Design of a Low Profile Archimedean Spiral Antenna using Compact Defected Ground Structure as a Reflector

Abstract

In this paper, design and realisation of a low profile Archimedean spiral antenna is presented. The low profile Archimedean spiral antenna is printed on a substrate and backed by a reflector consisting of DGS. The DGS unit cell consists of a parallel combination of meander line inductors and inter-digital capacitors. This, DGS is one of the forms of electromagnetic band gap (EBG) structures providing electromagnetic band gap characteristics. It is used as a reflector with spiral antenna to achieve unidirectional radiation properties and a low profile of antenna. A modified version of uniplanar EBG cell is used as a DGS cell. This cell is used for configuration of the DGS ground plane. This ground plane is evaluated for its electrical characteristics and used as a reflector for the spiral antenna. Archimedean Spiral antenna is designed and simulated in the frequency band of 1-6GHz with DGS as a reflector. The antenna characteristics are studied for physical parameters of the antenna. These parameters are optimized for better electrical characteristics. The performance of the proposed antenna is also compared with conventional metallic (PEC) reflectors. Simulated results of an antenna are validated by measurement. Antenna height reduction of 60% is achieved compared to conventional cavity-backed spiral antennas.


(a) Simulation model of DGS ground plane, and (b) Photograph of realised DGS ground plane.
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Simulated axial ratio comparison over the frequency band.
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Simulated axial ratio variation of proposed antenna as a function of direction.
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Simulated and measured S11 magnitude of proposed antenna.
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(a-f) Simulated radiation patterns of proposed antenna EbG.
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Description