Showing papers on "Conformal antenna published in 1984"

Phased antenna array for wind profiling applications

Abstract: A diagonal phased antenna array for use as a wind profiler by means of Doer shift measurements comprises a plurality of Yagi-Uda antennas which are oriented in a predetermined direction such that Yagi-Uda antennas have a polarization 45° offset from the principal planes of operation of the antenna array resulting in similar radiation patterns subject to a geometric taper in the array aperture with respect to the principal planes.

A compact flush-mounting antenna with direction finding and steerable cardioid pattern capability

Abstract: A flush-mounting antenna is described which could be used, in lieu of present antennas, to provide direction finding and steerable directional pattern capability in airborne beacon transponder systems. The antenna is comparable in size to the existing, omni-directional antennas presently used for air-traffic control and military identification, friend or foe (IFF) functions. The design and performance of an experimental model of the antenna are discussed.

Broadband Microstrip Matching Techniques

Abstract: : Microstrip antennas are used in many applications where a low-profile conformal antenna is desired. They are rugged, lightweight, and easily fabricated. However, it is desirable to increase the bandwidth of these antennas. Through the use of proper matching techniques, standard microstrip antennas can be matched to bandwidths of 35% or more. A rectangular half-wave microstrip radiator was built and tested with and without broadbanding to show the capabilities of these matching techniques.

Some design considerations for biconical antennas

Abstract: This paper discusses the use of the body of revolution moment method formulation to predict the radiation patterns of biconical antennas, and describes a novel and practical feed point arrangement for fine-tuning the antenna reflection coefficient.

Advanced Antenna Measurements

Abstract: Over the last decade, increasing interest has been observed as to the indoor test techniques on microwave antennas. A number of these methods which have been developed recently, for instance the near-field/far-field transformation technique and Compact Antenna Test Ranges (CATR) will be described in this paper. The requirements for General Purpose Facilities (GPF) as well as for satellite system level testing will be discussed. A comparison of capabilities of indoor measurement techniques for various applications will be given.

Applying CATV technology and equipment in guided radio systems

Abstract: CATV amplifiers, cables and coupling devices have been successfully used in radio signal boosters systems in Canada and Saudi Arabia. The equipment is very reliable and the gasketed housings afford proection from adverse environments. CATV equipment can be used in either leaky cable antenna systems, or in distributed antenna systems consisting of small antennas, spaced as required, and fed by splitters from a trunk line CATV cable. Procedures for making signal quality and signal margin surveys are described, and the design parameters of a large two way signal booster system are explained.

A variable power dual mode network for reconfigurable shaped beam antenna

Abstract: A three output port variable power dual mode network is described. This network can be useful in driving a three element feed array feed of a communication satellite antenna to provide a dual mode reconfigurable shaped beam pattern.

Systematic design of a dual offset reflector antenna with an elliptical aperture

Abstract: The systematic design of an optically shaped dual offset reflector antenna, capable of illuminating a given elliptical aperture over which the phase is uniform and the power is arbitrarily prescribed when fed by a scalar horn, is described in the paper. A conformal mapping transforms the ellipse to a circle, allowing the present problem to be solved by an existing method. Designs based upon Cassegrainian and Gregorian systems are derived.

Multiple‐beam antennas for contiguous coverage of europe for business service applications

Abstract: Demands for increased channel capacity in future communication satellite systems coupled with basic limitations in terms of satellite power and frequency spectrum will lead to requirements for advanced multiple-beam antenna systems with frequency re-use capability. This paper describes the results of a study of multiple-beam antenna systems suitable for an advanced European business services satellite. Initially, background work is described which serves to define the overall system, analyse the link performance and specify the antenna requirements. A generalized parametric study of the capabilities of a model antenna is discussed to set the bounds of feasibility, as it was appreciated that some specification targets might prove impossible to attain. In parallel, a comparative survey of a wide range of antenna types is presented to determine the most promising configurations. Based on these two outputs, candidate antenna configurations are analysed in detail to predict accurately the capability of the more promising antenna types to meet the range of performance objectives. Finally, detailed electrical design studies are performed for specific example missions.

