Low Curing Temperature Ferromagnetic Ink Development and Application in 3D Printed RF Antenna Design and Miniaturization
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In recent times, there has been an increasing demand for smaller size electronic and mobile devices because of advances in engineering and nanotechnology. This has pushed further the need for small size RF antenna with light weight and ease of fabrication especially in areas of communication, biomedical, automobiles, aerospace and military applications etc. Effective antenna miniaturization with improved performance remains a bane to achieving reduced size electronic devices. This is largely due to the inevitable tradeoff between the antenna dimension which depends on its electrical wavelength, and performance of the antenna which is tightly bound to the fundamental limits based on its size. New generation mobile devices are required to have multiple antennae in one device to span multiple frequency ranges such as GSM, LTE, WiMAX, WLAN or Wi-Fi, hence miniaturization becomes imperative.
Integrating ferrite materials in antenna structure have been recently identified as a potential means of reducing antenna size and improving its performance. Magneto- dielectric material, which has both permittivity and permeability greater than unity has been used to demonstrate this possibility. Since this idea came to light, the field of antenna miniaturization has witnessed a meteoric rise in research interest among device engineers. The major research focus is in printed electronics.
Printed electronics has revolutionized the electronic component and device industry. Since its introduction into the main stream of electronic manufacturing industry, inkjet printing technique has attracted a lot of interest because of its low cost of fabrication of integrated circuit, compatibility with various substrate. This technique has been used in fabricating functional electronic components such as organic thin-film transistors, light-emitting diodes, solar cells, conductive structures, memory devices, sensors, and biological/pharmaceutical tasks. Single and multi-layer printing with various thicknesses have also been achieved using inkjet printing without rigorous effort. Despite these abilities, inkjet printing technique is not commonly used in magneto-dielectric substrate fabrication because high quality ferromagnetic ink that yields magneto- dielectric material with good microwave performance is not readily available in commercial mainstream and therefore need to be synthesized using novel approach.
The objective of this thesis is to develop a high quality ferromagnetic ink with good microwave performance suitable for inkjet printing technique and investigation of the microwave performance of 3D inkjet printed antennae using the developed ink. Different characterization methods are used in this work to evaluate the performance and suitability of the developed ferromagnetic ink in inkjet printing technique. Furthermore, the potential for antenna miniaturization is also demonstrated using different measurement data. Several antennae design and configurations on different magneto- dielectric material substrates are discussed, and compared in terms of their performance with other antennae on conventional high dielectric constant material substrate. Both simulation and measurement data shows that an antenna on magneto-dielectric material substrate has better and improved microwave performance compared to an antenna of the same dimension on a conventional high dielectric material substrate.