Design Of Conformal Array Research Articles

High Aperture Efficiency Arced Conformal Array With Phasor Beam Steering Antenna

A phasor beam steering stacked patch antenna with abilities of both the amplitude and phase pattern reconfigurations is proposed and used for improving the aperture efficiency of arced conformal array. The phasor beam steering antenna is composed of two parasitic patches on the top integrated with four PIN diodes and a driven patch on the lower layer. By switching the bias states of the PIN diodes, the induced complex current of the top patch is alterable and the phasor beam steering can be delivered. Thus, in the conformal array design, the phase compensation can be realized by the phase pattern reconfiguration of the phasor beam steering antenna instead of the conventionally used phase delay lines. Meanwhile, the amplitude pattern reconfiguration of the phasor beam steering antenna can also be used for enhancing the contribution of side elements to the gain of axial beam. A four-element arced conformal array with the phasor beam steering antenna is designed and measured for verification. Both the simulated and measured results indicate that the realized gain of the proposed conformal array is 12.0 dBi, and the corresponding aperture efficiencies are improved up to 51.48%, which is better than the results of the arced conformal array with the phase compensation network.

Conformal Antenna Array Design Using Aperture Synthesis and On-Platform Modeling

Conformal antenna arrays have long represented an attractive solution to challenges imposed by an electromagnetic aperture on an aerospace platform. This allows designers to trade between array positioning and geometry, and avoids the significant aerodynamic drag of a planar array. This is hampered by the expense of the design and computational modelling required to ensure that a conformal array will meet its performance requirements. The proposed approach uses raycasting techniques to predict the rectilinear projection of a conformal aperture onto the farfield to calculate the maximum achievable beam coverage (aperture maximum directivity envelope). In order to compare aperture projection with the performance of the modelled arrays in a consistent manner, the steering efficiency (SE), which is the fraction of the farfield steerable to within 3dB of the maximum directivity, was calculated for the aperture, stacked patch, and conical monopole elements. The stacked patch elements demonstrated a SE of 18% over the steering plane compared with 40% for the arbitrary directional elements, and the optimum of 38% for the aperture overall. The Conical monopole elements achieved a SE of 8%, compared to 20% for the measured elements, and 33% achieved with arbitrary omnidirectional elements. These results demonstrate that, for both omnidirectional and directional elements, the aperture projection method offers a compelling tool for conformal array design, which is consistent with the achieved array performance for the stacked patch and conical monopole elements.

Design and Analysis of Conformal Antenna for Future Public Safety Communications: Enabling Future Public Safety Communication Infrastructure

Future 4G wireless communication systems include, in their capabilities portfolio, emergency-specific needs, such as data support, broadband communication, and extremely high reliability. An emergency situation can be addressed with undoubtedly more chances of success if augmented information is enabled within the public safety communication novel capabilities. In this article, for a fully augmented information provision based on broadband transmission, a user-end (UE) communication-capabilities enhancement is addressed by deploying multiple antennas without compromising the portability and light weight of first-responder equipment. With this aim, we propose the design of a 4.9-GHz conformal antenna array at the rescuer side (integrated in a helmet) and evaluate its performance in terms of relative data rate gain. The conformal array design is based on traditional patch antennas that consider the need for deployment over an ellipsoidal surface. The antenna array is simulated and then built, and several parameter characterizations (bandwidth, radiation pattern, reflection coefficient, and MC) and measurements are undertaken to ensure the suitability of the design. Furthermore, an analysis of the specific absorption rate (SAR) is performed to guarantee that the exposure to electromagnetic fields is below the standardized levels.

Conformal array design on arbitrary polygon surface with transformation optics

A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

Tracking With a High-Resolution 2D Spectral Estimation Based Automotive Radar

This paper concerns the tracking of automotive radar targets by a radar using a high-resolution 2D spectral estimator in order to detect the radar targets. We show how to implement the tracking, discuss the measurement variances, and show how we can exploit the high resolution in order to make a better tracking filter. Existing automotive radar systems are affected by a limited field of view, poor angular accuracy, or low measurement update rate. By using a combination of a waveform solving, the target ambiguity problem within a short measurement time and a conformal array design, we eliminate these problems and by the use of the 2D APES estimator, we achieve a high angular resolution, which is used in order to improve the tracking. The simulation results show that we are able to track a laterally moving vehicle very accurately and that the new improved tracking filter achieves more robust and accurate tracking along with a short initialization time. These attributes can be very important for safety critical applications.

