The slots in spiral antennas induce stress concentrations and hence may adversely affect the load-carrying capacity of the structural antenna. To minimise the detrimental effect of the slots, appropriate fillers are required to provide structural reinforcement without compromising the radar performance of the antenna. This paper presents an investigation of the effects of electrical and mechanical properties of potential filler materials on the performance of slot spiral antennas. Finite element analysis is carried out for a slot spiral that is designed to work in the C-Band range of frequencies (4–8 GHz). Computational simulations performed using commercial software packages ANSYS® and HFSS® show that by using commercially available filler materials the stress concentration factor of the spiral slot can be reduced by 20%. The results from this research enhance the previously introduced advantages of this type of conformal load-bearing antenna structure (CLAS). This CLAS concept provides a promising solution of replacing conventional externally mounted antennas, thus reducing aircraft weight and aerodynamic drag.

Deterioration of concrete structures has become a widespread problem with high repair costs. The corrosion of rebar is one of the major causes. GPR has potential for rebar corrosion detection. But the rapid survey generates a large amount of data, which require an automatic approach for effective data processing and information extraction. This paper proposes an automatic process to effectively extract the rebar reflection in the radargram image and estimate the concrete condition above the rebar. The process uses template matching to locate the hyperbola position, image processing to extract hyperbolic region, and algebraic fitting to rapidly estimate hyperbola parameters. The estimated parameters can be used to calculate the wave propagation velocity and relative permittivity in concrete above the rebar, which can be used to further evaluate the concrete condition. The effectiveness of the proposed method is validated using experiment testing.

Ground penetrating radar (GPR) is one of the most extensively used nondestructive evaluation methods with rapid development in civil engineering in the past few years for its efficiency and high resolution. The evaluation mechanism of concrete materials using GPR is generally based on the reflected signals from the rebar. According to rebar reflections, the corrosion level of the rebar and the material deteriorating condition above the rebar can be deduced. GPR has been successfully applied to shallow subsurface rebar detection in concrete structures. However, very few literatures have addressed the detectability of reflected signal from the deeper layer of rebar. As the result, only a small shallow section of the bridge deck can be evaluated by GPR data so far. In this paper, the detectability of the deeper rebar layer in concrete bridge decks using GPR is investigated with the help of data processing and image processing techniques. The GPR data collected from both a simulation model and a test slab are used to demonstrate the proposed methods and the preliminary results show the reflected signals from the second layer of rebar can be extracted using proposed methods.

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.