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. 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. 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

The design and realization of uniplanar CPW fed PICA slot antennas

In modern wireless communication system design, antennas with wide impedance bandwidth are desirable for numerous reasons. An antenna with a wide impedance bandwidth may be used for transmission and reception of multiple narrowband services in a multi-purpose platform. Alternatively a single wideband service may be of interest for various radar and imaging applications, or for impulse based radio communications in the FCC ultra-wideband (UWB) regime from 3.1 GHz to 10.6 GHz

Experimental study of the effect of paint on embedded automotive antennas

In years have seen the advent of new types of automotive antennas, such as blade or 'shark-fin' antennas and conformal planar roof mounted antennas. In many cases it is desirable to paint these antennas to improve the appearance of the vehicle. In this communication we present an investigation of the effect that both metallic and non-metallic two-pack polyurethane paint has on a structure radiating at approximately 1.5 GHz (GPS Ll-band), with a particular emphasis on the impedance bandwidth and radiation performance

Parametric Evaluation of Communication Devices in Smart Composite Structures

This paper reports on some of the rheological results of the selected composite materials. The base material components comprise unsaturated polyester (uPE) reinforced with randomly distributed short strands of fibreglass (E type). This material is commonly known as sheet moulding compound (SMC) and is currently used in the automotive industry for different applications. This work will further look into t he parameters involved in the processing of the SMC with respect to its visco-elastic behaviour. These parameters involve viscosity, elastic and viscous modulus with respect to the processing temperature. This paper reports on some preliminary results of material processing parameters such as pressures, temperatures, cure times and volume fractions of resins, fillers and reinforcing materials. Also included is an evaluation of the electrical properties of different grades of SMC as a precursor to the encapsulation of a microstrip antenna within the material

Custom-directional wideband PICA for multi-service vehicular applications

A wideband antenna for use in the vehicular environment is presented, based on the uniplanar CPW fed PICA slot antenna. The antenna provides a very wide impedance bandwidth from 730MHz to 15GHz, sufficient for many of the wireless services used in modern automobiles. The radiating mechanism of the antenna is able to be described in two ways at various frequencies, leading to alternate radiation patterns for various services

Embedding of communication device in a polymeric composite material

In this paper, an attempt is amde to extend the deformation model of a communication device embedded in a viscoelastic thermoset composite polymer commonly known as sheet moulding compund (SMC). The original model takes into account time dependent heat transfer from the mould surface into the SMC charge and the consequent time dependant viscosity propagation during the initial stage of the mould closing and subsequent filling. The required model parameters for viscosity and elasticity have been determined from rheological testing

Deformation modelling: Embedding a communication device in a polymeric composite material

In this paper, an attempt is made to extend the deformation model of a communication device embedded in a viscoelastic thermoset composite polymer commonly known as Sheet Moulding Compound (SMC). The original model takes into account time dependent heat transfer from the mould surface into the SMC charge and the consequent time dependent viscosity propagation during the initial stage of the mould closing and subsequent filling. The required model parameters for viscosity and elasticity have been determined from rheological testing. The extended model will examine the effects of a number of process parameters such as mould closing speed, mould temperature and initial charge temperature. The effect of these parameters on the deformation of the communication device is discussed and is compared to experimental findings

Deformation evaluation of embedded antennas in vehicular components

In this paper, an attempt is made to extend the deformation model of an antenna embedded in vehicular component, where the component consists of a viscoelastic thermoset composite polymer commonly known as Sheet Moulding Compound (SMC). The initial model developed takes into account time dependent heat transfer from the tool surface into the SMC charge and the consequent time dependent viscosity propagation during the initial stage of tool closing and subsequent filling. The required model parameters for viscosity and elasticity have been determined from rheological testing. The extended model examines the effects of some process parameters such as tool closing speed, tool temperature and initial charge temperature. The effect of these parameters on the deformation of the antenna is discussed and compared to experimental findings. In addition the signal quality due to antenna deformation is investigated by comparing simulation and experimental results

Performance of embedded multi-frequency communication devices in smart composite structures

Lately, there has been an increased demand for vehicle manufacturers to incorporate a large number of communication, security, guidance and entertainment devices in their new vehicle models. In recent decades, the list has expanded from the AM and FM radio antennas to include GPS, mobile phone, collision avoidance radar, Digital Radio and Digital TV antennas. In addition, new technologies such as vehicle to vehicle and vehicle to road side communication are being implemented at 5.9 GHz in the next generation of vehicles. In the past the AM/FM antenna was typically a mast antenna protruding from the vehicle's exterior, recently however, the trend has been to limit the visibility of vehicular antennas as much as possible to improve vehicle design and aerodynamics. This has lead to integration of antennae so that they become a seamless part of the vehicle structure. This paper reports on a parametric study of embedding an antenna in a polymeric composite substrate in relation to several material processing and coating parameters

Deformation modelling of an embedded communication device in a polymeric composite material

In this paper, an attempt is made to extend the deformation model of a communication device embedded in a viscoelastic thermoset composite polymer such as Sheet Moulding Compound (SMC). The original model takes into account time dependent heat transfer from the mould surface into the SMC charge and the consequent time dependent viscosity propagation during the initial stage of mould closing and subsequent filling. The required model parameters for viscosity and elasticity have been determined from rheological testing. The extended model will examine the effects of a number of process parameters such as mould closing speed, mould temperature and initial charge temperature. The effect of these parameters on the deformation of the communication device is discussed and compared to experimental findings. In addition the signal quality due to antenna deformation as a result of its embedding process is investigated by comparing simulation and experimental results