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Mobile terminal antennas for helicoptersIn this paper, the feasibility of using an L-band low gain antenna (LGA) as a mobile terminal antenna for helicopters is described. The objective is to select the lowest cost antenna system which can be easily mounted on a helicopter and capable of communicating with a geosynchronous satellite. To ensure that all the antenna options are being considered, the steerable high gain reflector and medium gain array antennas as well as LGA are studied and compared in an exhaustive survey. The high gain reflector antenna in L-band is usually very large in size and heavy in weight. In addition, a bulky and expensive tracking system is needed to steer the antenna beam to the satellite direction. The medium gain antennas (including mechanically and electronically steered arrays) are also more expensive and less reliable than an LGA due to the addition of a beam steering system to track the satellite. The omni-directional LGA is simple, reliable, and inexpensive. It is typically ten times smaller than the medium gain antenna. This makes the position, selection, and mounting on the helicopter relatively easier. Therefore, the LGA is selected as a mobile terminal antenna for helicopters. Among the many LGA's (cross-dipole, helix, spiral, and slot antennas), the helix antenna is the most inexpensive. One can also change the size, shape, or pitch angle of the helix to optimize the gain in the desired direction. Therefore, the helix antenna is selected for further study. Both 2-arm and 4-arm helices are studied theoretically and experimentally to determine the antenna's performance and the scattering effects from the helicopter body and the blades. The multipath, Doppler, and Doppler rate issues as well as the periodic fading effects caused by the helicopter rotor blades will be briefly discussed in the paper.
Document ID
19940015985
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Wu, Te-Kao
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Farazian, K.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Golshan, N.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Divsalar, D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Hinedi, S.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Woo, K.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1993
Publication Information
Publication: gress In Electromagnetics Research Symposium (PIERS)
Subject Category
Communications And Radar
Accession Number
94N20458
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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