Showing papers on "Reflective array antenna published in 1985"
Book•
01 Mar 1985
TL;DR: Aperture Distributions and Arrays Synthesis as discussed by the authors is a technique used to synthesize antenna arrays, which are then used to measure the distance from the source to the sink. But it requires the antenna array to be symmetric.
Abstract: Preface. 1. Properties of Antennas. 2. Radiation Structures and Numerical Methods. 3. Arrays. 4. Aperture Distributions and Arrays Synthesis. 5. Dipoles, Slots, and Loops. 6. Microstrip Antennas. 7. Horn Antennas. 8. Reflector Antennas. 9. Lens Antennas. 10. Traveling Wave Antennas. 11. Frequency-Independent Antennas. 12. Phased Arrays. Index.
816 citations
TL;DR: The MU (middle and upper atmosphere) radar of Japan is a 46.5-MHz pulse-modulated monostatic Doppler radar with an active phased array system as discussed by the authors.
Abstract: The MU (middle and upper atmosphere) radar of Japan is a 46.5-MHz pulse-modulated monostatic Doppler radar with an active phased array system. The nominal beam width is 3.6° and the peak radiation power is 1 MW with maximum average power of 50 kW. The system is composed of 475 crossed three-subelement yagi antennas and an equivalent number of solid state power amplifiers (transmitter-receiver modules). Each yagi antenna is driven by a transmitter-receiver module with peak output power of 2.4 kW. This system configuration enables very fast and almost continuous beam steering that has not been realized by other mesosphere-stratosphere-troposphere radars. Also, a variety of sophisticated operations are made feasible by dividing the antenna array into several independent subarrays. A brief description of the system, particularly its antenna and power amplifiers, is presented herein.
269 citations
17 Jun 1985
33 citations
TL;DR: A brief account of some concepts and developments in my experience with antennas is presented under three headings: A-wide-band matching to a long line; B-small antennas; C-planar arrays.
Abstract: A brief account of some concepts and developments in my experience with antennas is presented under three headings: A-wide-band matching to a long line; B-small antennas; C-planar arrays. They cover the half-century from 1935 to date.
20 citations
TL;DR: In this article, the power gain radiation patterns of mobile antennas mounted in six different locations on a test vehicle were measured with and without typical lights and sirens mounted on the roof.
Abstract: Power gain radiation patterns of mobile antennas mounted in six different locations on a test vehicle were measured with and without typical lights and sirens mounted on the roof. The measurements were performed at frequencies representing the frequency bands of 25 to 50, 150 to 174, 400 to 512, and 806 to 866 MHz. In addition, special antennas consisting of three disguised antennas operating at discrete frequencies of 40.27, 162.475, and 416.975 MHz and one slot antenna operating at 413 MHz were also measured. Plots of power gain radiation patterns are given for the mobile antennas mounted in six different locations on the test vehicle and for the special antennas. Results showing the effects of poor grounding characteristics are also included. Recommended locations for mounting the mobile antennas are given for specific frequency bands.
18 citations
17 Jun 1985
16 citations
17 Jun 1985
12 citations
17 Jun 1985
TL;DR: In this paper, the authors proposed a multibeam antenna design to obtain high beam-to-beam isolation, which is the most difficult problem to be solved in the design of multibam antenna.
Abstract: Introduction Large high capacity communication satellites with multibeam antennas are being developed in Japan(l), Ilnited States(2) and so on. The merits of multibeam antenna are ( 1 ) high EW, (2) reuse of frequencies. But in the design of multibeam antenna, one of the most difficult problems to be solved is to obtain the high beam-to-beam isolation. In conventional antennas, for instance Offset Gregorian, the increase of scan angle causes the increase of sidelobe level and scan loss on account of aberration and increase of cross polarization level, so beam-to-beam isolation becomes lower.
10 citations
TL;DR: In this article, a type of spherical triangular array composed of turnstile elements is numerically analyzed and discussed, and it is found that the spherical array proposed here is able to scan its beam up to large angle without variation of the directivity and the circular polarization property.
Abstract: Radiation characteristics of a type of spherical triangular array composed of turnstile elements are numerically analyzed and discussed. It is found that the spherical array proposed here is able to scan its beam up to large angle without variation of the directivity and the circular polarization property.
9 citations
Patent•
30 Aug 1985
TL;DR: In this paper, a polarization separating reflector is constructed for use in microwave transmitting antennas or in microwave receiving antennas, where the signal supply to the transmitting antennas and the signal retrieval from the receiving antennas may be symmetrical or nonsymmetrical.
