Miniaturization and Optimization of Electrically Small Antennas, with Investigation into Emergent Fabrication Techniques

With the paradigm shift in personal communications favouring wireless over wired, the demand for efficient, low-cost, and compact antennas is booming. The proliferation of mobile electronic devices (laptops and tablets, fitness trackers, ‘smart’ phones and watches), together with the desire for longer battery life, poses a unique challenge to antenna designers; there is an unavoidable trade-off between miniaturization and performance (in terms of range and efficiency). The size of an antenna is inherently linked to the wavelengths(s) of the electromagnetic waves that it must transmit and/or receive. Due to real-estate pressures, most modern antennas found in electronics are classed as electrically small, i.e. operating at wavelength(s) many times greater than their largest dimension. Theory dictates that the best possible compromise between size and performance is achievable when an antenna fully occupies a volume, the radius of which is defined by an imaginary sphere circumscribing its largest dimension. This Thesis demonstrates the design and optimization of low-cost, easy-to-fabricate, electrically small antennas through the integration of novel digitated structures into a family of antennas known as inverted-F. The effects of these digitated structures are catalogued using simulated models and measured prototypes throughout. Whereas the limitations of traditional industrial processes might once have constrained the imaginations of antenna designers, there is now tremendous potential in successful exploitation of emergent manufacturing processes – such as additive manufacturing (or 3D printing) – to realize complex, voluminous antenna designs. This Thesis also presents pioneering measured results for three-dimensional, electrically small antennas fabricated using powder bed fusion additive manufacturing. The technology is demonstrated to be well suited for prototyping, with recommendations provided for further maturation. It is hoped that these promising early results spur further investigation and unleash bold new avenues for a new class of efficient, low-cost, and compact antennas.