నైరూప్య

Design of Linearly Polarized Sinuous Antenna in the Range of 2.5-6GHz

Meera S, Prof. A K Prakash

Sinuous Antenna, the most recent Frequency Independent Antenna, invented by R.H.DuHamel in the year 1987 is a derivative of spiral antenna. It hasN identical sinuous arms extending outward from a common point and arranged symmetrically on a surface comprising of bends and curves.Each cell is interleaved without connecting between adjacent cells of otherarm. The major advantages of sinuous antenna are in terms of polarization, bandwidth and its self-complementary structure. It can provide dual linear as well as dual circular polarization and is having a flexible bandwidth. It is also having a low profile geometry compared to other patch antennas for similar performances. These features make it suitable for various applications like surveillance for military and civil systems such as direction finding systems, radar warning receivers and reflector feeds due to their superior broadband characteristics and simultaneous polarization capability. In this paper, a 2- arm selfcomplementary sinuous antenna in the range of 2.5-6GHz is introduced. The sinuous antenna is fed with a Balun in order to provide unbalance to balance transformation. Tapered Balun also provides impedance transformation and matching in this realization. A cavity backing is provided in order to make the pattern unidirectional. This paper also describes how a loaded cavity backing improves the return loss with the help of relevant results. Andfinally the parameters of sinuous antenna like return loss, beam pattern and gain are compared over the frequency band. Stimulated design and analysis are carried out, to optimise the configuration. Hardware design and realisationare the final goals.