Conformal cymbal array: A broadband, wide beamwidth underwater acoustic projector

The development of “cymbal”-based acoustic source technology in recent years has been an essential advancement in improving NRL's capability for shallow-water acoustics. The cymbal's unique attributes of high acoustic output from a lightweight, thin profile configurable array is a central technology in target identification programs at NRL. This talk will present a review of cymbal array development over the past ten years. It will start with conventional piezoelectric ceramic (PZT) cymbal elements and end with current research on advanced cymbal designs utilizing new formulations of piezoelectric single crystal materials. In particular, the contributions of Kim Benjamin to the initial development work of the conformal array design will be highlighted. [Work sponsored by the Naval Research Laboratory.]

Optimization Design of Conformal Array on an Irregular Curved Surface

Optimization Design of Conformal Array on an Irregular Curved Surface

Impact behavior of composite antenna array that is conformed around cylindrical bodies

In this paper, one structurally integrated array that is conformed around cylindrical bodies has been designed and fabricated for a part of the aircraft outer skin. The effects of the mechanical topology are considered in the antenna design, confirming the optimal integration without compromising either the mechanical or the electrical performance. The measured results show that the radiation pattern is strongly dependent on the radius of curvature. The results of a study of the response and failure characteristics subjected to low-speed impact damage are presented; they indicate that the value of the contact force decreases as the radius of curvature decreases. As the impact energy was increased, the specimens experienced significant damage consisting of a dent localized in the region of impact. These results suggest that the radius of curvature is an important electrical and mechanical parameter in the design of conformal arrays.

Evaluation of a hemi‐spherical wideband antenna array for breast cancer imaging

Using similar techniques to ground penetrating radars, microwave detection of breast tumors is a potential nonionizing and noninvasive alternative to traditional body‐imaging techniques. In order to develop an imaging system, the team at Bristol have been working on a number of antenna array prototypes, based around a stacked‐patch element, starting with simple pairs of elements and progressing to fully populated planar arrays. As the system commences human subject trials, a curved breast phantom has been developed along with an approximately hemi‐spherical conformal array. This contribution will present details of the conformal array design and initial results from this unique experimental imaging system as applied to an anatomically shaped breast phantom.

Conformal Array Based on Pattern Reconfigurable Antenna and its Artificial Neural Model

This paper presents a new method for overcoming the structure curvature influence on the antenna properties and processing of conformal array to produce almost ideal pattern by using pattern reconfigurable technique. Artificial neural network (ANN) models of radiating element and conformal array are also created through measured or simulated data. Once the model is developed, it can be used in the design of conformal array and provide fast answers of the tasks.

G.T.D. solution of slot admittance on a cone or cylinder

The input admittance of an elemental radiator on a curved surface, e.g. a slot on a cone, plays an important role in the design of conformal arrays. A search through the literature reveals that, at present, there is no reliable theoretical method available for computing this admittance. The objective of this paper is to provide a solution to this problem using a surface-ray approach–within the framework of g.t.d. The solution is verified for the limiting case where the cone degenerates into a cylinder, and it is shown that the g.t.d. results compare extremely well with the exact modal solution to the cylinder problem. Extensive numerical results are presented in the paper for the input admittance of a cone as a function of various design parameters.

Ray analysis of conformal antenna arrays

The aperture design of conformal arrays is predicated on the knowledge of the element patterns and coupling coefficients in a mutually coupled environment. For equispaced identical slits on a perfectly conducting cylinder, a previous analysis has utilized the modal theory of periodic structures to simplify the calculations. Modal procedures are rather difficult to apply when the array surface has a more general, though rotationally symmetric and separable, shape; they become practically inapplicable when the surface is nonseparable. These difficulties may be overcome by recourse to the geometrical theory of diffraction and utilization of surface rays whose properties are determined from an appropriately defined local environment on the array surface. Depending on the problem under consideration, the local environment may involve either the unperforated array surface or a surface with periodic loading. It is shown how the surface ray technique can be applied to the analysis of mutual coupling in full ring arrays and finite arrays on a circular cylinder, and in nonperiodic or almost periodic arrays on surfaces of variable curvature. For finite arrays, a theoretical model leading to a representation of finiteness effects in terms of multiple scattering of surface rays of the periodic array structure between the edge discontinuities is confirmed by independently calculated numerical results. Although the demonstrations in this paper are confined to two-dimensional geometries, the procedure is applicable also to three-dimensional configurations.