Potential Measurement Errors Due to Mutual Coupling Between Dipole Antennas and Radio Frequency Absorbing Material in Close Proximity

Abstract: The mutual coupling between dipole antennas and radio frequency absorbing material was determined experimentally. A comparison of the mutual coupling before and after wall treatment is presented. These results can be used to determine the minimum distance which should be maintained between a dipole antenna and radio frequency absorbing material. A broadband antenna and several quarter-wave monopoles near resonance were measured.

Design of Vivaldi Antenna for Microwave Integrated Circuits Applications

Abstract: A computer-aided design of the vivaldi antenna is developed. A gain of 12db and a side lobe of-17db are obtained from antenna of length 2?0, and operating in the x-band. The VSWR is less than 1.55 and the gain varies by only 1db over a bandwidth of nearly 3GHz. The 3db beam widths in both E-and H-planes are about 20° and 30° respectively, while the 10db beamwidths in the corresponding planes are about 52° and 55° respectively.

Conformal array analysis

Abstract: : The idea of having conformally mounted phased array antennas has rapidly gained popularity in the past few years High performance for conformal arrays however is more difficult to achieve than with the more conventional planar arrays The primary reasons for this can be seen with the aid of figure 1 First, the individual element patterns of the radiators point in differrent directions, which produces an undesirable amplitude variation as a function of observation angle Secondly, the path lengths from the radiators avary in a manner which is not harmonic in sin theta, as is true with planar arrays Thirdly, the formal array has the problem that for certain region of space some of the elements are physically blocked and cannot contribute to the far field pattern (Author)

A new class of broadband time domain element space antenna array processors

Abstract: This paper describes a new approach to the design of broadband element space antenna array processor which can handle a variety of steering situations. The approach is applicable to array processor without pre-steering, with coarse pre-steering and exact pre-steering. Furthermore, the approach presented enables mismatch between signal model and actual signal scenario to be incorporated in the problem formulation. Analytical as well as simulation results on the new class of antenna array processors are presented.

Cellular "On-glass" antenna technology

Abstract: The application of an "on-glass" antenna to the 800 MHz band offers a real solution to otherwise unacceptable antenna performance. Consumer preference in Cellular Radio has indicated that holes in "my car" body are unacceptable and that another alternative must be found. In addition, the electrical performance must be as good as, or better than, conventional antennas. Solutions to these problems have been found by using the windshield itself as an integral part of a new generation of mobile antennas.

Bounds of Uncertain Interference Between Closely Located Antennas

Abstract: The uncertainty in the characteristics of two antennas located close together and operating at different frequencies is considered. The formulations of antenna performance indexes on one antenna by admittance parameters are obtained with respect to the load impedance at the feed point of the other antenna. All the antenna performance indexes obtained here are expressed as the ratio of quadratic functions of the load impedance, and exact formulas are derived for the quick calculation of their bounds with respect to the load impedance which is uncertain and changes with frequency.

Spacecraft multibeam antenna system for 30/20 GHz

Abstract: The major technical tasks that led to the definitions of operational and demonstration multiple beam antenna (MBA) flight systems and a proof of concept model (POC) are described. Features of the POC Model and its measured performance are presented in detail. Similar MBA's are proposed for transmitting and receiving with the POC Model representing the 20 GHz transmitting antenna. This POC MBA is a dual shaped-surface reflector system utilizing a movable free array to simulate complete CONUS coverage. The beam forming network utilizes ferrite components for switching from one beam to another. Measured results for components, subsystems and the complete MBA confirm the feasibility of the approach and also show excellent correlation with calculated values.

Sampled aperture antenna technology

Abstract: As suggested by its name, the sampled aperture technique consists of taking time samples of the composite signal arriving at an antenna aperture using a large number of receiving elements. Such a configuration enables advanced signal processing techniques to be applied for optimizing an antenna's performance in complex and demanding environments. Results obtained with a one-dimensional prototype will be presented to highlight some of the concepts. As well, results from a two-dimensional digital beamformer will also be presented. The beamformer is capable of deriving 256 beam-space components at a maximum rate of 312 kHz.