Abstract: A polarization separating reflector is constructed for use in microwave transmitting antennas or in microwave receiving antennas. The signal supply to the transmitting antennas and the signal retrieval from the receiving antennas may be symmetrical or nonsymmetrical. Such antennas may or may not be equipped with subreflectors. Such antennas have a polarization selectively reflecting lattice structure on or within a dielectric carrier. This antenna structure is resonantly constructed out of separate dipoles having different lengths, preferably in the form of a linear dipole lattice. The dipoles are arranged in a staggered manner, colinearly, or at an angle relative to a reference line, such as the vertical, as desired.
9 citations
24 Oct 1985
TL;DR: A wide variety of antennas have been designed or are currently under study for the millimeter wave region as discussed by the authors, and an overview over these antennas is presented in this paper. But, as mentioned before, the antennas of conventional configuration and antennas based on new design approaches are distinguished, and antennas with significant features that are peculiar to the mm-wave band can be distinguished.
Abstract: A wide variety of antennas has been designed or is currently under study for the millimeter wave region. An overview over these antennas is presented. Two classes of antennas are distinguished, i.e., antennas of conventional configuration and antennas based on new design approaches. The former class consists of radiating structures, such as reflector, lens and horn antennas, whose characteristics are well established. The latter class is comprised of antennas with significant features that are peculiar to the mm-wave band and includes radiating structures such as microstrip mm-wave antennas, dielectric antennas and integrated antennas.
17 Jun 1985
TL;DR: In this article, the authors present three problems that must be overcome if a single antenna is to be used over the entire band: 1) antennas designed to fit within a limited space are necessarily electrically short at the low end of the HF hand where wavelengths are on the order of 1 0 0 meters or greater.
Abstract: Modern HF communication systems are being designed to utilize either the entire HF (2-30 MHz) spectmm or a significant portion of thereof at any one time. O n e of the fundamental limitations of wideband HF systems is the fact that antennas designed to fit within a limited space are necessarily electrically short at the low end of the HF hand where wavelengths are on the order of 1 0 0 meters or greater. For transmitting purthis limitation presents three problems that must be overcome if a single antenna is to be used over the entire band:
TL;DR: There exists a need to establish a standard of merit or worth for multi-element antenna systems that involve the use of amplifiers and a proposed figure of merit for evaluating such antenna systems is presented.
Abstract: In recent years a new class of reflector antennas utilizing array feeds has been receiving attention. An example of this type of antenna is a reflector utilizing a moveable array feed for beam steering. Due to the circuitry required to adjust the weights for the various feed array elements, an appreciable amount of loss can be introduced into the antenna system. One technique to overcome this possible deficiency is to place low noise amplifiers with sufficient gain to overcome the weighting function losses just after each of the feed elements. In the evaluation of signal processing antennas that employ amplifiers the standard antenna gain measurement will not be indicative of the antenna system's performance. In fact, by making only a signal measurement, the antenna gain can be made any arbitrary value by changing the gains of the amplifiers used. In addition, the IEEE Standard Test Procedures for Antennas does not cover the class of antennas where the amplifier becomes part of the antenna system. There exists a need to establish a standard of merit or worth for multi-element antenna systems that involve the use of amplifiers. A proposed figure of merit for evaluating such antenna systems is presented.
01 Aug 1985
TL;DR: In this paper, Tandem constructed a semi-anechoic chamber with the goal of testing small systems and peripheral devices for compliance with the FCC limits for Class A (Commercial) computing equipment.
Abstract: In 1981, Tandem constructed a semi-anechoic chamber with the goal of testing small systems and peripheral devices for compliance with the FCC limits for Class A (Commercial) computing equipment. This chamber, provided by Scientific Hardware, is 15.24 meters (50 feet) long, 9.92 meters (.26 feet) wide and 3.66 meters (12 feet) high (steel dimensions). RF absorber cones, provided by Advanced ElectroMagnetics Inc., ranging in length from .61 to 1.22 meters (2 to 4 feet), are mounted on the walls and ceiling with the 1.22 meter cones mounted in the center of the chamber (point of maximum reflection) and shorter cones at either end. The chamber saw little use other than for conducted emissions testing for some period of time due to a lack of knowledge about its correlation to an open field test site.
