Lester Low

Hidden Automotive Antenna Performance and Simulation

A new printed antenna system mounted in an aperture in the roof of a car is evaluated for broadcast signal reception from 88-108 MHz. Results from simulations on the vehicle are compared with measurements. The overall performance of the antenna is also compared to common types of vehicle antennas, the roof monopole and a glass based antenna. Overall the average gain of the antennas was better than -3 dBi for vertical polarization and -10 dBi for horizontal while the input return loss was generally better than -2 dB before matching sections in the tuners and comparable with common automotive antennas. The antennas in the roof aperture offer an alternative place to mount antennas on automobiles

Numerical Investigation of the Impact of Dielectric Components on Electromagnetic Field Distributions in the Passenger Compartment of a Vehicle

Numerical methods have been used to investigate the possible impact of various dielectric components of vehicles on internal electromagnetic field distributions for frequencies up to 2 GHz. The electrical parameters used in the models were derived from measurements on samples obtained from vehicle components. It is found that the dielectrics investigated have a relatively small impact on the internal field populations due to sources located inside the passenger compartment. Under plane wave illumination from the front, however, the dielectric parts dampen the low frequency resonances, while the glass reduces the internal fields for horizontal polarization. Simulations of lossy materials in a vehicle-like cavity indicate that it may be possible to reduce field levels using readily available materials.

An Automated System for Measuring Electric Field Distributions Within a Vehicle

An automated, low-field disturbance probe positioning system for measuring 3-D electric field distributions inside vehicles or similar resonant environments is described. Correlations between measured and simulated electric field distributions for a simple rectangular cavity demonstrate that the probe positioner has little impact on the measured field levels. Comparisons between measurements and simulations for a real vehicle indicate that the predicted field population distributions are within the estimated uncertainties of the measurements.

Computed field distributions within a passenger vehicle at 2.4 GHz

Numerical simulation has been carried out to assess the effects of different source antenna locations on electric field distribution within a vehicle cabin at 2400 MHz. Only fixed onboard antennas mounted within the vehicle cabin are considered. The car model contains only metallic parts and ignores dielectric furnishings. Localised electric field visualizations within the vehicle cabin are obtained using simulated 2D cut-planes. They are complemented by histograms describing the distribution of electric field amplitudes within the vehicle cabin volume relative to a 1W power source. The averaged electric field levels obtained were used to compare the effectiveness of the source antennas placed in various locations within the vehicle.

Dual patches microstrip fed antenna with wide bandwidth

An antenna with broadband operation is presented. The design combines a conventional PIFA antenna with capacitive coupled patches and a pair of wave trap. The first patch is attached to a 50Ω microstrip feed line and the second patch is shaped similarly to a slotted C patch used in a conventional PIFA design. The antenna achieves an impedance bandwidth of 62% at SWR < 3. All antenna elements are situated above a fixed sized ground plane and can be manufactured using PCB etching and moulding technology. The dimensions of the antenna are 160 mm long, 60 mm wide and 31 mm high. Details of the antenna design and its typical characteristics are presented.

Automotive antenna performance and simulation

A novel antenna installed under an aperture in the roof of a sports utility vehicle below a plastic panel akin to a sun roof slot is presented. It provides an alternative location for antenna placement on a vehicle. The antenna measures 88.2 cm times 18.5 cm and is highly suited for placement in a limited size vehicle roof aperture. It has seven feeds and is capable of covering simultaneous operation of the following communications systems; FM, AM, TV, TMC and DAB audio reception. Two extra antenna elements/feeds are used for diversity reception purposes. A comparison of measurements and simulations of the proposed antenna system was carried out at 100 MHz. Simulated performance of the antenna system are shown for 200 MHz and 450-800 MHz.

Planar Roof Mounted Automotive Antenna

A planar antenna installed under an aperture in the roof of a sports utility vehicle is presented. It provides an alternative location for antenna placement on a vehicle. The antenna measures 88.2 cm times 18.5 cm and has seven feeds and is capable of covering simultaneous operation of the following communications systems; FM, AM, TV, TMC and DAB audio reception. A comparison of measurements and simulations of the proposed antenna system was carried out at the FM broadcast band at 100 MHz.

Recommendations for mitigating low frequency magnetic field exposure in hybrid/electric vehicles

The need to assess the possible exposure of vehicle occupants to low frequency magnetic fields is an emerging vehicle design requirement that is of particular significance for hybrid and electric vehicles. This paper outlines the nature of the potential threats, methods for their evaluation, and practical mitigation measures that could be adopted to limit the exposure.

Feasibility of estimating in-service vehicle occupant exposure to electrical powertrain magnetic fields using non-local magnetic field measurements

In-service monitoring of magnetic field emissions from vehicle electrical powertrain components could provide useful information relating to the development of possible faults. Such changes may also have implications for human exposure to low frequency magnetic fields, but the permanent installation of magnetic field sensors in occupant locations is not practicable. This paper outlines a simulation-based investigation of issues relating to the estimation of occupant exposure to magnetic fields using magnetic field measurements made in the vicinity of powertrain components and identifies processing implications.

Field distributions within a rectangular cavity with vehicle-like features

A model vehicle cabin is constructed to investigate 3D field distributions generated by an onboard transmitter within the large partial cavity. Simulations performed using FEKO and CST microwave studio (CST MWS) are found to be in good agreement with internal field measurements acquired using a low disturbance automated probe positioner at 870 MHz. Results show vehicle furnishings change field distribution within the cavity and should be included for electromagnetic modelling and field exposure assessments. The study enhances understanding of complex field behavior within a vehicle. The results (e.g. E-field hotspots) can be used to optimize placement locations of on-board transmitters and introduce field mitigation techniques in appropriate locations if required.