Title :
Finite element analysis of VHF/UHF antennas on helicopter airframes
Author :
Dong-Ho Han ; Polycarpou, A.C. ; Balanis, C.A.
Author_Institution :
Dept. of Electr. Eng., Arizona State Univ., Tempe, AZ, USA
Abstract :
In VHF and UHF bands, antenna patterns for short range airborne communications are required to be omni-directional. Contributions from reflections and diffractions from the airframe usually distort the primary radiation patterns of antennas mounted on airframes. Moreover, these diffractions and reflections become increasingly important as the frequency of operation increases. Therefore, for this type of application, an antenna performance simulated without the airframe is not an accurate representation. In this study, an accurate and versatile finite element method (FEM) based on the discretization of Helmholtz´s equation has been developed to analyze VHF and UHF antennas mounted on helicopter airframes, parts of which may include composite material and anisotropies. The FEM code was implemented with linear edge-based tetrahedral elements and first/second-order Absorbing Boundary Conditions. Possible material anisotropies in the computational domain are accounted for by using a permittivity and a permeability tensor. Radiation characteristics are predicted for absolute gain, spatial field distribution, input impedance and return loss, and then compared with measurements for verification.
Keywords :
Helmholtz equations; UHF antennas; aircraft antennas; antenna radiation patterns; antenna theory; electric impedance; finite element analysis; helicopters; losses; FEM; Helmholtz equation; UHF antennas; VHF antennas; absolute gain; absorbing boundary conditions; antenna patterns; composite material; diffractions; finite element analysis; helicopter airframes; input impedance; linear edge-based tetrahedral elements; material anisotropies; omni-directional pattern; permeability tensor; permittivity tensor; radiation characteristics prediction; reflections; return loss; short range airborne communications; spatial field distribution; Anisotropic magnetoresistance; Antenna radiation patterns; Diffraction; Equations; Finite element methods; Frequency; Helicopters; Reflection; Reflector antennas; UHF antennas;
Conference_Titel :
Antennas and Propagation Society International Symposium, 1998. IEEE
Conference_Location :
Atlanta, GA, USA
Print_ISBN :
0-7803-4478-2
DOI :
10.1109/APS.1998.699123