17 Jun 1985
01 Apr 1985
TL;DR: The feedpacking problem is not unique to reflector antennas and exists in lens type antennas as well, and the BFN and associated problems are present in the phased array antennas and on a much larger scale.
Abstract: Contiguous multiple beams are used to make use of the set of frequency bands at different beams at different geographical locations and achieve the most efficient use of precious frequency allocation. This is feasible only if the interference among cochannel beams is below some acceptable level, by carrier/interference (C/I) ratio. Individual beam patterns of very low sidelobes, which in turn necessitates narrow feed are required. A physically realizable solution to this problem entails either more than one reflector, more complicated optics, or breaking of each feed into a cluster of smaller elements, some of which would then be shared by adjacent beams. The latter, however, requires a complicated beamforming network (BFN) for the proper feeding of the elements. The feedpacking problem is not unique to reflector antennas and exists in lens type antennas as well. The BFN and associated problems are present in the phased array antennas and on a much larger scale. Poor scan capabilities are associated with reflector systems. The scan properties of offset fed reflector systems can be improved by choosing a very large focal length to parent reflector diameter ((F/Dp) ratio, which requires a longer boom to support the feed. In the case of reflectors with cluster feed arrangements, the scan capability for smaller F/Dp ratios is improved by proper adjustment of cluster element excitations. Such a system seems to be appropriate for up to 10 beamwidths scan. For a larger number of beams, systems with wider scan capabilities, such as phased arrays or phased array/reflector combinations, become more appealing.
01 Oct 1985
TL;DR: In this paper, an electronically steered phased array antenna is proposed to eliminate the need for mechanical stabilization in shipboard terminal applications, which is conceptually similar to the Chalmers antenna, however, circuit implementation is radically different.
Abstract: Commercial marine satellite communications over the Inmarsat system has as a rule seen a predominance of dish antennas used in shipboard terminal applications. A notable exception has been a phased array built by Chalmers University of Technology (Ref.1). In any case the shipboard antenna must track satellites in the presence of severe ship dynamics. For dish and fixed array antennas this requirement leads to the widespread use of relatively elaborate and costly inertial stabilization mechanisms. To eliminate the need for mechanical stabilization an electronically steered phased array antenna is proposed. The antenna is conceptually similar to the Chalmers antenna; however, circuit implementation is radically different. Two flat plate arrays are used. An array comprises 64 radiating elements each independently driven by a 3 bit phasor. To minimize component inter-connects and assembly cost, radiating elements, phasors and corporate feed network are implemented in microstrip on large (0.9m × 0.9m) circuit boards in a multi-layer laminated assembly.
17 Jun 1985
TL;DR: Rotman and Shih-Ming Shih Lincoln Laboratory Massachuse campus MIT's Lexington, Massachusetts, USA campus as discussed by the authors, where the shape of the beam was chosen by the authors.
Abstract: Walter Rotman and Shih-Ming Shih Lincoln Laboratory Massachuse t t s In s t i t u t e of Technology \ Lexington, t lassashuset ts -.; \ k /-d j 4, t i: E Ear th coverabAantennas for sa te l l i t e communica t ions f rom geosynchronous orbi t require a shaped r ad ia t ion pa t t e rn , w i th a maximum irr the d i r ec t ion o f t he ea r th ' s l imb which compensates f o r t h e d i f f e r e n c e s i n r a n g e and a tmospher ic a t tenuat ion as a func t ion of incidence angle (Ref . 1) . A t millimeter wavelengths , d ie lect r i c l ens an tennas a re p rac t i ca l fo r p roduc ing these shaped beams s ince the i r phys ica l d imens ions a re mal l , and they can be designed for specif ied aper ture i l luminat ions (Ref . 2) . Several compet i t ive synthesis techniques for generat ing the desired farf ie ld pa t te rns wi th aper ture an tennas , such as l enses , a re eva l u a t e d i n t h i s p r e s e n t a t i o n . . .
17 Jun 1985
01 Feb 1985
TL;DR: In this paper, a 6X6 array of fan-dipoles was designed to operate in the 510 to 660 MHz frequency range for aircraft flight test and evaluation of a UHF radiometer system.
Abstract: A 6X6 array of fan-dipoles was designed to operate in the 510 to 660 MHz frequency range for aircraft flight test and evaluation of a UHF radiometer system A broad-band dipole design operating near the first resonance is detailed Measured VSWR and radiation patterns for the dipole array demonstrate achievable bandwidths in the 35 percent to 40 percent range