Planar and Conical Projections of Multifunctional Two-Arm Sinuous Antennas
M.C. Buck, D.S. Filipovic
Department of Electrical and Computer Engineering, University of Colorado, Boulder
Two-arm, unconventionally phased sinuous antennas are proposed. Unlike traditional sinuous antennas that are operated in a broadband type mode, multiband and multipolarized performance can be achieved by taking advantage of the inability of the sinuous aperture to filter certain senses of circular polarization and by implementing a non-unique and ambiguous phase progression between the arms of the structure. By operating an antenna in this fashion, one can achieve bidirectional and multifunctional characteristics over a wide bandwidth, limited by the finite size of the sinuous aperture itself. In this manner, linear polarized bands occur between circularly polarized bands of opposite sense handedness. A conical projection of the planar sinuous geometry is also investigated to achieve unidirectional performance (front-to-back ratio > 10dB) without the use of lossy, absorptive materials typically used for planar, unidirectional sinuous and spiral-like antennas. The proposed antennas can be excited using simple and inexpensive feeds, eliminating the need for baluns, hybrids, etc. Validated numerical analyses will be presented. Parameters to be addressed include gain, axial ratio, azimuthal pattern symmetry (WoW), and input impedance.
Antenna Applications Symposium
2006
September
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