Reduced-sized Antenna for Mobile Computing

Student: Konstanty Bialkowski

Supervisor: Adam Postula

Category: Engineering Thesis Project - Communications

There is a strong demand for reducing the size of mobile computers to open new application areas such as wearable computers for monitoring purposes. Being of very small size, wearable computers require reduced size antennas for their operation. However, reducing antenna size can have an adverse effect on a communication link. To counter this situation new antenna designs are required.

In the project, two categories of reduced size antennas are considered to maintain good quality communication link between mobile computers. The first category concerns planar, reduced size antennas with fixed pattern offering high cross-polar radiation level. When polarization of an incident wave is changed, such type of antenna is still able to receive it due to its cross-polar component. The investigated antennas in this category include Printed Inverted F Antenna (and its derivatives) and a Circular Slot Antenna on finite-size ground plane. The second category antennas are Adaptive Polarization and Pattern diversity antennas. The antenna offering polarization diversity consists of a circular slot antenna with perturbation segments and P-I-N diode switches. By turning ON or OFF the diodes and hence the perturbation segments Circular or Linear Polarization is obtained. The antenna offering pattern diversity is a Dual Slot-Ring antenna with P-I-N diode switches. By turning ON or OFF P-I-N diode switches three different radiation patterns are generated.

All the investigated antennas have been analysed using electromagnetic simulation software Agilent Advanced Design System’s Momentum. This software uses a graphical interface to input dimensions and electrical parameters of antennas and generates S-parameters, radiation patterns, polarization axial ratio and gain. It offers layout capability so that the simulated antennas can be developed using photo-etching techniques. Using this capability, selected antennas for operation with IEEE802.11b and Bluetooth standards at 2.4GHz are developed.

In the experimental part, quality of communication link between Bluetooth modules equipped in selected antennas is assessed. The modules are attached to PCs running Linux using the BlueZ Bluetooth stack. The ‘Quality of communication’ between the Bluetooth modules is monitored by Bit Error Rates (BER) and end-to-end delay.

Thesis Document (PDF)