energy from a transmitter into a communications medium or, alternatively, from the medium into a receiver. Because of the reciprocal properties of these devices, their characteristics can be measured or analyzed in either the transmit or receive modes, as convenient, with the qualifications that the medium must be both linear and isotropic. Of the many types of antenna available, those based on the parabolic reflector are most commonly used for satellite communication purposes. The most important primary properties of antennas are power gain, directivity, efficiency, and equivalent noise temperature.

A systematic approach towards the design of multimode quasi-integrated horn antennas for receiver applications

Abstract: A systematic approach has been developed for the design of multimode pyramidal horn antennas for quasi-optical receiver applications. The method is applied to the design of quasi-integrated horn antennas at millimeter-wave frequencies with a gain in the range of 18-25 dB, a fundamental Gaussian coupling efficiency around 97%, and a 10% bandwidth. The design criterion chosen is the maximization of the fundamental Gaussian coupling efficiency, and the corresponding necessary conditions are determined directly from the aperture fields. Also, for the analysis of the gradually flared gain-enhancing and phasing section, an improved technique is introduced which accounts for mode conversion. The optimized design is tested by performing a final full-wave analysis on the structure, using the generalized scattering matrix technique, and by pattern measurements at 91 GHz and 370 GHz. >

Progress in integrated-circuit horn antennas for receiver applications. Part 2: A 90 GHz quasi-integrated horn antenna receiver

Abstract: A receiver belonging to the family of integrated planar receivers has been developed at 90 GHz. It consists of a planar Schottky-diode placed at the feed of a dipole-probe suspended inside an integrated horn antenna. The measured planar mixer single-sideband conversion loss at 91.2 GHz (LO) with a 200 MHz IF frequency is 8.3dB plus or minus 0.3dB. The low cost of fabrication and simplicity of this design makes it ideal for millimeter and submillimeter-wave receivers.

A magnetic current loop array in a parabolic reflector

Abstract: To eliminate the blockage caused by mechanical support, a self-supported magnetic current loop array operating at 9 GHz has been designed as a feed for a reflector antenna. In the present arrangement, the feed is a circular waveguide that protrudes into the paraboloidal reflector through the center. To generate magnetic current loops, circumferential slots can be cut on a coaxial or circular waveguide. For narrow slots, energy radiated per slot is small and negligible; the electromagnetic field inside the waveguide is therefore not affected. A number of prototype antenna feeds have been fabricated and compared. In the Fresnel zone, the E-plane and H-plane radiation patterns of the feed at center frequency, 9 GHz, are illustrated. The estimated efficiency of the antenna is greater than 80%. >