This thesis presents the research carried out on the integration of filters and antennas for wireless transceivers. Filters and antennas are parts of wireless transceivers of all wireless communication systems. Filters and antennas, albeit connected, are separate circuits which take up their own individual space in wireless transceivers. Moreover, since they are individual circuits, the cost to manufacture them is also separate. Hence, to effectively combine them together in the form of a single component has a number of advantages. The overall size of the wireless transceivers with such a single component will reduce. There will be a decrease in the manufacturing cost as well. In addition, the single component will use a single feed network and may also utilise a common ground plane.
The research is driven by the goal of achieving a successful and efficient integration of filters and antennas for wireless transceivers of various wireless communication systems. The research further aims to show that the integration of filters and antennas can address issues pertaining to broadband and narrowband antennas and achieve their solutions. These include the integration of bandstop filters with ultra-wideband bandpass filters and within broadband antennas in order to reject some specific interfering frequency bands and the integration of bandpass filters with narrowband antennas in order to suppress frequency harmonics and noise.
In order to achieve the goal of the research, a methodical approach was adopted. Initially, individual components were designed and electromagnetically simulated. These included bandstop and bandpass filters and broadband and narrowband antennas. After that, bandstop filters were integrated with broadband antennas — forming “broadband filtennas” — and bandpass filters were integrated with narrowband antennas — forming “narrowband filtennas”. Furthermore, the ability to switch off or switch on the bandstop filters in broadband filtennas was incorporated by making the broadband filtennas reconfigurable using standard PIN diodes and novel Graphene based switches. Both sets of filtennas were designed, electromagnetically simulated and their prototypes fabricated. The prototypes were fabricated using the conventional printed circuit board technology and the newly emerging inkjet-printing technology. Hence, both rigid and flexible filtennas were constructed. The fabricated prototypes were then measured.
The simulated and the measured results include S-parameters, current density, distribution of surface currents, radiation patterns, gain and efficiency. Satisfactory and desired results have been obtained for all the developed filtennas; with a reasonable agreement between the simulated and the measured results.
With such results, it can be concluded that the research presented in this thesis reached the intended target and made a significant contribution to knowledge.