Characterisation of conducting polymer-loaded composite materials at oblique incidence and their application in radar absorbers

• Published in: Ninth International Conference on Antennas and Propagation (ICAP)
• Main Authors: Wong, T.C.P, Chambers, B, Anderson, A.P, Wright, P.V
• Format: Conference Proceeding
• Language: English
• Published: London IEE 1995
• Subjects: Composite materials (engineering materials science); Electromagnetic wave propagation; Microwave measurement techniques; Polymers and plastics (engineering materials science); Radar equipment, systems and applications; free space microwave characterisation; complex impedance surface; electromagnetic wave polarisation; conducting polymers; morphology; electromagnetic wave absorption; radar absorbing materials; microwave frequencies; Salisbury screen RAM structures; transmission line; microwave measurement; radar absorbers; equivalent circuit; percolation effects; chemical oxidation; oblique incidence; incident polarisations; polypyrrole-loaded composites; conducting polymer-loaded composite materials; radar equipment; composite materials
• ISBN: 9780852966372; 0852966377
• DOI: 10.1049/cp:19950346

In previous papers, Wong et al. (1992), Wright et al. (1994), we have reported on the fabrication and microwave characterisation at normal incidence of large-area conducting polymer composites and radar absorbing materials (RAM) based on both paper and textile fabrics loaded with polypyrrole (PPy). The PPy-loaded composites were fabricated via a chemical oxidation technique. The morphology of the latter is such that it behaves as a complex impedance surface at microwave frequencies. This impedance surface can be modelled by an equivalent circuit comprised of a transmission line incorporating parallel R and C elements. Relationships between the amount of PPy loading on the substrate and the sheet values of R and C have been derived and their behaviour explained in terms of the substrate morphology and percolation effects. Typical variations of R and C with PPy loading are shown for a paper-based composite material. In practice, RAM has to be effective over a range of angles of incidence and incident polarisations; hence, in this paper, we present new data on the oblique incidence microwave characteristics of PPy-loaded paper composites and their performance in Salisbury screen RAM structures. (4 pages)