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Description
The research presented in this thesis includes the design, fabrication, and experimental verification of a novel multiband log periodic dipole array antenna. The antenna was designed to provide both omnidirectional and directional radiation patterns across its operational frequency bands at 1.8 GHz, 3.0 GHz, and 5.0 to 7.0 GHz, respectively. It was designed to provide reconfigurable operation with switching elements implemented with PIN diodes and associated bias networks. It was also designed for inexpensive fabrication and assembly processes, using industry-standard FR-4 and commercially available surface-mount components. The antenna was modeled and simulated using Ansys High Frequency Structure Simulator (HFSS). Additional circuit simulation for the lumped components, switching elements, and their bias circuits was performed using the circuit simulator in Ansys Designer. The antenna was first fabricated by milling unused copper from copper-clad pre-preg FR-4 stock material. However, as the copper cladding became delaminated during the measurement process, the antenna was refabricated using an inexpensive prototyping service. The simulated and measured scattering parameters (S__) and radiation patterns are generally in acceptable agreement. However, there are some discrepancies in the simulated and measured radiation patterns in the low frequency bands. This was investigated further by performing an additional set of measurements with copper tape switches instead of PIN diode switches. With the copper ribbon configuration, there was good agreement with the simulated data in both the S__ data and radiation patterns. Finally, it was concluded that the differences between the simulated data and the measured data with PIN diodes was due to the wires required to bias the PIN diodes.
