Embedded antenna technology in smart polymeric composite structures

One of the fastest-growing uses of sheet moulding compound (SMC) material is in the area of manufacturing of vehicle body components for both structural and non-structural applications. This trend is accelerating, driven by original equipment manufacturers (OEM) and their need for lighter and more fuel-efficient vehicles. In addition, over the last 20 years, the number of entertainment and communication systems in vehicles has also been expanding. <br><br>The aim of this research is the development of a single wideband antenna that is capable of receiving all of the major services of interest. Taking this approach one step further and embedding such an antenna in a polymeric composite vehicle body panel would combine the benefits of reduced coefficient of drag, lower vehicle weight, reduced assembly complexity and shorter assembly time. These benefits would manifest themselves in the form of lower overall design and manufacturing vehicle cost for the OEMs and lower fuel consumption for customers. This thesis will deal with the development of such an antenna and the challenges faced in embedding it in a polymeric composite vehicle panel to such an extent that it becomes a seamless part of the vehicle body. This application required the development of a detailed understanding of the following three areas. Firstly, understanding of the interactions and effects of SMC material and automotive paint on antenna signal quality and performance through experiments and electromagnetic modelling (EM). Secondly, the development of the manufacturing process and material used to embed the antenna and its impact on the physical properties of the antenna through rheological testing, analytical modelling and experimentation. Lastly, the development of a wideband antenna capable of receiving pre-determined signals, through EM and field testing. <br><br>The effects of paint application and presence of SMC resulted in a frequency shift of less than 1%. The experiments correlated well with the analytical model developed for compression moulding which incorporates a novel inclusion of the Maxwell’s model to predict the shear forces in the material flow within a confined space. A modular planar inverted conical antenna (PICA) was developed and optimised for the frequency range 700MHz – 9000MHz, which includes the commercial global positioning system (GPS) frequency. This development was then deployed as an embedded prototype in the deck lid of a test vehicle. Comparison against commercial GPS and mobile phone antennas was undertaken. This field test comparison showed that the developed PICA antenna performed better than the commercial antenna by up to 17%, especially in spaces devoid of multi-path signals.<br><br>