| dc.description.abstract | In this thesis, microfabrication processes are developed to fabricate two types of microstrip patch antennas. In Chapter 2, a Ku-band tunable microstrip patch antenna is designed and fabricated on high-resistivity silicon substrate. Eight ferroelectric varactors are loaded, equally spaced with four on each side, along the two radiating slots of the patch antenna. By changing the bias voltage of the ferroelectric varactors, the resonant frequency of the antenna can be adjusted. Simulation results show that, when the capacitance of the varactors varies from 0.25 pF to 0.1 pF, the operating frequency of the antenna would go from 14.5 GHz to 18 GHz, corresponding to a frequency tuning range of 21.9%. Within the frequency tuning range, the maximum antenna gain is −2.38 dBi. We have developed the recipe for fabricating through substrate via (TSV), which allows us to connect the ferroelectric varactors to the ground on the back of the substrate, making tunable patch antenna possible. Measurement results show that, when the bias voltage of the ferroelectric varactors is changed from 0 V to 9 V, the operating frequency of the antenna varies from 16.9 GHz to 17.98 GHz, corresponding to a frequency tuning range of 6.2%. After re-simulation, we suspect that TSV for some of the ferroelectric varactors may not be successfully punched through, causing the reduction of the frequency tuning range.
In Chapter 3, a 28-GHz aperture coupled E-shape patch antenna is designed and fabricated on double-side-polished sapphire substrate. Patch is fabricated on the frontside of the substrate, whereas aperture and microstrip line are fabricated on the backside. Double-side mask aligner is used to align the patterns on the front and back sides of the substrate. Benzocyclobutene (BCB) is used as the dielectric material for the microstrip line. Recipe is developed to etch the BCB layer to make via holes. Measurement results of the aperture-coupled E-shape antenna show that, the frequency range where return loss is greater than 10 dB is from 28.86 GHz to 31.09 GHz, the corresponding bandwidth is 8.2%. The measured operating frequency is higher than the value predicted by the simulation. After re-simulation, it is found that the dielectric constant of the substrate used in the simulation should be changed from 11.5 to 10.
| en_US |