Finite-difference time-domain analysis of HF antennas on helicopter airframes

Andrew, W.V.; Balanis, C.A.; Tirkas, P.A.; Peng, Jian; Birtcher, Craig R.

doi:10.1109/15.584932

Cited by 9 publications

(4 citation statements)

References 16 publications

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“…1. Two VHF monopole antennas are mounted on the bottom of the helicopter [4]. The airframe may encompass a variety of composite and inhomogeneous regions, but it is modeled as a PEC structure.…”

Section: Radiation System Modelingmentioning

confidence: 99%

“…Con-sidering its geometric complexity, the helicopter model along with the FEM code should be validated before including the lossy ground effects. Andrew et al [4] used the FDTD to predict the radiation patterns of both antennas and compared the results with actual in-flight measurements. It was indicated that the FDTD model for the 24-ft antenna element needed staircasing because it was mounted along the vertical stabilizer in a direction that is not along a principal axis.…”

Section: Radiation System Modelingmentioning

confidence: 99%

“…To deal with those material complexities, the FDTD or FEM is often suggested as the most suitable approach. In fact, the FDTD method combined with a perfectly matched layer (PML) was used in [4] to analyze the radiation characteristics of HF antennas mounted on a helicopter. The FEM is even more promising for this type of application due to its versatility; most modern helicopters contain nonmetallic and composite materials on a streamlined airframe.…”

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confidence: 99%

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Ground effects for VHF/HF antennas on helicopter airframes

Han

Polycarpou

Balanis

2001

IEEE Trans. Antennas Propagat.

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In this paper, the finite element method (FEM) is used to predict the space and surface wave radiation patterns of VHF/HF antennas mounted on a helicopter in the presence of a lossy ground. The equivalent sources of the radiation system are obtained by solving an FEM problem in conjunction with an absorbing boundary condition (ABC) or an impedance boundary condition (IBC). From the equivalent sources, the total radiated field is calculated using the equivalence principle and superposition; the original problem is converted into a set of properly combined Hertzian dipoles referred to as the Sommerfeld problem. Instead of evaluating the Sommerfeld integral rigorously, Norton's approximation is used to improve the overall computational efficiency. The validation of this method is accomplished in two steps: first, the FEM is compared with the finite-difference time-domain method (FDTD) in the absence of a lossy ground; second, the Hertzian dipole problem is solved in the presence of a lossy ground and the results are compared with analytic solutions. Finally, this technique is extended to analyze an antenna on a helicopter above a lossy ground.Index Terms-Ground effects, HF/VHF antennas, helicopter airframe.

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Section: Radiation System Modelingmentioning

confidence: 99%

Section: Radiation System Modelingmentioning

confidence: 99%

mentioning

confidence: 99%

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Ground effects for VHF/HF antennas on helicopter airframes

Han

Polycarpou

Balanis

2001

IEEE Trans. Antennas Propagat.

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“…In these models, FDTD can resolve scattering by inhomogeneous, anisotropic, and arbitrarily shaped charged or uncharged particles [6], so that it has been applied to such diverse applications as antenna scattering [7], analysis of microstrip circuits [8], absorption in tissue [9], optical absorption by biology cellula [10][11][12][13] or scattering by atmospheric ice crystals [14], irregular aggregates [15], multifaceted concave and convex particles [16], spheres with nonspherical inclusions [17], hexagonal columns with air bubble and soot inclusions [18] or clusters of particles with or without inclusions [19], consistent and rigorous analysis of infinite graphene layers is developed [20], electrically thin dispersive layers [21], calculation of reflection coefficient for the plane wave incident on planar periodic structures [22], light scattering and absorption by nonspherical particles embedded in an absorbing dielectric medium [23], an arbitrary beam's interaction with an arbitrary dielectric surface [24], to name but a few examples. So FDTD is chosen.…”

Section: The Criterion For Unusable Optical Systemmentioning

confidence: 99%

Study of Factors Making Space-Contaminated Optical System Unusable

Zhou

Sun

2012

Advances in Optical Technologies

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Molecular and particulate contamination of space optical surfaces can be extremely detrimental to optical system performance. In order to determine whether optical system is unusable, we must do a lot of tests. For reducing experimental effort, computational criterion for unusable space optical system is put forward, which is based on experimentation and calculation by 2D-FDTD (finitedifference time domain). And then factors making optical system unusable are studied when distribution of light intensity is consistent with the criterion. Results show that small particulate is more detrimental to optical system than big one for particle with high permittivity is. The distribution of particles making optical system unusable is also obtained.

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References

2000

Light Scattering by Nonspherical Particles

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Finite-difference time-domain analysis of HF antennas on helicopter airframes

Cited by 9 publications

References 16 publications

Ground effects for VHF/HF antennas on helicopter airframes

Ground effects for VHF/HF antennas on helicopter airframes

Study of Factors Making Space-Contaminated Optical System Unusable

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