The research project is intended to expose designers to the methodologies and techniques used in antenna engineering, and the increasingly important role that advanced electro- magnetic modeling software plays in the overall design process. It is also intended to give designers scope to research techniques for improving performance of a ‘core’ antenna design, and how these techniques can be quantitatively assessed. In this project, designers can expect to learn how to design a dual-band Planar Inverted-F Antenna (PIFA), assess its performance, and identify strategies for synthesizing improved designs. In the project, CST Microwave Studio can be used as the analysis tool.
The geometry of a simple single-frequency PIFA comprises a rectangular patch element suspended over a ground plane. The patch is fed via a coaxial aperture on the bottom side of the ground, the centre conductor of which passes through the substrate and connects with the patch,shorting objects are also included which bridges the patch to the ground plane. resonant frequency of the PIFA is strongly related to the length and width of the patch, and the input impedance is dependent on the location of the feed and shorting plate, and the dimensions of the ground plane.

Specification:
Antenna type: Dual-band PIFA implemented as a single conducting (PEC) layer above a ground plane;
Frequencies of operation: 2.4 2.5 GHz (2.4 GHz ISM band) and 5.1 5.2 GHz (5.2 GHz ISM band);
Ports: 2 x coaxial ports one for each band;
Nominal input impedance: 50 (each port);
Bandwidth: VSWR less than 2 over indicated frequency ranges;
Substrate thickness: No more than 5 mm;
Substrate dielectric: Air/vacuum;
Port/feed electric: Air /vacuum;
PIFA thickness: 17 um;
Ground plane: Dimensions 50 mm x 20 m The ground plane thickness is not critical to this design, but to allow accurate estimation of port impedances a thickness of 5 mm is suggested;
Coaxial aperture dimensions: a=0.3 mm, b=0.69 mm, dielectric er=1.0.

A radio-controlled model car that normally operates off a series of alkaline batteries is to be converted to operate contactlessly using inductive power instead of batteries. The car will be raced on tracks. These race tracks have six wires buried in the surface that are supplied constant three phase current at 38.4kHz to produce a moving magnetic field above the roadway surface. Inductive pick-ups will be placed under each car to capture this field and provide power. This power will need to be processed appropriately for the on-board DC motor controller.

Two regulators are needed to replace the function of the battery. The first is a pick-up regulator. The second is a DC-DC converter.

The IPT pick-up regulator
The pick-up will require a single winding with a number of turns on a ferrite bar placed in close proximity to an IPT track to couple power from the IPT track. Under short circuit conditions and when placed at a defined distance from the track.The winding should be parallel tuned with suitable capacitors. The output voltage of the pick-up must be regulated, using a hysteretic op-amp regulator. Actual power delivery is also dependent on how well the pick-up coil is positioned over the three phase IPT track, the tuning of the pick-up circuit, and the control. A suitable op-amp/comparator will be required for voltage regulation.

The DC-DC Converter
A Buck converter is to be built to properly interface the IPT pick-up regulation board with the drive electronics of the car. This should be designed with fast acceleration and high speed. Protection for accidental over-voltage must be provided in the design. The controller chip for this converter will be a Unitrode UC3843 current mode controller. The inductor must be wound on an EFD20 core to ensure that your design will fit in the space available. Feedback & grounding issues will need to be considered.